# 2.7T engine light misfire, Please help!!!!



## robv27 (Feb 22, 2002)

Hey guys, I got a 2000 A6 w/ the 2.7T 6 speed tranny and i'm having some issues w/ my motor. It has a very light misfire at idle but not on higher RPM, (at least i can't feel it) this misfire seems to be on cyl #6 because the codes i'm getting are from cyl #6, I've replaced spark plugs and installed a new coil pack, and still getting the same thing, Here's the VAGCOM print out i took. 
VAG-COM Version: Release 303.1
Robert V.
Control Module Part Number: 4B0 907 551 K 
Component and/or Version: 2.7l V6/5VT G 0005
Software Coding: 06612
Work Shop Code: WSC 02325
4 Faults Found:
16487 - Mass Air Flow Sensor (G70): Signal too High
P0103 - 35-00 - -
16502 - Engine Coolant Temp. Sensor (G62): Signal too High
P0118 - 35-00 - -
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16690 - Cylinder 6 Misfire Detected
P0306 - 35-00 - -
Any ideas on what's going on?[headbang] does it have anything to do w/ the Maf? I got a code for it too... and this G62 coolant sensor? is this the one on the lower radiator hose? I'll be selling this car soon and i need to get this issues addressed. any input will be greatly appreciated. Thanks in advance[up]


----------



## The_Mailman (Feb 13, 2009)

I don't know what causes this but I'm starting to have the same problem. A I'm driving the engine simply starts misfiring.


----------



## robv27 (Feb 22, 2002)

Ok, Here's the latest!!! Replaced G62 coolant temp sensor, Installed brand new, MAF and air filter, and cleared codes... No MAF and G62 Codes anymore, but i'm still getting the missfire #6 code and now i'm also getting Missfire #5 code, they are same bank too.. (driver's side) still iddles rough.... drives normal... I'm going crazy w/ this car!!! Ideas??????


----------



## GLS-S4 (Jun 6, 2005)

*Re: (robv27)*

Have you tried swapping coils to see if misfire follows?
Have you tried new plugs?


----------



## robv27 (Feb 22, 2002)

just swapped all the coils from bank 1 to bank 2 and spark plugs too. Still getting Missfire on cyl 6. I guess i'm going to swapping injectors arround now, because i think it's the only thing left to do...


----------



## robv27 (Feb 22, 2002)

BTW did compression test in all cyl and i'm getting between 125-150 all the way around... number 6 in specific i'm getting 130 so i know compression is good...


----------



## ajax1977 (Mar 16, 2005)

*Re: 2.7T engine light misfire, Please help!!!! (robv27)*

I'm having the same concern, at idle after coming to astop I have misfires on 6, 2 and 3. Goes away when I start to drive. Also misfires shortly after staring up. Replaced ECT, new OE plugs, swapped coils, compression between 150-160 all the way around. Hmmmmmmm..... Have also swapped injectors. Fuel trim is OK.


----------



## robv27 (Feb 22, 2002)

Another update... swapped injectors from #1 to #6 and still missfire on number #6 so i know now injectors are good, i did also the ignitors swap and still getting #6 missfire, so i also know the Ignitors are good... Missfire on # 5 cyl has gone away, but #6 still continues, i guess this problem has to do between wiring harness on cyl 6 and ECU... Do you guys know if it could be anything to do w/ timing? I don't think so bc if it was timing it would give me some type of code on cam sensors or something like that right? could it be a timing issue and only give me missfire on 1 cyl? in this case # 6?


----------



## GLS-S4 (Jun 6, 2005)

*Re: (robv27)*

Bentley has info for testing ign wire harness.
Are there any visible cracks in the wire jackets? I ask because I fixed same problem on an 01 TT 225HP by replacing a connector due to cracked jackets.


----------



## robv27 (Feb 22, 2002)

*Re: (GLS-S4)*


_Quote, originally posted by *GLS-S4* »_Bentley has info for testing ign wire harness.
Are there any visible cracks in the wire jackets? I ask because I fixed same problem on an 01 TT 225HP by replacing a connector due to cracked jackets.

No, No cracks, I checked them... Now here's something weird... I pulled the coil pack number 6 out again and i tested it outside the engine w/ another spark plug and to my surprise, i have really good Spark... so i did another compression test on cyl 6 and i got 140, which is good, so i pulled out the injector harness and tested it and ine wire i have 13.8V and the other i have 3.60V so i checked number Inj. harness number 5 and 2 and they are giving me exsactly the same readings, so injectors are getting power, got spark from the coill to #6 and good compression.... i just don't know what else to check or to do!!!!







Now pordom my question but i'm so confused by now that i have to ask this.... The cyl number 6 is the one in the back of the motor, drivers side by the firewall right???
I'll see if i can kinf of draw what sequence i'm talking about
(3) (6)

(2) (5)

(1) (4)

Front of car
Check this link out, this is where i got this from...
http://autorepair.about.com/li...7.htm


----------



## GLS-S4 (Jun 6, 2005)

*Re: (robv27)*

Your Cyl map is correct.
As seen in some injector test video's, can you setup inj 6 out of cyl to see it spray into a pop bottle, etc?
IIRC and please double check to confirm but I thought injector power was switched on ground by the ECU... so in theory a bad switched ground between injector and ECU could cause your problem.


