Sharan 1.9 - poor idle occasional stall - EGR vacuum Pipe plugged = Stall OR Removing maf = no turbo? /power

[champagnecharly]

Hi, I'm new on here.. recently purchased a 1.9 sharan and its sadly not without issues. I hope somebody can shed some light.

It seems to run quite well and have a good MPG return


however at idle and at lower revs it hesitates. idle is not entirely smooth.




I have tried to and rule out fault MAF as I was getting readings in excess pf 200mg or 50% above specified. When i drove with maf disconnected it ran like of bag of nails. No power and i could barely get past 3000rpm. or 60mph

I also tried the blanking of EGR vacuum pipe but that resulted in stalling.
The EGR was absolutely caked even the entrance to the cooling pipe was almost entirely blocked when i cleaned.

Since cleaning the egr valve i am getting valve either at 84% or 4.4% under throttle it does fluctuate a little in between but only for short bursts and it will be back at 84%

Could anybody please offer some suggestions? intake Pressure actual 1017.9 compared to 1020mbar without engine running and 1043-1050 at idle. Pressure is constant other than when throttle is pressed and appears to peak as it should then settle around the 1500 on WOT 3000rpm




Also note.. emissions pre egr clean were very high. Not got it tested sine/yet.




i'm clutching at straws.
1) Rough running without maf connected is because the EcU is now dependant on EGR? and egr not working as it should so it causes the issue?
2) EGR 4.5 -85% doesnt seem (from my ignorant perspective) to be full range. Although cleaned there is lack of vacuum to open/lose fully.. vacuum leak in hose or diaphragm or solenoid?
3) Stall when vacuum pipe blocked off ie simple delete. has got me. could it be intake manifold is cruded up? As said i cleaned the EGR and it was almost entirely blocked with muck. as was the end of the cooler pipe.








Any thoughts?

[Crasher]

If you disconnect the EGR vacuum pipe it stalls?

[champagnecharly]

If you disconnect the EGR vacuum pipe it stalls?

It did yes and when reconnected it was fine. tried a second time and it stalled again. That was done after cleaning the EGR. To be honest after cleaning it it was a bugger to start. When it did a huge cloud of black smoke came out of the exhaust.
That said i tried it again and it didnt stall. since my 250mile drive yesterday it ran a lot better however MAF actual still around 200 over specified.

[Crasher]

Air Mass Meter testing is very difficult, the latest systems have a built in plausibility test and it still gets it wrong. When done professionally the cheapest and easiest test is to fit a new one BUT genuine VW exchange only, there are huge numbers of Bosch forgeries out there and many a £ and hour has been wasted by people when they have fitted an aftermarket AMM because they are still chasing a fault, but a new one which they have unwittingly introduced themselves, mind you 99% of people take no notice of this advice and insist on learning the hard way.

[champagnecharly]

Air Mass Meter testing is very difficult, the latest systems have a built in plausibility test and it still gets it wrong. When done professionally the cheapest and easiest test is to fit a new one BUT genuine VW exchange only, there are huge numbers of Bosch forgeries out there and many a £ and hour has been wasted by people when they have fitted an aftermarket AMM because they are still chasing a fault, but a new one which they have unwittingly introduced themselves, mind you 99% of people take no notice of this advice and insist on learning the hard way.

I had similar maf issues on a rover 75.. So will keep away from cheap options. Bosch forgeries.. how to tell them apart and how rife are they? Ideal would be testing with a know good

Any thoughts on the 4.5-85% EGR Duty?

However i have a more frustrating matter on my hands now.. I cant open the bonnet. I took the bumper off and in my haste to get it back on didnt feed through the latch thing..

[Crasher]

We had that on a friends Octavia 1U on Friday, with it 6 feet up in the air we could get at the cable (he forgot to reconnect it after cleaning) but on the deck, I feel for you....

[champagnecharly]

We had that on a friends Octavia 1U on Friday, with it 6 feet up in the air we could get at the cable (he forgot to reconnect it after cleaning) but on the deck, I feel for you....

Actually took no more than 10 mins. A torch and a long cold chisel i managed to unclip the latch.


So with regards this i finally got myself a mity vac.. tested egr and its holding no vacuum at all. tested the vacuum hose in combination with vcds measuring blocks and all works as it should. So. EGR has given up completely..

