spuratic tach then P0300

[MilitaryTalon]

Alright I have been having this problem for a week now and can't quite chase it down.
At random times my tach starts acting up, i.e. jumping around then to zero. My ECU is still reading RPM's b/c my ECU+ is reading them strait from the ECU. Soon after the tach starts acting up I get a CEL P0300 (random multiple misfires) Then the car has no power til I clear the code. It comes back in about 2-3 miles of driving. I did notice today that when the tach is acting up and I push the clutch in it jumps to about 3k as soon as I release the clutch it goes back to 0.

Things I have done to trouble shoot:
BLT
Comp Test
replaced Power Transistor
replaced CAS
replaced plugs and wires


I have searched the site and cannot find any answers. Please help.

 

[tenn-gsx]

Do you have link? If so do you have a 6 bolt swap? If that is a yes as well them disable random missfire cel. The 2g ecu dont like the 1g cas. If you dont have the above setup then check the wires to the transistor and other ignition components WHEN you have the problem. If its a broken wire it may not show during testing except with a hot engine.

 

[MilitaryTalon]

Do you have link? If so do you have a 6 bolt swap? If that is a yes as well them disable random missfire cel. The 2g ecu dont like the 1g cas. If you dont have the above setup then check the wires to the transistor and other ignition components WHEN you have the problem. If its a broken wire it may not show during testing except with a hot engine.

I am running ECU+ and have a 7 bolt.

I checked the wiring on all the ignition I can see and get too: the transistor, coil, and plug wires.

 

[MilitaryTalon]

Alright let's start from the begining; where does the tach recieve it's signal from?

Come on guys help me out

 

[EclipticalGS]

dude, check your crank postion sensor, its a real biotch to get to on a turbo dsm. Unfortunately, that controls your timing to a degree. Then the CAS controls too. Without crank sensor signal, your car goes into null mode and is a slug!

here ya go....This code also plagues me on the highway once a week.



"P0300 Code - Cylinder Misfire
Technical DescriptionRandom/Multiple Cylinder Misfire Detected

What does that mean?Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.

A P0300 OBD code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.



SymptomsSymptoms may include:
the engine may be harder to start
the engine may stumble / stumble, and/or hesitate
other symptoms may also be present
CausesA code P0300 may mean that one or more of the following has happened:

Faulty spark plugs or wires
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Defective computer
Possible SolutionsIf there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open."

 

[rush2252]

If your car is bone stock no ECU swap etc. Check coil packs. Ive heard of the nuts fastening the leads vibrating loose. Also check if youve had the ECU out sometimes the plugs dont clip tite. If its a 97 I hate to say it but you could be a victim of CW. One problems with CW is the crank will eventually eat into the Crank sensor and you will have intermitent problems or the car will just eventually quit running.

I would start with the simple things then possibly pull the timing cover and check the cam and crank sensor.

Have you check the power transistor pack next to the coil packs?


Kolby

 

[MilitaryTalon]

Alright, I think I fixed the problem. When I noticed that the tach jumped around when I depressed the clutch as well as when I moved the shifter around, I kinda figured there may be a short in the wiring around the ECU. I was right I started shaking the wires around and I got an arc and the car died. So I pulled out the ECU+ and found a few naked wires and when one of them touched the frame piece it arced and killed the car. I covered all exposed wires and drove the car about 10 miles with no problem. I hope that was the entire problem.

Thanks for the input guys.