_Modified by GLS-S4 at 1:57 PM 2-15-2009_


----------



## ajax1977 (Mar 16, 2005)

*Re: 2.7T engine light misfire, Please help!!!! (robv27)*

Performed "running compression" test today and found "0" compression on number 6 cyl during misfire period. Compression rose to 70 during non misfire period, consistant w other cyl. Feel problem is w/ valve(s) for #6 cyl. Will need customer "OK" to pull head and inspect. Will keep you informed if anything is found.


----------



## robv27 (Feb 22, 2002)

*Re: 2.7T engine light misfire, Please help!!!! (ajax1977)*


_Quote, originally posted by *ajax1977* »_Performed "running compression" test today and found "0" compression on number 6 cyl during misfire period. Compression rose to 70 during non misfire period, consistant w other cyl. Feel problem is w/ valve(s) for #6 cyl. Will need customer "OK" to pull head and inspect. Will keep you informed if anything is found.

yes, please keep us informed, I still have not figured mine out. I phisicaly saw the injector spraying outside of the cyl. and i saw spark through spark plug and coill pack outside of cyl too, Good spark!! i found out there's a vacuum leak somewere couse i can hear, i bought a vac tool to troubleshoot it but have not had time yet!!! i believe my missfire is from this vac leak, just got to get around to do it...  
what exsactly do you mean when you do a "Running compression" during missfire and during non missfire periods? if you are getting a "0" missfire that means that it should be idling worse than mine right? I'm getting like 140 just at crank!! i misses just a little at idle, that's why i think it's this vacuum leak issue,


----------



## Zba (Jan 1, 2002)

*Re: 2.7T engine light misfire, Please help!!!! (robv27)*

Sticking lifter?


----------



## ajax1977 (Mar 16, 2005)

*Re: 2.7T engine light misfire, Please help!!!! (robv27)*

The vehicle I am diagnosing will go into "spells" of misfires (#2, #3, and #6) without being provoked, lasting about 1-2 min. During a "normal" compression test I was reading 155-170 psi per cyl. During a "running" compression test, I disconnected the fuel injector for cyl I am testing, I install compression gauge in saprk plug cavity and let engine idle (I leave the coil plugged in, install spark plug and let plug ground against valve cover, to see if I am losing spark). On said vehicle, when misfire is not present, running compression on all 6 cyl is around 70psi. During misfire spells, #6 will drop to 0psi. I have a feeling it is a mechanical concern w the head. 
I heard today from a reliable souce that carbon could be the problem, however it is not the dry carbon that intake cleaners can remedy, it might be a wet, gooey carbon build-up that requires removing of the head to clean the valves the proper way.... 
Reguardless, I am waiting to see what my customer would like for us to do.


----------



## ajax1977 (Mar 16, 2005)

*Re: 2.7T engine light misfire, Please help!!!! (robv27)*

*****WHOOOOOOO_HOOOOOOOOO!!!!!!*********
While removing intake manifold in preperation to remove cyl head, my technician found what appears to be cam adjuster debris in intake runner of #6 cyl. Removed debris and let idle, misfire did not return. The shop was busy yesterday and he nor I got a chance to road test. Will drive it today and update.


----------



## Zba (Jan 1, 2002)

*Re: 2.7T engine light misfire, Please help!!!! (ajax1977)*

Are you going to check the adjusters too?


----------



## ajax1977 (Mar 16, 2005)

*Re: 2.7T engine light misfire, Please help!!!! (Zba)*

found the debris to be the guide pin for mating cam adjuster to head (round sleeve that is inserted into cam adjuster). Someone at one point in time had had the adjusters loose/ removed. Current owner is second owner and it was at 2 other shops before mine for this concern.
Glad we found something.


----------



## vtraudt (Mar 1, 2010)

Reviving this old thread since it best describes my issues. In my case, persistent misfire on cyl 3. 

I would have long pulled the cams (good compression, good leak down), but there is NO valve noise/clatter. 
I am used to hear noise if bad valve adjuster (hydraulic lifter). Stuck (long) results in low compression and leak down. With both perfect, it would be a collapsed (or not pressuring) lifter, causing incomplete valve opening or delayed opening and early closing. 

My spark plug is plug (indicating rich, or unburned fuel). Ditto confirmed by gas smell in exhaust. 

Would that point toward exhaust or intake lifter?


----------



## diyGarageMatt (Nov 6, 2016)

*How To Video*

Hello - If anybody is still using this thread to fix their misfire, the video below really helps! 

https://www.youtube.com/watch?v=zR3ZrwdylPg


----------



## GRMNMUSL (May 22, 2009)

Did you check both cam tensioner's? When they begin to fail chain slacks thus timing off.
When chain is off by too much it will kill that bank of coils to protect motor. 

Had that on a 2.7T that multiple shops missed.


----------



## vtraudt (Mar 1, 2010)

GRMNMUSL said:


> Did you check both cam tensioner's? When they begin to fail chain slacks thus timing off.
> When chain is off by too much it will kill that bank of coils to protect motor.
> Had that on a 2.7T that multiple shops missed.


Interesting. But would such a sloppy chain (tension) not make a horrible rattling noise. 

And wouldn't that show up in the blocks 90-93 (cam timing) and a LOT of positive of negative deviation?


----------

