Bad Cpu Diagnosis

[turb0talon92]

i was just wondering what would be the symptoms of a bad cpu? any info would be greatly appreciated ty

 

[MyTGSX]

taken from the Vfaq on cap replacement:

A rapid clicking or chattering from under the dash. Usually accompanied with the engine stalling or losing power during the noise. This is the microcontroller going into reset over and over and over again due to a bad power supply. Every time it resets, it will turn the fuel pump relay on and off. This could also be a bad fuel pump relay, but not usually.
An usual smell that seems to come from the center console. Especially if it smells like rotten seafood. Consider that it could also be your heater fan motor, unless accompanied with a power loss or stalling.

 

[turb0talon92]

well my car just died on me one day, about a month ago, i was driving it and all of a sudden it wouldn't accelerate anymore then stalled out....then it wouldn't start back up....when i go to start it it sounds like something is missing, like theres no back pressure coming out of the exaust..its weird....i changed the fuel pump, checked if the CAS was loose, I'm getting spark,changed the fuel filter,and its not like the exaust is clogged,also the timing belt was turning fine, well i thought the cpu might be bad but i don't know..... i have an extra one i was going to try....any info would be great.... Ty

 

[MyTGSX]

if you pull the ecm, unbolt the 4 little screws and take the top off, look at the attached file, it shows a really bad cap leak.

if yours looks like this, replace it. Also once ya get it running, take it to autozone(or where ever) and have them do a Alt. test in the car, and have them look for AC voltage, anything over 2V AC and you can fry an ecu.

 

[turb0talon92]

well i changed the CPU today and the car is doing the same shit it was before....it has spark, changed the fuel pump,timing belt was turning,the CAS is not loose....its so weird it sounds like not everything is there when you try and start it....something is turning but something is missing.....there was no back pressure comming out of the exhaust......i don't know but its really stressing me out now so somebody please help.....Ty any info would be greatly appreciated....

 

[BISHILVR]

Your car probably jumped the timing belt. Just because the belt is turning does'nt mean that it has'nt jumped a few teeth. Physically take the timing covers off and check the cam and crankshaft timing marks align where they are supposed to. Check vfaq for the steps.

 

[Spyderman7]

Jumped timing gets my vote.Do a compression test,doesn't sound like you have any compression.

 

[turb0talon92]

thankyou for your help....i haven't checked yet because i have no garage and its been so cold....now if that is what happened doesn't that mean I'm going to need a new head?

 

[K_Hill]

If it has jumped time you could have multiple things wrong ( bent valves, scared pistons, etc. ). It is not going to be cheap to fix it. You will have to send the head to a machine shop to get it fixed. Plus all the parts and labor its going to be to fix it.

 

[BISHILVR]

thankyou for your help....i haven't checked yet because i have no garage and its been so cold....now if that is what happened doesn't that mean I'm going to need a new head?

Usually just some bent valves.

 

[Old Mitsu Tech]

When you can get it inside, pull the oil filler cap off and see if you see any movement while having someone crank the engine over.

No movement means timing belt has probably stripped the teeth off at the crank.

If it moves, remove the top timing cover and take a white marker and mark the timing belt. This is a reference point. Slowly hand crank the engine over via the crank pulley bolt and ovserve the belt for missing or damaged teeth.

If you find them, then there you go.

Replace the timing belt and associated components we've recommended in here before. I can give you the "list" if you can't find it.

Do a compression test to see if you are one lucky DSM'er who missed bending valves. It has happened so don't laugh.

Very few, but I would still do the belt first.

And finally if you've bent valves you at least know where you are at and can begin preparing for a valve job and timing belt job.

Good Luck