20V CQ Tidy Up

[Bowie69]

Thanks chaps

Oh and brand new Bosch ISVs leak like sieves!

Hey Alex, not sure if you are aware that Bosch ISVs fail 'open' a bit, so that if they do fail, your engine will still idle. To actually close an ISV it is quite common you need to run it at 25% duty cycle.

Forgive me if teaching a granny...


Also interested in what you think has made the difference in driveline shunt? I still get some though it is better, have new OE engine, OEM gearbox, OEM diff mounts (and a big poly one in the back) and a new snub rubber, oh and poly subframe bushes.

[Error404]

Yeah sorry I meant leaks under boost, through the plastic cover on the rear of the housing

I've been saying for a few years I thought the inherent driveline shunt in the B3/B4/B5 quattros was due to the centre diff and it looks like this is proven, since the T3 Torsen in the OA3 box is a totally different design and there is virtually no lash in it compared to the older Torsens.
It is a reasonable back to back comparison as have reused the same engine, gearbox and diff mounts as used previously with the 01E

[Bowie69]

Cheers Alex!

So in other words I am gonna have to live with the driveline shunt as I'm not changing the box

[Kieron20V]

Did you rebuild and reshim your rear diff while you had everything apart Alex? I think that's a good proportion of the driveline shunt in the backlash there.

[Error404]

Nope, I looked at it a few years back when I fitted the Torsen, it was fine so didn't adjust it

[andy10v]

What are you going to do about the ISV?

I think PRJ said you have to epoxy them.

[Error404]

Yeah I have filled the back in with Araldite. Seems to have done the job.

I have an annoying problem with a low, rough idle and car stalling coming to a stop.
It also sometimes hesitates for a second pulling away, and twice has cut out for a couple of seconds, where it would drop to an idle at around 500rpm but no amount of throttle would have any effect, it would pretend to stall a couple of times, then it would spring back to life and away I went. So it seems like a sensor is playing up somewhere and at least contributing to he problem.

Of course I have leak tested it, and I can only find a tiny leak through one of the injector seals/seats (all new of course, so not sure how I'm going to solve that yet).
Still, it holds well up to 1bar, taking around 30 seconds to drop to zero. So large intake leak is ruled out.

Going to test the MAF later. I wondered if the fuel pressure reg might be dodgy but short of buying a fuel pressure gauge and fittings I'm not sure how I can test that?

[s2driveruk]

presume the lambda is in good health?

[rynaqui]

Yeah I have filled the back in with Araldite. Seems to have done the job.

I have an annoying problem with a low, rough idle and car stalling coming to a stop.
It also sometimes hesitates for a second pulling away, and twice has cut out for a couple of seconds, where it would drop to an idle at around 500rpm but no amount of throttle would have any effect, it would pretend to stall a couple of times, then it would spring back to life and away I went. So it seems like a sensor is playing up somewhere and at least contributing to he problem.

Of course I have leak tested it, and I can only find a tiny leak through one of the injector seals/seats (all new of course, so not sure how I'm going to solve that yet).
Still, it holds well up to 1bar, taking around 30 seconds to drop to zero. So large intake leak is ruled out.

Going to test the MAF later. I wondered if the fuel pressure reg might be dodgy but short of buying a fuel pressure gauge and fittings I'm not sure how I can test that?

MAF sensor always gave me a dodgy idle and would cut out sometimes when coming to a stop. Whenever this was a problem, the car would start to idle badly after about 30 seconds of startup.

[Error404]

David - Lambda is band new Bosch

MAF is not new, and history unknown.

[s2driveruk]

i may have to go check my pins on the maf as mine has been wobbly on idle recently and i thought lambda was toast

[newsh]

Could be maf connector

[bikerjim]

Not 100% sure how the throttle works on these cars, I know its not fly by wire but it kinda sounds like it needs a throttle alignment doing. TPS sensor maybe?? Something along those lines.

[Wizard-of-OD]

So I drew up the spacer and machined that, and then just needed to make up a little bracket for he hall sensor. Did some zinc/nickel plating with some help & advise from Eric (cheers mate )

Future components one piece bent?
Good work mate! Opens up the doors to the B7 RS4 boxes for sure!
btw 2 on ebay.co.uk for under 400 GBP!

[Error404]

I've stripped the connector down and cleaned the gold plated terminals down with some 800g, plus used some De-Oxit on them, so I am sure the connector & pins are fine

Codes I am getting:
00537 - Lambda (Oxygen Sensor) Regulation: Upper Limit
00561 - Mixture Adaptation: Adaptation Limit (Add) Exceeded
00518 - Throttle Position Sensor: Implausible Signal

The first two are classic boost leak codes, but I have barely had it above 0.2bar as I have only been tickling the throttle (on mineral oil). As above it holds reasonable pressure for a while. So something is amiss. Typically MAF and TPS are the only two sensors I didn't fork out to replace