This is my first post. I have been reading the board frequently for a while now. It seems like you guys realy know your stuff. This little problem has been driving me nuts for a while now. When the car is cold it is hard to get it to idle( it likes to die alot). When I try to take off from a dead stop the car boggs down and then suddenly kicks in it also does this if I just jab the gas be it while driving are out of gear. At around 3000 rpms loud popping can be heard coming through the exaust. At full throttle the car seems to surge. It does not trough any codes. I have had some friends that work up at the chevy delearship take a look at it. They put it on the scope and tech 1 and could find nothing wrong with it. This has done this now on two different engines. My first engine consisted of stock bottomend, miniram, afr 195's, tpis zz409 cam, and all the bolton. The second is a stock crate motor from GM for a 93 caprice. It is stock execept for the addition of a slp cam i had laying arond I believe the specs are somthing like 207-212,480-487. I put the miniram on this motor along with all the boltons. Then car seemed to run fine on the new motor untill it hit about 400 miles on it, then the problem crept back up. The first engine took an early leave to the grave because of a dropping valve. I have tried changing the tps sensor, mass air flow sensor, ignition module, and swapping compurters and proms. If someone could please figure this one out for me I would appreaciate it.

Thanks



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1989 Irocz
350 T-5

 

Stock,

Welcome to TGO!

It sounds like you need to start at the top and eliminate all the general possibilities.
Afterfire (exhaust popping) is commonly an intermittent ignition of rich mixture problem, but could be late timing. A worn distributor could also cause inconsistent ignition, and some of your symptoms.

Cold idle problems could be due to mixture, timing, or low vacuum. The control system could also be out of adjustment. TPS setting, minimum air position, a clean IAC, and good vacuum are things to check. A faulty CTS can really confuse your ECM, too.

There are many possibilities. Do the spark plugs indicate a rich condition?

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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
Adobe Acrobat Reader

 

I havnt checked the plugs on the new engine yet. I will do that tommorow. I did however check the plugs on my old engine when it had the same problem, they indicated a slightly lean burn. What on the distributor would wear out, I replaced the distributor cam gear when the new engine went in. You may have to clarify a few thangs for me cts? control system? minimum air position?

 

CTS= coolant temperature sensor, I replaced mine and made a huge difference.

You problem sounds like the one I was having. Inconsistent no idle, and dying. When I would hit the gas, it would bog down and then kick in. It ended up being a bad fuel pressure regualtor, it was pushing extreme pressure, and the injectors were pouring, instead of spraying when they opened up, and a few of them died completely on me. So I found a used set here at TGO and a new regulator, for about 75 bucks, no problem since. Runs great. Might check your injectors if nothing else works. Just an idea. I am no mechanic, but me and my dad, with assistance of a Haynes manual and the great people herre at TGO, did the injector replacement ourselves. No biggie, just took a little time. Hope I am some help. Also, the dealership here in my town had to unplug each injector and use an ohmeter to measure ohms. They said they should read about 16, i had one at 3 a couple at 12 and so on. You can do this yourself if you have the meter

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1991 WS6 Trans Am
Medium Green Metallic
Beechwood interior
305 TPI
TH 700-R4, Auto
T-Tops, PW, PL, PM
Keyless entry, alarm
Flowmaster Muffler
Monza Dual Tips
K&N Filter

[This message has been edited by ADMZ24 (edited March 22, 2001).]

 

I have tried two different sets of injectors, no change. My fuel pressure regulator is the tpis billet one that came with the miniram. Fuel pressure seems to be good.

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1989 Irocz
350 T-5