Corrado cutting out at junctions - checklist of possible cures?

[DPS 10]

Right, I have a 94 VR6 Automatic, just under 78K miles. Last full service was at 73,031 miles (included spark plugs)

 

Sorry for the really long post I just don't want to miss out any detail that may be important.

 

Problem:

When she gets hot she cuts out at junctions, its right when she changes down from 4th to 3rd, the revs drop (I'm guessing this is the clutch kicking in) they don't then pick back up and engine dies. It's a real pain as she's an auto I have to put her in Park to restart. I have prevented the problem from occurring by manually changing down a little sooner (about 35mph rather than 28/29mph) this means the revs are maintained by momentum and she doesn't cut. Ideally though, this is not how I want to HAVE to drive.

 

 

Tried so far:

Initially the biggest issue seemed to surround the MAF sensor plug as the rubber boot was corroded and was letting water sit on the metal pins. Every time it rained the car ran like a bag of nails and cut out. I had to spray in some contact cleaner, re-seat the plug and all was fine, until the next downpour. I filled it with Dielectric Grease and set about sourcing a new one. the car ran better, but every few weeks the problem would re-occur.

 

In the interim period I decided to replace the MAF for a brand new Bosch one - I did this because she was experiencing random occurrences of slipping into limp home mode. - The new MAF fixed this but the cutting out suddenly increased. I wondered if the new MAF couldn't connect with the corroded pins but figured as the only thing that had changed was the MAF, perhaps it had an air leak.

 

I took off the entire induction system and greased all the connections and fitted new jubilee clips. - No change.

 

Then, I finally managed to get hold of a new MAF connector, I remain eternally grateful to Fla (Hasan) for supplying this! - This made the car run so much smoother and I can park her out in the ran again without fear. It really made a huge difference to the cars running. Sadly though the cutting out is still occurring.

 

I removed the cleaned the ISV - Still no difference although her tendency to hunt occasionally was resolved.

 

So thats what I have done so far...

 

Except I also had the car run though diagnostics and the only fault codes returned were

 

005537 - Passive/Sporadic - Oxygen Sensor control, Value below lower control limit.

00513 - Active/static - Engine speen sensor - G28 - No signal (I had a friend take it down in his lunch break as I was in a meeting and he later confirmed they tested the car with the engine off :bonk:)

 

 

She has an MOT booked tomorrow and also an ATF oil and filter change. I can't find any proof this has been done before so I am (perhaps naively) expecting a huge improvement in gear changes when the car is cold (her changes have become terrible since the autumn kicked in)

 

Assuming she passes I need to focus on resolving the cutting out once and for all.

 

Next on my list:

So, taking the diagnostics into account, the Lambda is next on my list - Would this cause the problem? (assuming it doesn't need replacing for the MOT tomorrow)

 

After that, My PCV is leaking oil onto the exhaust manifold from either side of where the hose meets the dormant US emissions sensor. Yesterday I took it off, wiped it over, cleaned the manifold and fitted two jubilee clips to each side of the join in the hope of sealing them. I also think the disk bit has blown a little as if I squeeze it I can see oil oozing out, ever so slightly. I have put some sealant around this join and will set about getting a replacement from either VW or for Ford (Part# F7364573). Again, could this cause an air leak?

 

Technically, providing the car isn't about to blow up, the most expensive thing has been tried (the MAF), so it's now a case of eliminating all other possible causes until one works.

 

Typically, what else could cause this? TPS? :scratch: knowing my luck a £20 sensor :cheers:

 

It seems everything I try fixes something but never fixes everything... I guess thats Corrado ownership :dance:

 

Cheers

Dawn

Edited November 16, 2014 by DPS

[fla 9]

There are a few things worth trying as well:

Check the dashpot - its the spring loaded damper on the side of the throttle which prevents the throttle slamming shut when you lift off the throttle. This might need to be moved up a bit

Oil the isv after cleaning

Don't worry about the pcv valve - it shouldn't affect the cutting out

 

If you have vagcom it might help to do a 'basic settings' reset

[easypops 8]

Also check the condition of the ISV damper box

[CazzaVR 0]

As above. Check the isv hoses are all clear of sponge (from the damper box) and also check all the intake pipework is free of holes and splits.

[DPS 10]

Wow! thanks guys

 

I've just been out to take a look at the dashpot, when I lift the throttle the red gaiter expands smoothly and the white bit lifts up. I took a picture of it resting though, incase anyone thinks it looks like it could do with adjustment. The two plates behind it (in front of the spring) rest at about 1.5mm apart. Is this correct? perhaps it's worth adjusting it upwards a mm or two to widen the gap? I'm guessing if these two plates touch the throttle is completely shut?

 

[ATTACH=CONFIG]80154[/ATTACH]

 

 

I will check the ISV again when I get her home tomorrow from the MOT (assuming she's not overnighting to get anything fixed) I need to get some more jubilee clips for the hoses as I used cable ties temporarily. My car is held together my jubilee clips I think! I didn't lube it when I cleaned it and I did'nt take off or check the damper. With it being a 94 Corrado, is it safe to bypass this damper with some tubing or does it have an integral purpose?

 

I did inspect the whole intake today and cannot see any cracks. Is testing the system for air leaks quick and easy? I'm wondering if it's worth asking the garage to try it tomorrow.

 

Thanks for for all the suggestions, I'm willing to just try anything I can to get this finally resolved. Not that driving the car as a semi-auto isn't fun, its far better when I can control the gear changes to make her go faster. I just don't want to have to do the same when slowing down ;)

[Portent 0]

Also check the battery clamps aren't loose. When I first got mine it cut out at junctions as the negative cable was loose.

[DPS 10]

Also check the battery clamps aren't loose. When I first got mine it cut out at junctions as the negative cable was loose.

 

I'll check tomorrow, I left the bonnet up to remind me to check the oil anyway. It never ceases to amaze me how many things can cause one problem on a Corrado :afro:

[Jim Bowen 1]

Are any fuses blown?

[DPS 10]

No as far as I know, I had considered replacing the few under the bonnet, just because they look a bit ropey, the two uncovered 7.5amp ones at the back of the engine bay look terrible. Not sure what they are for though. The coolant fan ones look okay, but they are covered.

[fla 9]

With the dashpot, open the throttle manually by hand and then let it go. When it hits the contact plate it should then slowly move back to its rest position. Check that the opening in the throttle is clean and also wipe both sides of the butterfly.

[DPS 10]

With the dashpot, open the throttle manually by hand and then let it go. When it hits the contact plate it should then slowly move back to its rest position. Check that the opening in the throttle is clean and also wipe both sides of the butterfly.

 

I don't think it hits the contact plate, I think it stops 1.5mm above it because the Dashpot is fully compressed I will check it in the morning though, perhaps when it springs back there is some more movement there. Should the rest position mean there is a gap between the two plates? So te throttle is slightly open?

 

I'll clean the butterfly in the morning too :-)

 

Thanks for your help (again)

[DPS 10]

well... the gearbox is shagged so none of this matters. Thanks for all the time taken to help me though.

 

Time to make another post for advice on a whole other matter now then :(

 

gutted...