What to try next for intermittent misfire problem
03-23-2011, 02:22 PM
#1
AudiWorld Newcomer
Thread Starter
Join Date: Mar 2011
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
What to try next for intermittent misfire problem
I've been having a misfire come and go for a couple of weeks now and haven't found the source of the problem yet. Based on my searching here, I first tried swapping the ignition coil from cylinder #3 which has had the misfire based on the codes I get. I'm getting a P1300 code, something to do with the fuel supply and a P0303 cylinder #3 misfire. After swapping coils (and buying a new coil for #3) I still got the misfire in #3. I replaced the plug in #3, same thing. Then I went to the fuel injectors and swapped them around, still misfiring in #3. I did find a vacuum leak from a piece that had a hole and was sucking air, I replaced that but still misfiring in #3. My next move was going to be to replace the ignition control module, but I thought I'd post here first and see if anyone has any other ideas. I should mention that the misfire comes and goes, it isn't always misfiring. Sometimes I can drive for quite a while with it running fine and then it will suddenly start misfiring for a while, then go back to running fine.
Any ideas? Thanks!
Any ideas? Thanks!
03-23-2011, 03:55 PM
#3
AudiWorld Super User
Could be an electrical connection problem, possibly the ECU's connectors? Try spraying contact cleaner into the coil, injector, and ECU connectors.
03-24-2011, 09:18 PM
#4
AudiWorld Member
Join Date: Mar 2000
Posts: 527
Likes: 0
Received 0 Likes
on
0 Posts
I have had this prior and it ended up being the ICM. Hard to diagnose until it got worse with a check engine light and it still was difficult. there is a way to test the unit using a DMM and a battery with some wire I found in this forum that helped. i have replaced three ICM already on my car. Also, don't buy the cheap stuff and make sure it has heat sink grease or the life will end prematurely.
Since you already tested the Coils themselves and the misfires stayed, I would think to test the ICM. Check your sparkplugs as well.
Since you already tested the Coils themselves and the misfires stayed, I would think to test the ICM. Check your sparkplugs as well.
Last edited by sparkster; 03-24-2011 at 09:21 PM.
03-25-2011, 07:36 AM
#5
AudiWorld Expert
I have had this prior and it ended up being the ICM. Hard to diagnose until it got worse with a check engine light and it still was difficult. there is a way to test the unit using a DMM and a battery with some wire I found in this forum that helped. i have replaced three ICM already on my car. Also, don't buy the cheap stuff and make sure it has heat sink grease or the life will end prematurely.
Since you already tested the Coils themselves and the misfires stayed, I would think to test the ICM. Check your sparkplugs as well.
Since you already tested the Coils themselves and the misfires stayed, I would think to test the ICM. Check your sparkplugs as well.
03-25-2011, 02:57 PM
#6
Audiworld Junior Member
Join Date: Feb 2010
Posts: 81
Likes: 0
Received 0 Likes
on
0 Posts
ive had the samme problems but in cylinder one. I've changed coils, plugs, icu, and change the injectors location and still now luck. and i even change the valve cover gasket.
I've been having a misfire come and go for a couple of weeks now and haven't found the source of the problem yet. Based on my searching here, I first tried swapping the ignition coil from cylinder #3 which has had the misfire based on the codes I get. I'm getting a P1300 code, something to do with the fuel supply and a P0303 cylinder #3 misfire. After swapping coils (and buying a new coil for #3) I still got the misfire in #3. I replaced the plug in #3, same thing. Then I went to the fuel injectors and swapped them around, still misfiring in #3. I did find a vacuum leak from a piece that had a hole and was sucking air, I replaced that but still misfiring in #3. My next move was going to be to replace the ignition control module, but I thought I'd post here first and see if anyone has any other ideas. I should mention that the misfire comes and goes, it isn't always misfiring. Sometimes I can drive for quite a while with it running fine and then it will suddenly start misfiring for a while, then go back to running fine.
Any ideas? Thanks!
Any ideas? Thanks!
