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Jerry Newton
Jerry Newton, Cadillac Technician
Category: Cadillac
Satisfied Customers: 4458
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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2000seville North Star bank one engine miss. I am a tech

Customer Question

2000seville North Star bank one engine miss. I am a tech myself 25 years. But I admit I don't know it all. Anyways 1,3,5,7 misfire only at idle. Vacuum leaks none. Grounds okay. Coil good. Injectors good. Compression 150 n above fuel pressure 45 psi. Maf clean, cat okay. Freeze frame had CRank senser codes. One cam sender code. Crank cam correlation code. N a po701 code for pcm. Had ign module codes as well bank one n two.
Submitted: 1 year ago.
Category: Cadillac
Customer: replied 1 year ago.
Clean fuel. I'm thinkin bad pcm. Carrying it to be flashed tomorrow just thought I would have second opinion
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 1 year ago.
Do not need phone call
Expert:  Jerry Newton replied 1 year ago.

You have a cam/crank correlation code? That suggests a timing chain issue.

Since it's only on one bank, I would be inclined to remove both valve covers, bring the timing marks up on the cams, and just see that all four of them point where they should.

Customer: replied 1 year ago.
Yea I got this car from family member who had head gaskets done here while back. These codes I'm sure has been n it for awhile I'm sure no one had diag equipment were it come from. Can not get none of these codes to return though or I could fix it. Ever correlation code I have ever dealt with was hard fault n it would show back up instantly though ! That's what I was leaning toward when I seen the code but it will not return so I don't know if they have already repaired that or not.
Customer: replied 1 year ago.
Don't have the codes n front of me but will bout five thirty will u be available.
Customer: replied 1 year ago.
All yea it misses the most on #3. Number 1. N very little on 5 n 7 ,
Expert:  Jerry Newton replied 1 year ago.

I will be available later this evening to help you out, or tomorrow morning at the latest.

Customer: replied 1 year ago.
If it was cam crank correlation wouldn't it be hard fault come back immediately ?
Expert:  Jerry Newton replied 1 year ago.

You would think so, but if it's mixed in with the other crank/cam sensor codes, maybe it's just a byproduct of a failing sensor. Crank position sensor failure was very common on these cars, GM made several updated sensor designs. If you have sporadic codes like that, that you can't really put your hands around, I would start with two new crank sensors from your GM dealer. Don't buy aftermarket on these.

Replace those first, then see where you end up.

Customer: replied 1 year ago.
Po300,po102,po335,po340,po385,p1372,p1360,p1359,po601,-PCM has recognized six malfunctions,,,,po386,,all n history but nothing coming back hard fault except po300.
Expert:  Jerry Newton replied 1 year ago.

P0335 and P0385 are dead giveaways, if you ever have those on a Cadillac from 2000-2003, you simply replace the crank sensors. The sensors were that bad. Like I said, I'd replace those first before going further.

Expert:  Jerry Newton replied 1 year ago.

Every Cadillac from that era has a P0601 banging around in it. Disregard it. Everything else might just go away with new crank sensors.

Customer: replied 1 year ago.
Yea I repair everything on the road with no problems at all cause it's not my money but when it comes to my personal stuff I have to bang my head cause it's my money lol. Thanks. Will try that tonight!!!
Customer: replied 1 year ago.
N u suppose they r causing the misfire possibly
Expert:  Jerry Newton replied 1 year ago.

The PCM is using a very high resolution reading from the crank sensors to determine misfire counts. If those sensors aren't dead on, you'll get phantom misfires.

Yes, I think the P0300 is caused by faulty CKP sensors as well.

Customer: replied 1 year ago.
No help with crank ck sensors, even started to miss on bank two a couple counters! How much is a phone call ?
Expert:  Jerry Newton replied 1 year ago.

You installed new CKP sensors, and the symptoms are still present?

Customer: replied 1 year ago.
actually #2 started miss firing when I done it. N never did before
Expert:  Jerry Newton replied 1 year ago.

You have misfires, and still all of these codes? If you clear all the codes, all of the same ones come back?

