AUDI S4 2.7T expert advice needed so so much

[bamsetand]

hey all audi people. i have a 2.7 biturbo AGB engine in my kitcar which i have used 4 years on building so i really would love to solve this issue and get on the road this summer . But the engine cause a lot of fault codes that we cant seem to solve or find solutions for. we checked the temp sensor and replaced it also MAF, lamdasonda and egr was replaced
my kitcar does not use audi cluster, and the engine is not connected at all to the rest of the car.
perhaps this is a problem. (solution needed)
Anyhow 3 month ago the engine wires had some fire damage cause by a small fire on the wires because of a Lucas coil.
sensors on the burned side has been replaced.


I took the wires and sensors from a donor enigne ARE 2.7t and replaced them but now the engine is running like /&%/%/&crap and misfires also totally chaos.
so i had a vag-com on to check all values on the engine and fault codes.
i hope some one can be so helpfull to give their knowledge of expertise on this subject.

here are the codes when engine is off.
18057owertrain data bus:missing message from abs controller (Well abs is not on my car)

18028:engine coolant temp signalpen or short to plus

here are the codes when engine is ON:

18084 epc warning lamp (k132) circuit: electrical malfunction

18057.powertrain data bus: missing message from ABS controller

17931 crash signal from airbag controller implausible signal

18028 engine coolant temp signal: open or short to plus

i did check the the 4 wires from the G62 temp sensor. but the blue/red wire has no location in my case since i dont use a cluster. is there perhaps something i can link it too that would simulate a cluster for the ECU to recognize as a signal.
or what it takes to get the engine running smooth. i hope some one can guide or advice me on this matter.

best regards
bamse

[McFsC]

Okay, get this out of the way, I know very little about engines. However, in my work I deal with control systems and circuits a little bit.

The ECU will be looking for closed circuits on the sensors, between a certain resistance, say 2ohms to 50 ohms, anything outside of this is either open circuit, ie sensor not there, or short circuit, ie sensor broke.

If you do not have them connected they will show faults, such as connected to plus, or whatever it said. Regarding the engine misfiring etc, I would guess this engine was controlled from the ECU, mapping, turbo control etc so this would cause you an issue, you may have to find a stand alone AUDI unit... Maybe an engine/AUDI expert can help.

Regarding the sensors, if you don't want to use them, put a small resistor in if they are monitored, or just short them if not.

I hope some of that makes sense.

[bearman68]

I'd be tempted to fault find the engine without reference to the codes.

It's going to constantly give codes refering to missing CAN BUS signals, and this may be an issue (or it might not be).
I'd personally check the basics - is it getting coil signal and feedback - does it give good ignition sparks and waveform.
How much fuel is it injecting - what are the long and short term fuel trims - what's the injector duration (This is a good one to look up on VCDS). (Or measure)
Worth checking the MAF output.
If you measure the sensor values at the ECU, and the actuator values at the actuator, you'll have a better idea of what's wrong. Especially if you've had a fire, you might have possibly crossed a wire reconnecting.

Hope it works for you - the kit looks awesome.

[bamsetand]

bearman68 said:

I'd be tempted to fault find the engine without reference to the codes.

It's going to constantly give codes refering to missing CAN BUS signals, and this may be an issue (or it might not be).
I'd personally check the basics - is it getting coil signal and feedback - does it give good ignition sparks and waveform.
How much fuel is it injecting - what are the long and short term fuel trims - what's the injector duration (This is a good one to look up on VCDS). (Or measure)
Worth checking the MAF output.
If you measure the sensor values at the ECU, and the actuator values at the actuator, you'll have a better idea of what's wrong. Especially if you've had a fire, you might have possibly crossed a wire reconnecting.

Hope it works for you - the kit looks awesome.

thanks bearman. i will post the engine values later this week since i may have over seen something?
the reason i ask about the temp sensor is because in some cases it does shot of the egr etc.
best regs

[Royce44]

Unless i missed it, have you checked for continuity on the cables to the colant sensor? Find someone with a wiring diagram of the engine code, then check you hav continuity form sensor pin to ecu pin.

Also the rest of them codes arent too much of an issue, certainly wouldnt cause running issues anyway.

Finally check all the pcv/vac hoses, they get very brittle from the heat so they split very stealthily, that will cause horrible idling and general running issues

[bamsetand]

Royce44 said:

Unless i missed it, have you checked for continuity on the cables to the colant sensor? Find someone with a wiring diagram of the engine code, then check you hav continuity form sensor pin to ecu pin.

Also the rest of them codes arent too much of an issue, certainly wouldnt cause running issues anyway.

Finally check all the pcv/vac hoses, they get very brittle from the heat so they split very stealthily, that will cause horrible idling and general running issues

HEy royce thanks for the advice i will check the 4 wires again tomorrow, i did track wires already only one wire brings a signal (grey/red wire) to the ecu. two(brown/yellow and brown/grey) wires are ground also from the ecu and the last wire (blue/red) is a signal wire for the temp gauge/cluster which in my case has no place to go since i dont use the audi cluster.

in regards of the pcv and vacuum i did check all the vacuum hoses, but one of the tube going too the air distributors could be damaged from the fire. i will check asap.

[Spangles]

Was it running fine before the fire?

[bamsetand]

hey audi people.. thanks for all the advice. somehow the engine started behaving well after i checked the pcv system and the wires?? i surely dont know what happened but it is acting as an engine now. the engine does jump every 3 min or so. but i think new sparck plugs and ignition coils will do the job.

SOoo i went for a drive and came back without any problems with my rs4/ ultma gtr.

thank again.
best regs.