Driving with disconnected ISV?

Update:

I disconnected ISV electrical connector, and result is that engine idles OK when warm (50 deg Celsius or more). The higher the engine temperature, the higher the RPM, but no more than ~900.

When I stop, rpm does not drop low to ~600 rpm and then up to ~900 and then to normal 750 as it does with ISV connected. It just goes down to to ~900 or less depending on engine temperature.

Am I right to assume that my problem is ISV?

How do I find out if it is exactly ISV an not some sensor somewhere that sends wrong signals to ECU? I have oscilloscope and digital multimeter so I would appreciate if anyone can give me details, or point me to some url on the net with detailed specification of voltages (or any other way to determine what is not functioning correctly).

I ordered Haynes manual from haynes.co.uk, but it has not arrived yet.

I do not see a thread where you described what problem you are trying to correct.

Also, What car is this?

If a T44, you might want to see numerous threads on this at Audiworld:

The ISV is operated with the ISV controller (in T44s it is in drivers side under dash in Aux relay panel).

Nedavno Tony pise:

| I do not see a thread where you described what problem you are trying | to correct.

I have problem that I briefly described in my previous post. When I stop the car rpm drops to some 500-600 and then sometimes stalls, and sometimes goes up to 900-1000 and then back to standard 750.

| Also, What car is this?

1989 Audi 100 2.3E (NF 5-Cyl. engine).

| If a T44, you might want to see numerous threads on this at Audiworld: |

It is not V8.

| The ISV is operated with the ISV controller (in T44s it is in drivers | side under dash in Aux relay panel). | | One input that it uses is a temp sender (on T44, I5 it is under the | upper radiotor hose)

I found some instructions here:

but it seems it is not for my NF 5-Cyl. engine. But I am going to test it like this anyway.

Tony, Yvan has a Type $$, but he's running an LPG convertion on his car. You'd have to look at the a.a.a archives to see the troubleshooting that went on a couple of months ago. Cheers! Steve Sears

1987 Audi 5kTQ 1980 Audi 5k 1962 and '64 Auto Union DKW Junior deLuxes (SPAM Blocker NOTE: Remove SHOES to reply)

Yvan, The temperature:rpm correlation should be about right, as the LPG will turn to a more diffuse gas with greater heating, and you are using the engine coolant to heat the LPG, right? It sounds like the ISV is indeed working, but the feedback from it being designed for a different purpose than LPG sounds like it may be causing the problem (by working properly!) - I suggest that you may have to rig in a way to disable the ISV when you are running LPG, as the engine runs properly when you're running on gasoline, correct? Thus, when the LPG turns on (engine at required temperature), then you would have to take the ground connection away from the ISV. I expect that there may be a relay doing that already - to shut off the fuel pump. BTW, the Audiworld type 44 (aka type $$) forum, which covers 100/200/5000/V8 (and, apparently 500 in South Africa and other places) - appears as:

it's not just V8's covered in thereAnd the "Haynes" manual?.......ugggh! When you read "Assembly is thereverse of removal" you'll realize why the Bentley Manual is worth the extra$ for those who actually do work on their car.Steve Sears

1987 Audi 5kTQ - Bentley Manuals (2 volumes) referred to often 1980 Audi 5k - Bentley Manuals (2 copies of 1 volume) close at hand - Haynes/Chiltons manuals use to keep Bentley Manual pages from blowing aroung as I work outside - and as Joke Books 1962 and '64 Auto Union DKW Junior deLuxes - pre-Bentley Factory Manuals (in German and English) in use....along with Babelfish (SPAM Blocker NOTE: Remove SHOES to reply)

I have an '87 VW Golf GTi with CIS-e (= KE-Jetronic) fuel injection. I too had a problem with idle speed earlier this year. I first suspected the ISV and replaced it (the replacement cost me $4, so replacing it was cheap troubleshooting). No change. I then found out the the idle position switch (the switch that closes when you release the gas pedal) was broken. The fuel injection system would never know to get into idle mode, and thus the idle speed was off. A new switch (they are sold only in a set with the wide open throttle switch for my car) was over US$100 from the dealer so I went to a local junkyard. What I found was that a large number of both Audis and VWs at the junkyard had broken idle position switches, so it seems to be a common problem for VAG vehicles of that vintage. I eventually found a working one from a slightly newer car with Digifant, not CIS-e. The switch is the same for the two, but the wiring is different. The switches are located on the throttle body, on mine there is one switch in plain view on top, which is the WOT, or wide open throttle switch, and another underneath the throttle body. This is the idle switch. Your car may be different.

