This awesome video deals with a 2002 Chevy trailblazer that came in with a stalling condition and stored codes P0340 and P0172. Join me as we tackle this common 4.2L issue.
A lot of you people out there are looking this for a fix a quick fix on your vehicle you need to listen to the man how heExplains everything it’s not just throw parts on vehicles you have to test things test wires and have the knowledge I listen to a lot of the comments and a lot of these people don’t have no common sense if you don’t know what you’re doing don’t touch it take it to somebody knows how to properly diagnose the problem don’t just throw parts at it or might be ThisThrowing parts at the vehicle never fixes the problem you have to properly diagnose the problem if you don’t know what you’re doing dn’t touch it I listen to a lot of the comments and a lot of these comments are the stupid ass people this man is talking about a Vehicle stalls out check your alternator check your idle control motor check your variable timing check your crank sensor if people don’t realize you’re turning the steering wheel putting a motor and a strain the idle will not come back upThis man is talking about an engine stalling out intermittently and one comment on there I replace the shift solenoid and it’s doing the same thing people don’t listen how is the shift solenoid that makes the transmission shift have anything to do with the damn motor stalling out people don’t listen everybody’s in a hurry to get it fixed they want to throw parts at it but a bitch and whine when it doesn’t fix the problem if you don’t know what you’re doing to a vehicle don’t touch it take it to a technician they will properly diagnose the problemNot you wanna bees out there at throwing parts at all there is tricks and trades that we know how to fix the problem and the symptoms but you have to have common sense didn’t know how to work on a vehicle and people don’t have that today
I will say that sometimes throwing a cheap part on a vehicle can be the least expensive way to diagnose or repair a vehicle. I do it from time to time and I know it rubs folks the wrong way but if $20 saves me three hours of diagnostic labor time I’m good with that. When my guess is wrong sometimes I just have to suck up the cost of a part and find the actual problem. I realize it can be frustrating when people don’t take the time to listen and learn but it’s also up to us to help instruct and inform as long as they listen and are willing to learn. And for that I appreciate your input and caution for those in the thread who sound lost and confused. If I listen closely I can hear their desperation. Blessings to you!
I want to give you the most sincerest thanks for this video...you saved my car...I was ready to trade it in and take on a note for something else. we cleaned the throttle housing and fixed my car! I was only $308 over budget bc we chased the alternator and battery stuff first and it didn't fix it. Your $6 throttle cleaner has the car running like a new car. I'm so thankful for your concise and precise video. You're awesome!
Can you help me again? After my fix, I ended up with a slow start turnover...it seemed to improve a little and will start every time on one long crank...but this morning I noticed I was driving way too fast even though it didn't feel like it. After the interstate, at a red light I see that my speedometer is zeroing out at 14 mph. Got any advice where to start this fix? thank you!
@@mlemaneThat is a goofy instrument stepper. Mine does that one day a week. Usually starts off 10mi fast then after ssy stopping for fuel or groceries it settles down to reading 5mi fast. Rest of the week it's spot on. It's actually a cheap part going sour but need to take it to say a computer guy to have it replaced. Paper thin board like in a laptop. Do not have to buy another instrument cluster.
You should warn folks about the razor sharp edges on the butterfly on the throttle body. An old or dedicated tooth brush also works great for scrubbing the deposits. Great video.
Emilthehun that’s exactly what I’m going threw now I started with replacing all my coils then it still started stalling then I cleaned throttle body ran better now it’s stalling again. I’m heading to get the cam sensor now my only other issue is that I’m getting blowback in the resonator but I did add some marvel mystery oil to the oil witch made it a lil high I’m guessing that’s why I’m getting more blow back then previously.
Thx for your response car doctor. I really dont know how the gas pressure or the back exhaust pressure is. I just watched some videos on how to check them. I will need to borrow a kit from autozone to check them out. Is there a quick way to check the gas and exhaust pressure with out using the kit. Also let me ask when they do a diagnostic, are they suppose tho check them?
