i got a g20 van with a 350 tbi that drives me crazy. i am throwing a lean code but cant figure it out.i clear it out and about 100 miles it comes back on .it runs alright but every once and a while the idle surges up and down. i got to run 89 octane or it runs like totall crap.i have replaced o2 sensor ,fuel filter, checked fuelpressure rebuilt trottle body ,regulator and injectors,temp sensor and cleaned egr valve. it seems to run great when cold outside but if its hot out runs like totall crap ,sluggish and rough. i also hooked up a vacumm gauge no leaks,bad valves, gaskets etc. what gives its driving me nuts about to just give up on it and sell it.
fuel injection help
- Thread starter gwhiz
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Which temp sensor did you change out? The one in the head or the one in the intake? The one in the intake is for the computer and is commonly corroded, same with the wiring connector for that sensor?
You wont be able to get the surge out. You can change everything on the motor and it still will. I owned a cammed 355 tbi in my monster blazer. I changed everything. Still does it. That was the downfall on these motors. Good luck if you want to spend the money changing every little part.
79malibubbctt said:
X2 i basically rebuilt the whole top end and still had all the surging on a 91 Chevy truck... performed a compression and everything was good. replaced tbi, fuel pump, sensors, cat, etc etc basically everything!! i hated that truck with a passion
I still never figured out what was actually wrong with it. WORSE part is that none of the other mechanics wanted to touch it and my boss just tossed it to me!!! It would surge when cold and then clean up a bit once warmed up. But when taking off at idle it would buck and and act like it was starving for fuel. once it got going it ran like champ!! :| they told me to redo the heads but still nothing i did fixed it..... OH well glad it's crushed now cuz it was a registered off the road truck and and couldn't be used on the road. The company i worked for just salvaged it when the went belly up :lol:I have lost all faith in gm fuel injection.over the years i have had dodge and ford trucks with higher miles and less problems in fact i had to junk or part out because they rotted away but still ran like a top. IMO any gm motor after 85 is junk. never had these problems with old school carb motors. all my older gm cars never gave me fits other than carb rebuild here and there. they dont make to last anymore just last long enough to pay them off and their worth barely more than scrap. 
yeah pulled the old one out and cleaned and tested it .tested or replaced all sensors and cleand connecter with qd electric cleaner and apllied dielectric grease. every thing is in specs and in good condition.ran copression test and vacumm test and even added extra grounds . just makes no sense.
I said that you can change everything and it wont fix it. You could replace the whole motor like i did abd it still does it. Only thing i didn't try was a new ecu.
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