I Thought I Finally Fixed My CL65 AMG! INFURIATING Problem With My Twin Turbo V12 Engine! 

Ok, everyone. What in the world do you think is wrong with the car?

Favorite line in the video "One last test before I burn this car to the ground." Been there done that.

Hey Alex, check if the cooling fan has the right wattage. On the ML W164 V6 for example there are different wattage fans available, depending on if the car comes with a trailer hitch from the factory. If you retrofit the trailer hitch, you have to replace the fan. The ECU doesn't monitor the fan current, though. So it doesn't know if it has the correct fan at all. Maybe someone replaced the CLs fan and ordered a much cheaper one from a lower spec car?

As you have installed better and bigger turbos than original, the new tubros are compressing the air at faster rate and producing more heat. The oem water cooled intercoolers are designed or matching to the original turbos on the car. If you think about it, as you drive the car normal condition the system is working fine. After some hard pulls the intercooler system are not able to remove heat fast enough. Onces that point is reach you have to let the system rest or cooled to make it function again. It just a thought, the current oem intercooler are not robust enough to handle the extra heat.

Alex I gotta say as someone who has dreamed of owning a “65 amg” car, this series completely changed my mind in ever wanting to own one 😂

Response to the intro: Yes, I’ve had a car like that. But I learned SO much about cars/repair because of it. I can only wish I had the skills Alex has. Then no car issue would intimidate me lol thanks for taking us along for the ride and showing us that Master-tech thought process!

If the water to air intercooler is pressurized, check the cap. The spring can fatigue and a standard pressure test doesn't check the cap function. Love the content. Keep it up.

This is just insane to follow. Never in a million years would I buy a car like that (maybe a V12 E38), but it’s so fun to live vicariously through this process. The quad air intake filters is just so freaking cool!

I'd recommend checking the resistance of the wires leading to the intake air temperature sensor. If the resistance of the circuit is too high, it could make a good sensor have an off reading. A wire getting way too hot will raise its resistance, so check the harness and see if it's touching somewhere it shouldn't. They likely aren't the issue, but who knows.

Hey Alex, I think replacing the pump was probably the right thing to do. I have an 03CL 55 super low miles, the pump was bad 2 to 3 runs, and the car would just die. Lost all power. I messaged you about a year ago on it because at full boost when you immediately let off the throttle, there was some bucking and surging. One of my buddies is an AMG mechanic in Grapevine, Texas, and he replaced the pump and the relay. That returned drivability 100%. I would suggest replacing the relay that drives the pump. It may also drive the fuel. Next thing I would do is I would just disconnect the cats and make a hard run and see if that helps. Only other thing I could suggest is, are you getting cold air from the traditional intake vents that route in front of the radiator. I suppose the inner coolers could be somewhat clogged, but don’t know. You could also try adding an auxiliary one.

Hey Alex, its possible that your pump is turning off, on the E55, the pump is controlled by the rear SAM that talks over CAN to the engine ECU (Who knows who designed this). Any weird electrical issues and its possible the pump won't turn on. You can maybe do a common mod that I've done on my E55, and simply hook the pump power line up to ignition voltage, that way whenever the engine is on, the pump will be on, no matter what. I've had this working on my E55 for over a year now, and the OEM pump is fine.

Alex, I would advise to ohm test the original intake air temperature sensor that you removed when you first got the car. The part that makes me suggest that is that MBZ couldn't tell you the ohm test spec on the new sensors. It could be possible that MBZ is now selling a superseded part number that is actually the incorrect spec for your engine. Wouldn't be the first time I have seen this. If your original sensor reads differently than the new ones, that could be it. You also did the thermometer test on the intercooler outlet which showed lower temps than the sensor did. Also make sure the sensor connector and wires in the harness aren't burnt up or broken or shorting. You could also install an independent aftermarket IAT sensor to compare to the stock readings.

