1990 90 2.3E (NG) running problem?

dgacampbell · 10-03-15, 08:16 PM

Hi all, back again, car still not running right, although I decided to start a new thread as the running issue is imo not related to the intermitant rattle?

Ok so, the car starts, runs for a bit then the idle dies down to about 200rpm and the car has no power and feels like it is off 3 cylinders.

When it does this, depressing the W.O.T switch seems to make the engine recover and regain full power, albeit for a limited amount of time. The whole process is repeated.

Up until the point where the car looses power the exhaust does smell a bit rich to me when I'm kicking at the loud pedal.

Related?

Any ideas?

I'm sort of making an uneducated guess and thinking lambda sensor and or MFTS?

TIA

Dan.

msh · 11-03-15, 07:04 AM

I hate these guessing games, because they usually goes nowhere. But I can join it - if it really idles at low revs and does not stall, sounds like rich mixture. What happens if control pressure regulator is disconnected from ECU, how does that affects mixture?

missfire · 11-03-15, 09:10 AM

I was going to recommend your CIS thread msh.

http://www.classic-audi.co.uk/forum/...ad.php?t=29491

Or isham research, or the sjm website, because it could be bloody anything!

My 'guess' was a problem with the differential pressure regulator on front the metering head, or it's control. As it and all other mixture/emmisions related stuff are being bypassed, (and mix changing from 14 parts air to one fuel, to twelve air to one part fuel - ish) when the WOT switch is depressed. But just a guess!

dgacampbell · 11-03-15, 11:43 AM

Thanks for reply folks.

Yeah, I hate these guessing games too, could be anything, no one over here seems to have any knowledge of the KEIII-jetronic system here, the usual response is erm it will cost you lots of money or forget about it.

I have never had any luck with these bloody NG engined cars.

Vems or ms is looking like the way forward.

More information I am only remembering .......... if it is any help?

The first two times the car done this was after spending maybe 10 miles or so at erm as fast as the car goes on a private runway.

It now happens even after just sitting idleing for a short while as i said previously.

Maybe useless additional information, maybe it could help pinpoint the problem.

I can't get to where the car is until the weekend at any rate.

dgacampbell · 11-03-15, 01:10 PM

Anyone know how much and where I would get a differential pressure regulator?

Or have a known good one for sale?

TIA

Dan.

msh · 11-03-15, 01:30 PM

Did you measured the pressure it's putting out, if you're looking for control pressure regulator?

In my current experience [more than dozen cars; I've made similar thread in our biggest local audi forum, the only reason why I don't have queue waiting for me is because I'm at the edge of our country], the problems usually are 1) things that normally age - oxygen sensor, injectors, knock sensor [ignition troubles], MAF potentiometer [idle troubles]; 2) mechanical items not really specific to KE-jetronic, like intake boot or filtering sieve in fuel supply bolt; 3) something with engine management, items that could be found in every normal car - like damaged or corroded ECU connector. I've twice in moment of weakness managed to change something in my car, that appears to be the cause of problem but was not - fuel pump when system was blocked by clogged sieve, and whole metering head when the real problem was caused by shorted ISV and CSV - so it's always, repeat, always, important to do troubleshooting, before changing something.

dgacampbell · 11-03-15, 01:58 PM

No Msh,

Have checked nothing yet,

I do not have any of the equipment to check, and from the sounds of things my mechanic hasn't either.

I imagine this is going to be the beginning of a garage hopping session and getting nowhere fast.

Very frustrating!

jamiecoysh · 11-03-15, 07:26 PM

how did you test for the isv and cs valve for shorts

my idle is lumpy and up till having the cylinder head re-built used to pulse between 1000 - 1200 rpm. That's stopped now. I do have a multi-meter but was wondering if anyone could tell me any tests I could do also I here a relay clicking up under the dash when the engine changes tone at idle so was wondering if it may be the culprit

the car is a 3A engine 1989

BTW I used to have a 90 with the NG engine and it suffered from similar problems like yours and it turned out to be a faulty part somewhere on the metering head

jamiecoysh · 11-03-15, 07:38 PM

Also did I read somewhere that when WOT is engaged the ecu ignores lambda and some other functions I might be wrong

wondering if you may have blocked ( collapsed ) cat / exhaust I might try taking of the exhaust and seeing what happens

msh · 12-03-15, 05:08 AM

Quote:

Originally Posted by jamiecoysh

how did you test for the isv and cs valve for shorts

my idle is lumpy and up till having the cylinder head re-built used to pulse between 1000 - 1200 rpm. That's stopped now. I do have a multi-meter but was wondering if anyone could tell me any tests I could do also I here a relay clicking up under the dash when the engine changes tone at idle so was wondering if it may be the culprit

the car is a 3A engine 1989

BTW I used to have a 90 with the NG engine and it suffered from similar problems like yours and it turned out to be a faulty part somewhere on the metering head

IIRC I've told you a couple of times that you likely have worn out MAF potentiometer.

