Car back to stock: Running issues ensue
 

So my 92 is back to stock, and just about buttoned up. I am having issues with the car running SUPER rich, and throttle input does not make the car rev at all. Let me begin by going over the modifications that were done.

1) I had cut off the afm connector when I went Adaptronic. I used the stock wiring there for the GM MAP sensor. The MAP has been removed and the AFM harness soldered back in. 2) I had cut 1 of the grounds at the IM because it caused a GND loop wit hthe CLT sensor and the Adaptronic on the 1.6. That has been reconnected and soldered. 3) The stock O2 had been removed and and connector was cut when the car was modified. Since then a new Bosch single wire has been installed and soldered directly into the harness.

When I start the car it starts instantly, like a new motor should. It runs rough and will die without a little throttle input. When mashing the throttle, the RPMs do not change and the car will die after a second or two. I have been over all the AFM wires and they are all soldered back in color for color. When I pulled the plugs they were wet as hell and stunk of fuel. When forcing the motor to "idle" (if thats what it can be called), and then shutting it off it reaks of fuel as well. Obviously my issue is fueling related somehow, I'm just at a loss right now because everything that was removed or cut has been put back or resoldered back to stock.

My questions are a few. 1) Even though all the wiring diagrams I look at show the 2 Black/Lt Green wires on the AFM connecting both inside and outside the AFM, is it possible that hooking them up backwards would cause my symptoms? 2) Is my issue of the motor not revving with throttle input directly related to the AFM? What would cause that?

Brian

Brian,
Check the injector harness for a bad ground, or ground wire contacting frame, other wire, bare wire etc. Sounds like your injectors are staying open flooding the car. Grounded injector will cause this. All it takes is a single wire from the harness hitting metal.

Any modifications to TPS or CAS wiring?

Frank

Yep sounds like it's possibly the afm giving max flow as opposed to min flow. I had a similar problem with a freinds car that had a crack in the vaccum hose going to the FPR and it was giving way too much fuel at anything under wot. I'm not sure why it would bog and die when given some throttle.

No, those are stock/never modified.

I'll check the FPR vac hose tonight, I'm pretty sure its hooked up, but at this point I don't know wtf I'm missing. So its possible.

I'll also double check the injector harness to make sure that there are no exposed grounds.

Well the inj harness is from a running car, so I think its ruled out. I'm going to test another stock ecu tonight as well to see if that might be it.

Is the AFM a mechanical gate in a 92? Is it jammed in one position? Is there a rag in the pipework?

It is mechanical, but it is from a running car, nothing stuck in it. I've also tested a AFM from another running car.

Try testing the AFM signal at the ECU and see if it's reading correctly. Check it when off and at idle and you should be able to tell.

Probably a stupid question, but they are the right blue top injectors, I'm assuming?

Yes, injectors are stock.

Hold the afm open and see if it changes anything n

If I can get it to run long enough to try that I will. I would have thought that mashing the gas with it running would swing it open though.

Not it doesn't have pressure, huge intake leak or spring too tight/loose. Just have someone start it, and play with the throttle car and flap, see if anything changes.

SO... I went back to work on the car again after work, 2hr round trip :(. Pulled out Lars's ecu, put in my car, no starty. Double checked ALLLLLL wiring. Everything looks exactly like his stock 92. Untaped the AFM splice, desoldered both black/lt green ground wires and swapped them incase that might be it....Nothing. I finally just called my buddy Braineack and he didn't really have a clue either. On a whim he said to just try putting the CAS all the way to one side, try it, put it to the other side if that doesnt start, and try it. So I loosened it and turn it all the way to the passenger side, and proceeded to start up the car. VROOOOMM, car started right up, running a little rough, and reved with throttle.

Immediately I thought, the timing belt has to be off. The CAS was never touched at all when removing the head from the blown block and then being installed onto this rebuilt shortblock. So the timing shouldn't be more than +- a couple degrees. Well I took out the intake, WP pulley, VC, etc, and put piston #1 at TDC. Intake cam looks good, E on cam pulley matches up with E on cam plate, CHECK. Next, Exhaust cam looks a little strange.....HOLY FUCK, its turned about 5 teeth too far counter clockwise..... So I fixed the tbelt, put it all back together, turned the CAS back to where it was originally (I marked it, I so smrt). Fired right up, purring like a kitten, revs freely, not leaks anywhere, great OP. I went ahead and held it at 3k for a minute and let it warm up a tad, then gave it high revs with quick throttle closes to seat the rings.

How the timing got off that much is beyond me. Lars and Scott can both attest that the timing was on before we dropped the motor in, they both verified it. My guess is that as much as Lars has been complaining about me being in his garage so long he secretly has been sabotaging me. So I'm going back again tomorrow after I ship a long overdue torsen to a member, and buttoning it all up so that I can drive it home on Saturday when my brother is coming up to visit and can drive my other car home behind me.

I'm so fucking sick of working on this car....

Brian

Glad to hear you sorted it. I suppose all the unburnt fuel on the plugs was from all the cranking needed to try and get it to fire up at all..hmmmmm....misleading. Noted for future reference