7A starting issues

[8690q]

The fault code reader lives ! It was a blown fuse in the car that was causing it.

It's been for a few runs today so I pulled the codes earlier. Battery hasn't been disconnected since fitting spare MAF.

I got 2232 MAF
2242 MAF pot
4431 ISV

I checked the MAF wiring and got all readings to spec.

I disconnected the battery and went for a cuppa. Reconnected battery and went for a drive around the back roads.

I read the codes and got all the 4's so no more fault codes.

The car starts and idles fine when hot or cold now. Drives really nice on part throttle but still doesn't like being under load or revving much. Still bogs down after changing gear.

I'm thinking about doing the lambda probe tomorrow and then check the knock sensors if that doesn't work.

[andy10v]

Update in case anybody has any more suggestions

Little update.

I've been using the car everyday for ages now and it's good to be back in a quattro avant again. Good cars.

It's holding back on me though.

My thought's are lambda probe or the rest of the breather system.

When it's cold it seems fine but as soon as the temp gauge rises at all it's all over. You could part throttle it about all day and still get up to some funny speeds but as soon as you go for foot to the floor it protests.

Lambda made no difference when disconnected.

I don't have the breather connected between the throttle body and carbon canister. I don't have the carbon canister, just a bung on the throttle body.

Goes well considering the above problem and the boot full of spares and tools. Wee 106gti the other night will be wondering what happened to him anyway.

I stuck on a spare knock sensor I got from Andy10v when I got home from work tonight. I changed the front one seeing as it was easier to get to.

I've just been for a run to Kirkcaldy and back. 56 miles the scenic way.

Tiny wee bit better once it does get up the revs but pretty much the same.

It definetly does lose power more as the temperature rises.
Another thing is that as the temp gauge rises so does the fuel gauge.

This car used to have the v6 radiator setup across the front and now has the radiator in the 5cyl position. The gauge does sit quite low when cruising anyway, top of the first thick part on the gauge. When moving slow the temp gauge rises and the fans kick in as expected.
If the temp gauge rises at all from the cruising temp then it feels gutless and flat.

A few times on the way home once we got onto the back roads and away from traffic it pulled like a train only coughing straight after a gear change. I dropped 3rd to 2nd at 50ish and it took off like a stabbed rat, few corners later I went for full throttle again only to be disappointed.

[mcandmar]

Dont like the temps changing, it should warm up and stay there unless there is an issue with the thermostat. I think these engines run in open loop mode until the engine temp sensor reaches a specific point, so when it seems to drive normally (lower temps) i bet its not even using the O2 sensor or knock sensors as it thinks its still in warm up mode.

Assuming the temps are fine and the sensor is giving good info to the ECU the only things left to check are MAF, Knock Sensors, and Fuel pump. Issues with any of those will make the engine feel flat and down on power. Stuttering under heavy load suggests fuel pump to me, or fuel starvation for some other reason, old filter, dirty injectors etc.

[8690q]

Just noticed Andy had updated this.


Tonight on the way home from work it started revving up itself then dropping again, kind of like when the ISV goes daft. It still does it with the ISV removed though.

Anything else give these symptoms ? Leak ?

Need this fixed as I have a wee holiday next week and I'll be well pee'd off if I need to go in my Forester.

[8690q]

This car is a cursed

Just been brought home on a breakdown truck.

Driving out of a roundabout in 2nd gear and all is normal, just away to change up to third at about 4k when car loses power and engine changes note. Manage to pull into the side of the road for closer inspection.
Car really stuggles to start then when it does start it sounds really tinny and like it's not running on all 5. While this is happening the airbox is jumping about and making popping / banging noises.

I'm hoping something like the timing has slipped but kinda sounds more like something serious like a dropped valve or burnt ring.

I can stick a wee video up to let anyone hear it if that would help.

I'm gutted

[andy10v]

Engine turns over by hand as per normal.

Timing appears fine, cam, flywheel, dizzy and crank pulley marks all line up, belt tension appears ok.

Car starts really rough, not running properly, makes a weird exhausty loud banging noise. Also sounds like fuel burning in the exhaust manifold.

Tried swapping in another injector resistor pack.

Pulling the injectors plug to each cylinder one at a time, get to cylinder four and no change. Pulled the plug in cylinder 4, its soaking wet and reeking of fuel.

Placed sparkplug on intake manifold and ran engine, plug is sparking.

Shine a torch down onto the piston, no visible damage. When turning the engine over by hand fluid can be seen sitting on the piston (reflects the torchlight). Injector appeared to leak fluid in at one point.

So thought the injector might be jammed open, or leaking. Swapped in a full set of injectors removed from a running car, no change.

So we have spark and fuel, but no bang :?

Compression tester should hopefully reveal something tomorrow.

[mcandmar]

Strange one, dosent sound good though

Sounds like a bent valve to me, BTDT. In my case i had a broken helper spring which caused valve bounce over 6000rpms, didnt know what it was at the time until i pushed it too far and bent a valve. Either way that should show up with a compression test.

[8690q]

Found this tonight. Not good.

[mcandmar]

wow, wasn't expecting that

[8690q]

Well the car is back together now but it still has the same problem as before the cam snapped.
A wee video just to show what the car's doing. You can see and hear it not wanting to tickover. It does this when your driving as well. That's me revving it when it goes higher. Any ideas ?

[newsh]

Does the 7A have an ISV? If so try washing it out with WD40 and check the wiring.

Is idle switch closing in TPS?

Also check for vacuum leaks.

[chezz]

This site might be of use to you Fella http://www.20v.org/indexb4.html

[Error404]

have you done a compression test yet? Never seen a cam break like that in one of these engines, are you sure there is no valve damage?

[8690q]

Thanks chaps.

Newsh, the 7a does have an ISV. I cleaned it with carb cleaner at the weekend and it made no difference. It revs like this with the ISV disconnected as well.
Throttle switch can be heard clicking when returned to it's stop.
I'm not ruling vacuum leaks out but I have been round and round the engine looking for leaks. New gaskets were fitted after rebuilding head after cam snap.

Chezz, That's a good site and I've been all over it since I got this car.

Error404, I haven't done a compression test since I rebuilt the head. I'm certain there was no valve damage, another compression test might show different I suppose.

[Acidburn]

well thats now the original engine thats been knackered in this car plus the problems your having from what i've read/heard after speaking with andy. personally since its not local to just the one engine i'd be looking at wiring/ecu incase something there is causing it problems since its a conversion. One other thing is could it be something fuel pump related since this isn't the original engine for this car and its a v6 pump unless it was changed?

You can't keep going on like this as its going to cost a fortune at this rate. Might be worthwhile if you can afford it speaking with tonk's about it after he did jolfa's car and got his 20vq sorted.