There are no relays for engine management, apart from fuel pump relay, that particular relay should be engaging something that drains enough power to change board voltage/alternator load, and again, likely because of worn out potentiometer, ECU doesn't react well enough.

As for my problem of the past - I just wanted to try different ECU and found that I've managed to bend a couple of pins.

11-03-15, 01:58 PM	#7
dgacampbell Senior Member Classic Audi Club Member Join Date: May 2011 Location: Co.Armagh, N.Ireland Posts: 1,442	No Msh, Have checked nothing yet, I do not have any of the equipment to check, and from the sounds of things my mechanic hasn't either. I imagine this is going to be the beginning of a garage hopping session and getting nowhere fast. Very frustrating! Last edited by dgacampbell; 14-03-15 at 12:31 PM.

11-03-15, 07:04 AM	#2
msh 4 ring whore! Join Date: Jun 2008 Location: Rucava, Latvija Posts: 3,816	I hate these guessing games, because they usually goes nowhere. But I can join it - if it really idles at low revs and does not stall, sounds like rich mixture. What happens if control pressure regulator is disconnected from ECU, how does that affects mixture?

11-03-15, 09:10 AM	#3
missfire making wooden things Classic Audi Club Member Join Date: Dec 2009 Location: cow land Posts: 8,156	I was going to recommend your CIS thread msh. http://www.classic-audi.co.uk/forum/...ad.php?t=29491 Or isham research, or the sjm website, because it could be bloody anything! My 'guess' was a problem with the differential pressure regulator on front the metering head, or it's control. As it and all other mixture/emmisions related stuff are being bypassed, (and mix changing from 14 parts air to one fuel, to twelve air to one part fuel - ish) when the WOT switch is depressed. But just a guess!

11-03-15, 11:43 AM	#4
dgacampbell Senior Member Classic Audi Club Member Join Date: May 2011 Location: Co.Armagh, N.Ireland Posts: 1,442	Thanks for reply folks. Yeah, I hate these guessing games too, could be anything, no one over here seems to have any knowledge of the KEIII-jetronic system here, the usual response is erm it will cost you lots of money or forget about it. I have never had any luck with these bloody NG engined cars. Vems or ms is looking like the way forward. More information I am only remembering .......... if it is any help? The first two times the car done this was after spending maybe 10 miles or so at erm as fast as the car goes on a private runway. It now happens even after just sitting idleing for a short while as i said previously. Maybe useless additional information, maybe it could help pinpoint the problem. I can't get to where the car is until the weekend at any rate.

11-03-15, 01:10 PM	#5
dgacampbell Senior Member Classic Audi Club Member Join Date: May 2011 Location: Co.Armagh, N.Ireland Posts: 1,442	Anyone know how much and where I would get a differential pressure regulator? Or have a known good one for sale? TIA Dan.

11-03-15, 01:30 PM	#6
msh 4 ring whore! Join Date: Jun 2008 Location: Rucava, Latvija Posts: 3,816	Did you measured the pressure it's putting out, if you're looking for control pressure regulator? In my current experience [more than dozen cars; I've made similar thread in our biggest local audi forum, the only reason why I don't have queue waiting for me is because I'm at the edge of our country], the problems usually are 1) things that normally age - oxygen sensor, injectors, knock sensor [ignition troubles], MAF potentiometer [idle troubles]; 2) mechanical items not really specific to KE-jetronic, like intake boot or filtering sieve in fuel supply bolt; 3) something with engine management, items that could be found in every normal car - like damaged or corroded ECU connector. I've twice in moment of weakness managed to change something in my car, that appears to be the cause of problem but was not - fuel pump when system was blocked by clogged sieve, and whole metering head when the real problem was caused by shorted ISV and CSV - so it's always, repeat, always, important to do troubleshooting, before changing something.

11-03-15, 07:26 PM	#8
jamiecoysh Grown up member Join Date: May 2013 Location: Torquay, Devon Posts: 119	how did you test for the isv and cs valve for shorts my idle is lumpy and up till having the cylinder head re-built used to pulse between 1000 - 1200 rpm. That's stopped now. I do have a multi-meter but was wondering if anyone could tell me any tests I could do also I here a relay clicking up under the dash when the engine changes tone at idle so was wondering if it may be the culprit the car is a 3A engine 1989 BTW I used to have a 90 with the NG engine and it suffered from similar problems like yours and it turned out to be a faulty part somewhere on the metering head

11-03-15, 07:38 PM	#9
jamiecoysh Grown up member Join Date: May 2013 Location: Torquay, Devon Posts: 119	Also did I read somewhere that when WOT is engaged the ecu ignores lambda and some other functions I might be wrong wondering if you may have blocked ( collapsed ) cat / exhaust I might try taking of the exhaust and seeing what happens