What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

350 tbi dies/stalls at idle/ shifting into reverse

AugustDiesel said:
Sorry for asking dumb questions...
Click to expand...
Look, one day when I'm working with a diesel, I'm going to feel entirely lost and have to ask the most basic of questions. It's conceptually similar but I feel entirely lost when looking at something that isn't a gas motor. You not being familiar with a late 80s fuel injection system isn't remotely dumb.
 
The_Tomato said:
Look, one day when I'm working with a diesel, I'm going to feel entirely lost and have to ask the most basic of questions. It's conceptually similar but I feel entirely lost when looking at something that isn't a gas motor. You not being familiar with a late 80s fuel injection system isn't remotely dumb.
Click to expand...

Lol thanks. It’s not limited to late 80s fuel injection motors. Anything that uses a carburetor or gas and I’m totally lost. Even with my weed eater, which is currently dead.
 
MPC-8212E-DS
Wes Harden said:
When you pull the IAC have a wire pipe brush on hand and a couple can's of brake/carp clean. there is a passage the IAC pintle opens and plugs, it gets sluggy so you will want to clean it. Also the use the brush on the throttle bore near the throttle plates that gunks up too.

I fact it may be your problem. If it were mine I pull the TBI off, clean the throttle bores the IAC passage and pintle. Put a drop of light machine oil on the pintle plunger threads.
Put it on start up truck let it get warm, then re-snuge the TBI bolts.
It really is a simple system. Keep a clean fuel filter inline, good cap and rotor, weakest link in my opinion. The truck will run well for years.
Click to expand...
Don't remove tbi unit unless you have a new gasket. They are pretty flimsy.
 
Is the idle adjuster plug still present? I didn't see where idle RPM has been mentioned yet... Having replaced the IAC I'd still do the "minimum air" adjustment regardless of plug presence, especially since it's still stalling. Free, easy, could help. Definitely won't make it worse.

https://itstillruns.com/reset-baseline-idle-gm-tbi-7959677.html
 
Did you ever figure this out? If not take the vac line off the egr plug it with a golf t or bolt ect... and re test. had exact same issues and that solved it for me. I dont need egr i left it that way occasionally get a check engine light but thats it. Give it a try.
 
mrgoodwrench said:
Did you ever figure this out? If not take the vac line off the egr plug it with a golf t or bolt ect... and re test. had exact same issues and that solved it for me. I dont need egr i left it that way occasionally get a check engine light but thats it. Give it a try.
Click to expand...

Sorry for not responding sooner. Haven’t figured it out yet. Truck went to the paint shop for 4 weeks and been spending time on my truck as of late. But - it hasn’t died on us yet. It idles rough still, though.
 
Before i did my LS swap, my old TBI 5.7 would turn off in gear idling. Through some general maintenance (Spark plugs, wires, cap rotor) i found that the distributor shaft had some of what I perceived as too much slop and slide to slide play. I finished the tune up, and left the dizzy as it was, and the blazer continued dying on me in gear idling. I ordered the distributor, when it came in, it had next to no slop in it. I dropped it in, set the timing as per service manual (wire unplugged and set to 0*) and my problem was solved. i believe what was happening was the pickup in the distributor would lose signal at low rpms because of the slop, and would turn off, but would somehow center itself at higher RPMs, or maybe even engine inertia kept it running when it would lose signal at higher RPMs, but would catch itself and stay on. I'm not entirely sure. Ultimately, it ran great for years before i swapped my current 5.3 in it......Food for thought
 
Thanks for all the ideas. I’m compiling a list:

- plug the egt vacuum line
- replace the fuel filter
- adjust the timing
- replace the distributor

These are the ideas y’all have given me that I’ve yet to try. Time is short, but as time allows I’ll give them a shot - one at a time - in that order to see what makes a difference.

Right now the truck seems to be running fine. Hasn’t shut off on us in months, just seems to idle rough. Doesn’t mean it’s not worth investigating, though.

Thanks again.

Andy
 
Yes the distributors for 90's gm were/are crap, early vortech engine had crap distributors too.
Normal gm parts doesn't even list the complete dist, you have to order all the parts and assemble it yourself.