I had a similar problem with my E400 CDI, the IAT would rise up to 85C/185F on the highway, and it would stay there. For me it was a partially blocked intercooler radiator. You should check the radiator, to see if that's working ok.

Hey Alex I had a similar problem back in 2005 when I was a young Viper Tech who got the great idea to twin turbo my SRT10 Ram. Try measuring the AF ration from each side of the block not at the rear exhaust exit. My issue ended up being one of the turbos was not performing as well as the other the right side back was producing more boost when running wide open even though they where identical units. This was resulting in the right side back running leaner and heating the manifold on that side of the block, much like you it wasn't something I was able to tell via ECU data and I spent a long time thinking it was my intercooler set up. Final fix was sending my turbos back to be rebalanced to give near identical boost output at all levels of the RPM range. Hope this helps and good luck with the Benz.

The complexity and amount of work you have to do on this car is crazy 😯.

These videos are super motivational. Thanks for keeping on the CL65. Definitively a childhood dream car of mine, and I love this channel as a result of even just your CL65 content. You keep it light and fun. Love it!

Had a s600 , heat soak in inter coolers is standard on this gen especially tuned. Put a 5 gallon tank in spare tire well run 3/4” hoses to pump and swap pump to q7 replacement pump( available from Germany for 220$ ,huge volume increases ,and with additional volume you will never go above 120 , even at the track.

Hey Alex, I suggest comparing your IAT sensor with a known good one from another vehicle- you installed one new during the build and had online info that said it was bad when you tested it, you then replaced it again with the same new item- it is likely the two new sensors you’ve tried aren’t right- contact one of the 65 guys that have commented on here and ask to check their sensor values and compare to yours. Also at 36:37 I noted when you had the Y duct disconnected and had 154degF IAT on your reader, then measured 105 at the exchanger outlet, is the 154 a plausible value given it was sucking ambient air, ie was the air entering the intake really that temperature- guess it’s possible given the engine was hot and cooling fan on blowing hot air, but worth confirming IMO? Seems like the IAT sensor is very close to the intake entry so can’t imagine it’s engine heat soak heating the intake air. Anyway, super easy to triple check the IAT sensor values are correct with a know good one to rule that out. Great video mate, these challenging cars are the most interesting videos to watch, you’ll solve it and it’ll be great seeing it getting a flogging on the dyno!

Hey Alex, can I suggest to give a shot at my theory. Try to feed the pump water with ice from a bucket and make it somehow return in the same bucket. If it still rises the intake temp you have another issue which is not related to the intercoolers.

It’s called a charge cooler, not intercooler. Intercoolers are air to air and charge coolers are water to air with its own water pump. They’re not as efficient as intercoolers which is why most people replace charge coolers with a good quality intercooler. I did the same with my MK1 Focus RS and it reduced temps massively and helped it make More reliable power too.

I am so glad you have done this series on the CL63. It has stopped me from buying a used one regardless of how many things I love about this car.

Great to see the CL65 back on the channel and looking forward to the final result.

alex is so genuine in his approach that i honestly forget it’s a show with edits and stuff i’m always so surprised when the outtakes pop up 😂

Hi Alex, I ran across this issue a long time ago, from everything you've done, I would say your heat exchangers are dirty and not transferring heat properly. Take them out and wash them or send them out to be boiled at a radiator shop. I hope this helps you out.

My nightmare car, Alex, is an Audi A8…amazing car, luxurious , somewhat understated, and oh surprise, so complicated. Every time I finish fixing something and think the car is finally good to go well, something else needs attention! I truly appreciate you man!!!

Hey Alex, just a theory. Larger injectors; under boost; the ecu is reading it as fat then trying to lean it out, and by the time the ecu catches up it looks normal. Like a micro lean spike. Not sure if fueling or AIT “logic” / Safety’s can be adjusted in the tune. Hope this helps; fingers crossed

I think you need to validate the actual intake temp with a separate unit. I would get a fluke meter with a thermocouple and side into the intercooler outlet. Measure the actual temp. If the is resistance in the harness it doesn't matter if the sensor is good or not.

