misfiring CELs - vagcom reads and datalogs


Registered User
Apr 13, 2008
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Newark, Delaware, USA
Hey all,

Been having problems with my 1998 A4 1.8tQ...i bought it used with Piper 270 degree cams, GIAC chip, and borla catback. It has a CEL due to misfiring. I have been told by a few people who also have the Cams that they should not be causing a misfire.

108,000 miles on the chassis.... ~5000 on the rebuilt engine

My VAGCOM scans bring back:


Sunday, 13 April 2008, 09:23:42

VAG-COM Version: Release 409.1-S

Control Module Part Number: 8D0 907 557 P

Component and/or Version: 1.8L R4/5VT MOTR HS D07

Software Coding: 06001

Work Shop Code: WSC 05314

5 Faults Found:

16684 - Random/Multiple Cylinder Misfire Detected

P0300 - 35-00 - -

16688 - Cylinder 4 Misfire Detected

P0304 - 35-00 - -

16686 - Cylinder 2 Misfire Detected

P0302 - 35-00 - -

16687 - Cylinder 3 Misfire Detected

P0303 - 35-10 - - - Intermittent

17708 - Misfire Detected. Probably Reason: Low Fuel

P1300 - 35-10 - - - Intermittent


additionally here are 2 datalog scans (sorry I had to upload them as CSV files on file hosting site)

if it requires a PW to open it is "audi" without the "" , if you have a better place or idea how to host the files, let me know please

1st log is for timing, viewing Blocks 02, 03, and 18


2nd log is for misfires, viewing Blocks 14, 15, and 16 (and HOLY CRAP, LOTS OF MISFIRES!!!!!!)

oh yeah,

Things replaced so far:
- Spark plugs with BRK7E 0.028 gap
- all 4 coil packs
- engine coolant temp sensor
Have you checked your fuel lines and the Air Fuel mixture? As the fault code says, it could be due to low fuel in the cylinders caused by a blockage. I am assuming the tank is full...

Have you run the car on the new plugs and coil packs with no problem in the past or is this a 100% new setup?

I would check the wiring to the coil packs too, just to make sure they are connecting properly.
fuel lines + mix not yet

low fuel due to FPR running at 4bar i think, raised to 5bar and its gone so far

yeah electrical / igntiion have been in for a while, no change

am checking for vac leaks, fuel issues, and wiring this week and plan on logging a bit later today

does 5 bar sound too much for a US spec AEB engine...remember i only have the 210cc injectors at 16.23msec
I must admit, I have never hear of anyone using a 5 bar FPR on any set up. I am not sure what the IHI or hybrid turbo boys use example though?

With a stage 2 remap with the required hardware, (FMIC, 100 cell CAT etc) the tuners recommend a 4 bar FPR.

I am not sure what the Piper cams are doing for your fueling. It might be worth contacting Piper to see if they recommend using an FPR that high a spec. Especially with those injectors too.
well dont the stock FPR rated at 4bar? dunno, maybe ill switch it back

ive tried to contact them thru email and no response, as they are in UK its hard for me to call...

i forgot to mention some of my mods so here is everything:

Piper 270 cams
ABT drop in filter
FMIC 2.5" piping
Borla 3" catback
GIAC chipped
SARD FPR rated at 5 right now but might switch to 4
random BOV that came on the car

im going to do a boost leak test in a few hours, and my o2 sensors still are not reading due to readiness test...hopefully they come online so i can do fuel trim tests or maybe its just broken

i dunno :(
STD FPR is rated at 3 bar and changing to 4 bar is reccomended with phase 2 maps.

If you have a BOV that doesn't recirculate like it should, you will get problems too. I would change that if its an atmospheric one asap.
i have a 1998 1.8t....they came 4bar stock....maybe only in the US..but i know they did, the stock one even has a 4bar stamped onto t

yes mine vents to ATM....but is that enough to throw a CEL for misfire? :(

another thing to add, did a boost leak test last night and found big vac leaks in my injectors...going to replace the orings this week
The valve to atmosphere will definitely throw up the CEL. I have heard about this problem loads. Not sure about the misfire though. Its worth putting it back to recirc just to see.

In terms of the FPR. I am sure Leon Cupras and Cupra Rs have a 3 bar as std on AUQ and BAM engines. Perhaps there is a difference between engine codes.

I will be interested to hear how you get on after changing the injector o rings.
AEB engine code , longitudinally mounted = 4bar....

ill check the reroute thing later on...it looks like this is a TurboXS bov, its a tall blue anodized cylinder .... dont know for sure havent taken it off yet ... im also upgrading to an APR TIP since my stock is getting nasty and prob cracking

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