Hey all! I have a 2008 Vue with a 3.6L that I recently scanned and a P0300 code came up, no CEL just the code at this point. After browsing around the internets a bit I decided to put in new spark plugs because that seemed like the lowest effort possible fix and it was probably time to change them anyway. Unfortunately this was not the problem. In fact, after I put in new spark plugs, the CEL came on and a P0107 code came up with the P0300.

So I checked the MAP sensor and I think it's okay because the scanner shows it has a constant pressure at idle and moves around a bit when I rev the engine. During this time a P0106 code came up in addition to the others, so maybe it is the MAP sensor.

However, then I checked the actual misfire count for each cylinder and it appears that only the cylinders in bank 1 (#1, #3, #5) are misfiring and not very often. Maybe 1-4 times each after running the engine and revving it a bit for 20 minutes or so. At this point the P0106 goes away and the CEL turns off.

Now I'm wondering what my next step should be. I could change my MAP sensor but I'm not super confident that's the problem since the misfires are only happening in bank 1. Any thoughts or advice? Thanks.

 

Thank you for solid information.
no, seriously. Not being a ***** this time.

Since you have a scan tool capable of looking at misfire, check your fuel trims as well. May be dirty injectors. But since its only on one side, the fuel rail could possibly be slightly clogged up.
coil packs would be my next guess. Swap one set around and see if the misfire follows (say swap cylinder 1 and cylinder 2 since theyre on different banks)

If none of that works id follow up with a compression test.

Another note. I'm not looking at a picture or remember off hand.
Check the wiring as well. See if the map sensor wiring is in correlation with the injectors and coils on bank one.
Ive seem nicked wires do some weird crap like this before.

 

I wonder if the timing chain is starting to stretch and fail maybe the one cam is one tooth off? There have been a few threads about chains stretching on this engine.

 

Thanks for the responses! I'll read up on the posts about the timing chain. The fuel trims for each bank hand around +/-3% and don't go up any more than +/-6% so I think they're okay. This engine has individual coils but per your suggestion, I did switch the coil from #1 -> #2 just to make sure and the misfire did not seem to follow it. So the coils seem okay as well. Yesterday I cleaned out the throttle body and changed the MAP sensor which did seem to help it run a little less rough. However, the CEL light came on and P0107 and P0108 are pending now but I think I might just have to drive it a bit with the new sensor.

Something new I did discover yesterday was that there is a small bit of oil in the air intake.



Which appears to be coming from 2 -> 1 in the picture below.


I'm not sure what's causing this oil to spit out, but I wonder if it may be causing the misfires.

 

That is the fresh air to crankcase metered air hose. The other valve cover probably has the crankcase vent hose and metering device to manifold vacuum. Either a pcv valve or metered orifice of some kind. Oil vapor gets into the intake duct if the vehicle has more blowby than the system can handle. You may need to clean or replace the pcv/ orifice which ever it has.

 

I believe I figured it out! I found a technical service bulletin about the P0300 code and it said to clean the fuel injectors. So I hooked up a fuel injector cleaning kit to the fuel rail and ran that through, then I reset the codes and it hasn't been back since. It also seems to run a little more smoothly which is an added bonus. I monitored the actual misfires with my scanner and there are still a couple, but significantly fewer than before. It might not hurt to clean the injectors again because it's never been done. Thanks all for the help!

 

I usually recommend an injector service every 30k miles to my customers.
I'll throw a bottle of lucas fuel treatment in the tank at least once a month as well (on my personal cars)

 

Specifically what are you referring to as injector service? Do you mean having it hooked up to a dedicated fuel injector cleaner machine, or are there specific products to put into the fuel system that actually work to clean the injectors? Please advise. Basically can I do this myself or do I need someone with a machine?

 

derf, I've been using Techron Fuel System and Fuel Injector Cleaner for over 20 years and have NEVER had a fuel injection problem with any of the cars I've owned. I don't use them at the same time, but alternate a bottle of each every 10,000 miles in the fuel tank. I usually wait until I have between 1/4 and 1/2 tank of gas and then dump a bottle in and fill it up. Techron is the top rated cleaner on the market and the only one recommended by different car companies.

 

If you have an air compressor and the cleaning kit with the tank and the hoses, it's super easy. I'm a programmer and I was able to do it no problem 😁 The kits that I saw were around $200 so it mostly depends if you want to spend that money and already have an air compressor or just get someone else to do it with the equipment.