I have a 2009 Envoy. The car was going into limp mode with a code P2135. (rough idle, stalling, ..... 2 times same day). Replaced the throttle body with a new Bosch unit for the 2009 Envoy. The old TB was fairly well carboned. I performed the relearn, it is idling at 700-800 after about 5 seconds after starting. However, when you start to press the accelerator, the car leaches because the engine jumps to 1200 RPM. You just have to barely move the pedal for this to occur. If you are moving and stop, wait 5 seconds, the idle will return to 700-800. If you are in park and you place the car in drive, sometimes the car will increase to 1200 rpm as noted above. I did not have this issue with the old Throttle body. I have driven the car 50 miles with speeds of 50 mph with many stops and go, I am not seeing any improvements. Any ideas? I can't find anything on the internet describing this issue I am experiencing when replacing the throttle body.
Make sure you're using AC Delco sensors, on the trailvoy forums people constantly talk about how aftermarket ones don't function properly in these vehicles, that being said I got the exact same problem and I havent tried an AC Delco Camshaft position sensor yet, but I'm about to.
I just changed my battery and when i cranked up and turned my ac on, it started cutting off when the ac compressor kicked on. I bought a can of throttle body cleaner and MAF cleaner while i was sitting in front of Advanced Auto. So after i clean everything and change the camshaft sensor, How do i clear the codes? I dont have that snazzy Snap on scanner but it is a nice one 👍.
Hello Doc....just started having a stalling problem with my 2003 trailblazer...was going to entertain doing this myself. There was another sensor that was replaced someone else's video solenoid cam timing sensor. The screens were clogged. If I choose to attempt this myself...are the "learns" you mentioned required? I don't have the scan tool to do that.
Just disconnect the battery and let the engine run a while after the service. Then just be aware it might stall for a couple hours of driving at stops but likely not.
My 2003 chevy trailblazer kinda has a rough idle and lately when it's cold it takes two or three times cranking it before it starts what could this be attributed to?
Hey Tim, I have a 2004 trailblazer and it’s been acting crazy I’ve changed the air injection control valve, an the air pump an relay the check engine light keep coming on could it be the PCM
What about if I replaced the cam shaft sensor clean the throttle body still runs run but when I get on the freeway it runs great until I get of the freeway an back to runni g like crap
Hey Car Doctor I have a 2003 Envoy XL with the same engine 4.2L. recently I replace the Camshaft Actuator Sensor and Cleaned the Throttle Body as well. I'm wondering if you had any suggestion on the following issue that I can't seem to resolve as I'm getting a built up of a Liquid (water) or a mixture of Water and Fuel in the Air Resonator. This causes a P1515 & P1516 and I can't seem to get this fixed, I never had this happening before. Any recommendations? Thanks, Sparky
Hey Tim, could you suggest a good scan tool that I could use on my 2004 Trailblazer LT? Sounds like my new to me 2004 Chevy Trailblazer isn't any better than my old 1991 VW Vanagon as far as electronic. :(
Blue torque scanner that links to a smart phone you pay a monthly subscription for the full version but it's a pretty capable scanner for the price and you can cancel the subscription at any time and just pay when you need the scanner it's 5 bucks a month I use mine all the time if you need one to do abs pulse bleeds and all that some of the knock off scanners around 200 dollars on Amazon will get you all that at a 20th of the cost of a snap on mac or cornwell scanner and gave pretty good software and update support
My 02 envoy stalls coming to a stop and loses some power while driving, but seems to idle pretty good. It has thrown a code while back about EGR but can't pull an EGR up on this model or find one. Today it threw po130 I do believe that's an 02 sensor but couldn't it be other stuff that can cause a 02 sensor look bad. Please help
I cleaned intake and change crankshaft and camshaft sensors no codes but when test drove it stalled and turn engine off on an inclined Hill any suggestions
Hey Doc, when truck starts to heat up up it loses power and hesitates to shift. Not getting any transmission codes though I am getting 02 sensor and catalytic converter codes
Hey I have a 2004 trailblazer and was fine then all of a sudden it’s very rough idle like it has a miss in it going down the road not as bad. I cleaned the throttle body and reset computer but still extremely rough idle. Any suggestions
Nathan Modlin I have had to replace a lot of the original coil on plug packs. They are easy except the back one or two. I have a cheap obd 2 scanner with Bluetooth that I watch with obd check app. So for under $100, you can diagnose and repair a couple of bad COPs. Just look for misfire during idle.