Like these kind of video’s Alex. The more difficult the issue the more satisfaction when you get things solved in the end. My current struggle is an M102 engine from 1985 down on power. Hope to get this fixed in the following weeks

I have an idea. You have two temperature sensors. Leave one in the engine. The second one attach to a extension and keep the sensor I don’t know in the cabin may be nice and cool 😂 or somewhere the temp is not that high. Go for a test drive. If it works then we can look at the next step. Have to be really sure that yes the car does that at that temp sensor reading.

This is my favorite of all your cars. I envy your expertise and optimism in fixing it. Thank you for persisting and telling us about all the problems. On other channels the “problem” cars just disappear, never to be talked about again (:cough: Tavarish lol). Great video!!

Honestly, I want to thank you for not only putting yourself through this, but showing it to us. This is kind of how my first attempt at restoring a car went. One thing after another, followed up by mistakes and basically every bit of bad luck you can imagine. I spent a lot of time feeing stupid and inadequate. Watching people like you go through similar situations makes it feel a lot better.

Alex, we stand with you! I really hope you can enjoy this car more, because you deserve it, and because this car is lovely when running right. Cheers!

I used to be a tech for VW during the V10 TDI Touareg days. I have had my clock cleaned so many times but it’s always a learning experience. It’s very hard to see that in the moment and not be frustrated or feel like giving up. Great video’s always love watching and feel your pain! You’ll figure it out at least your not flat rate anymore🎉

Had a car that wouldn't start in the morning. It would sound like it had no compression. This is back when I worked as a technician at Lincoln Mercury Ford. Replaced the heads,and the car ran beautifully. But low and behold in the morning, it wouldn't start with the exact same problem. Car sat for a month we just couldn't figure it out. Turns out the vehicle owner was a teacher and someone had put sugar in the gas tank as we would later find out 😂

Thanks for the video Alex. I have a silver 2005 CL65 in Morton Grove if you need it for comparison... I know there are not that many around locally for you to look at if needed. I had a similar issue of the engine cutting out but my "certified Benz mechanic" fixed it with new coils and spark plugs. You seem to have a different issue. Also, I can show you a few quick aftermarket mods I did on mine (for an "easy" post-fix video idea) :) Hopefully, you solve it on the next one and take it to Chicago Auto Pros for its final dress-up. PS. The cup holder on your car is broken but I am sure you already knew that. It should not swing like that.

I'm sorry you're having all these problems, but selfishly I'm glad for it because it's helped me diagnose some ignition stuff on my own S600. Love your videos.

Hi Alex, thx for the video and I have also been breaking my brains with your latest video. In my experience in working with cars, read tuning them, I found that if everything is working fine but the engine is running hot I switch over to colder spark-plugs and if possible to the one’s with 3 or 4 electrodes. On top of that and as a rule of thumb I only use NGK for Asian car brands and BOSCH or preferably BERU for European cars brands! Otherwise there is no other option but to play with the ignition timing until you hit the sweat spot, but this is very time consuming! Well best of luck with this conundrum and hope everything works out in the end, cheers m8😊😊

Love to see your troubleshooting process and even the unsuccessful attempts. Great episode, thanks!

I’m not sure the intake temp has anything to do with it, It may just be a proxy for boost. With it running great until you get under high load I’d really be looking at fuel pressure and ignition. Whenever I have a weird problem I try to eliminate any aftermarket add ons to verify operation. If you can I’d try to swap out the ignition components with OEM stuff for diag. Also if you suspect a clogged catalytic converter you can loosen the pre cat A/F sensor, then go beat on it, if its clogged it will make a loud hissing sound, and sound different from B1 to B2. BTW I’m a dealership Gold technician

