2000 Bora 1.6 16v AUS engine - Bad hot idle and hot stalling

[SammoVWT]

I got over-rev just after it was about to stall at idle but recovered, or when stopping and then opening the clutch at standstill (or near enough) when my injector was playing up. Will it hold revs below 1200 and and not be lumpy? I found my lumpiness stopped at around 900-1000 revs, but then the engine has enough momentum to mask things there.

Did he give you the old TB or was that an exchange part?

If it can hold revs, I think it would lest likely to be TB, could be though - but I would have thought that is more likely to result in hunting rather than a loping idle

[Crasher]

You have done the Basic Setting check 074 of the EGR valve but not its test which is Basic Settings 075, rev the engine bit I mentioned.

[Col]

I cannot rev the engine to do the 075 test.

Once it is up to temp it goes to 1200rpm by itself and pressing the acc pedal does nothing other than make the car stutter.

[Col]

Had another play.

From cold I can freely rev the engine.

From cold I held the revs above idle varying them from 1500 upto 3000 ish and sometimes beyond. It revs freely and smoothly.

If I come off the throttle it either runs very lumpy or stalls, mostly stalls.

When I restart it, it runs lumpy but will rev freely but then stall, if I re-start it and leave it running lumpy the engine light will come on and the revs will pick up with no input from to about 1200'ish.

I've done the Adaption 000, TB060 and EGR074 thing countless times. In the times I've been revving it I've tried to do the 075 EGR test numerous times but have not been able to get the test to run despite revving the head off it attempting to do so.

This car does not want to play the game!

I keep getting the same fault codes coming back as a few posts above, the implausible correlation and air leak detected. I've checked everything again and again physically on the engine. I used a new intake manifold gasket and made sure everything was squeaky clean on re-assembly of the engine.

There is obviously something wrong beyond the scope of my ability with this damned car and I do count myself as being a competent DIY'er having undertaken very complex jobs on many of the cars I've owned along the years. I've been running VW TDI's for many years and have probably been spoilt by there reliability. I've also run older VW petrols which were simple machines that gave no bother. I've run newer Ford 16v petrols, have changed cambelts on them and sorted out the odd bad running issue but this Bora has got be beat!

I'm on the verge of giving the scrap man a ring despite the time, effort and expense I've lavished on this car. Even if I do get it sorted, I don't think i'll ever have any confidence in it and would constantly be worrying about the Wife driving it with the kids in it.

[Doctle Odd]

I have my nieces car here for several months. It's 1 2001 golf 1.4. It starts and idles perfectly and will do so all day. There's been a fortune spent on it with no joy. I read somewhere that the after cat lambda sensor can cause weird problems with the ECU . Last time it was scanned it was showing a temperature of -32. she's currently saving for a new ECU.

[SammoVWT]

Lean injectors would surely cause it to think its an airleak? If the valves think they are at 50% duty (maybe delivering 25%), ecu is expecting 50% duty, and a certain afr. The O2 sensor reads too much O2, the engine light comes on. Air leak fault code. It seems to fit for me. :/

Its already had burned exhaust valves, it fits the profile valve 2 is probably in a hot spot in the engine because its in the middle and probably due to gasflow, 3 probably was a bit worse for wear - could also explain your hot exhaust, and your seemingly fine cold revs, rich mixture.

Exhaust temps soar as the car reaches temp (injectors back off as you expect, fuel flow drops to unsuitable level to idle due to lean run), so the car increases injector duty probably to full chat to compensate in an attempt to cool things and fix the afr, but just makes it worse.

Pressing the pedal will make the car attempt to match the fuel to the pedal position and fail because the duty is less than idle, and so when it tries it will have conflicting logic and will cause a stutter due to opposing injector duty positions happening from the pedal position request check and the engine idle stability management throttle position scale. Implausible correlation between pedal and idle duty. Thats how I would program it, and thats how they appear to have done it.

It also has 'limp' mode until it gets to its temperature sweet spot where the engine temperature matches the deliverable duty from the injectors and then when it goes past this point the problems start a lot.

I think your TB is fine and doing its job, your fuel pressure/injectors might be an issue

I just cant even see an exhaust leak before that O2 causing that kind of heat to glow an exhaust if its delivering fuel properly, the lean-running is happening before that point even if there was an exhaust leak, cylinder level gotta be.

[Crasher]

Is it throwing out a manifold barometric pressure sensor fault?

[Col]

Yes, the Implausible correlation fault and air leak faults. I've changed the MAP / Thrust sensor, did this before the head came off.

