Help? A6 MISFIRING CEL

[kuruca]

I have 98 2.8q I'm having some problems.
CEL s comes on when I go over 4000rpm


here is the codes
P0300 random multiple cylinder misfire
P0304 cylinder 4 misfire
P0306 cylinder 6 misfire
p0305 cylinder 5 misfire

pugs, wires and coils already replaced
ANY SUGGESTION WHAT SHOULD I DO?
thanks guys

[rc1985]

I have a 98 a6 2.8 with the same problem. I was in the garage letting it idle and checking all connections and discovered when I disconnected the camshaft adjustment valve that the misfire was eliminated and the idle restored. Obviously there is an issue, but I have been driving it like this for a while and it is operating just fine. Anyone have an idea???

[masboykie]

Originally Posted by kuruca

...ANY SUGGESTION WHAT SHOULD I DO?
thanks guys

Hey Kuruca

If you have a new set of plugs in there, it could be the ignition module for the 456 bank. There are two of them on to of your airbox. What you can do is turn the car OFF and swap the wires between the two. If the miss-fires move to cyl 123 then the ignition module needs replacing.

Hope that helps

Cheers
Massboykie

[kuruca]

Thanks masboykie but Which one is that.

I changed vacuum hoses today and swapped the

injectors 1,2,3 to 4,5,6 and I'm still receiving

misfire code for 4,5,6. The thing is when I clear all the codes

no check engine light comes on while idling, When I go over 30mph

it comes back on,



WHAT SHOULD I DO GUYS
THANKS

[masboykie]

Originally Posted by kuruca

Thanks masboykie but Which one is that.

Hey Kuruca

On my 2.7 the two modules are on the outside of the stock air box. I am not sure if these are in the same location on the 2.8.

Attached some pics.

Cheers
Massboykie

[kuruca]

I tried modules butthats not it either.
What should I do??

[masboykie]

Originally Posted by kuruca

I tried modules butthats not it either.
What should I do??

Wow, I would try swapping the offending plugs.

On mine I did get some misfires after the dealership put new plugs in (big service). They replaced it and it went away. I always figured they never replaced the plugs the first time, but maybe I was wrong and plugs can be bad out of the box.

Worth a try I think.

Cheers
Massboykie

[kuruca]

I tried the plugs and still same issue.
Compression is fine also.
I'm going to swap the O2 sensors
and camshaft sensors. maybe that would help
do you have any pictures where 02 sensor connected
thanks alot again man

[masboykie]

Originally Posted by kuruca

... do you have any pictures where 02 sensor connected...

Not a problem

The O2 sensors on the 2.7T connects on the firewall behind the airbox (2) and behind the ABS module (2). I think the set behind the Airbox is the "After Cat" sensors and the others are "Before Cat", but to be honest I am not sure. I was going to change mine and I still haven't gotten round to it. My CEL also stayed off for a another tank of gas so I've been putting it off.... I would suggest buying the universal Bosch sensors though as it looks like a b!tch to get the harness loosened on mine... it runs right on top of the tranny and you cannot see in there, all by feel... The universal ones are spliced in right by the sensor location so no harnes removal is necessary. And they are a 1/4 of the price! The Bosch part number for the universal Kit on the 2.7T is 15733 (# 025 898 6602). On the 2.8 it would probably be different, but they make them for all their OE ones.

Hope that helps

Cheers
Massboykie

[kuruca]

Originally Posted by masboykie

Not a problem

The O2 sensors on the 2.7T connects on the firewall behind the airbox (2) and behind the ABS module (2). I think the set behind the Airbox is the "After Cat" sensors and the others are "Before Cat", but to be honest I am not sure. I was going to change mine and I still haven't gotten round to it. My CEL also stayed off for a another tank of gas so I've been putting it off.... I would suggest buying the universal Bosch sensors though as it looks like a b!tch to get the harness loosened on mine... it runs right on top of the tranny and you cannot see in there, all by feel... The universal ones are spliced in right by the sensor location so no harnes removal is necessary. And they are a 1/4 of the price! The Bosch part number for the universal Kit on the 2.7T is 15733 (# 025 898 6602). On the 2.8 it would probably be different, but they make them for all their OE ones.

Hope that helps

Cheers
Massboykie

Thanks again masboybie
you are the only one who replies back
rest of the forum is dead.
I got the problem solved.
It was the clogged up catalyst
converters
I took them out and emptied them
right know it drives awesome.
thanks for the help again.
I'll prefer you to cut the O2 sensors
and splice them, they are ***** to
take it out I took of Works fine