Ok....i am a new member as of today... i am having misfire issues on a 2007 Volvo xc90 3.2 misfiring on 1,2,3 now...it was 1,2,3 and 6 but now it seems no misfire on 6...i have changed the plugs and new coils because of the mileage and also it was slow to start, but if i would turn key on and let it set for a couple of seconds longer it would start up normally. So i decided that with the mileage that the fuel pump was getting weak, changed that and that solved that issue. I found 1 bad ground wire in the coil pack loom and i think that fixed misfire on 6. but also found a bad wire firing cylinder 1,2,3, so i fixed that but did not change that issue. But maybe the ground is broken further up and i will check that tomorrow. pulled wires on injectors 1 by 1 and motor changed , also did coil packs 1 by 1. motor stumbled on each one. Did a compression check a few thousands miles ago, and it was 160 all cylinders. It idles nice but when i push the bring up the rpms, it stumbles, and check engines lights come on. I am also thinking about pulling the fuel rail to see what the injectors look like....maybe that could be the issue. but at this point i am at a loss, when idling the rpm stays steady at 650 rpms..Any recommendations on where to look i am all ears. Ok...so i ran a compression test and all cylinders were highest was 210 and lowest 185. So all seems good there, could there be a issue with the computer on top of the air cleaner, i was thinking bad gas but then it is not showing a lean condition on any of the cylinders. i have ordered new connectors to splice them in and see if that makes a difference as they were pretty cheap and the connectors on them were cracked and spliced open at the end...pretty common issue i guess. But i am running out of things to check. Thanks for any info and listening.

 

Posted some new information... Thanks again

 

your compression sounds fine (180ish is good for an NA engine) your initial low reading may have been due to a cold engine etc. Since you have replaced the coils and plugs, have you gone back to look at the plugs since? Are they all the same color - are there any differences in the burn lines (ie where the tip of the electrodes are different from the bend by the base)? Have you collected run time data as to what the O2 sensor is reporting during a drive cycle? Many OBD2 readers can do this otherwise a shop can do a diagnostics test. That leaves fuel mix issues in my mind. Is the MAF and intake clean? A failed PCV oil separator can gum things up in there... what's the fuel pressure at start up and after warm up? (you have a variable pump so its another thing for a pro to measure the pumps duty cycle). Have you you inspected for intake air/exhaust leaks etc? Finally you noted fuel quality. Try running a brand name 93 high test or throw a can of Techron fuel injector cleaner in the tank. that may help clean up the injectors and its a good maintenance item. Based on what you are describing would lead me to investigating the fuel pump / pressure sensor / pump controller. This can more accurately be done with a pro with a VIDA system (of course you can buy your own VIDA/DICE on Ebay) so to me it would be worth the $150 for a pro to do a diagnostics scan/road test for you.

 

Plugs are all the same color and look good. Fuel pressure is about 69 psi at start up and stays consistent after warm up so that seems to be good. I have cleaned the MAF a few thousand miles ago but does not mean it is not dirty. will check that out again...but would that not also throw a lean code also with the maf, not just a misfire on 1,2,3. 4 ,5, have always been fine, but then i had a misfire in 6 but that has gone away..only 1,2,3,.Fixed ground on some wiring harness as they were only a few strands holding on ground that goes to coil packs. i have not checked the PCV but will do that also. Fuel pump and pressure regulator has been changed in the last week plus a new fuel filter. Just because of the mileage on it. fresh gaskets on intake but have not checked on exhaust leaks...will do that also. Thanks

 

just thinking aloud - fuel trim is an averaging code while misfire codes can happen pretty quickly given certain conditions. Since you've done the plugs and coils, next thing is the wiring harness to the coils. On older models (like my son's 2000 s40) its not uncommon for the connectors to crack and that will give the appearance of a bad coil. When you say pressure regulator, did you mean the fuel pressure sensor?

 

sorry yea the pressure sensor. that is my next step as i looked at the coil wiring and they seem to be cracked at the end...maybe they are arcing over....i will keep you posted ...and thanks again

 

ok...here is the update, before i send it down to the shop and see what is going on. Thanks for all the info ..it has been helpful. So after looking at a bunch of stuff. i have cleaned the maf sensor...it was pretty dirty. i have taken out the injectors and cleaned those...a couple of busted o rings but they are good now..in have taken the leads off each of the injectors to see if it is firing and the motor stumbles. I found cracks in the coil wiring and addressed them with all new ends. compression is good, and spark plugs look good and so do coil packs. but i get a misfire on 1 2 3 cylinders. but it idles nice but when i bring up the rpm is stumbles and shift up or lower speed comes on with the check engine light and it stumbles hard and dies. I took it to my drive way and it has no power like the exhaust is plugged or catalytic converter on 1 side is plugged. i am wondering if the previous mechanic bought the low end cat and exhaust manifold as if had a issue from previous owner and he replaced them but had a misfire all the time he could not trace and i figured out he did tighten some of the exhaust bolts and left some out which it turn caused the issue. so maybe he put junk ones on and it lasted only a year. i am just thinking out loud. i am at a loss....i had to replace a axle because he bought one at oreilly and it came out the joint. to put a volvo in it and that fixed that. any other ideas would be much appreciated. i am going to drop the exhaust manifold and cat to see how that looks . i have put a live scan on it and it all checks out with the parameters so not i am looking more downstream....exhaust does sound off...so i going there ...



Thanks

 

ok...here is the update...pulled off exhaust manifold from the car and the honeycomb separated from the converter. and this is the side that is mis firing on 1 2 3 cylinder. so it looks like a new converter manifold is in the works. Just thought i would let you know. the other side was fine and not throw any misfiring codes.

 

Another update. Not only did the converter separate, but it also heated up the 2nd cat and melted it and it was plugged. Fixed that and had no issue with it for the last week...all good now.




Thanks for any info

 

Search Girls in your town for night