Fascinating. I had a truck 10 years ago that I spent thousands on trying to fix. Everything I did improved the car but it had this mysterious electrical problem where it would go in limp mode, shut off and take 5+ minutes to start again but then would run perfectly. I literally did everything from coil packs, plugs and wires, 02 sensors, solenoids, throttle body replacement, distributor module and much more. Some days it would run perfect and other days it would just shut off on the interstate and I’d have to bump it in neutral and try starting it while coasting off to the shoulder. It never left me stranded but I finally sold it for a deep discount to a dad that thought he could fix it for his 16 year old son. I gave him a really good deal and the file with over $4k in receipts for all of the repairs I’d done. That cost is all DYI, I have no idea what happened to it, I never heard about it again but these stories fascinate me

My Man Alex 🙌🏼 good trouble shooting! I’m sure you will figure it out. You are one of the best mechanics out there and the way you approach things in steps is so professional! Good luck.

You could have a few problems that you are not looking at. The aluminum of the radiators, or the intercoolers could be clogged. Not the coolant pasages, but the aluminum itself. If that has happened, the cooling capacity of any of it is shot. I had a car that had that happen to the radiator. Chased it around, and around, and what finally fixed it was replacing the radiator. Check that.

Prime example of how the toughest problems are also the most interesting, at least for your viewers, and because I feel that we learn the most, just as do you.

Respect! You have a lot more patience than me when it comes to restoring a car brother! Your skills are amazing! Those coil packs and 24 spark plugs alone steer me so far away from the V12 Mercedes hahaha.

Hey Alex, long time subscriber here! I had a similar issue with my 2003 S600. You can't take out the Schrader valves to bleed the intercooler, as that puts air into the system. Any air will mess it up. Happy to chat you through my setup to bleed the system without using the factory tool!

I would continue with verifying temperatures. Add more temperature probes to the system. One in the Y pipe where the turbos flow into the intake, one in the water side of each intercooler, one on each side of the front mount rad for the intercooler. Something you can monitor while doing a pull to verify that your built in sensor is reasonably accurate, and that you have reasonable water temps.

Hey Alex, love your channel. I’d have to say you seem like the most patient person I’ve ever seen. You always seem upbeat and don’t curse, swear, throw things around when things don’t go your way. I’ve seen a lot of channels where the people swear, hammer on stuff and throw a tantrum when shit don’t happen, but you are so in control. Hats off to you for that, it makes for better viewing not seeing the anger and aggression of other channels. Good luck with it, I know you’ll figure it out in the end.

I feel your pain. My old BMW840 used to cut out and go into Limp Home Mode when I hit 300rpm. Turned out that was blocked cats. I also had a 1992 BMW850i V12 that broke my will to live (like the CL65) . When I finally fixed it, it was sold to a dealer, who just wanted it as a static model. I knew about the spark plug gapping from my drag racing days, so I took that knowledge to my tuned CL55. I still have my Highly Tuned CL55 here in the UK. Good luck Alex.

Thank you so much for the time & effort you spend in these videos. I have an SL-500 and two Cayennes, so I feel every pain and aggravation that you go through when repair events don’t happen according to plan. However you are pure comedic genius, I can’t help but laugh at your pain & suffering. Sorry, I routinely go through many painful episodes on German car repair & maintenance, but I don’t handle the stress well at all. You on the other hand maintain incredible composer in front of the camera. For us motor geeks you are extremely entertaining, more so than most anything on television. Keep up the good work, keep up the great attitude. Us German car owners will go broke together, but some will maintain their sanity better than others.

Seen a couple people say it but you should separate the heat exchanger from the radiator and the condenser to check and make sure there’s no built up dirt or dust. Same thing as when a car overheats with the ac on! Good luck!

Although, boost was showing IAT rising, the IAT's were increasing at idle & with no boost to >150° before the sensor was replaced. Something is causing temperature rise in the intake; Check the coolant lines to the intake plenum & associated flow. GL

@LegitStreetCars I once had a M275 do this same thing. In my case, the turbo wastegastes where unsyncronised and where causing increased backpressure on one side of the engine. I only had misfire codes 4000RPM+ at full throttle. Sometimes all one bank, but often only 3-4 from one side. I applied 5psi to the wastegate lines and syncronsied the wastegate actuators so they moved the same amount by adjusting the rod length on both turbos, then reset the adaptions in ME. Been rock solid for 3+ years now.