However gm performance did have the complete distributor, I kept 3 in stock at all times for my little 2 man shop with 240 units to maintain.
 
Wes Harden said:
Yes the distributors for 90's gm were/are crap, early vortech engine had crap distributors too.
Normal gm parts doesn't even list the complete dist, you have to order all the parts and assemble it yourself.

However gm performance did have the complete distributor, I kept 3 in stock at all times for my little 2 man shop with 240 units to maintain.
Click to expand...

I halfway want to bet this is my problem.

My wife mentioned the truck’s engine seemed to feel kind of week driving around. I’ll have to give it a spin to see if I sense the same thing. I am leaning strongly towards taking the truck to a mechanic my father-in-law recommends has had good success with his gmt400. Will see how she drives over the next few days.
 
I have been having the same issues on my 91 TBI 5.7. It seems to idle low in gear at stop lights. It has stalled when pulling into parking spots and also switching from drive to reverse or at idle and turn wheel to full lock. I just got this one and have replaced the fuel filter as well as the plugs/wires/cap/rotor. Otherwise has been great to drive. I will be trying these suggestions and report back.
 
I finally just took the truck to a trusted mechanic because I just don’t have the time to figure it out. First he tried swapping in ACDelco plugs and wires and he also turned up the idle speed. Those two things, while beneficial in general, didn’t cure the problem. Idled smoother but still died at idle. He then cleaned out the Idle Air Control valve, and says he’s certain that fixed it. I had replaced that already, but, reading back through this thread I see there was something I should have cleaned at the same time and I don’t remember doing that, so maybe the mechanic did. Only time will tell. He did inspect the distributor and said it had some slight play, but not enough to cause these problems.

We will just drive it and see what happens. I’ll make sure to post up an update after we’ve had some time and miles on it.

Andy
 
AugustDiesel said:
I finally just took the truck to a trusted mechanic because I just don’t have the time to figure it out. First he tried swapping in ACDelco plugs and wires and he also turned up the idle speed. Those two things, while beneficial in general, didn’t cure the problem. Idled smoother but still died at idle. He then cleaned out the Idle Air Control valve, and says he’s certain that fixed it. I had replaced that already, but, reading back through this thread I see there was something I should have cleaned at the same time and I don’t remember doing that, so maybe the mechanic did. Only time will tell. He did inspect the distributor and said it had some slight play, but not enough to cause these problems.

We will just drive it and see what happens. I’ll make sure to post up an update after we’ve had some time and miles on it.

Andy
Click to expand...

If he was messing with the idle, my faith would be shattered in his abilities. You don't mess with the idle on these unless you are adjusting minimum air. Screwing with the idle adjustment screw simply makes the computer "fight" the IAC, since the ECM specifies what idle RPM is (or should be).
 
dyeager535 said:
If he was messing with the idle, my faith would be shattered in his abilities. You don't mess with the idle on these unless you are adjusting minimum air. Screwing with the idle adjustment screw simply makes the computer "fight" the IAC, since the ECM specifies what idle RPM is (or should be).
Click to expand...

I’ll admit I haven’t been impressed with the fact that he hasn’t come up with anything new.

It could be that he adjusted the minimum air and that’s what he was talking about. Because I remember mentioning to him in a phone call several months ago the idea of turning up the idle speed and he said exactly the same thing you did.

So something could be getting lost in translation here.

Either way, the experience, while the best I’ve had with mechanics, reminded me of the pain points of dealing with mechanics, so if this issue doesn’t go away, I’ll return to my efforts to fix it myself.

Andy
 
Rather than buy a whole distributor, if you can get a new AC Delco pickup coil, that may be worth a try. The lower the RPM, the weaker the signal. Of course the module could be equally to blame.

I also wonder if you just have bad wiring or a poor ground connection off that coil. Shifting to reverse is basically identical to dropping it in drive, from a load standpoint, but it does move the engine in its mounts differently.
 
You must log in or register to reply here.

Latest Posts

Top Bottom