View Full Version : 01 Deville Cylinder #1 misfire

11-23-13, 01:43 AM
Ok went to work one day car was running fine, got done with my shift at work hopped in my car started it up and i was running rough.....:(. So i swapped out plugs with new ac delco plugs, still a misfire. secondly i got new coil packs still misfiring. Finally OBD Found codes as follows.

p0107 map
p0201 cyl #1 injection problem
p0202 2 " "
p0203 3 " "
p0204 4 " "
p0205 5 " "
p0206 6 " "
p0300 random misfire
p0335 CKP sensor "A" problem
p0340 CMP sensor problem
p0385 CKP sensor "B" problem

Now at home with my ohm meter........

Ohm tested all 8 injectors were within ballpark of 12.5 ohms no less.
I also verified that there was 12volts to injectors (with car running)

ohm tested the ICM in the rear from left to right there are 7 probes
and got the following results...

1) 1.600 ohms
2) 002.7 ohms
3) 20.5 ohms
4) 20.5 ohms
5) 20.7 ohms
6) 20.7 ohms
7) 20.9 ohms

Front ICM going right to left

1) O.L
2) 000.0 ohms
3) 35.7 ohms
4) 35.8 ohms
5) 35.8 ohms
6) 35.9 ohms
7) 35.9 ohms

Different ohms ? O.L on 1? in the front ICM?

I cannot test the harness going to ICM's because I have noone to turn over car for me. Is it even worth a shot?

Also I did the old school stethiscope trick with a screw driver to listen for the click of the injectors and all seem to be clicking.
then i decided to pull the harness going to injector 1 and it did not intensify just stayed the same. i pulled the one next to it and idle got worse so my guestimation would be either #1 a clogged injector? or no spark in cylinder 1#
Now I am clueless to what to do now.

Could it be the Engine control module / PCM?

Not 100% positive i checked these the right way but i assume i was correct. Any help would be greatly appreciated. Thanks, Stephan.

11-24-13, 03:19 PM
Any help? Please and thanks.

11-24-13, 03:51 PM
Hang in there - I'll move this from the PCM Tuning (as in: Modification) forum to the Northstar diagnosis forum.

11-25-13, 10:58 AM
Your crankshaft position sensors are malfunctioning causing the computer to not know when to inject fuel, ignite spark, etc. Check for faulty wiring first (the wiring runs behind the front exhaust manifold. make sure it isn't burnt from improper routing). If the wiring checks out, replace the sensors. If your camshaft sensor code is still present after the crankshaft sensor change, check to see if it is plugged in and the wiring is good to it. If it is, replace that sensor as well.

11-26-13, 06:15 PM
ok well I will have to update later on as I do not have the funds to cover the parts at this time. Thanks for the help I will update as soon as possible.

12-01-13, 06:42 PM
OK so i did a compression test all cylinders are 120 psi. Took out #1 injector and thats clean as a whistle. So when i did a compression check sparkplug # 1 seems clean and saoked in fuel. So I assume no spark in #1. Checked all leads going to injector,coil pack wiring harnesses and lines coming from PCM. So now all I am left with is crankshaft position sensors. Would faulty crankshaft position sensors cause only cylinder #1 to misfire???

12-01-13, 08:36 PM
Would faulty crankshaft position sensors cause only cylinder #1 to misfire???


Did you verify that you had spark to #1? Might be a bad plug, wire or coil.

12-01-13, 09:24 PM
swapped out coils with new. new plugs. wiring is intact. ohmed out coils and injectors, tested voltage to injectors and coils. Literally stumped.It couldnt be PCM because voltage to coils seem within spec.

12-02-13, 01:41 AM
Have you changed the crankshaft position sensors yet?

12-02-13, 03:21 AM
not yet because I have a plan. I am going to local junk yard to pick up a used pcm to be reprogrammed to my car tomorrow morning. I just stumbled across a similar post on here thaty seems to be my problem. here is the link


So before I buy 2 new crankshaft sensors im gonna give this a shot. Both sensors were bad well before this problem occured. I just never looked into how to change them in the past. As of lately i seen how easily it is to change. So if the PCM doesnt fix it im going for the crank sensors. They do need changed though, this i know. I will update @ around 9 pm on 12/2.

Also i did forget to mention the this misfire is constant from idle to acceleration all the way to shutdown. I think if it was a bad cranksensor I would notice "fluctuation" in misfire and other cylinders.

12-02-13, 04:11 AM
I saw that post you mentioned.

Good luck with it........

12-02-13, 09:56 PM
Wasnt able to get the PCM today :/. Also the dealership I called wants 90 to reprogram. So I will update on 12/5/13. Thats my next payday.

12-07-13, 12:11 AM
so I decided to go ahead and replace the crankshaft position sensors. Still no difference in misfire but it does seem to be running a lot better then it did so injectors should be firing at the appropriate time now. Tomorrow morning I'm going to a GM dealership in going to have this computer I got from the junkyard reprogrammed. So I will update tomorrow as soon as possible

12-12-13, 09:10 PM
PCM reprogrammed and no change in engine misfire......... very disappointed right now. End of the road.

12-13-13, 07:03 AM
What DTCs do you still have current?

Sent from AutoGuide.com Free App (http://www.autoguide.com/mobile)

12-13-13, 09:09 AM
........ and have you continued your resistance checks to the entire fuel injector wiring harness/connectors ?

