DIY Repairs & Testing - LB9/L98 Tuned Port Injection (TPI) Engines Part 1/2 

This is part one, of a two part series to keep videos relatively short! There's a LOT of information in this one, soon to be followed up with fixing the TPI engines idle/hesitation issues. Stay tuned!

This is a super helpful video! I have been looking for a video with exactly this content for a long time. Your filming and presentation are superior. I have an L98 on a ZZ4 in a 1975 Toyota Land Cruiser and have issues with idle and cold start. Your diagnostics and testing procedures are exactly what I needed to see. Thanks!

Love the Menards gloves! Got some just like it. 😊

the spark advance is what was wrong with mine. ty so much for putting this vid together

I started having this issue last year. I pulled and rebuilt the LB9 of my '88 IROC about 5years ago. All new hoses, sensors, and IAC. My RPMs increase when I depress the clutch to shift gears and the idle is often high (1100ish) when sitting at a light in neutral (shif up light comes on!). A quick tap of the gas gets it back to 750rpm. I set the IAC voltage down to about 0.47VDC and adjusted the idle screw all to no avail. Reset ECU. Cannot find any idication of a vacuum leak. I may just bite the bullet and get a new IAC again.

A Vacuum hose connector that is a Y fitting was cracked. The hoses split one going to the throttle sensor. I had changed out the sensor with a new one. That was also cracked. Had the engine smoke checked which showed both issues. I know you can use fluids to check, but that worked better in my opinion. I had changed out the intake manifold gaskets and RTV due to an oil leak out the back side. Doable but not a one-day job. Changed out the EGR with a new Delco EGR. It wouldn't hold Vac. PSI. After 3EGR's I found one that held PSI. New parts aren't worth poop now a days. The other thing I learn was those Vacuum hoses may look good. But unless you check each and every line. You could be throwing parts at a leak. Hey at 30+ years rubber breaks down. Sorry to wine about my journey with an L98. Hope you get that nailed down. CHEERS

The IAC relearn you have to jump the A & B terminals in the OBD1 (ALDL) Then turn the key for it to open. You should heard it clicking rapidly. If you do this without jumping the terminals the IAC won't actually open... Remove the A/B connection, plug the IAC back in and then start the car.

I haven’t watched part two yet but I’m very pleased with everything I have watched so far! Keep up the good work man. Hell buy a beater and make how to videos on the regular!!!!

The corvet has same issues ...they changed the fuel pressure thing on the fuel rail..made big change...no more die outs

Excellent video. Thanks

Those gas tanks on those rot always from top down usually and you may be sucking air from holes in top of your fuel tank just saying as this is what was going on with my 3rd gen and I had to replace fuel tank pump and sending unit and bam runs amazing. The guy I bought the car from really cheap had done all those things your doing. Timing , pugs wires fuel filter and all new injectors etc etc… but bought it took it to gas station tried filling it full and gas was pouring out everywhere so I replace the tank and everything that goes with it. Night and day

I bought a 91 formula 350 last year and whoever messed with mine had the timing all screwed up. Resetting the timing like you did made it a whole new car. Isn't that a PITA of Having to remove the coil to adjust the distributor? BTW, nice looking ride!

Have you had any check engine codes with these problems. My iroc has always ran really well but also is prone to high idle and has had vacuum leaks over the years. My issues have translated to code 36 more than once. It’s like reoccurring issue for me.

Bad ass! Guys that can't fix carbs n tune neither can't fix tbi n tune cars.

Do you have to do emissions testing? All of that EGR piping always made me cringe, as well as the horrible log manifolds. Headers and shift kit would be my first "updates". Great job on research and methodically going through the steps instead of just throwing parts at it.

I have one Camaro f body 1993 And i wonder if the 20 amps fuse to ecu are in the same place behind the headlamp?

The last time I had this problem with a car it was a clogged catalytic converter. After changing it, it ran like a new car. Drove me insane before I was able to find the problem.

Everytime I've had this idle problem (I've owned three TPI cars) it was always the IAC and or throttle position sensors.

Way to have patience brother!!! Chasing down problems like that could drive you insane. Sounds like you're hot on it's trail!!!!!! I am enjoying nthe ride, and rooting for you to fix it!

Another awesome video!

Mister hand likes giving a solo performance??

Nice video bro, do you know what voltage from the maf sensor in idle shold be?

The car sometimes dying of during the first few miles after an ECM reset is normal. At least on the 3.1 V6 with the same ECM. But of course not the idling of your car.

I turned my into a carb engine after I did all you did and then some but still couldn't resolve the issue

Do you happen to know how strong the block is? I have one its been bored 40 over cant find anything on this block just dont wanna spend the money if the block is weak

Should buy a performance chip and a air foil, with a cold air filter and add a decent exhaust u won’t be disappointed😁

How do I get my car to you lol. My vehicle wont idle until hot. And its a lil low even warm. Stalls after quick throttle on - off acceleration.

FOR SALE - 1999 WS6Transam 29,000 miles, six speed. I had damaged the front end and the driver side rear quarter after hitting some ice. It is a great car and I loved driving the car. The first time I drove it in bad weather, and I crashed it. But due to the damage I do not have the knowledge or abilities to repair it. I do have another Firebird to use for parts and it is the complete body with good front end and good driver side quarter. The exhaust is a Borla cat back system. I would sell it and put what I can for a down payment on a corvette. If I must, I will also sell my 2004 GTO made by Holden company from Australia it has the 350/350 corvette engine, this has an automatic transmission with a factory shift kit. It is faster than my WS6 and I enjoy driving it. The GTO is yellow, and it does not have the hood scope. Most people do not know what a GTO is. Except for people that like the WS6. Please help me sell this I have had the WSW since 1999. Oh, it is the Red model. If someone lives near 03101 and could help me fix the damage, I will make it worth your assistance. I had an accident that ruptured two discs and herniated two more. This is the bad part about my accident I can not bend or reach for things like tools and reaching around things. If anyone knows what the best website would be to put the car on “For Sale” could you, please let me know. Thanx so much. I wish I found this website earlier. Contact me at lonrace@comcast.net thank you Jeff. It broke my heart when I crashed it. Now selling it will do the same.

Good Video 👍

Try timing @ 10 btdc

Check battery cables,ignition, plenum clean.

Anyone know where i can get a gauge cluster like that one or have any suggestions

I had 2 LB9's ... i beat the hell outta them .... it was an animal..... they need a nice modern 5.3

Mass air flow sensor

Need a good tune up.

Give the firebird the respect it deserves, and get it some good shocks . Get rid of that wood.prop.

Never mind