I know, not an S2, but help - '89 Jetta Syncro T

[macspring]

I have an S2 (Avant) which is being refettled, but I also have a 1989 Jetta Syncro with a 1.8T. Trouble is it's in Ireland and was done recently in England, and true to sods law it developed this problem once back in Ireland.

It will boost to 0.6 bar and then if the revs are increased past say 3/4K it will move up slowly to 1.0 bar of boost. When this unknown problem is not holding it back from boosting, it boosts up to 1.5 bar immediately once it goes past say 3K. Rolling road said 362 @ 6150 and 472 @ 4800.

It has a new IHI turbo, steel rods, s3 pistons, running remapped original loom and ECU etc..

I've replaced the boost solenoid valve and the blue 4 pin temperature sensor, but have not yet discovered the problem. Obviously the loss of almost 1 bar of boost detracts from the enjoyment of driving the car.

I know I should get the ECU read for fault codes but the dealers are too busy with long leasd times and I'm not convinced they would be interesrted or care.

I will probably blag a vag-com read, reset, and reread from Mark over here as soon as he can oblige, I still have to ask him, but in the meantime if the cure to the problem is standing out a mile to anyone, needless to say I'd be greatful for their tuppence worth?

The principles should be the same as the S2 with less complication if anything, well less sensors anyway.

Thanks!

[topsparky]

pm paul nugent (s2central)
he's in your neck of the woods and does
generic chips for s2/s4/s6
so i would assume he has vag com
he maybe able to help

[Greg_S]

Yeah def worth giving paul a try. Hopefully the fault codes will show up the fault

[mcandmar]

Vagcoms not a problem David any time, i cant wait to see this street sleeper

[Corey]

She is very good, David brought her to show us just after he picked her up.

Ultimate sleeper

[mcandmar]

Can any ECU boffins give us a clue as to the first error here?

I suspect the intermittent throttle body signal is making the ecu drop into some kind of fail safe mode when it only boosts to .5bar. (i assume that’s dictated by the wastegate?)

We did discover if we stop and restart the engine it resets and boosts to 1.5bar again. Its some adrenalin pump when it does


Control Module Part Number: 8D0 907 558 M
Component and/or Version: 1.8L R4/5VT MOTR HS D01
Software Coding: 06001
Work Shop Code: WSC 00028

3 Faults Found:

18010 - Power Supply Terminal 30: Voltage too Low

P1602 - 35-00 - -

17967 - Throttle Body (J338): Fault in basic settings

P1559 - 35-10 - - - Intermittent

17968 - Maximum Engine Speed Exceeded: Engine Warranty VOID! :-)

P1560 - 35-10 - - - Intermittent

[Corey]

I caanot remember if your ecu was DBW or a NDBW, I didn't pay that much attention to the detail as the whole package made me giddy!!!
Your car had been converted to NDBW? Which if it has is the ecu still expecting a signal from the DBW throttle?

It may be worth checking the ecu is seeing the correct throttle angle, which you can do with VAG-Com in the measuring blocks, block 3 if my memory serves me correctly.

[mcandmar]

It does have a throttle cable, but David said something about it being from a 2litre or something like that?

In vag com it reads 3 degrees at idle, and seemes to count up smoothly through the range. Only weird thing i noticed is when you blip the throttle the reading in vagcom dropps to 2.2, 2.4, and then settles at 3 degrees again. But moving it manually 3 is the lowest reading when you hold it fully closed?

Mark.

[Corey]

Is it seeing 100% throttle?

[mcandmar]

Dont know, i could only read the raw data or the labeled degrees but i had no idea of the range they should be in.

[macspring]

Back to intermittent again

All of yesterday and all of today it boosted and if it stopped boosting, it starting boosting again when the engine was stoppped for a couple of seconds and then restarted, but tonight it stopped boosting properly, i.e. fully, after the engine was stopped and restarted so the temporary "cure" may be over, but no doubt someone on here will probably cop what it is?

I think the throttle body, which is cable operated, is from a 2.0L Mk 3 Golf?

Thanks again for your time Mark, and to the others for the childminding duties.

Regards.