The 350 TBI in my truck gets a very lopey idle after the engine has been warm for awhile. Most of the time it idles fine. It seems to happen after it gets warm enough to "heat soak" the TBI. Is this an injector problem? I recently got a code 32 and replaced the EGR valve. I figured that this was the idle problem, but it still does it, but no more code. Like I said, it only does it after it gets "heat soaked", like when towing or stop and go traffic. Any Ideas?

 

I wonder if you might be having a problem with vapor lock, im not even sure tbi can suffer from that though.

Clean the IAC passage with some carb cleaner.


Im assuming the car is in good general tune, has had a recent tune up and all that good stuff

 

OH and check the injector spray pattern when its idling lopey... I had an injector that would crap out when it got hot once... that could definately be your problem

 

You may want to check your ignition module. A friend had trouble with his 92 RS 305TBI that seemed like a fuel problem. The car would start and run fine sometimes then it would die and not start again for a while(though it would crank). He also complained about the idle fluxuating too much. He took it to a shop and they diagnosed the ignition module and replaced it. He said it works fine now with no complaints. Sometimes what seems like a fuel problem ends up being an ignition problem. Hope this helps.

------------------
Shouldn't bother putting this but hey what the heck:
1988 Maui Blue Firebird 305 TBI stock (w/ 190,000+ miles and still running strong )

 

Yeah, it acts just like vapor lock on a carb. I'll clean the IAC passage. If that doesn't fix it I'll start checking the injectors.

 

Yeah, I'd check the ign module, too. They don;t like HEAT and if it regularly getting hot, it may be on its way out. Cheap to just get a new one, anyway...

 

Right on man, it seems like you have a falty fuel system but it turns out to be somthing like an ignition problem!!

------------------
91 camaro 305 Tbi(I love it!!!)
*Teal green
*z-28 Grille(red bowtie)
*Z-28 Fog lights
*tail light black outs
*limo tint
*Polished 16'z-28 rims(In side groves too)
*Flowmasters,flowtech headers with cut out
*K&N with dual snorkal ram air(in air dam)
*Accel,wires,cap,rotor,coil,rapid fire sparkplugs
*And all the free tbi mods
*B&m shift kit with hurst HotShift fuild and trans cooler
*Best Et 15.34 at 90 mph
*Neg traction and 2.73 don't help very much

Furture mods(Limited slip with 3.42s, mallory ignition box,ram air hood,and...........

 

When I just got started with the GM TBI stuff (around July 2000) I had a used module that would start hard cold (several cranks) but then at the touch of the key when it got warmed up. Weird. Replaced it and all is well. Replaced the pickup coil a bit later , too, and it ran/started even better!!!