Hi Doc. i watched your video and i did the same but it didn't help with solving my problem, my issue was some time during idling and i turned the A/C on my engine went off but my idle rpm is normal. and the second issue during driving at 4th speed and rpm 2000 the rpm start staling up n down between 1600 to 2100 so do have any idea what cause that please help.
I have an 06 GMC Envoy and I am wondering why it dies when the weather is cold? What happens is when you turn it on it will turn over and then die you leave it for a couple minutes and try it again and it's fine. Any ideas?
I recently had subs and amp installed and now I have no throttle I have a 2005 4.2 4x4 trailblazer had someone to check if everything had the right voltage and they couldn't find anything please help
How can you do the relearn sequence without a mechanic's computer? Will the vehicle relearn after a series of ignition on ignition off Cycles? Thank you
i cleaned throttle body, relearned it and changed fuel filter, spark plugs and coil packs, replaced evap system and replaced acceleration pedal. still stalls out with heat/ac on and rough idle. not sure where to go next.
2006 Tahoe stalls out, starts up the stalls back out, replaced crank sensor, mass flow sensor, due to codes stored, he had fuel pump replaced, cleaned off ground points on chasis ...i need help?
I just got the 340, while removing the big hose the locking clip on the air intake pressure connector dropped and couldn't find it. So I can clean the TB, Any idea where can I get one. Thanks you for video. +1 subscriber.
04 gmc envoy xl l6 4x4 when driving loss of power on take off and any incline and can feel a little go then little drag no bad jerks though but idles great engine smooth no shaking. Check engine light on showed a few codes misfire cyl.1, speed sensor, and some motor to do with the 4wd.? Just feels like something is holding it back.
Sorry I know this is old. But I am at a loss. I have a 2004 envoy slt 4.2 I cannot seem to find the mass air flow sensor. There is a sensor that is on intake tube before the TB. But it doesn't seem to resemble any maf sensors I've felt with. Plz help
My 2002 trailblazer a/c started turning itself on today. I turn it off and in a couple minutes it just starts blowing again. It happened 4 times in about 5 miles. What could this be?
Hi, I have a problem with the engine power of the Chevy TB 02, I do not know what it is. Idle OK, the control is not lit. The throttle is clean. Max. speed is 60 miles, and the engine is noisy. Thank you for any help.
Hey Car Doctor. Great stuff. I have a Sienna 2007. It looses power going uphill, sometimes in freeway if going above 60 and very few times on road. On Freeway also stability control beeps and then trac and vsc turns off/ on and stops beeping. Not long ago change tires and also took it for an aligment. I changed oil and oil filter as well as air filter and checjed for leaks. I cleaned the trottle (without removing it) and clean the sensor with the proper spray. It does not have any check engine light. Mechanic did a dianostic, but said only run it for a few minutes on the road and nothing happend, but said the steering wheel module needs to be replace according to the computer. Said it cost $2,250. + labor. Not sure he took the time to test it right. I was hoping van just need it new spark plugs since never been changed since it only has 70,000 miles. Can you share your toughts on this one. Thx in advance.
Thx for your quick response. Honestly do not know. I just checked some videos on how to check them. I will have to borrow a kit from auto zone to find out. I am just a guy that has learned to fix some car stuff watching your videos and other you tubers. Any advice on how to check the fuel pressure and back axhaust presure beside using the kits?
