P300 and P0340 while cruising?

[Kooldino]

This is the second time this has happened to me, and both times were in the past 2 months.


Incident #1 (a month and a half ago)
I'm cruising down the highway at 75-80mph. I glance at my WBO2, and notice that I'm running a 13:1 AFR, though I'm at light throttle and off of boost. I am NOT adding fuel via extra injectors in this state. Eventually, out of nowhere, I get a flashing CEL. I recall a P300 (random/multiple cyl misfire) and perhaps a P0340 (Camshaft Position Sensor Circuit Malfunction). I hook up my laptop and noticed that at the RPM and TPS I may have been running, that I was pulling timing. So, I put the timing back to stock in that area, since I was not on boost during that time anyway.

I've noticed that when you pull timing with the MPI, the car tends to run richer with the same amount of fuel. I figured that since I was retarding timing, that explained the rich A:F ratios. To top that off, I'm running 8.5:1 compression, so I'm probably not getting as much of a burn as I would with stock compression.

At that point, I figured the problem was solved.

Incident #2 (this morning)

I was running the car for about 10 minutes, and I was on the highway. I'm cruising down the highway at 75-80mph. I was not paying attention to my WBO2, though I'm at light throttle and off of boost. I am NOT adding fuel via extra injectors in this state. At complete random I notice a flashing CEL. P301 (cyl 1 misfire), P300 (multiple cyl misfire) and P0340 (Camshaft Position Sensor Circuit Malfunction) again.

What could be causing this issue? The car drives fine, and the only thing I notice is a flashing CEL. No funny noises, no bucking, nothing weird like that.

Is there a chance that my Camshaft sensor is screwed up?

Could the wiring of the MPI affect this? I forget if it takes the cam sensor signal or not. Or perhaps something that would affect what the cam signal should be (ie, the crank sensor?).

For all I know my plug gaps could be screwed (which I'm about to go check), but I figured I'd come get some ideas.

Also note: my EGR is completely blocked off.

 

[Bigg Tim]

The MPI doesn't do anything with the cam sensor. Did Nick K. have you try anything with the cam sensor way back when? That does seem very odd, how old are the plugs??? I wouldn't think the plugs would cause this, but I'm no mechanic.

 

[Mr. Win]

Is there a change that my Camshaft sensor is screwed up?

my geuss other people have had them go bad... its put mp5jeffs car outta comission.

 

[Matthew]

i got the misfire code at high speeds before i turned down my fuel press...seems to be gone, though i still have a rich code. im at my wits end with it.

 

[acidbug]

Sounds like that new intake cam you put it might be causing some problems..

Might wanna check that out!

chas

 

[Bigg Tim]

Sounds like that new intake cam you put it might be causing some problems..

Might wanna check that out!

chas

Oh yeah, I forgot about that. You might want to make sure the sensor did not get damaged.

 

[Kooldino]

The MPI doesn't do anything with the cam sensor.

Right, but does it have something to do with the crank senor, or any sensor that has the cam sensor as any part of the equation?

Did Nick K. have you try anything with the cam sensor way back when?

No.

That does seem very odd, how old are the plugs??? I wouldn't think the plugs would cause this, but I'm no mechanic.

These plugs are from this summer.

 

[Kooldino]

my geuss other people have had them go bad... its put mp5jeffs car outta comission.

Wait...MP5Jeff's cam sensor went bad? When/how? What were the symptoms?

 

[Kooldino]

i got the misfire code at high speeds before i turned down my fuel press...seems to be gone, though i still have a rich code. im at my wits end with it.

That's because your car was so rich it wouldn't fire properly.

 

[Kooldino]

Oh yeah, I forgot about that. You might want to make sure the sensor did not get damaged.

How in the world would an intake cam change how my cam sensor picks things up?

AFAIK, it's picking up a signal from the cam gear, not the cam itself.

Furthermore, AFAIK, it picks up the signal from the EXHAUST cam, not the intake cam.

