Camel riding - misfires? with new spark plugs

boris ivanov

boris ivanov

Greenie N00B Member
Howdy

Today I got my 2006 MS6 from the shop as I left it for a lookup and cause in 4th and 5th gear mostly, on high boost, ie under high load, would start lurching.

Initially I thought it might be something to do with the awd, but thats all good, and it is the same regardless DSC on/off.

So the owner of the shop gave it a drive and diagnosed it with misfires due to bad spark plugs. Got in new iridium ones with the proper gap, however the problem is still there...


------- Update from a couple months later

The logs showed that ignition timing is retarded from 82~ where it should be @3700+rpm at full throttle, to mid 40s when under load, hence random misfires. The load itself is at over 85% for those instances, but I can't say whether this is due to the misfires themselves.

Up next is to find out whether the cat is what the ECU is worrying about.

I should note that after clearing the IAF high circuit input fault code, the engine ran well for a drive - revving fine when accelerating all the way up to 6500. On the next drive it had reverted back to misfire territory.
 
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The ECU records per cylinder misfires. Dont know what software you are using to get a read out though.

What is your mod list?
 
Except for wheels and suspension, it is as close to stock as you can get.

The guys at the shop had it connected and saw no error codes. To be honest, Im still not 100% sure it is misfiring exactly: power does cut and the car starts stuttering and then lurching forward, as if wheelspin, but thats not possible, and thats why i initially thought it had to do with the awd; it does depend on load/boost and gear.

Im currently running 95 fuel (91 us), i wonder if itd help going to 100
 
Have you considered getting a method to data log? Static logs post event arent going to help much.

Look up Cobb Accessport, or Verstatune.

edited: testing -> logs. words are hard. :-/
 
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These look like good addons, but is currently out of the budget.

*update: it happens in 2nd gear, when going up a slope even, on full throttle/full boost, it starts cutting off rather frequently. So, under high load with high boost. Ignition coils still main suspect?
 
Late to this thread, but I’d suggest you run a fuel injector cleaner such as Lucas’ product.

I actually had a very similar issue recently. It had been getting a little worse over the course of a few weeks or a month and I had no CEL codes. I thought it might be the spark plugs or a vacuum leak, so I did a few things and nothing helped. Then I went on a hunch and ran the Lucas Upper Cylinder Lubricant and Fuel Injector Cleaner. Within 4 miles the car was mostly back to normal and within 30 miles it was totally fine. It’s been fine ever since.
 
Here is the belated update*:
- new copper spark plugs
- new Bosch induction coils

The misfire situation deffinitely improved, however it is still currently guaranteed to misfire on full throttle above 4k rpm. Fuel consumption is now improved still and idle stalling no longer occurs. Yet the troubleshooting goes on.

So today I finally connected via OBD2 and it showed P0113 Intake Air Temperature Circuit: High Input, no other faults.

Hopefully by getting new MAP/MAF sensors it will be fixed. Stay tuned for more updates!


*ty for your advice, guys!
 
boris ivanov said:
Here is the belated update*:
- new copper spark plugs
- new Bosch induction coils

The misfire situation deffinitely improved, however it is still currently guaranteed to misfire on full throttle above 4k rpm. Fuel consumption is now improved still and idle stalling no longer occurs. Yet the troubleshooting goes on.

So today I finally connected via OBD2 and it showed P0113 Intake Air Temperature Circuit: High Input, no other faults.

Hopefully by getting new MAP/MAF sensors it will be fixed. Stay tuned for more updates!


*ty for your advice, guys!
Click to expand...

What did you gap the plugs to? You could be experiencing spark blowout due to too large of a gap setting.
 
Final update, hopefully: this is now fixed after clearing the High circuit input fault, and I'm so glad to hear it rev smoothly all the way to 6500rpm on 3rd and 4th gear.

The MAF sensor was replaced yesterday, but that didn't fix it. Today I connected via VCM to the FOCOM app (weirdly enough, the 6 MPS 2.3 ecu isn't there, so had to pick cx7's), ran a couple of test runs with logging, with the misfires still present. Then I come back and cleared the fault and tried a couple more test runs, and shortly after there wasn't any issue at all. Smooth revs, that awesome growling sound, and most importantly, no misfires!

So all in all, new spark plugs with proper spacing, new coils, alternator bearing and belt, and new MAF sensor. Totally worth it!

Cheers from Bulgaria!
 
Did somebody say premature celebration?

Ye, the problem persists. I have no clue how all the symptoms disappeared and it ran fine, and today it's back to the old routine - boost under load over 4k rpm = misfire.

While driving the check engine light finally came on and diagnostic showed P0300 - random/multiple cylinder misfire. No duh. So I cleared that fault code, did a test run and got a .csv out of it. Some hill climbs on full throttle on 2nd and 3rd gear, and as soon as I go over ~4200rpm its bambambam. However check engine light hasn't come back on.

I've uploaded the logs for whomever feels both curious, experienced and generous enough to give me a hand. Otherwise I'm eyeing the MAP sensor next.
 

Attachments

This log has 189 columns, with a blank row between each; the log resolution is nearly 2 seconds per row. Basically what I'm saying is there's a ton of data being logged that doesn't need to be and it's fucking up the log resolution, and making the log basically unreadable.

The hell did you even use to log this?
 
VCM-USB cable into FoCom diagnostic tool.

Previously I had some logs with selected values like AFR, RPM, Throttle pos, timing, but for this one I didnt bother and just wanted to see everything. Something like this here makes it easier to filter and view: http://www.epifansoft.com/logViewer-downloads.html

From the logs I can see the ignition timing being significantly retarded above 4k rpm. That should be the cause of the misfires. Now I gotta find what is making the ECU do that.
 
I'm having the same issue, but for me it only happens after 5k in 2nd and 3rd gear at wot. My car is modded, at first I thought it was a boost cut, so I lowered the boost a little bit but it did't help. I will change coil packs with a friends MS3 and data log.
 
If you can see on your logs the ignition timing being significantly retarded when on boost, I'd say it's the same issue. I have some strong suspicions that it'll turn out to be the cat being clogged or overheating and the ECU trying to be eco-friendly.

How's your catalytic converter and ECU tuning situation?

Troubleshooting has been postponed on my part until mid-January, when I'll check back with more logs if I haven't been able to solve it by then. Keeping a look on and appreciating any input.
 
No cats and custom tune. When I started with this problem it was a coil connector, replaced it and the issue was gone, but now is doing the same.
 
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