Running very very rough

[Jackthesubieripper]

Hey guys, I just replaced my clutch and hooked up some nice valve cover breathers in place of the old brittle ones. when i put my motor back in the car wouldn't start.. i found that the wiring for the crankshaft position sensor was cracked and brittle, so i re-wired that. Now when i start my car it runs very rough and is shaking very badly with the rpms jumping all over the place. as soon as i give it throttle it almost stalls, making the misfires even rougher.. I have tried replacing fuel pump, switching coil packs, igniter.. and various other things. Bit i have never seen one of these cars start and run so poorly. really confused on what is going wrong. any suggestions appreciated! thanks.

[Jackthesubieripper]

And also was curious if that copper shielding around the crankshaft position sensor wires (on harness side) needs to be grounded. I know that the knock senor has a shielding wire that serves as a ground, is this the same??

[Legacy777]

The first rule in troubleshooting is to ask yourself, "what has changed between now and when everything worked ok". From your post I would say it's the valve cover breathers and the crank position sensor wiring. I don't think the valve cover breathers are the primary issue, but could be a contributor depending on how you have them setup. A question I have is, are these open vent breathers to the atmosphere or are they going back through the PCV system? The breathers should be "closed loop" and back to the PCV valve and/or inlet piping.

For the crank position sensor, what exactly did you rewire? The crank sensor generates very small voltages and is very sensitive to outside influences which is why the wiring is shielded. If you did not get the rewiring done properly it very well could be the cause of your problems.

If you can provide more details on what exactly you did for both that will help in troubleshooting.

[Jackthesubieripper]

Thanks for the reply! I hooked up the breathers just as they were before (back into the PCV system) and I made sure the camshaft position sensor (I meant to say cam not crank^^) wiring was done correctly and I shielded the wire to prevent any static interference. I have been doing some testing and found that I am only get 0.8 volts to the positive wire to the cam and crank sensors coming from the ecu.. not sure what could cause the low voltage. I highly doubt it is an ecu problem as the car sputtered out (just like it does now) but then went back to running normal.. this was a few days before the motor was pulled. I feel like if the culprit was the Ecu it would have stopped working, instead of an intermittent problem. I believe it has to do with ignition timing, something that could affect the voltage to cam and crank sensor.

[Legacy777]

Have you looked through the crank & cam sensor troubleshooting steps in factory service manual? If not, I might suggest doing that as that will give you appropriate ranges for voltages and resistances.

https://www.main.experiencetherave.com/ ... and_Elect/

[Jackthesubieripper]

Yes I have already checked all hostages an resistances and my resistance is to spec by my power is low. I'm starting to think I have a bad ECU but I am having trouble finding one that I won't have to wait a week for shipping on. Does anyone have an oem, revtronix, or rob tuned ECU for sale in the greater Seattle area on here?

[Legacy777]

If you're in the seattle area you may be able to find someone that has a spare or might be willing to try meeting up with you and swap for testing purposes

[Jackthesubieripper]

So I have replaced my ECU with a known good one. And just last night I found that the timing belt had skipped a tooth, so I got a new timing belt, tensioner and re-timed it. Still nothing! Are there any relays that could possibly let the cat run but as soon as fuel is applied cut out?

[Legacy777]

Do you know why the timing belt skipped a tooth? I ask because if it happened once, it could happen again if you haven't identified the cause.

The ECU controls the fuel pump relay based on the crank sensor input. If the ECU doesn't see a consistent input from the crank/cam sensor it could cut off those relays.