91 Audi 80 starting issues

Old 07-19-2005, 03:41 AM
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Join Date: Jul 2005
Posts: 24
Default 91 Audi 80 starting issues

I started this post in another thread but wasnt getting any responses.
So I thought Id try here.
Its kinda long so if you dont read it all I understand ,it is a good step by step trouble shooting guide, LOL.
The following is a up to date condition of my car.

I just bought this car.

1991 Audi 80 , auto , FWD , 2.3l 5 cylinder.

I have worked on ALOT of VW but this is my 1st Audi.

Car will not catch while turning over.
When it does catch I have to baby the throttle to keep it from dying and while Im babying the throttle it sounds like its running rich and smells rich.

It will catch , with help, like every 1 out 20 trys.

The PO had cut the ground wire off the cold start injector and ran it inside the car so he could manually ground out the cold start injector when trying to start the car.

That is how He got it started for me to test drive.
It drove great once it got started.

Where is the Coolant temprature sensor?
Also what is inline , electrically , before the cold start injector?
I need to test why the cold start injector isnt shutting down after it starts, or is it not suppose to shut down after start?

(next post)
Heres what the starting scenario is at the moment.
I have reattached the wireing to the Cold start valve and checked for voltage @ the cols start inj. and it was good.
This resulted in the same non start issue.
I then found the CTS and disconnected it .
The car would then start , rpms would climb to about 1200 and then dye out, and the car would die.
I can hold the rpms up with the foot pedal but as soon as I let go of the pedal it dies out.

I believe the Cold start valve is going continuously and that is the reason for the non start and flooding issue.

I also found 2 extra cold start inj in the trunk and a fuel dist assembly.
Also the fuse relay box under the wiper cover was open and there were 2 extra fuse relays floating around in the wiper cowl.
They were obviously dealing with the same issue.

How do I , if I can , retrieve any codes ?
Or does this car not have a way to do that without a VAG?

(next post)
After going out to the garage and doing somemore trouble shooting I found out the following new things.

1st - I disconnected the CTS and then went and started the car .
it started , I had to throttle it alittle and hold the idle @ around 2500 for about 30 sec.
then it held its own idle , at around 2500 rpm.
Then , while the car was running, I went to investigate the high idle and noticed the throttle stop screw was WAY tightened down .
Allowing the throttle to not folly close.
I unscrewed the throttle screw till I got the RPMs around 1000 and then shut the car off.
plugged the CTS back in and then tried to start the car.
NO start.
Unplugged CTS.
Car started back up.
So I turned it off .
I suspected at this point that maybe the throttlw wasnt hitting the idle switch.
Sure enough it wasnt.
Adjusted that.
Turned the key .
car started but barely held an idle, turned car off.
Suspected ISV.
checked for voltage to ISV , good.
checked for operation of ISV via plugging into another + source, worked, opened and closed.
But no operation while connected to the factory harness.(weird)

So I know this much.
Bad CTS.
Bad electrical connection at the ISV or Corroded connection.

(next post)
I am going to clean the ISV terminals with some electronics cleaner.
Has worked well in the past on all the VW I have worked on.
As far as testing the CTS with a ohmeter.
I have a meter , just dont know how to use it yet, its analog.
I also dont have my Bentley yet, in the mail, so I dont know the procedure.
Im just gonna buy one for $30-40 so that I can take it out of the scenario.

(next post)
Cool , my bentley just arrived.
My wife and 3 yr old son are gone this weekend so Ill have lots of time to get this bugger runnin.
As long as I dont run into any parts that have to be special ordered.
More than likely I will have special order parts, boo hoo, LOL.

I was thinking the same thing about the idle switch.

Im sure there is a procedure in the bentley for testing it.

Is there always voltage @ the electrical harness for the ISV when the ignition is on?

(current state )
I installed a new CTS and it made no difference , meaning , no start.
I need to check codes and from reading my bentley it seems as though I need a VAG to get em.
I did see something about makeing a light and then jumping the terminals ?
This should give me some basic codes right?
Can I just build a light with wires and such?

