2.3 NG Starting issues

[John.]

[Colin Aitchison]

You guys need to be careful, I did say to some of you that going for a drive is now out of the question for me for this very reason, it is nice to have a wee blast with the old cars but I seen the writing on the wall at the end of last year, sheep / blind summits don't mix, neither dose single track roads in third giving it the beans, others on this forum refuse to go for a run due to incidents in the past, I love the 80's Audi's and seeing a group of them together on the road is wonderful but going out as a group is over for me, please please be careful.

[Hanuman]

Following on from wha Colin was alluding to.
If the engine is starting and running normally again, with the crank breather isolated, then you may be able to reproduce the problem simply by removing the oil filler cap, if I'm not mistaken.

In a normally aspirated vehicle, the induction system will be operating with a depression in the manifold. In a turbo application, the manifold will be pressurised on boost, hence the check valve. The valve opening when off boost and closed on boost so as not pressurise the crankcase.

In both cases, the breather system should be closed/sealed, if working correctly. Poor running then indicates that a fault exists leaving the system open, allowing too much unmetered air into the system. (Such as removing the oil filler cap). Mixture control can only compensate so much, before running out of adjustment.

One favourite place on the WR mentioned previously, and waxed lyrically about, was the rear crank seal. Being I5 engine, I'd imagine that this could still be a possibility.

From what I have read so far suggests that what has actually been done is the crankcase ventilation has been isolated from induction system; something that would also be done if investigating such issues. One item already attended to being a split hose. I'd be inclined to believe that there is still an opening somewhere.

ooh...maybe time for a pic

[Colin Aitchison]

Hanuman, that is what I was trying to say but you nailed it, well done.

[Colin Aitchison]

Originally Posted by Hanuman

If the engine is starting and running normally again, with the crank breather isolated, then you may be able to reproduce the problem simply by removing the oil filler cap, if I'm not mistaken.



In a normally aspirated vehicle, the induction system will be operating with a depression in the manifold. In a turbo application, the manifold will be pressurised on boost, hence the check valve. The valve opening when off boost and closed so as not pressurise the crankcase.



In both cases, the breather system should be closed/sealed, if working correctly. Poor running then indicates that a fault exists leaving the system open, allowing too much unmetered air into the system. (Such as removing the oil filler cap). Mixture control can only compensate so much, before running out of adjustment.



One favourite place on the WR mentioned previously, and waxed lyrically about, was the rear crank seal. Being I5 engine, I'd imagine that this could still be a possibility.



From what I have read so far suggests that what has actually been done is the crankcase ventilation has been isolated from induction system; something that would also be done if investigating such issues. One item already attended to being a split hose. I'd be inclined to believe that there is still an opening somewhere.


ooh...maybe time for a pic

Parts 10, 17, 17a look like one way valves if fitted

[Hanuman]

Item 10 actually lists as a check valve. (Could easily be something similar to that in the WR)

17 and 17a list as chockes, which might indicate an open restrictor. As emissions became increasing limited, it's only to be expected that more and more 'refinements' to a working system were added, until such time as it required a complete redesign.

[Cynical26]

Unfortunately the schematic shown isn’t the same as mine. I don’t have the branch with parts 17 & 17a. The breather pipe is pictured below:





There’s is no cylinder head cover vent either, so no 10. (Edited from 10a)



I did remove the oil cap with the engine running out of interest, it didn’t make a difference, car ran smoothly.

On another note, the car has returned to needing around 5 seconds of cranking to start (but not always) So, while it’s not running like a rough ‘ol dog on 3 cylinders, it is unhappy.

The air/ fuel mix is my main suspect. Might have to fully remove some of the vacuume pipes as there’s is a few places I can’t see while fitted to the car.

What about the air box and air flow meter itself?

[Hanuman]

The diagram I posted was the one from 7Zap- but whether it's the right year is another matter. It will essentially have all of the possible variations on the system, but not necessarily will they all be installed as standard. For instance, item 10 is a check valve, linking another branch, but item 10A is a bung, which would isolate that part of the circuit.

So, referencing what you actually have with what's in the diagrams, you should be able to establish which components are, or should be fitted.

Isolating the breather system completely is not a bad way to go. I've no specific knowledge about how the mixture is set in the NG injection setup. But introducing an unmetered supply of air through the cam cover I would normally expect to disturb the idle. Unless your rubber glove has isolated that section.
If, however, your rubber glove is further down stream*, then it would hint at mixture being excessive.


*using the convention of flowing from high to low. upstream being where the air comes through the air filter, and downstream where it gets converted into noise and pollution.
On that basis, the airbox with filter is before the metering unit.

If that makes sense...(several glasses of vino in...)


...thinking about it.... didn't someone on here once have a split rubber igloo, from where it had been clamped up badly?

[Cynical26]

Originally Posted by Hanuman

The diagram I posted was the one from 7Zap- but whether it's the right year is another matter. It will essentially have all of the possible variations on the system, but not necessarily will they all be installed as standard.

Got that. That one shows variations for four engine codes: KV, NM, 7A & NG. The One I posted only applies to the NG, again from 7Zap. Certainly plenty of variations possible.

Originally Posted by Hanuman

For instance, item 10 is a check valve, linking another branch, but item 10A is a bung, which would isolate that part of the circuit.

My mistake, I should have typed 10, not 10A.

Either way, it’s a different system without check valves or one-way valves as far as I can see. Pity, as that would have been easy to check. Worth a try, all possible issues and fixes welcome

The intake rubber duct was replaced on mine (pictured previously) as the clamp branch for the breather pipe had split. Probably from being over tightened too. I did put photos up at the time, not sure if that’s what you are remembering?

[Hanuman]

Where is (was) the breather system blanked off, currently?