I have an 84 Camaro that I JUST put a new motor into. It's an 89 355 TPI motor converted to speed density. I drove it this morning and it ran great. Filled it up with Amoco premium and drove it home. Next time I started it up, it idled like complete crap. It was very rough and the engine keeps "surging" - fluctuating between 500 and 1500 RPM, keeps going back and forth. I put it into gear and started to drive. It was still running crappy. Half way down the street and it dies. It starts fine, but continues to run like crap. Everytime I would either touch the gas pedal or shift it into gear, it would die. I FINALLY got it into reverse and got it home backwards. I didn't even touch the gas on the way home, and the car continued to surge.

My first thought was low fuel pressure. Nope, after checking it, it was okay. Then I thought it could be a batch of bad gas. So I took the tube from the pressure tester and dumped some gas into a jar. The gasoline has not separated or anything - it appears to be okay. The strange thing is that sometimes it will start up and idle great for about 5 seconds, and then start running like crap. By the way, the check engine light has not come on.

Does anybody have ANY other possible ideas?? Could it be one of the injectors?? ANY help would be greatly appreciated. I want my car back! Thanks.

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1984 Camaro Sport Coupe - 73K Miles, Rebuilt 355 TPI L98, Crane 2032 CompuCam - 214/220 @ .050", Crane adjustible fuel pressure regulator, custom burned PROM, stock TPI intake, gutted air box with K&N filters
F41 Suspension Package, 700R4 Tranny, TCI Breakaway torque converter, 3.27 Disc Brake Posi Rear
Hooker Shorty Headers, Catco High-Flow 3" Cat, Flowmaster 3" American Thunder Cat-Back
New Paint
Best 1/4 Mile Run (with old LG4 motor):
16.760 @ 80.74 MPH

Coming Soon:
Aluminum Drive Shaft

 

possibly EGR, is it throwing any codes?

 

Nope, not throwing any codes. Thanks.

 

X84,

Make sure the MAP sensor is connected directly to a source of manifold vacuum. Test the MAP resistance with an ohmmeter and hand vacuum pump.

Scan for DTCs anyway. There may be some pending codes that have not set the MIL lamp yet.

Does the engine runn better with the EST bypassed?

Does the engine run better with the ECM in a forced backup fuel mode?

What is the fuel pressure at idle? What is the TPS voltage?

Just some random thoughts.

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

Well, I found the problem. One of the injectors is screwed. I unpluged the injector from the harness and the car ran fine with 7 cylinders going. Thanks for the ideas.