Old 07-19-2005, 12:42 PM
2nd Gear
Join Date: Mar 2004
Location: Swamplands of NJ
Posts: 761
Default RE: 91 Audi 80 starting issues

The engine on your '91 5-cyl 80 should be the same as in the '91 100 models. If you are not familiar with sjmautotechnik.com then get yourself acquainted.

Here is the diagram for the test light. Unless you have the 50 states model a.k.a. California emissions, the CIS-III ECU has no store function and the information is very limited and practically useless.

Unplugging the Engine Temperature Sensor simulates a cold start condition, enrichment takes place via the differential pressure regulator.

Do you have emission inspection in your area? If so this might be the reason why your car was butchered up.

If I was in your place I would switch gears and take a different approach. Start by going over all the engine bay connectors and ground points, inspect them for corrosion and clean them. Then start with the mechanical timing, make sure all the timing marks are aligned. Check the ignition timing and spark plug sequence/firing order.

Do you have the temper proof plug for the fuel mixture adjustment on the airflow-sensor/fuel-distributor? Does it look factory installed or did somebody mess with it.

Obviously check the wiring harness for melted, cracked or damaged wires. Check the cold start injector circuitry and verify it with the Bentley manual. Check the relays, some of the Audi relays have micro circuitry inside, often these develop cold solder joints resulting in intermittent or complete breakdown.

Check the current going through the differential pressure regulator, unlike the previous VW/Audi models, on 91 models it should be close to 0mA when fully warmed up and everything working properly.

I would replace the filter if it hasn’t been already and do a system pressure test. Next pull the injectors and check them for leaks, spray pattern and volume delivery. Replace bad injectors and the injector seals. I would also check the distributor to make sure that it is not leaking excessively through the plunger. Check the air flow sensor flap to make sure that it is moving freely, clean and adjust if necessary.

When you get the engine running hook a Vacuum gauge to the intake manifold. This will give you some idea to the condition of your engine. A vacuum gauge might be a very low-tech device when compared to a modern day OBDII computer but any mechanic who doesn't know how read one shouldn't be allowed to touch even a lawnmower! A compression test would hurt either.

One last thing, Voltage? One thing I have noticed on my car is that when I first start the engine the dash voltmeter reads just below 12V. Warming up engine for a few minutes and or racing the engine doesn’t seem to kick in the voltage regulator. It only kicks in if I start driving. However the engine drives and idles differently between “no voltage regulation” and “normal voltage regulation”.
Old 07-19-2005, 06:46 PM
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Join Date: Jul 2005
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Default RE: 91 Audi 80 starting issues

Thank you , thatnk you , thank you.
I am not good with measuring amperage and ohms and what not.
I have a analog multimeter but dont know how to read it or set it up?
I am going to attack it at a new angle and pull and clean all the electrical connections under the hood and check and replace all the vacumn hoses.
Oh yeah, the rubber grommet on the brake booster is gone= vacumn leak.
Also there are 2 hoses coming off the intank mani and 1 of them is plugged up, PO did this.
I can see the small 1/4 vac line that should go to that plugged up vacumn line coming off the intake manifold , I just need to find or build a adapter to connect it.
Old 07-20-2005, 04:17 AM
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Default RE: 91 Audi 80 starting issues

I fixed 1 vacumn leak I found.

I know there is suppose to be a plastic adapter that goes from 1-2.
Im hopeing this will suffice , for now?
Here is a pick of the brake booster grommet i need.

