3.2L running rough after rebuild
 

I recently rebuilt my motor and upon starting, it runs very rough (idle and higher rpm) like it's missing on a couple of cylinders. I have a couple of ideas of what could be happening, but wonder if anyone has experience with this. I am afraid that I may have the had mixed up the Z1 mark (there were two marks close together) when setting the timing.

I drove the car and it has very little engine breaking which seems to suggest that the timing is off. If this is the case then the timing is set some number of degrees before TDC.

The other idea is that the fuel pressure is low, but I don't think it would run rough at all rpm ranges like it does.

Does anyone have any suggestions?

Eric

Ignition timing is the easiest thing to correct, I would start there. The 5 deg mark is clockwise after the Z1 mark. If it does not improve things, I would pull the injectors one by one and make sure they all spray well. Was anything done to them? Are you sure your firing order is correct too?
My car (3.0L) was also running very rough just after rebuild. Now, after new fuel pump, new fuel accumulator, new fuel filter and correctly set ignition timing, it is purring like a kitten...

Good luck!
Aurel

It could be the chain timing. The thought of reopening the housings doesn't sound fun but it's a good possibility if all the exterior simple fixes aren't solving it. Each veh. year has it's own time settings. As to correct TDC. Z1 should be marked on your belt pulley just below the correct notch of the 2. TDC is easy to check by following the #1 spark plug wire to the top of the destrib. cap. If you are at TDC the rotor will be pointing to that lead wire where it attaches to the cap. I always buy new plug wire for a build with the metal mesh. Some people don't realize the mesh is necessary to prevent electrical arching between wires and surrounding metals. It also can be simple as getting a new fuel filter. Good luck to you.

Thanks for the input. You make me fell like I'm headed in the right direction. I guess I should have told you my car is a '86. In the rebuild, I installed new ignition wires, plugs, cap and rotor, and fuel filter and flow matched injectors. I have not changed the fuel pump, but it was running fine when I started the rebuild. However, I probably should check the fuel pressure to make sure it's not low.

Since starting the motor, I have rechecked the firing order and that looks OK (all the right wires on the right plugs and distributor ports).

I think the inevitable thing to do now is check TDC on 1st cylinder. Then I will remove the intake valve cover on that side and check the valve opening at TDC to see if I messed up the original timing by selecting the wrong mark on the pulley. If so, can I perform the timing procedure in the car, it looks like I may be able to, am I correct? The image is right before I put the motor in the car.

Thanks,
Eric
http://forums.pelicanparts.com/uploa...1213046089.jpg

Eric,

Another possible area to explore:

I recently had issues with my reference sensors, I replaced them and after installing them, the engine ran poorly including missing and popping. The engine has about 3,000 smooth running miles on it since the rebuild, so I checked the gap between the sensors and the flywheel and there was too much distance. I moved them closer and the engine ran like a top.

Good luck.

Than

You can not adjust timing on a 3.2 - this is done in the Motronic. Just make sure both sensors are mounted correctly at the bell housing. I would guess intake vacuum leaks, poor valve timing, or crossed ignition wires....

Im not sure if it is possible with stock lines, but make sure that you dont have your fuel lines (pressure and return) mixed up. Ive seen this before and it runs like a fresh bag of dog crap.

Thanks for the continued suggestions. I have rechecked the reference sensors and they appear to be OK. As I was preparing to readjust the valve timing, I removed the spark plugs and noticed that only 2 of them appear to be used. Cylinders #1 and#3 have the normal insulator discolorations from use. The remaining 4 plugs are very clean looking and #2 looks brand new. They do appear to have fired electrically, but they have not burned any fuel. I have replaced all of the fuel lines (old ones leaked), but did not replace the fuel pressure regulator.

Will the injectors operate if the fuel pressure is too low?

I need a fuel pressure gage, where do I get one to fit the Porsche connector port?

Eric

Eric,

I do not know the answer to your question, but if two injectors are firing, I would be inclined to check the four that are not. Do you have access to extra injectors?

Can you swap a firing cylinder's injector for a non-firing one?

I had one cylinder that did not fire on my rebuild and it was one of the freshly rebuilt injectors. I may have had them sit too long after that were rebuilt.....

Good luck. Sounds like you are narrowing the possible issues.

Than

Hi if everything check and still run rough , two things worth to try remove the battery terminal both + AND - and connected together ( hold by your hand approx 1 min) and also check terminal wire connection ie corrode etc and good ground stripe. good luck.

Your fuel injectors may be frozen up. Mine were after sitting for about 6 months, even after being reconditioned. Rap them lightly with a small ball peen hammer on their body, and see if it helps.

double check that one of the cams is not 180 degrees out... it happened to me and has happened to others.. very embarassing.. ran rough and had low power.. was amazing it ran as well as it did

All of the my problems we fuel related. I had not replaced the fuel pressure regulator and damper when I replaced all the fuel lines. So I replaced them and It ran better but still missing on #2 cylinder. I checked the injector and it was not firing, so I tried hitting it with a small hammer with no luck. I then removed it and worked on it with some carb cleaner and WD-40. It eventually started working and I installed it. The result was a smooth running engine and lots of joy.

Thanks for all of the suggestions and ideas to help solve this problem!

Eric

that is such a good feeling when you find the root cause.. congrats.