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More rough running & smoke 2.5L Petrol AVT

1K views 1 reply 1 participant last post by  laurence91 
#1 ·
Still having the issue with poor running on my 2000 Caravelle, 2.5L Petrol. Iv been attempting to cross off possible causes at a snails pace (Which just about keeps up with the van...)

VCDS reports the following EVAP error with no MIL on

1 Fault Found:
16825 - EVAP Emission Control Sys: Incorrect Flow
P0441 - 35-10 - - - Intermittent
Readiness: 0000 0000

This evening, after more forum searching, I decided to monitor the warm up of the engine from cold to observe the warming up temperatures as recorded by the ECU. I had VCDS on with measuring blocks group 4 looking at what is listed as

RPM, Voltage, Temperature, Temperature

Both temperatures started at around zero degrees (I am in Scandinavia). They the first temperature steadily rose towards 90 degrees commensurate with the dial on the clocks the other got up to around 13 degrees in the 25 min or so I was freezing my ass off outside.

I was watching in the hope that the rough revs (+/- 40 revs) would track with the bumpy ECU voltage. I think it does a little but the ECU voltage only changes a maximum of 1 V around the 13 V mark. Not the several volts I thought I would see (Based on a Thomas EXOVCDS video on YT). This may suggest a potential issue with relay 30 - And I must admit, it felt warm when I wiggled it.

The other thing I did, suspecting the VCDS fault being either the vacuum hose or the N80 valve, was pinch the hose whilst it was running. Upon doing this, the engine got worse. I then noticed a load of white smoke coming out the exhaust that had a rough smell to it. I haven't noticed mush smoke before. The VC scope of measuring block 4 hadn't dipped (i.e. revs or voltage) or anything whilst this was occurring. The van after driving doesn't sound right and the revs are continually hunting, it almost stalls at junctions on occasion (But didn't this evening when just idling).

I have looked at most of the vac pipes, and doesn't seem to be any leaking, although as iv posted previously, i haven't replaced yet. One thing I couldn't find is there is nowhere (seemingly) on my ECU for a vac pipe connection?


My questions / thoughts / requests for advice :-

As the temp sensor output looks sensible through warm up, i presume my temp sensor is working as it should?

Is a variance of 1V in ECU power enough to cause issues?

Could relay 30 be causing rough running, and should it be warm to the touch?

Could a failed N80 valve cause rough running (VCDS do not say rough running a symptom with P0441)? (I just picked up a new one)

Can anyone give me any pointers on things to watch on VCDS that may show the culprits for rough running?

Should I be looking at anything else if the above does not seem to fix it?

I would add, I am a avid reader of the forum, whilst I wont say Iv exhausted every search, I have spent a considerable amount of time reading many posts (And learnt a lot in the process Ill add). Of course, Im also planning to drive back to blighty from Sweden at Christmas... thus Iv bought the most comprehensive breakdown cover i could find!

Thanks for reading!
 
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#2 ·
Update

I replaced the relay 30, which is ECU voltage. There was no change.

I replaced the N80 valve, VCDS now shows no faults

I replaced the Vacuum hose from the inlet to the idle control valve (Or what I think is the ICV)

Seems to be a lot better, smoother and more consistent power on driving today. No Codes which is nice.

I still feel a bumpy idle though and Im certain its running rich, its smells pretty bad in fact.

Next off, thinking fuel cap, fuel filter and perhaps more investigations to the vacuum lines.

I got the EVAP canister off, looked fine.

Had a look at the injector voltages in measuring blocks today I get

1) 0.540V 2) 0.440V 3) 0.500V 4)0.520V 5)0.580V

Does anyone now if this sort of deviation is acceptable? Im not entirely sure this is the injector voltage as it seems so low? Any ideas welcome!
 
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