On a 02 GMC envoy Getting mass air flow got an odd sensor sticks out on side. Cleaned throttle body on insde run fine for awhile started doing same thing p1514 code? Thanks
My AC don’t work on my 2006 envoy at all it loves to make the battery dead even tho it’s new but has no problem going after the occasional jump and it does start up right away again but if you leave it for too long, it won’t just replace the rear air suspension with a regular suspension. Now I need to do the brake pads. I know that I would like to know why it stalls out like that though.
hey car doctor i have a 2004 trailblazer ls ext idles great. but when it gets to operating temp it stalls on me when i shift it to any gear. HELP!!! new plugs new coil packs (was getting miss fire codes) cleaned throttle body. Any suggestions would be a big help Thanks
I have 2003 envoy sputtering and vibrating pretty bad. Cylinder 5 misfire, camshaft position sensor and evapotive emmision. I have changed all sparkplugs (no better) camshaft position sensor (no better) now it says MAP sensor? Have you figured yours out yet cause i would love to know. Thanks.
Hi Have a problem with the chev trailblazer sport 2007. DE fan works fine defrost and air at feet work fine, but no air on Centre settings. Please advise
My 2004 trailblazer is leaking gas from the gas tank. It drips from the bottom of the gas tank. my auto friend says it might be the fuel pump, BUT it starts great & the sending unit works too. I started it when i was leaving a friends house & it drove fine all the way home. Now it's sitting until i figure out what it is. It's not coming from where the gas neck go's into the top back of the tank either. Could it be the gasget from my fuel pump? HELP! Thank you. I just went outside & started it for ONLY 2 mins & it's dripping still at the bottom middle of the gas tank a LOT. Can you help me please?.
If it leaks only after running it then its probably a rusted line. Youll probably need to drop the tank to inspect. Might be better off taking to a shop since its dangerous if you aren't familiar with the process. Take care
thanks for sharing good videos i have problem with my trailblazer 2003 LTZ when i start in morning it is perfect working good after driving 1 hours if i stop the cars for a while then it will not start up again so i have to wait may sometime like 40 minute to cool it then again it will start and work , the parts has been change 1 fuel pump 2 crank shaft sensor 3 cam sensor but still i have same problem can someone advise what to do ,if check with tech-2 tool no fault code showed
@@zephead843 on my 2004 TB 6cylinder, the Idle Air Control (IAC) is built into the throttle body and can not be serviced separately. I pro scan tool might be able to see if it's working correctly. The throttle body assembly in around $250. Not something I want to guess at.
Idk if you still respond to your videos. I would like you to pour some of your trailblazer knowledge on me, I have a 2004 trailblazer 4*4 4.2 I've changed my knock sensor #2 and I've changed the purge valve, still having a slight but erratic shake only when I turn off the engine, I have great oil pressure sometimes while it's running and I'm ready to take off it does have a slight jump In rpm it drives great it doesn't cut off on me it doesn't struggle up a hill or anything just that slight but erratic shake when I turn off the truck.
Arturo Gonzalez I have the same blazer what purge valve are you referring to everything I’ve looked up says the 2004 4.4 4.2 does not have a purge valve.
I have a 2005 trailblazer LS 4.2L When I place the vehicle in reverse to back out of my driveway while holding the break it vibrates like crazy, then when stopping at a stoplight it starts doing it again. When I place it in park or neutral the vibration stops. It’s not the motor mounts because they are completely intact and not worn out. I just replaced the throttlebody with a new one and the the part you replaced in this video and it still didn’t fix the issue. There are no vacuum leaks whatsoever. What else could it be? ***I also purchased a new fuel pump and will be installing it tomorrow, but I thought I would ask you if it could be anything else before I did that, not sure how responsive you are to your RU-vid but I figured I’d give it a shot, but I have to put the pump in tomorrow.***
My 2004 Chevy trailblazers rear A/C vents will not consistently blow our air. Fronts blow cold and strong rear, intermediately at best. What could cause it to blow only sometimes??
rain drips onto top of engine and collects in #4 spark plug well Cheap GM bastards redesigned the hood seal but never recalled the truck. Go to Home Deport and buy a strip of weatherseal to deflect water to either side of the engine. Its crap that like this that made me swear off GM ever again.
trying to remove the intake housing off a 2002 trailblazer, i took off all the bolts I thought was holding it in place but still not coming off. Anyone with experience ??? I'm not a mechanic....
maybe Oxygen sensors. Because they heat up (before the engine does) If they are not heating that could be a problem. They aren't that much and they're probably due new ones.