I could be wrong with that, but assuming I am right, I don't see how it's even remotely possible that the intake cam has anything to do with it.

 

[acidbug]

Did you have there CEL before the intake cam install?

Or they recently..aka after you installed the cam?

chas

 

[Kooldino]

Did you have there CEL before the intake cam install?

Or they recently..aka after you installed the cam?

chas

I had the same issue last year before I switched over to the new plugs. At that time I had a stock cam. I appreciate you trying to help, but unless you show me a scientific reason why my intake cam would cause this, then please drop the intake cam idea.

If you saw how the cam timing pickup worked, you'd realize why changing your intake cam would have nothing to do with it.

 

[acidbug]

I was just thinking of a scientific law..forgot the name..but it goes somethng like this..

"The easiest answer is usually the right answer"

 

[KzA]

I had the same issue last year before I switched over to the new plugs. At that time I had a stock cam. I appreciate you trying to help, but unless you show me a scientific reason why my intake cam would cause this, then please drop the intake cam idea.

If you saw how the cam timing pickup worked, you'd realize why changing your intake cam would have nothing to do with it.

I think what they meant by the cam install was that maybe the cam sensor was damaged during the install...At least thats what I took from this...

Check the cam sensor..it wont hurt..

 

[Kooldino]

I was just thinking of a scientific law..forgot the name..but it goes somethng like this..

"The easiest answer is usually the right answer"

And how is the intake cam the "easiest answer"? Again, as far as I'm concerned, the intake cam has nothing to do with the pick up on the exhaust cam gear. Anyway, enough about that.

 

[Kooldino]

I think what they meant by the cam install was that maybe the cam sensor was damaged during the install...At least thats what I took from this...

Check the cam sensor..it wont hurt..

Yeah, I'm going to go ahead and replace it just to eliminate it as a possibility.

 

[Bigg Tim]

I had the same issue last year before I switched over to the new plugs. At that time I had a stock cam. I appreciate you trying to help, but unless you show me a scientific reason why my intake cam would cause this, then please drop the intake cam idea.

If you saw how the cam timing pickup worked, you'd realize why changing your intake cam would have nothing to do with it.

Damn dude, you ask for help and people try to help. You come back with "where's the scientific reason" WTF!!! If you don't think the help people are offering is good enough then don't ask. If you don't think that's it, then just say that, don't sound like a geek and get defensive about you precious cam!

 

[Kooldino]

Damn dude, you ask for help and people try to help. You come back with "where's the scientific reason" WTF!!! If you don't think the help people are offering is good enough then don't ask.

Well, no offense to acidbbg, but it's not like I went directly to him and asked specifically for his help.

If you posted about an injector issue and i told you it was because you had a yellow car, you'd at least ask for an explanation. No one offered a remotely plausable explanation to why a (slightly longer duration than stock) intake cam would have anything to do with measuring how fast my exhaust cam gear rotates. Like I said, if it works the way I think it does, then they have nothing to do with each other. You'd understand if you saw what I was talking about.

If you don't think that's it, then just say that, don't sound like a geek and get defensive about you precious cam!

Well, I don't think that's it, and I was simply asking for justification. Chas just shouldn't jump to the conclusion of "Sounds like that new intake cam you put it might be causing some problems." without so much as an explanation.

At least you and KzA wondered if I possibly damaged it during the install, which is a reasonable concern. But pointing a finger at the intake cam itself makes zero sense to me at this point. I should have quoted Chas with my reply there, I didn't mean to direct the intake cam rant at you.

Anyway, enough of that noise, I orderd a brand new sensor (read: rip off). I hope to God it fixes my problem, but I'm not getting my hopes up.

 

[Mr. Win]

Wait...MP5Jeff's cam sensor went bad? When/how? What were the symptoms?

ill ask him... i think he is on his third.

 

[Kooldino]

ill ask him... i think he is on his third.

If you can, get the man himself in here. Thanks.