Hey people, I posted this on gEn. Tech but was hoping for some good responses from the TPI board...

First off my car is an 86 LB9/700R4 with its cat-back removed.

My problem is the car has a pretty rough idle while in N or P, and a VERY rough idle when its in gear. I mean its at about 400-500rpms and the whole car shakes a lot.

When the engine warms up (220* or so) the idle at Park becomes OK but it remains exactly the same when the car is in gear. To make problems worse it bogs off a dead stop and the engine is very reluctant to rev up.

I think I narrowed it down to these prolems, please tell me which is the culprit:
- The ignition system: The plugs havent been changed since I got the car, the wires were changed but they lay around for a LONG time before I put them in and might bad.
- I have a vacuum leak. How do I fix this? Tighten all the bolts and hoses leading to intake and manifold?
- Exhaust system: Either the fact that I have my cat-back off or that my cat converter is plugged (and rusted on)
- Lack of oil pressure
- Cracked head, explains idle getting smotther when engine heats up, expands, and seals the crack

Please please somebody help me, I have been trying to get this car streetable on a very tight budget and this problem just keeps tripping me up.

BTW IS 30psi of oil pressure too little or acceptable?

-Max

 

i can help u find a vacuum leak from experience that i had when i swapped to TPI. My car would idle pretty rough with the leak also. I went to the local parts store picked up a can of carb cleaner and sprayed some everywhere that there is a gasket. The car will rev a bit and smooth out the idle for a second if there is a vacuum leak where you are spraying. My leak was in my cold start injector. To fix it, your best bet would be to get new gakets from where ever you found the leak. If you dont feel like getting new gaskets, you can always try some rtv. Good luck and i hope this helps some. atleast it will give you a starting point

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*1989 RS
*Red, Daytona Turbo fiberglass hood, chrome 16x8 IROC wheels
*355 CID
*TPI ported plenum, SLP siamesed runners, Edelbrock high flow intake
*Edelbrock TES Headers (getting SLP 1 3/4 this summer)
*Richmond 3.73, Auburn Posi
*Modded 700-R4, 2800 stall converter
*NO recent time slips.

 

Thanks,

So you and a guy form Gen. Tech both say sounds like Vacuum Leak so I'm going to check for a vacuum leak today. IF anybody has any more opinions, plz respond.

 

If you have a vacuum leak that is substantial it will set a code 44. Make sure your manifold itself is tight (torqued to 40lbs) especially the center 4 bolts.

Check your airflow connections from aircleaner to MAF to Air Box to TB Bellows. Making sure the airbox has no cracks on the seams.

Definitely change the plugs.... wires if necessary as well as the 02, (check the 02 wire) and fuel filter.

Pull the codes and see if you have a 44 or 33.

 

Resently when my 383 was started for the first time it idled like ****. It was the Camshaft that was able to move a little forward and backward and caused the ignition to act strange.....

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GTA -89:Free flow muffler,dual 3" HF cats, Edelbrock headers, Vette heads, 1.52 RR 7/16, ZZ-9 cam, Big Mouth, AS&M LTR, !plenum, 52 TB, MSD 6AL, TPIS level V prom, Superior shift-kit and all the minor mods, a Canfield headed 383 in the works!! ready May 2001...ok..june...july..and with Accel DFI....looking for SR or miniram....
http://www.itv.se/tacs/members_cars/m279/m279.html (Swedish Trans Am Club)

 

man talk about scaring someone. your camshaft isnt walking back and forth or youd know it. what exactly is it doing? is id just idling at a certian rpm and then surging up (raising rpms then falling back down) or is it dropping rpm like it has a miss in it. first thing i would do is replace the plugs since its cheap to do anyways. then set the Idle Air Control if you havent already done so.

 

Thanks for the help,

I don't think I'm going to rip my engine apart fixing the loose cam before checking for simple problems first.

I did pull a code 33 but that was becasue I disconnected the MAF temporarily to see if the problem would improve.

This week I'm going to change the plugs, and put in the spare O2 sensor I ahve lying around. About the manifold bolts, won't I need to remove the plenum and fuel rails to get to the 4 center bolts?

-Max

 

Another thing, I read about adjusting the IAC and I was wondering where it is. Is that the thing on the TB between the DS runners that has a white metal cap on it?

Thanks for the help.

 

..courtesy of Vader

 

Another question, I get the connector off, but where is the actual Torx bolt I need to adjust to set the idle speed? Can somebody please post a pic or describe it for me?

Thanks,

-Max

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86 Trans Am LB9/700R4
-Flowmaster 3inch exhaust, K&N, Ported Plenum, Redone Ignition system

 

Never mind, I'm and idiot, I can't even read the friggin diagram.

-Max