12-13-13, 12:02 PM
P0300 -engine misfire.

no spark / incorrect firing time Cylinder 1 constant misfire

New crankshaft position sensors. Both were re-learned yesterday and camshaft aswell.

And injectors are fine and working.

So now im wondering if this SOB jumped time? I highly doubt it but it could be possible.

12-13-13, 01:17 PM
You replaced the PCM, does the 01 have one ICM or 1 for each bank?? If one I'd say it was bad.
The only thing even remotely close was this post(diff year) that mentions the problem was a poor connection at ICM.

See post 17. apparently the pins were collapsed a little and not making contact. might be worth a look.
Good luck.

12-13-13, 04:37 PM
Are the injector codes gone?
If the misfire is steady on cylinder 1 swap the coil packs from bank to bank and see if you get a different cylinder misfire.

12-13-13, 05:51 PM
2000 - late 2003 Northstar has two (identical) ICMs - one in each coil cassette L-leg.

Each is removable with 2 screws and 2 plastic snap tangs. Careful - and each ICM has a seal ring and connector at the cassette itself.

12-13-13, 08:59 PM
So now im wondering if this SOB jumped time? I highly doubt it but it could be possible.
Highly unlikely.

12-13-13, 11:20 PM
Well basic run down is i swapped packs misfire stayed in cylinder 1. even got a coil pack from the junk yard and still no difference. it is only a single misfire and not a whole bank. injector codes gone, just very stumped. i used a meter to measure voltage coming from pcm to coils and all checked out fine. ohmed out the coil packs aswell and all checks out fine.

12-14-13, 04:04 AM
Swap/ Replace injector number one..........

12-14-13, 11:04 AM
If you have the skills, try swapping more components, swap 2 of the injectors, swap some spark plugs....swap one thing at a time and recheck. When the miss moves, you have found your problem. If you can't find the issue this way you may have a mechanical issue.

12-14-13, 11:07 AM
Well as I said before I pulled out injector #1 and tested it myself. Fully functional and not plugged up....

@ ewill3rd in the beginning of my post i have already done that.

12-14-13, 11:37 AM
It may not be spraying enough fuel.

Yes, it's functioning but if the spray pattern isn't correct or enough isn't being injected, it could lead to a problem.

The only way to KNOW for sure is to have it flow tested.

To have an isolated problem in one cylinder like that is ironic. You have compression, the plugs should be gapped correctly. You have swapped coils, yes, the injector is firing, but is it enough? Possibly questionable. The only thing that is going to be left is a burnt exhaust valve, but that will affect compression to some degree.

Swap another injector......

12-14-13, 07:06 PM
Sorry I missed that earlier. If you have swapped the injector, the spark plug and the coils and you have a misfire on number 1 that won't move then you most likely have one of two issues. I would have to look at the schematics but depending on how the coils are triggered there could be a wiring issue for the #1 coil control circuit or you have a mechanical problem. Pardon my ADD but I think you said you ran a compression check? Another question is, you know that cylinder 1 is on the rear bank right?

12-14-13, 11:16 PM
yes cylinder 1 is rear left if you're in front of the car, near the coolant fill tank. Considering I had the PCM reprogrammed, wouldnt the dealer have noticed that during the reprogramming? Also on my first post i did and ohms test on the coils and a voltage test to pcm from coil connector harness, and all seemed fine and i compared to the front. Does anyone know if you can pull the coil out still plugged in ground the spring in the middle of coil to car and turn over key to see if any plugs are sparking???? or do i need to have plugs near metal to get it to spark? Id really would like to try it to see if the #1 is sparking...... im guessing its going to be near impossible because the boots have springs in them and it may be hard to keep plugs in boots and on coil properly so no spark can escape where its not supposed to. I also have the old coil i can temporarily hook up so i do not have to tear off rear coil.

12-15-13, 06:28 PM
If you swapped the coil cassettes from front to rear that eliminates the coils. Ohm testing is entirely worthless on a coil. Oh it can identify a truly bad one but I won't identify a marginal one that fails under load. If you really want to do some testing for spark you can get some lengths of 7/32" vacuum hose and use them as "plug wires" They will fit on the tips of the coils and the carbon content is high enough but you have to be careful because if you touch them and you touch the car you will be carrying the spark energy through your body. You would need to have a ground for the coil housing to the engine, a wire with some clips on it should work fine. If all your tests were done properly you could have a mechanical condition like a valve guide, spring, lifter, or seat issue. I would try doing a leak down test if you can get your hands on the proper equipment. If you have your compression tester you could try a running compression test but it will be very hard with that ignition system.

12-22-13, 09:14 PM
UPDATE what are the odds that the new coil pack i got was bad??????? I returned it and got another one and problem solved!!!! Im so relieved. I feel like a new cadillac owner!! Thanks for everyone that looked into this for me as i greatly appreciated the info and help.

P.S. while I was installing the new coil cassette, my key fob was in my pocket and i hit the panic button and about had a freaking heat attack!! i had to sit down for a sec to bring my pulse down lol.


12-22-13, 09:27 PM
UPDATE what are the odds that the new coil pack i got was bad??????? I returned it and got another one and problem solved!!!!
Generally speaking, pretty slim. The Northstar Gods where not smiling upon you.

12-23-13, 12:44 PM
Generally speaking, pretty slim. The Northstar Gods where not smiling upon you.

They were joking sround, cruel bastards