Coupe GT, engine bay identification.

[rakete]

Hi, I hope this is in the right section, first post so apologies if it isn't..

So I've just bought my first Audi, it's an '87 Coupe GT, 2.2 5cyl (KU engine) manual.

Just been tinkering around tidying it up a bit as it has been neglected, and came across something in the engine bay that is disconnected...
Located on the right side of the engine block, near the thermostat housing (I think) there is a small cylinder with two spade connectors, and just below that a sensor with a single spade connector.
I'm assuming the bottom sensor is oil pressure?
There are three loose wires next to them, and I would simply plug them in but I am not sure what wires to connect to what, and also why they would be disconnected in the first place if it was on purpose?
The wires are all spade connectors, the wire colors being;

-Blue/White.
-Grey/White.
-Blue/Black.

The Idle Control Valve has also been disconnected, as it is not functioning properly (idle pulses between 900-1200rpm). Could the two be related? I'm going to try and clean the ICV in the meantime while I try and find a replacement (harder than it sounds where I live!).

Any help would be greatly appreciated!

Jeremy.

[scotty33]

I'm not too sure on the sensor wiring, but as you say seem to be oil pressure, there are oil pressure low pressure, oil pressure high pressure and oil pressure sender for the auxiliary gauge (which I think may be the one with the cylinder) the other two are usually coloured brown or white. They often cause an oil pressure alarm, the system needs to see 0.4 bar minimum and approx 1.8bar minimum at approx 2000rpm which is why there are 2 sensors.

suggest you visit Vagcat (parts catalog) free to register and use, search your model/year/engine type/electrical, then the oil switches should throw up a generic image for a 5 cylinder with the different switches numbered with a key to their descriptions.


The idle valve won't be failed if it is making the idle hunt. It is trying to cope with a problem outside it's remit, possibles I can think of are vacuum leak (including the crankcase breather below the dizzy) incorrect mixture, incorrect timing, insufficient airflow into engine. The last being a build up of crud inside the throttle body, this reduces the idle airflow and leads to the ISV eventually having an impossible task. There is an idle airfow screw on the throttle body, which adjusts airflow through an air gallery that bypasses the throttle butterfly. Screw this anticlockwise for more airflow, or clean the throttle body innards. Also check the idle switch works ok, should hear a faint click just before the throttle comes to it's stop. (The throttle stop screw should not be adjusted, to do so can affect the idle switch operation)
it might be worth flushing the isv out with petrol or similar, if it is sluggish, but from what you said it must be operating?

switches/senders pic

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[rakete]

[QUOTE=scotty33;834317]I'm not too sure on the sensor wiring, but as you say seem to be oil pressure, there are oil pressure low pressure, oil pressure high pressure and oil pressure sender for the auxiliary gauge (which I think may be the one with the cylinder) the other two are usually coloured brown or white. They often cause an oil pressure alarm, the system needs to see 0.4 bar minimum and approx 1.8bar minimum at approx 2000rpm which is why there are 2 sensors.

suggest you visit Vagcat (parts catalog) free to register and use, search your model/year/engine type/electrical, then the oil switches should throw up a generic image for a 5 cylinder with the different switches numbered with a key to their descriptions.


The idle valve won't be failed if it is making the idle hunt. It is trying to cope with a problem outside it's remit, possibles I can think of are vacuum leak (including the crankcase breather below the dizzy) incorrect mixture, incorrect timing, insufficient airflow into engine. The last being a build up of crud inside the throttle body, this reduces the idle airflow and leads to the ISV eventually having an impossible task. There is an idle airfow screw on the throttle body, which adjusts airflow through an air gallery that bypasses the throttle butterfly. Screw this anticlockwise for more airflow, or clean the throttle body innards. Also check the idle switch works ok, should hear a faint click just before the throttle comes to it's stop. (The throttle stop screw should not be adjusted, to do so can affect the idle switch operation)
it might be worth flushing the isv out with petrol or similar, if it is sluggish, but from what you said it must be operating?

switches/senders pic

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Hey Scotty, thanks for such a concise reply!

I think you are right about the oil pressure senders, have registered to vagcat (thanks for the link should be a very useful site!) and they look similar to parts 1/2 & 16 in the above diagram. Still unsure about the wiring but I have ordered a Haynes manual, won't get to me until the end of this week at the earliest though unfortunately. The fact that they have been left disconnected makes me wonder if they were throwing on the oil pressure light, would you think this is because of a faulty sender or something more sinister? Would also explain why the Bar gauge in the centre console shows no signs of life.

In terms of the idling, I just had a quick look in at the throttle body, there was a small amount of buildup but not in an amount that I think would seriously affect its airflow.. but I did not take the actual throttle body off, only the black rubber intake tube thing so perhaps that would be the next thing to check. Started getting dark though so will have to wait until tomorrow. Is there an easy way to look for a vacuum leak? Or simply searching for cracks etc?

Will leave adjusting the airflow screw until further inspection.
Fairly sure I can hear the faint click of the idle switch as the throttle comes to a stop.
ISV is currently having a bathe in some petrol and will leave overnight.

Incorrect mixture/incorrect timing - may be getting a bit out of my depth there unless there is a simple way of checking? The spark plugs look a little dark but not extremely.. hmm.