Thank you for all these videos on cl65, your videos gives inspiration to work on my own cl's abc problems.

The cupholder is designer to anti-tilt. You go hard right, it maintains upright position by forcing itself left. It's not a bad design actually.

You could try connecting a resistor instead of the air temp sensor The value of the resistor would be proportionate to what temp you want it to show (100 F) then you can test to see if the problem still persist

I am having the same issues with my W215 CL600, so this is helping me a TON!!!! Thank you!

I've had my CL600 for 9 years I feel your pain, took 2 months to finally fix secondary air code issue. But keep the faith you got this!

This is my favorite car on the channel, I want to see you get this thing perfect then take Hoovie for a ride to show him what he could have had

I would HATE to figure how many man hours you have in "fixing" that. Maybe you should have your wife drop it off at the dealer and have them fix it...just for fun to see if they can do it, AND find out what they would charge LOLOLOLO LOVE the channel, I've been a supporter since the beginning!

Bro I learn so much from you, you’re ability to obtain such knowledge and explain it so fluently is what’s so sick to me

I've been a subscriber for almost a year and a half now. I work at a Toyota dealership in Salt Lake City. I'm actually in the process of becoming a lube technician possibly a mechanic in the future. Knowing of your expertise and being a mechanic for so many years may have inspired me to move up in my dealership and step away from the frontline of the service department and head in the back of the dealership to work on cars. I've always considered myself a shade tree mechanic I fixed quite a few things on my wife's Honda pilot also from watching a fellow RU-vidr ( ETCG ) which has help tremendously. 👍

I installed a turbocharger on one of my motorcycles, had to regap plugs clear down to .020" from .035" to eliminate a top end misfire under boost. That engine shot ducks(backfires)that would have made a hunter jealous! Smaller gap cured the problem and the bike then ran an indicated 171 mph on GPS with no misfires. Great video! Thanks Alex!

I give you a TON of credit, I’d rather gouge my eyes out than work on this thing. I very much enjoyed watching your troubleshooting process :)

I struggled working on a 1968 MB 250SE 4 door sedan, that was owned by a friend that passed away. It was a car originally sold in Germany. It was a 2.5L inline six with a 4 speed and bucket seats. A really unusual combination that I was told by the MB Center that there were likely no other cars with these options (which included skid plates front to rear) in the US. I replaced the clutch, completely restored the fuel injection system, rebuilt the brakes, suspension and any rubber parts-including window seals. Then fixed the bodywork and painted it in the priginal color. I replaced the original 4.06 gearset to a limited slip 3.23 setup (which was very hard to find). I worked on this car for 24 years only to discover a porus front frame rail that rotted from the inside out. I had an accident at work and had to sell the car. That damn thing drove me crazy.

Hiya. Love your channel and love seeing the content on Mercedes. I found a document about the M275 Initial Training and it says in that manual, Charge air temperature sensor (B17/8) Signal required for calculation of air mass (in combination with B28/7), as well as for monitoring the boost pressure system. Maybe you need to check this B28/7 sensor? This B28/7 sensor, is the Pressure sensor downstream of throttle valve actuator. You should also look at that M275 Initial Training document; I am sure that could help you further! Good luck and hello from Great Britain.