These keep coming back;

17961 - Barometric / Manifold Pressure Signals
P1553 - 35-10 - Implausible Correlation - Intermittent
17912 - Intake Air System
P1504 - 35-00 - Leak Detected

[Crasher]

I have had this before with the AUS and it was simply the set up of the throttle body and the EGR valve. The TB and EGR valve are new if I remember rightly so I think your way through this is going to be even more repeated attempts at adaptation and basic settings, if it is what I have experienced; it is not a component fault but an engine ECU software glitch you have to work around. Try clearing the fault codes even if there aren't any then clear the adaptations in 00 three times, then come out of that and go into Basic Settings 060 and do the TB adaptation and come back out and do it again twice more, after the third time wait 30 seconds before exiting 060 and then come back out into the main page and turn off the ignition. Wait 30 seconds and then turn of the ignition and then go back into engine 01, basic settings 04, then group 074 and see if ADP OK appears in block 4. Sometimes you will see ADP run in there but not often. Then come out again and turn off the ignition. Then wait 30 seconds, turn on the ignition and wait 30 seconds and then start it. I have sometimes had to do this 20 or more times before suddenly it clears and accepts the adaptation of the TB and EGR valve

Also, try this procedure

If the vehicle is equipped with an air conditioner, this must be switched off.
Exhaust system between catalytic converter and cylinder head must be free of leaks.
Coolant temperature, 80 °C minimum => display group 04, display field 3.
Intake air temperature below 60 °C => display group 04, display field 4.
Start the engine and enter "address code" 01 to select the engine control unit.
Check and erase fault memory

Note:
The readiness code returns to zero or is cleared each time the fault memory is cleared.

Note: Do not shut off the engine during the following operations

Step 1 Diagnosis of activated charcoal filter system (EVAP, fuel tank venting system)
Select basic setting 04
Select display group number 70, Go
When the ECU starts the diagnosis, the message in field 4 goes from "Test OFF" to "Test ON".
Continue with the engine idling until display field 4 reads:
Specification: "EVAP or System OK"

Step 2: Lambda probe ageing diagnostics
Select display group number 034, Go
Give two throttle bursts over 5000.
Hold engine revs at 1500 to 3900 rpm.
Maintain engine speed until display in display field 4 changes from "Test OFF" to "Test ON" and hold the speed until the specification changes to B1-S1 OK
Exit Basic Settings and select Measuring blocks 08
Enter display group number 030, Go
Observe the operational status of Lambda regulation before catalytic converter in display field 1
Specification: 1 1 1
Check operational status of Lambda regulation after catalytic converter (display field 2):
Specification: 1 1 0

Meaning of the 3-digit numerical block, display fields 1:

Meaning of display binary digits
1	2	3	Meaning
		1	Lambda regulation active
	1		Lambda probe operationally ready
1			Lambda probe heating on

Note:
The third bit of display field 2 will only change to 1 when the engine is running at half load (2500-4000 rpm).
If the specifications are not attained:
The 3rd display position is not set to 1 until in part throttle range
If the specifications are obtained: Exit

Step 3: Catalytic converter diagnosis
Note:
This diagnosis will end only if there are no faults related to the lambda probes and the activated charcoal filter system.
Enter Begin basic setting 04
Select display group number 046, Go
Hold revs at 1500...3900 rpm until the message in display field 4 changes from "Test OFF" to "Test ON". The catalyst temperature in display field 2 should be at least 300°c
Hold revs at 1500...3900 rpm until display field 4 shows the target value "Cat B1 OK".
Note:
It may take a few minutes for the message to change from "Test ON" to "Cat B1 OK"

Step 4: Exhaust Gas Recirculation system diagnosis
Select display group number 075, Go
Give the throttle five bursts to maximum revs.
When the ECU starts the diagnosis, the message in display field 4 changes from "Test OFF" to "Test ON".
Let the engine idle until display field 4 reads: System. OK
Check readiness code value in main engine table safe values. The value should be 00000000.

[Col]

Just finished work, had a deadline to meet.

Crasher, I thank you so much for the time, effort and care of your replies.

Information like that you simply cannot find and by god I've looked. Funnily enough a lot of what pings back from various forums when searching is written by you!


Right, I'm off to do battle with the car armed with a laptop and a cable. I don't think I'll win but I'll have a damned good try. One thing though that is against me is it going into what I call limp mode once it gets warm, it'll pick its revs from a lumpy idle to 1250'ish rpm and will not respond at all to the throttle. I have to let it cool down before it plays the game again. That worries me about getting it 80c before I can do any of the adaptions, the car probably won't let me do it before going into limp mode.