[scotty33]

I like those cars, I hope you can solve this. It looks like you probably don't have No.2 (No.16 fits instead of no.2 when you have the auxiliary oil pressure gauge, I think) I think the other oils pressure switch is the one on the oil pump housing at the front of the engine, (No.14). From their descriptions, you should be able to work out which is 0.4 bar and 1.8 bar (or figures thereabouts).
As said the switches are not 100% reliable so could be a switch issue, but the gauge feed off as well does make me suspicious of a low oil pressure problem.
My Haynes for the later 1988> coupe gives White/Grey for the 1.8 bar switch and blue/black for the 0.3 bar switch,
The engine's mixture is I think adjusted by means of a special extra long allen Key (3mm?) which is inserted into the fuel distributor. You really need to make adjustments with a gas analyser up the exhaust.
The timing if badly out usually causes rough running as well as affecting idle, From the factory it would have been set for 98RON fuel (4 star) but the engine can run on unleaded 95RON ok with the timing retarded by approx 6 degrees. (this knocks off a few hp). Again needs a timing light to check/reset. but if you want to fiddle, just mark the base of the distributor and the head alongside it. You will then be able to put it back as it is now.
You could try a plumbers smoke 'bomb' inside the inlet, smoke will come out of any leaks, or make up some kind of adaptor to 'lightly pressurise' the intake system, you will feel/hear any leaks

[rakete]

I like those cars, I hope you can solve this. It looks like you probably don't have No.2 (No.16 fits instead of no.2 when you have the auxiliary oil pressure gauge, I think) I think the other oils pressure switch is the one on the oil pump housing at the front of the engine, (No.14). From their descriptions, you should be able to work out which is 0.4 bar and 1.8 bar (or figures thereabouts).
As said the switches are not 100% reliable so could be a switch issue, but the gauge feed off as well does make me suspicious of a low oil pressure problem.
My Haynes for the later 1988> coupe gives White/Grey for the 1.8 bar switch and blue/black for the 0.3 bar switch,
The engine's mixture is I think adjusted by means of a special extra long allen Key (3mm?) which is inserted into the fuel distributor. You really need to make adjustments with a gas analyser up the exhaust.
The timing if badly out usually causes rough running as well as affecting idle, From the factory it would have been set for 98RON fuel (4 star) but the engine can run on unleaded 95RON ok with the timing retarded by approx 6 degrees. (this knocks off a few hp). Again needs a timing light to check/reset. but if you want to fiddle, just mark the base of the distributor and the head alongside it. You will then be able to put it back as it is now.
You could try a plumbers smoke 'bomb' inside the inlet, smoke will come out of any leaks, or make up some kind of adaptor to 'lightly pressurise' the intake system, you will feel/hear any leaks

I think you're right about not having number 2, although in the diagram it shows number 16 being below number 1, whereas on my engine 16 is above. Perhaps I am just getting confused with the diagrams. You say there is another oil pressure switch on the oil pump housing? What purpose does that serve? Sorry if these are ignorant questions I'm used to working on old British cars which are so simple! Anyway I'll wire the senders up once I identify which is which.

When i said the oil pressure aux gauge showed no signs of life, i mean none at all, doesnt illuminate, needle doesn't move at all. I checked the wiring on the back of the gauge and it seems all ok, and the other gauges (temp, volts) work so I assume that is just because it is not wired to the senders? Or does it get its power straight from the ignition?

In terms of the timing, I do not think it is that far out, as once the car warms up it runs very well and has a decent amount of power. I always run it on 98RON so there should not be an issue there.

as soon as it stops bloody raining, and i stop working overtime! Ill get into the engine bay and give it a really good clean. Should help me identify those senders, maybe sort out any airflow issues that may be throwing off the ISV, and will make it easier to inspect for leaks.

[rakete]

Should've looked this up before I posted, the sender #14 is oil temp, which seems to be working alright so thats not a problem. Have also found a local supplier of replacement senders, both 0.3 and 1.8 bar, they are decent quality and have used lots of parts from that manufacturer before- and they are pretty cheap. Could replace the originals with these to cross faulty senders off my list but that would mean the aux oil pres gauge definitely won't work as it would be a standard single plug sender in place of the two-plug one (#16).

[scotty33]

oops forgot about temp!

looks like there were two versions of the electrics, the 2 pole 'drum' type sender replaces/incorporates one of the oil pressure switches, the question is which one dependent on chassis number?

2 035919561
oil pressure gauge sender / F >> 85-D-250 000 0-5/0,3BAR M10X1 2 pin natural / (2) 035919561A
oil pressure gauge sender / F 85-E-000 001>> 0-5/1,8BAR M10X1 2 pin black /

so does your chassis code start 85D or 85E?

You might find the part number on the sender itself?
I guess you could meter the outputs from the switch, one will likely be a resistance that varies with oil pressure (rpm) the other will be either normally open or normally closed, it may/should 'change' state at certain rpm's but should be clearly open or closed, not variable if that makes sense.

As a guide, if the oil pressure IS low it will tend to starve the top end, yours being an 87 will have hydraulic tappets which will all be noisy if this is the case. That said it is not uncommon for these tappets to be noisy (at least one or two), and this usually improves as the engine warms up a bit, where it may be the opposite with a low oil pressure problem?

[rakete]

Hmm the drum type sender has a sticker on it but is way past being legible.
And my chassis code doesn't start with either 85E OR 85D, my chassis code is: WAUZZZ85ZHA029676. Same code on the engine bay ID tag as stamped into the firewall. Or is the one you refer to a different one hidden somewhere else?

And you are correct it has hydro tappets, as you are also correct they (or one or two of them at least) are a bit noisy when it is cold but once it warms up that goes away almost entirely.

[scotty33]

Ah, that confuses things, they all start W, the AU just means Audi (VW for VW) the z's are not used as such, just 'spacers' so it is a 85 (chassis type) H. I guess if you can identify the other single pole oil pressure switch (i.e. o.3 or 1.8 bar, by default this drum one is the opposite to it?

There have been threads with links to 'chassis codes explained' worth a search if you are interested.

The tappets sounds promising,