Like the title says, I have been having a misfire, a good spark, a fouling of spark plugs and lastly even some detonation on certain sparkplugs. I have changed wires, spark plugs (twice due to fouling and detonating), o2 sensors, Pcms, got injectors cleaned and even got coils! I am now thinking it might be a crank sensor (crossing my fingers AGAIN!!). So I pulled my CPS out and now I want to check and see if it works, so how do I do that, I have a volt meter so if you know let me know exactly how. I would appreciate it, THANKS

 

believe it would have to be checked in the car while cranking....im not sure on the spec for the voltage meter. maybe someone else could chime in

 

I hope so!
But I doubt while in the car, Thanks

 

Bad or failing Crank Shaft Position sensors don't cause misfires at all, or fouling of plugs. Maybe a Cam Shaft sensor though.

Best way to check if the CSP sensor is the culprit....and for free. Go buy a new one and put it in. Crank it up and go for a drive. If it works keep it, if it doesn't fix it, return it for a refund. Just clean it off and tell them it doesn't fit because its been modified. Works every time.

If those symptoms that you have turn out ot be a bad or failing CSP sensor.....it'll be the first I've ever heard of that doing those things. What they do is make the engine shut off totally randomly....and the engine will crank and crank and not start, then all of a sudden start and run just fine for a bit.

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So the symptoms I have are more likely a cam sensor?

I will try the modified excuse

 

And man.....detonation is a whole other animal. Not many things cause that. Too low of octane is one....and running real hot and getting pre-ignition from hot spots on the pistons or cylinder walls.

Are you able to have codes read?
Do you have an SES light on?

If your engine is running that bad and you're not getting codes or an SES light.....you may have a PCM problem. When codes stop showing up when they should be = PCM problem.

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No SES lights, no codes, I already have aeroforce guages and show no dtc codes neither did my tuner using hp tuners. I have switched pcms with the same symptoms.

I just bought both sensors do we'll see!

I appreciate your chiming in too!

 

Well I changed the cam and crank sensors and still runs like ****!!

It keeps missing and fouls cylinder 5 and in the other bank it runs lean! WTF

 

You very well have a fried PCM.........seems like alot of that happening lately.

If you are not getting any codes or SES lights.....thats a pretty good indication of a bad PCM. Not for sure....but I had one fry recently and someone just yesterday posted that they had a fried one last week.

Could be a loose ground from the PCM to Engine block too, that'll make you misfire like crazy.

Clogged fuel injectors.....

Pop the two tops off the PCM pin strips and see if anything is burnt or discolored.

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I'm with bad PCM. Engine running how you described should have codes and a SES light going crazy.

 

No guys read my first post, I even swapped pcms with the same results!

 

If the root of the problem is a loose PCM-Engine Block ground wire you will just keep frying each new PCM you put in until you fix it. So it may be a loose ground somewhere or a short in the wiring harness coming out of the PCM, that huge pack of dozens of wires. The 4 PCM ground wires run through that and meet about 10 inches down the line and merge into one larger wire, that wire then goes to the back of the block and bolts on. Thats the one that came loose on me 2 months ago and fried my PCM. Put a new PCM in, AFTER I fixed the ground....and bam, perfect again. Before that half my engine would not fire, it was spitting , sputtering and backfiring.

And no codes at all, no SES light at all. Tech II read nothing.

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I would rule out dirty injectors I guess because both sides are having problems. That means rule out bad coils too.

Looks like PCM trouble.......but maybe its because of a bad wire(s) somewhere screwing up the works.

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I'm gonna check those ground wires tomorrow, thsnks for the inputs I really do appreciate IT!!

Thanks
Zeke

 

Best way to do it:

Start the engine and grab that wiring harness coming out of the PCM and move it all over the place, every direction. Then grab it further down the line and do the same thing. See if anything changes. It would be good if you had a Tech II connected while you're doing it. The Tech II I had connected when my mechanic was moving that harness saw it flickering and beeping as it picked up and lost the PCM signal continuously as he moved the harness. Same thing with the guy who posted yesterday.......they saw it on the Tech II coming in and out.

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Gotcha, my friend has that NEW Snap on diagnostic tool so ill do that then!

Thanks Ill keep you posted.

 

I know this is old but this is what my 98 is doing. Any update on this?!

 

Gotta love when people fix things and then don't bother to come back and post the solution.

 

I am a little confused, please help me out here. When replacing the crank sensor (if the old one WAS defective) would you not have to run the relearn process on a OBDII machine to correct the relationship of the crank sensor to the cam sensor?

 

The crank relearn is for "recalibrating" misfire detection. Engine still runs without doing the relearn, but misfire detection will be wrong.