I have a 2004 Chevy Trailblazer some people say that when you mess around with these kind of cars you start having problems with it I don't know if this is true or not
Mec Alpsha mine ended up being cylinder 1 misfire. Replaced coil pack. Worked great. Now I have an evap leak to find. Also replaced thermostat and coolant sensor.
disconnect the negative battery terminal for an hour. reconnect terminal turn key to on position wait 15 seconds then start it up and let it idle a few minutes.
I have a 2002 trailblazer and every time it rains it starts idling very rough and stalling out and seems like it has a horrible misfire now it does not have near the engine power and I'm pretty sure the moisture or something is causing my
@@Gevans5472Also that or the very front coil pack goes dead. The moisture eventually ruins the coil. Mine went from perfect performance to it would barely run and almost died in traffic. Just the one coil but I'm expecting the other soon. My last vehicle had the 4.3 V type vortec and it also blew coils (and when they blew the truck would die on the road (far from home) and I'd need a tow truck. At least the TB will sorta limp to the shop on its own) every other year needed the complete wire/cap/rotor set replaced ($$$).
What would be the problem with a trailblazer that throwing code P0449 I change the perg solenoid, it started as shutting off while driving , cranking but no start change the perg solenoid still not starting an same code an idea what it is?
My 2007 trailblazer just stalled without warning at a stop sign last night. Earlier in the same day, the left blinker was flashing fast, but than went back to normal afterwords. Not sure if just coincidence. Any thoughts? Thanks
The Car Doctor Possibly. I was thinking one of the sensors. The tow truck driver thought maybe the alternator. I'll let you know when I figure it out. Thanks Doc!
The Car Doctor It cranks but won't start. The tow driver hooked a battery pack to the battery and it started up. Stalled when he disconnected it. And eventually the battery dies after more attempts. Will be testing alternator today and cleaning the throttle body.
The Car Doctor So I hooked the new battery up, turned the key and it started right up. Stalls 10 seconds later. Starts up again, then stalls. Now won't start at all but cranking. I'm lost. Fuel pump maybe or starter?
I have a 2004 TB, i have the same issue the truck runs fine but when I stop on a red light it turns off and it starts right up again but it keeps doing it once in awhile. Doesn't have no check engine light and no codes could it be my cam sensor going out 2?
I've seen several vids on NOT removing the throttle body. Like alot of uTube vids, you don't know what to believe. Maybe the key is they didn't take it somewhere to re-learn, I don't know but I now own a TB & am leery of screwing things up.
PLEASE SOMEONE HELP ME OUT... If the truck made a low winding up sound before it shut off on me while driving & you put a new starter + battery... should I go for alternator next? But what would have stopped my truck while driving while making a low winding up sound?!? Almost a knock? Please.. tell me my engine isn't seized up!?!!?!!!! I have power.. but it won't crank over...
so my 03 trailblazer @171k stalled when stopping at a red light....it didnt throw a code so if it happens again i will clean the throttle body and continue from there, but no code was thrown may have been a fluke, started right back up....its a 20 year old car sorta gotta expect these things especially on a gmc/chevy
So yea codes p0335 and p0340...crankshaft aensor and cam sensor code.getting sensors replaced today....mechanic wants me to replace timing chain which I said no we dont know if it is faulty sensors or not. If its the timing chain ill do it myself I m not paying 3200 for a timing chain job lol
