3.0 Misfires, no power and flashing CEL

[jrv666]

New here but wondering if any one can help. last month the esp light stayed on, cleared code re-adapted throttle (this sometimes happens btw) and all was well. A couple days later i could hear the exhaust note didnt sound right, as tho it was not running even or missing - a bit like a boxer sort of sound but not as pronounced. later that day the power started to die off, not at high RPMs but at low loads and engine speed. this condition rapidly got worse, it was running lumpy, no power at all between 1 & 3krpm accompanied with the misfire and my all time favourite the flashing CEL. Sorry no codes at the mo, i will update shortly but any ideas??
It has recently had 2 new head gaskets (1 was leaking coolant into oil) replaced them both to be safe, it also needed a new exhaust valve. got all that sorted and has been running great for a few months until now. It has 6 brand new NGKR plugs, recent coil-packs, good compression on all 6 - iv checked EVERYWHERE for vac leaks. the only codes showing are....
P0300
P0301
P0302
P0303
Basically the left bank is misfiring on all 3. no other codes were set apart from (P0102 - but im 100% certain thats because i dis-connected the MAF to see if it ran any different).
The car was scanned with a generic OBD reader not vag so i havent been able to get a full print of live data however i noted down some things that caught my eye - not sure if these figures will make a diff but here they are anyway.....
Maf reading was stable at 5.500 on tick-over( this was a volume not voltage reading - i think it was ltrs per sec or min or something but it rose to 80.000 ish with WOT so i assume it its working to some degree). ST FTRM1 -6%, LT FTRM1 0.0%, ST FTRM2 +5%, LT FTRM2 0.0% - These were at idle and just after clearing codes, i know i prob should have got readings prior to clearing but i feel these short term trims are a clue at least. the only other noticable thing was the O2 readings (S12 & S22) both sat level at about 0.7v but then would drop 2 0.1v before climbing again. this was at idle and repeated this drop and rise every 4 or 5 seconds or so. any help would be great

[mullardel34]

You really need to get a VAG.com readout from the car in order to find the detailed bread-crumbs that will lead to a problem solution. While we could make endless informed guesses as to the core fault behind the engine misbehavior (there's a lot of moving parts involved...), they'd only be guesses... ;-)

I strongly suggest that you take the car to a properly-equipped independent shop or locate a nearby Audi-Forum member who has a VAG.com system and is willing to give you a hand. Good luck!

[a8 tech]

Originally Posted by jrv666

New here but wondering if any one can help. last month the esp light stayed on, cleared code re-adapted throttle (this sometimes happens btw) and all was well. A couple days later i could hear the exhaust note didnt sound right, as tho it was not running even or missing - a bit like a boxer sort of sound but not as pronounced. later that day the power started to die off, not at high RPMs but at low loads and engine speed. this condition rapidly got worse, it was running lumpy, no power at all between 1 & 3krpm accompanied with the misfire and my all time favourite the flashing CEL. Sorry no codes at the mo, i will update shortly but any ideas??
It has recently had 2 new head gaskets (1 was leaking coolant into oil) replaced them both to be safe, it also needed a new exhaust valve. got all that sorted and has been running great for a few months until now. It has 6 brand new NGKR plugs, recent coil-packs, good compression on all 6 - iv checked EVERYWHERE for vac leaks. the only codes showing are....
P0300
P0301
P0302
P0303
Basically the left bank is misfiring on all 3. no other codes were set apart from (P0102 - but im 100% certain thats because i dis-connected the MAF to see if it ran any different).
The car was scanned with a generic OBD reader not vag so i havent been able to get a full print of live data however i noted down some things that caught my eye - not sure if these figures will make a diff but here they are anyway.....
Maf reading was stable at 5.500 on tick-over( this was a volume not voltage reading - i think it was ltrs per sec or min or something but it rose to 80.000 ish with WOT so i assume it its working to some degree). ST FTRM1 -6%, LT FTRM1 0.0%, ST FTRM2 +5%, LT FTRM2 0.0% - These were at idle and just after clearing codes, i know i prob should have got readings prior to clearing but i feel these short term trims are a clue at least. the only other noticable thing was the O2 readings (S12 & S22) both sat level at about 0.7v but then would drop 2 0.1v before climbing again. this was at idle and repeated this drop and rise every 4 or 5 seconds or so. any help would be great

check mvb for misfire recognition,if its jumping from cylinder to cylinder and quickly then check the cat has not broke up blocking the gases and causing irregular lambda readings due back pressure

[jrv666]

Originally Posted by a8 tech

check mvb for misfire recognition,if its jumping from cylinder to cylinder and quickly then check the cat has not broke up blocking the gases and causing irregular lambda readings due back pressure

ok, will do. I have been worried about the timing - namely that i fear one of the cam pulleys has slipped slightly due to the fact the cam and pulley connect purely under the torque of the pulley bolt. How likely is this and if it did happen would it throw a code(which i assume it would) due to the cam position sensor giving irregualr readings?? just to add, when i did the head and TB job i did it by-the-book and these pulley nuts were tightened to specified torque.
Also, if the scenario you suggested has happened - would lambda readings cause such a significant missfire or would it be the excess backpressure....or even a combo of both??

Thanks for your help

[jrv666]

Originally Posted by jrv666

ok, will do. I have been worried about the timing - namely that i fear one of the cam pulleys has slipped slightly due to the fact the cam and pulley connect purely under the torque of the pulley bolt. How likely is this and if it did happen would it throw a code(which i assume it would) due to the cam position sensor giving irregualr readings?? just to add, when i did the head and TB job i did it by-the-book and these pulley nuts were tightened to specified torque.
Also, if the scenario you suggested has happened - would lambda readings cause such a significant missfire or would it be the excess backpressure....or even a combo of both??

Thanks for your help

Originally Posted by a8 tech

check mvb for misfire recognition,if its jumping from cylinder to cylinder and quickly then check the cat has not broke up blocking the gases and causing irregular lambda readings due back pressure

Ok, timing is fine, after checking everything i drove the car down the end of my street and back to see how it ran. (No Better) got back, removed plugs to reconfirm compression and the plugs on 1,2&3 were blacked worse than i had ever seen. I rang an online CAT dealer for a quote, told him my symptoms and he said - especially with the recent head gasket failure and the coolant leak into the cyliner on that side that he is 100% certain the cat is at fault. Would anybody here agree?? or is he just going for the sale?? i do suspect it myself but at £520 for new cat and sensors on the off-side it seams like a costly experiment if it isnt that. and do i even need new sensors?? no faults were showing.