To start with, you are making awesome videos, spreading knowledge at the same time making good videos with some humor. Also congrats on the million subs 🎉 I have worked on many many mercedes lcv and trucks. As far as I can see you have checked the sensor. I would check the cables at the connector for the sensor but also for corrosion on the pins. If thats good I would backprobe the signal pin on the sensor and checked that its the same that the ecu sees. Have had some wiring issues on the om651 engines. Not the same engine at all but could have similar issue. Mercedes still uses very thin wires anyways. If thats good I would put extra sensors in the intake pipe from the intercoolers, maybe even on the turbo side. Like k type thermocouple sensors. Logg that temp to see if the sensor actually gives the real temp and at the same time see the performance of the intercooler system. Just my take on this without being there.

vacuum lines are a problem after you upgrade the boost. smart to upgrade the coil packs they are wear items and really mandatory when adding a tune. I would guess your cats could be an issue and worth checking because its easy. Borrowing a STAR diagnostic tool is a good idea but you also need a good 65 knowledgeable mechanic to show you what to look for. they did not make a lot of these engines overall when you think about it. 2005 was the first year and my favorite as they are less complicated than later years and easier to keep power to the wheels as there are less controls to electronically limit it. I put a lsd in my cl65 and when I sold it I went to a 2005 sl65 (the sl 65 comes with an lsd stock) I ran into so many 65 series related engine issues and my saviors where the tuner gods. I luckily have great relationships with 3 of the companies that tune the 65 series engines and everytime I talk to them I learn another crazy fact about this powerplant. I wish you luck on this quest and am sorry I cant be more help at this time.

I really want one of these! Amazing attention to detail 👏 can't wait to see you driving it in the next video.

It is such a great lesson in learning watching you Alex. I am sure you will solve the issue with your CL. However, I will point out to your subscribers that these cars can be and are great to own. My 2003 CL600 has never had a suspension problem, it has the original turbos and it has always been fast enough to pull the hair plugs out of your head. I did have a problem with the trunk not opening correctly so I took it to Mercedes and they fixed it. My biggest problem is trying to stay anywhere near the legal speed limit. It adds drama to your regular run to the grocery store wondering if you are going home or to jail! Great video.

Good to see this car back on the channel (and the OG LSC HQ!). Really admire you sticking with this one, looking forward to you getting to the bottom of it and finally fully fixed!

Thanks for the update. I’ve wanted a 65 for a long time. After watching these videos, I think I’m gonna admire from a far and look for another E55.

Get a resistor and make the IAT static. Possibly a resistance high enough to keep the intercooler pump running . Do a couple pulls and then check Temps with the IR thermometer. It could possibly help determine whether it's a logic/pcm/harness issue....or an actual mechanical issue

I don't know much about cars but I learn a lot from your channel. Keep up the great work

I believe the issue involves the welded water jacket that was discovered during rebuilding the engine. There could be a minor internal coolant leak or some debris impeding coolant circulation allowing the intake manifold to heat up. I have a sneaky suspicion that the issue is internal as all the external components have been ruled out. Good Luck

Those laser iridium plugs are great. They are OEM for the Abarth which is big boost (26 psi stock) and very high temps. But to avoid blowout you need to torque them to at BARE MIN to 17ft-lbs. The crush washer won’t even crush until then and most tuners recommend torqued to 20 but that always feels a bit excessive to me. I hope you see this and hope you realize that the normal “snug and then half a turn” isn’t enough to avoid plug blowout especially boosted. It’s a SUPER common issue.

I understand your frustration. I drive an old volvo 460 from -91 (62137.12 Miles) which is very difficult to start, I have changed everything that I can think of as the fault but nothing works so I am stuck. once it starts it runs great. love your channel my friend. and good luck now.

Many have mentioned the EGR, I agree that would be a massive source of extra heat into the intake if it's not sealing up when it's supposed to. But first verify that the IAT Sensor is actually correct by sticking a thermocouple probe for your multimeter down the hole and see if it's really that hot down in the intake. Then slip it in your "Y" pipe in front of the throttle plate and see what's coming out of the ICs. And just because the computer is saying that IAT sensor is reading something doesn't mean that there's not a wiring problem between the IAT and the computer that could be affecting the signal.

It is a lot of fun when you are in your zone of problem solving. Excellent video.

