Thread: engine problems

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OK, I have a 350 Chevy motor with TPI. Had trouble with surging. Found return line from fuel regulator plugged. Fixed that problem. Now it seems that every time when I slow down really fast the engine shuts off. It's like turning the key off. I put the car in neutral it starts right up. I had the computer checked out and seems to be fine. Can't get a handle on this one. Any one had this problem? The car runs great down the road. It's just coming to a stop. Like off an exit ramp. I can kick the car in neutral and keep hitting the gas and sometimes it stays running. I want to thank you ahead of time. Because you guys usually come up with a cure!

Just out of the blue I'm thinking a fuel pressure problem, dirty filter/s, plugged fuel line, and maybe junk in the tank. If the car has set for any length of time with any amount of fuel in the tank and ethanol, that's trouble. Just my assumptions.

Checked that. Hooked up pressure gauge and drove around. Was perfect 42-45 lb. That's what puzzles me. All that is good. Replace the fuel regulator too. The car has not set around at all. Using Sta-bil 360 in it all the time. It only does it slowing down. Other wise it runs great down the high way.

Idle air components------------you need to check resistance of the throttle position sensor-----


also-just maybe-your by pass regulator system is out of spec----you said tpi--------- so I assume you mean the tunnel port from around 86-92???????????

Also do you have what year ecm? MAP, MAF, o2 sensors? timing set where?? Cam, headers, IAT ?

Sorry, late getting back. Checked resistance on position sensor with in specs. It's a 350 done by Street and Performance with 90 Corvette parts and sensors. Map just changed, O2 just changed, timing set when ECM tested, is perfect per computer expert. Even changed out the computer. No different Don't know cam, headers are Sanderson shorty.
Since Street and Performance are no longer in business can't get info from them. Even the expert on these systems can't figure it out. Car runs great other wise.

Back in the days when the tp engines were more popular---------It sometimes took a small hole in the throttle plate butterfly to allow enough air at idle-We generally used one of those step drills and started with a smallest hole------then we could easily step it up size little bit at a time----- you can do this on the engine if you are care ful-put paper towem under open butterfly------drill hole , remove paper towel -chips-

If you do eventually think you have gone too big-you can use a rivet to close hole and start over-----

Another way is to take a saw sharpening file( 3 sided) and file a notch in the edge of the butterfly going larger until it runs good enough-------
Make sure engine is up to temp---------

I will check and clean the IAC. I'll look into the hole drilling. But, it idles fine. It just happens on a accelerator off during an off ramp or quick red light. Kick the car in neutral and t starts right up again. Thanks this one is really weird.

Thanks will check it out.

Denny that is a great source of info AND on many subjects-----------

Thanks everyone. I'll look at it soon. Getting behind on Honey-Do list need to Catch up. Then back to car. LOL Appreciate all your help.

OK, here's what happened. The Idle control solenoid was in bad shape ( carbon build up really bad. So I replaced it. Well that was not the problem. I took it for a test ride. Upon letting my foot off the accelerator going down a steep bridge to make a left turn. It just went quite and stalled out. Same as before. Man , this thing is driving me nuts. Runs great until you let off real quick and coast to a stop.

I have a computer expert on Tune port and Corvettes. He's actually scratching his head. This guy worked for GM for years. The carbon build up was caused by the return line from the fuel regulator was blocked. Car was running down the road with 78 lbs. fuel pressure. Running really rich and surging. Fixed that problem and now runs great just stalls on deceleration. PVC is clear and vacuum port is clear also. No codes at all on computer scan. Says everything is normal. Crazy

We tried that fuel pressure did not drop steady at 42 lbs. I hang out the passenger window holding gauge. Thanks, guess I'll just keep at it. Have to find it some time I hope. LOL

I'm not sure how that like that work on your Chevy but I can relate to a problem I had on a 91 Dakota. It would do about the same as yours and it also had an idle solenoid but there was a temperature sensor in line with it and the ecm. The temp sensor was bad and once I changed it and reset the idle solenoid it ran fine. Don't know if there's something like that in your system or not.

Thanks I'll check that out. I'm up for anything at this time.