I know it may look like theres one in there , but trust me , there isnt.

checked all the relative fuses .

right now all the electrical terminals in the engine are soaking in electronic cleamer.
It dries up in like seconds , 100% 0 residue.
Ill hook em all up tomorrow and see what happens?
Old 07-20-2005, 12:20 PM
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Join Date: Mar 2004
Location: Swamplands of NJ
Posts: 761
Default RE: 91 Audi 80 starting issues

I know exactly the grommet that you are referring too, I had one or similar to it on my old 4000S. I busted a plastic fitting and had to get another assembly. Audi dealer wanted something like ~$75 or more. I said forget it. I think this was the same scenario with your 80. Because of the sharp barbs on the plastic fitting, somebody busted the grommet that has hardened over time. I ended up getting one from a junkyard for $3. I don't know if Audi sells it by itself, I might actually still have one if I didn't ditch all of my old 4000 parts. I don't remember if there is a check valve but if you are getting a vacuum leak past that missing grommet, you car will not idle right, the AF mixture is going to out of whack, etc. not to mention the hard brake pedal. This explains why the idle was turned up so high. You would have picked up this leak right away if you hooked up a tune-up vacuum gauge available at Sears and many other auto-parts places. Fixing this leak may not necessarily solve your running problem as I think the previous owner just played around haphazardly. I wouldn’t be surprised if the mixture has been richened out to compensate for the vacuum leak.

Tuning With A Vacuum Gauge ... And What It Tells You
Old 07-20-2005, 06:43 PM
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Default RE: 91 Audi 80 starting issues

I hope this isnt taken the wrong way but...............

The PO was a group of hispanic men who didnt speak english .
He bought it at a auction about a year ago and also had 2 other cars.
He was selling the 2 cars (1 was the audi) and keeping his Honda.
The car was VERY butchered and they had NO idea of german cars.

This evening I plan on putting back all the electrical connections together and then cleaning allthe grounds.

Ill will post the results after doing so and thank you for your help.
Old 07-21-2005, 11:54 AM
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Default RE: 91 Audi 80 starting issues

It did start!
It takes some coerseing (sp) , like I have to give it throttle and hold the throttle @ like 2k rpms otherwise itll die , but ...............
Its alive .
It still wont hold idle and runs like its sick.
Old 07-21-2005, 03:48 PM
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Join Date: Mar 2004
Location: Swamplands of NJ
Posts: 761
Default RE: 91 Audi 80 starting issues

Butchery has no bounds and goes across all borders and nationalities. Maybe the guys pretended that they didn’t speak any English so that you wouldn’t ask too many questions.

I have had a few butchered cars in the past and it is not always easy to spot the obvious problem that has been made worse. My first Audi was a 4000S that was neglected. It had a somewhat similar problem. It just wouldn't hold idle unless it was at +2K, problem turned out to be a bad belt tensioner idler pulley. The car had skipped a tooth or two.

Have you done anything to verify that the engine is OK, like a compression check? If you haven't done one I suggest that you do, if you get low compression in any cylinders it could be a stuck/bent valve(s), hole in a piston, cracked head, bad gasket, etc. All are serious and have the potential of affecting the idle. Is the mechanical timing correct, as I have mentioned before, timing marks all align on #1 cylinder? The distributor is held by nut that is covered by a tamperproof cover, is the cover still there? You should not be able to move the distributor.

The electrical contact cleaners usually do not do a good job since they are more for removing grease. I usually 600 grit sandpaper or mag wheel cleaner which contains phosphoric acid. The acid is good for removing anything oxidized and grease. A 30 - 60 second application or dip is sufficient, don't leave it overnight! The only problem is that you have to do a very through cleaning afterwards to neutralize any remaining acid.
Old 07-21-2005, 06:54 PM
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Default RE: 91 Audi 80 starting issues

The dist was messed with as there are scrached on marks /alignment marks drawn on there by PO.
I didnt think you could adjust the timing on these cars since they have a knock sensor.
I will pull the #1 plug and rotate the engine , by hand, until I find TDC.
I did drive the car before I bought it and it seemed to "drive" ok.
Old 07-21-2005, 09:59 PM
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Default RE: 91 Audi 80 starting issues

Got home and went out the garage to try and start it.
1st try - no start but almost caught.
2nd try - caught but I had to hold the foot pedal and keep the rpms up @ 3k for 30seconds.
Then it held a idle at about 1400.
adjusted the throttle stop screw to engage the idle switch and it slowly died .
Then it wouldnt start.
I let it site for 15 min and went out to try and start it.
Almost caught on the 1st try and then just turns over and doesnt catch.

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