Customer: replied 1 year ago.
All them codes was n history been there forever. Codes cleared n nothing comes back but a misfire.
Expert:  Jerry Newton replied 1 year ago.

OK, let's start there.

Misfire only on cylinder 2?

Customer: replied 1 year ago.
Misfire on 1,3,5 only cold at idle. Changed crk sensor now it is missing on 2 as well, accelerate n all goes away, when it gets hot it will start switching back n fourth. 3 will hit for couple minutes n stop very erratic once warm missis all over the board.
Customer: replied 1 year ago.
I believe it's the PCM not sending proper grounds to crk senser is my guess.
Customer: replied 1 year ago.
Car has done this since head gasket replacement, n I found out last night that couple people have tried to repair but couldn't. I have just been weening it cause I'm suspicious of PCM. But I gonna take everything home tonight n I will get to the bottom of it. I was just curious if someone would suspect PCM causing this !
Customer: replied 1 year ago.
May be the darn converter since it had head gasket failure gonna remove b1s1 o2 tonight n see how it does. Cause bone cold it will only miss on bank one.
Expert:  Jerry Newton replied 1 year ago.

If there was a problem with the electrical circuits to the CKP sensors, you'd definitely have trouble codes to reflect it, and the engine probably wouldn't run.

I would go back to basics on this: if this happened after someone had the heads off, I'd be looking directly at the cam timing. I'd want to know that it's right, and that's a hard thing to determine without removing the front cover, but you could bring cylinder 1 up to TDC by putting a screwdriver in the spark plug hole, and very carefully rocking the crank back and forth until you're sure it's at TDC, then looking at the timing marks on the cam sprockets to see if they line up as they should. One tooth off will give you misfires at idle, and when you think about those cam/crank correlation codes you used to have, I can't help but wonder if the cam timing was set right.

It's not the converter, and it's not the crank sensors or the cam sensor. You have to go to basics on this: fuel, spark, vacuum leaks, cam timing, etc. I'm convinced that it's a mechanical issue.

Customer: replied 1 year ago.
Yea im gonna tear into it forsure. But looks like if it was cam #3 would never start back to hitting. N it don't explain when it gets warm it misses every were except number 6,7,8,
Customer: replied 1 year ago.
I will keep ya posted i will figure it out tomorrow, but that correlation code is kinda generic n acts like the crank sensors r not reading correctly n sequence. I have had a few engines tooth out before n it would set trouble code immediately, yea I gonna pop the covers to narrow it down.
Expert:  Jerry Newton replied 1 year ago.

I don't know how you're determining the misfires on cylinder numbers. If you're relying on the scan tool, it can be very misleading, don't rely too heavily on random misfires across many cylinders.

See if the fuel trim is also running lean while these random misfires are occurring. If so, it's probably a lean misfire caused by a vacuum leak. The rubber boot that attaches the intake to the water crossover is a common source for vacuum leaks, and it can be really hard to diagnose, as it cracks on the bottom side where you can't access it.

Cam timing that's off by one tooth is sufficient to cause all sorts of idle problems, but they'll go away off idle, and that seems to be what you're experiencing. Take a good hard look at the scan tool data and try to get everything that it will tell you, before tearing into it.

Expert:  Jerry Newton replied 1 year ago.

The correlation code hasn't come back, so that's encouraging. I agree, it probably would come back pretty quickly, but note that the PCM is only monitoring ONE camshaft for proper timing.... the other three could be off and the computer wouldn't have any way to know that.

It's not the crank sensors. Stop worrying about those, you replaced them and they're fine. Crank sensors don't cause misfires, they will cause the engine to stop running. You had a host of trouble codes pointing to faulty CKP sensors, and they needed to be replaced based solely on those codes. But that's gone now, no need to revisit the CKP sensors. You'll be wasting your time there.

Customer: replied 1 year ago.
Thanks, ***** ***** ya posted
Expert:  Jerry Newton replied 1 year ago.

My pleasure, please let me know how it goes.