2.0 GT TDi Throttlebody issues.

[The Mad Monk]

Hi,

been having 'throttlebody' issues with my Mk5 GT for a while now.

Started last year with a jammed throttle body which was blowing fuse 24.

Replaced throttlebody and egr valve which were both badly carbon encrusted and the throttle body control board housing was flooded with oil.

Anyhow, replacing both did not clear the fault code, which kept coming back sporadically.

Unfortunately before I could investigate further, started to get bearing whining from the turbo. Which was replaced by a local garage - but not before they blew it on a test drive!

So after having new turbo fitted, intercooler cleaned out and all turbo feed pipes replaced, was horrified to still find that the throttlebody error code was still coming up sporadically.

I re-checked the replacement throttlebody which was badly coked up again (presumably oil burning from the turbo blow) and had developed a 'rattle' from its internals which wasn't there originally.

So I invested in a new throttlebody to be on the safe-side; a febi-bilstein part, however the fault code is still there.


P3103:00/12547:00 - intake flap motor faulty - passive/sporadic


The fault code seems to be triggered on start up: when running a live diagnostic, the fault occurs at 0 rpm/0 torque and pings the engine warning light instantly on firing up the engine.

Other symptoms when fault is live/engine light on - reduced performance/sluggish and lower than normal average mpg - 40-42 ish.

After a few days, engine light goes off and car runs normally for 24-48 hours before light comes back on again... and repeat cycle.


I was also getting fault related to the ignition switch; which has been replaced (fault cleared)

Have had the wiring loom from the ecu to the throttlebody tested and that is ok, signals going ok from ecu to throttlebody.

All fuses ok.


In other work, new battery fitted.


Anyone come across similar issues before when replacing a throttlebody?

Could it be compatibility issue with an aftermarket part? I've gone for a febi this time because it was recommended (by Parkers) as OEM quality with 3 year guarantee?

Could it be ecu related?

Or is there a set-up/calibration I should be doing that I've missed - I understood they are self-calibrating?


Running out of ideas now. I've taken it to the garage who service my MX5 now rather then the local who seemed a little clueless. The MX5 garage are a racing team who I use mostly but unfortunately couldnt get the car to in the event of the turbo blowing - they have tested the loom and fitted the new ignition switch. They say the throttlebody seems to operate ok then throws up the sporadic fault and have suggested getting a second hand genuine throttlebody and fitting that to see if it clears the fault, otherwise they think there may be there is an issue with the ecu?

Desperate to get this resolved so I can continue work on the Mk2 instead!! ;)

2.0 GT TDi - 103kw - BKD - 2007

39146

[Crasher]

It would be unusual for a Febi V157 to be faulty, a problem with the power supply to SB24 would also show other problems such as no fuel pump. There is a 14 pin coupling called T14a towards the cars middle of the battery and the power for the V157 passes through this at pin 6 as a blue/red. Due to the position and angle of this plug it suffers corrosion so pop it apart and get some contact cleaner in there.

[mickeybo]

When seeking help 1 should post up engine code

[The Mad Monk]

Hi Crasher,

thanks, as a bit of an update, yesterday when I first started the car the engine light was off after having been on constantly from Monday evening. It came back on in the evening after about half a dozen trips, so 6 restarts...

I'll check the 'T14a' plug.

Is that the large connector hidden down here?

39147 39148

MM.

[The Mad Monk]

Hi,

thought I had - BKD?

39149

[Crasher]

Is that the large connector hidden down here?

39147 39148

MM.

Yes.

[The Mad Monk]

Re-scanned fault codes, 3 code present:

P3103:00/12547:000 - Passive/Sporadic - Intake motor flap - Faulty

00097:012 - Passive/Sporadic - Front passenger door central locking SAVE motor - Electrical error in circuit

00290:003 - Passive/Sporadic - Left rear ABS wheel speed sensor - Mechanical malfunction

Cleared codes and took the T14a plug apart.

No obvious signs of corrosion, gave it a good dose of contact cleaner and cleaned out. Some of the connectors looked a little loose so checked and tightened all and re-assembled.

Took for test drive and re-scanned codes.

Throttle body fault had registered straight away:

P3103:00/12547:000 - Passive/Sporadic - Intake motor flap - Faulty

39159
39160

39161

Also took apart the throttle body plug, cleaned out and checked all connectors.

Fault/engine light still persists?

[Crasher]

Looking like a faulty Febi V157, we have used hundreds of them without problems

[The Mad Monk]

Well this is certainly a brainteaser!

Haven't had chance to do any more investigation/work as yet but here is an update on symptoms:

I'm still driving the car - normal daily usage.
Last week the engine warning light reset itself on Monday am start-up and stayed off until a re-start Wednesday lunchtime. Then, re-set itself on starting up on Saturday morning and hasn't come back on since. (Famous last words no doubt - we'll see when it recurs...)

I will re-scan the fault codes when I can to see what has been logged over the last week, and I have acquired a second-hand original factory fit pierburg throttlebody, to try when/if it comes back on...


MM.

[The Mad Monk]

Well, over the weekend I scanned the fault codes, the usual suspect was present:

P3103:00/12547:000 - Passive/Sporadic - Intake motor flap - Faulty

Also logged was the lock error -

00097:012 - Passive/Sporadic - Front passenger door central locking SAVE motor - Electrical error in circuit.

I took off the Febi throttle body and replaced it with the second hand Pierberg unit.

The fault code came back immediately on restart:

P3103:00/12547:000 - Passive/Sporadic - Intake motor flap - Faulty

Although this time there was initially a difference in the occurance; it registered as at 819rpm, whereas before it has always been at 0 rpm:

391763917739178

Took it for a test drive and rescanned the codes, this time the readout was as before, same code and same ocurrances at 0 rpm.

391793918039181

This is the third throttle body I've tried now; an ERA unit, a Febi - both brand new - and now a second hand Pierberg, surely they can't all be faulty?

There are currently no other fault codes present, and as I've said before the wiring and plugs to the throttle body have been checked and have no obvious signs of beakage or corrosion.
All fuses ok.

Could this be an ECU issue?

Any further advice very much appreciated, although this fault looks like it is beyond my capabilities; probably time to take it to a specialist garage!

[mickeybo]

IM very curious to know how the wiring was checked out was it load tested to insure it was getting the required 12 vs the earthing has to be checked on this vehicle

[The Mad Monk]

The wiring was checked out by the garage last time it was in for the Turbo Overboost issue.

They checked the wiring from Throttlebody to ECU and fuse box for faults - connectivity, breakage.

It is now booked back in with them for further investigation, although the earliest I can get it in is first week Oct.

I will keep monitoring it in the meantime and post iof any other faults/issues arise.

What are the specific faults/other component failures I should be looking out/checking for that can cause mis-operation of the throttle body like this?