Hi, so I just bought a Camaro, I think it is a 88, I know for sure the motor and tranny came from an 1988 chevy silverado.
It is fairly cobbled together, I bought it with a miss. It seems a little strange of a problem. It idles fine, when I go over maybe 20 miles per hour it has a continuous stumble or miss. When I push the gas it smooths out, as soon as I back off it stumbles again. The idle has a very slight miss.
What is good, I swapped out coolant temp sensor, map, throttle position sensor, plug wires. Plugs look new, cap looks good, I am thinking maybe some moisture under the cap. Sprayed throttle cleaner all over, no change in rpm's. Fuel presure is good, as is filter. I poured heet in the fuel, no change.
I am not to sure about vacuum leaks, compression, maybe the throttle body is bad, dirty, injector spray looks good. Could maybe the fuel pressure regulator be going bad. I hope for something simple, I have not messed with the timing.
I am getting code 13, the kid I bought it from said it was giving a code 13(o2 sensor) for years. Anyone know what it could be?

 

It sounds like it's going lean and the code 13 supports that. Before you do anything else i would put in a new oxygen sensor. If you have headers or plan to get headers while you got it off convert to a heated O2, it's very easy and much better then the old 1 wire our cars come with and doesn't cost much more.

 

Do you know anything about the ECM and camshaft? If the PO just dropped the truck engine in then your ECM is probably having problems compensating for the different cam in the truck engine. Or if he swapped the cam for a different one, same issue. I ran into a similar problem when I rebuilt the engine in my 94 GMC Sierra. I swapped the cam and now I constantly get lean codes thrown at cruise and it stumbles at idle and off-idle.

 

Run the car in the dark with the hood up, look for spark leak.

Then mist with a spray bottle n look again.

 

I replaced the o 2 sensor, one wire purple. The emc is the one from the truck. It is somehow been switched as well.
When I take the air cleaner assembly off it smells of fuel, maybe it is typical, almost smells rich. But it could very well be running lean.
tonight I will actually pull all the plugs, checking each one.
I have been wanting to do the spark arcing in the dark check but I keep falling asleep on the coach before dark.
I took the egr off and it seemed to move pretty freely. Like I said, it idles fine, so I think the egr is okay.
I replaced all the wires, and I am thinking to replace the coil as well. I tried to get my meter leads down the coil but they would not fit.
Does this at all sound like maybe something to do with the injectors themselves. They are spraying in a good cone shape.
I did not see any obvious broking vacuum lines or wires.
This is getting frustrating, now I see why people sell there cars.

 

Have you checked the fuel pressure? If the engine is running lean, the ecm will try to compensate by increasing the pulse width of the injectors to add fuel. If the fuel pressure is not adequate the injectors will not have the fuel available to them and you get a lean condition. Has the fuel filter or fuel pump been replaced?

 

I replaced the fuel filter first, it was new and clean. I screwed a gauge dead to the fuel line at the throttle body, it read 15 pounds. There is no shrader valve so I used the plug method. I also put a cup under the fuel line and cranked, it filled the container fast.

 

Is this a TBI? If so...
Have you cleaned the TBI with spray cleaner, blast some cleaner into vacuum lines going to the TBI, pcv line, -thermac line, -brake booster line, butterfly, IAC, and spray linkages.
Is the code gone? did you disconnect battery for a few minutes to clear codes and allow system to re-orient itself after installing new o2?
Look for arcing on plug wires before you sell the car, make sure all are properly seated, no cracks or burns, not touching metal parts or surfaces.

 

yeah I cleaned the tbi, good, thinking of taking it off and really cleaning it. I am now wondering if this has to do with weak valve springs. Going to try and check that tonight. Ah pain

 

The fuel pressure regulator is on the back of the injector pod. They usually don't cause problems. The one on the TBI on my truck is from 94 with over
260K miles on it and its still holding pressure just fine.

Have you checked the IAC passage and pintle? They tend to collect all kinds of dirt/carbon and can cause all kinds of weird driveability issues.

Have you checked the EGR valve? Those trucks use a different style EGR than F-bodies do. The PO may not have connected it right or at all. EGR shouldn't be an issue at that speed, but if its opening when it shouldn't it can cause your problem.

 

Timing too far advanced?

 

I will check the idle control valve. I am going to pull the throttle body today, clean and throw a new base gasket on. I will post back.

 

cleaned up the idle control valve and replaced the base gasket. Is working much better but still a slight miss. I am thinking intake gaskets.