Hi Alex! I think it's the ECU. Last gen Saab 9-3 came with the ECU above the intake manifold-, lots of heat-, so the constant heat fries the computer and it leads to a misfiring and floods the Chambers with gas cause it leaves the injectors open. Solutions it's an ECU replacement and also a relocation out of the engine's heat. This happens to my 06 Saab 9-3 2.0 SS

I was looking forward to your further episodes on the CL65, thought you might have given up on it !

Congrats on 1 mil subs!!! Hope you solve this misterious problem

Ok Alex I still think it has somthing to do with the injection. I know there not related however it's certainly a rich misfire due to larger injection without tune. That will give you a hotter exhaust due to fuel dumping and misfires. My gess is go get a tune done for fuel correction. One problem is masking another. Yes still could have a tiny air bubble 🫧

Wow, I'm surprised that it wasn't finished..😮 I had forgot of this car thinking it was done. But that was a beautiful car when it came out.. So very happy it's still around

Love your channel Alex. Long shot- heat soaking and old wires causes resistance to change which may throw off sensor readings.

Sensors are often overlooked. I always like to eliminate the sensor being at fault before diving deeper

Hey Alex. Check the heat exchanger and the others in front and back of it to see if the fins are clogged. You should be able to see light through them all. Relocate the second IAT sensor away from the center top of the engine. Engine heat is adding to the sensor's temp reading. I hope you find the smoking gun soon. Good luck!

It takes a real man to admit when he's scared of anything...especially working on his own car. 😂😂😂 If anybody can figure it out you can. Your attention to detail is impressive. One day it will bow before you. 👍

Love watching your channel Alex you’re more thorough than a lot of other channels. You’re fun to watch.

My version of this is a BMW F30 335i, currently dealing with lifter issues and has been sitting for months because I’m too scared to blow up another n55. Good luck with the CL65, I predict burnouts next time!

I would check cooling stack. Common problem on diesels when you have the radiator, ac condenser and intercooler ( heat exchanger in your application ) stacked on top of each other. You’d be amazed how much dirt and debris get trapped in the fins due to their close proximity when stacked together.

Hi Alex ,great video as usual .I’m no expert but reckon it could be reduced coolant flow through the heat exchanger as the you didn’t have much variation between intake and outlet temp. my guess is that as the fluid temp rises the narrower the temp difference between inlet /outlet becomes due to a flow restriction ,therefore overall temp does not reduce fast enough between the high and low software temp presets during cooling cycle.

This is the car I originally subscribed for back in the day. Lovely to see it back on the channel and see you at the OG LSC headquarters!

I had a 2001 cl500, what a nightmare of a car. Every day there was a new problem. My weekend car now is a 1999 SL500 R129 with only 32k. It's like a new car. Love your videos.

Could you look into installing a higher flow coolant pump (aftermarket)? You would have to wire on a factory plug end on the pump or just run a manual switch into the cabin. That way the pump could run all the time (they might already...I don't know). It would be worth a shot. You could test it out before committing to a full install. Just an idea. You might have thought of that already.

Would be worth getting a flow test done on the Water to Air system as it can have a clog/blockage.

Hey Alex, I admire your endurance with this twin turbo car! I just smoked my twin turbo V8 Diesel Range Rover and I am close to giving up on it after 7 years of ownership. Keep the spirit up!

This is why we’re here! It doesn’t have to be all roses and daisies. You’re a fantastic diagnoser. This is coming from an Acura tech. This part of our industry is the hardest part.

Had the exact same issue with my S65, it was the intercooler pump. The impeller split on mine.

I think you need to datalog and do a strong pull before and during the fuel cut/ limp mode. You gotta see what the timing is doing and also check fuel trims.

I dunno how to help you Alex sorry mate, but it's a fascinating journey to go through with you, trying to nail down this problem! I was almost sure the new temp sensor would fix it for you but no! D'oh! I'm keen to see the next video in this epic series!