[champagnecharly]

ok so original second hand egr fitted. thoroughly cleaned and then tested vac which it holds well (12hrs no loss). The vac activates the valve rod as it should.

when EGR is open : MAF readings are as expected .
When EGR closed : MAF readings higher than Expected ie expected + aprox 200
EGR is open (66%is) idle is ok.
EGR closed (6%) idle is lumpy.. keeps missing a beat.

Things that make me wonder..
EGR Value doesnt go over 70% or below 6%.. Will check these again now.
When diaphragm faulty EGR readings still fluctuate but 0 vacuum so it can not open or close. Are these readings from the solenoid? and as such is solenoid faulty to only offer a range from 6-70%
How stable should IQ be at idle? Its fluctuating from memory around 15% which coincides more or less with the point in time of rough running/ drop in Revs.

Going for another test drive with and without maf connected. Since EGR change i noted a drop in performance at low revs which from the small experience i have 'can' be maf symptoms.

Any thoiughts anyone? Vac leak somewhere?

[Crasher]

Fit a new genuine VAG exchange Air Mass Meter.

[champagnecharly]

Fit a new genuine VAG exchange Air Mass Meter.


this should do shouldn't it?

Pierburg 722684080 Mass Airflow Sensor: Amazon.co.uk: Car & Motorbike (https://www.amazon.co.uk/Pierburg-722684080-Mass-Airflow-Sensor/dp/B0068M2IYK/ref=sr_1_1?keywords=7.22684.08.0&qid=1558955731&s=automotive&sr=1-1)

It just felt like something else was going on.. especially given that now once the EGR was shown working.. the maf shows expected data.

There is a little air filter on one of the smaller hoses near the airfilter box.. .. tiny little thing that is clipped in.. (edit: part 702129965) what is that? (vacuum line filter) . Should n't that line hold vacuum. It looses pressure not immediately but fairly quickly. What is it connected into?

[Crasher]

I won’t fit anything other than a genuine VAG exchange unit which I get from TPS. This way I am 99% sure what I am fitting is correct, in the past I lost hundreds of hours fighting issues caused by aftermarket faulty Air Mass Meters, mostly in a yellow Bosch box... A few weeks ago I relented on this as a new genuine unit was obsolete and so I bought a “guaranteed” after market unit made by an “OE” supplier, the car ran worse than ever and in the end I had to settle for a known to be good used unit, actually my test unit I keep for testing, obviously, but now I don’t have one. If you fit that Peirburg insert and still have a problem I won’t know which way to help you as the pattern sensor will always be in doubt. I say 99% for genuine as from memory I have had at least four be faulty straight out of the box but at the time TPS used to put impressed stock into my stores for easy access and I had a huge range of AMM’s so I could try another to prove it was faulty, these days I hardly ever get a failed AMM.

[champagnecharly]

Ok thanks.. There was me thinking Piersberg were better than Bosch. And given what you said about bosch fakes. So are you suggesting main dealer only? TPS are account only now aren't they?
Something tells me this is a red herring though. changing the EGR meant that the MAF readings estimated:actual with the EGR on were now inline with what they should be. Will a bad maf make vehicle stall?

Any idea on that vac hose with the filter on it? Any ideas if that should hold a vac or not?.

[Crasher]

Yes unless you have a mate there who is prepared to lose their job it is a main dealer part. The advantage being that IF it did go wrong under warranty it the dealers job to sort it out even if you buy it from TPS so they are a lot more friendly if you bought it from them. I need to check the diagram at work for the hose. Yes a failed AMM can cause stalling but not often.

[champagnecharly]

Yes unless you have a mate there who is prepared to lose their job it is a main dealer part. The advantage being that IF it did go wrong under warranty it the dealers job to sort it out even if you buy it from TPS so they are a lot more friendly if you bought it from them. I need to check the diagram at work for the hose. Yes a failed AMM can cause stalling but not often.

Thanks.. i'll give them a buzz tomorrow.. Its not often she stalls but it has done so a few times and threatens to far far more.
I didn't mention that running without maf must be putting it into limp mode as throttle can be floored and increase is sloooowwww.

I appreciate that.. I tried propane which gave no rev increase..