I don't know what type of fuel injection you have on your car, but I believe you said you do not have an oxygen sensor. That would be consistent with CIS (= K-jetronic), and I believe (but am not sure) that CIS uses the same switches as CIS-e. The simplest test of the switch is to open the hood and move the throttle by hand between closed and barely open. If the switch is working, you should hear the clicks at is turns on and off. The broken switches I have seen have had the plunger fall out, so that the switch would not operate at all. Another test is to disconnect the switch and short the two wires that goes to it. If shorting the wires make the idle go back to normal, you can be pretty sure there is a problem with the switch.

Nedavno Steve Sears pise:

| The temperature:rpm correlation should be about right, as the LPG will | turn to a more diffuse gas with greater heating, and you are using the | engine coolant to heat the LPG, right?

I think that engine coolant is used only to keep vaporizer from freezing and it perhaps heets lpg spmewhat, but I think that does not make any difference.

| It sounds like the ISV is indeed working, but the feedback from it | being designed for a different purpose than LPG sounds like it may be | causing the problem (by working properly!) - I suggest that you may | have to rig in a way to disable the ISV when you are running LPG, as | the engine runs properly when you're running on gasoline, correct?

No. It is the same, gasoline or lpg, I did some more testing. Perhaps a problem is not so big on gasoline as it is on lpg, but it is there.

| Thus, when the LPG turns on(engine at required temperature), then you | would have to take the ground connection away from the ISV. I expect | that there may be a relay doing that already - to shut off the fuel | pump.

I can install a switch to disconnect ISV, but as I just wrote I have the same problem with gasoline too.

| BTW, the Audiworld type 44 (aka type $$) forum, which covers | 100/200/5000/V8(and, apparently 500 in South Africa and other places) | - appears as:

| - it's not just V8's covered in there I will check thaere, thanks.

| And the "Haynes" manual?.......ugggh! When you read "Assembly is the | reverse of removal" you'll realize why the Bentley Manual is worth the | extra$ for those who actually do work on their car.

It seems like I will have to get the Bentley Manual, I just received Haynes manual for '77 Puch Maxi that I own, and I am completely disappointed. It looks like "complete idiots guide" to disassemble and assemble moped's engine. I did that without the manual.

Nedavno Randolph pise:

| > | Also, What car is this? | > | > 1989 Audi 100 2.3E (NF 5-Cyl. engine). | | I have an '87 VW Golf GTi with CIS-e (= KE-Jetronic) fuel injection. I | too had a problem with idle speed earlier this year. I first suspected | the ISV and replaced it (the replacement cost me $4, so replacing it | was cheap troubleshooting).

ISV for my car is $220 (BOSCH 0 280 140 512) Audi part 034 133 455B is probably more $$.

| No change. I then found out the the idle | position switch (the switch that closes when you release the gas | pedal) was broken.

One on my car works OK. I checked.

| I don't know what type of fuel injection you have on your car, but I | believe you said you do not have an oxygen sensor.

I have O2 sensor.

The forum link that I gave is for all Type 44s ('82 to '91) and most of the discussion is for the five cylinder engines.

Very good source for information. SMJ site is nearly the 'bible' for T44 series.

That would be a good start.

Good luck.

Tony '91 100q 5spd ISV BTDT

Oh, that's right and the thought is that on LPG the ISV might be functioning just opposite from gas due to the location of the LPG infection.

T> Tony,

Nedavno Steve Sears pise:

| It sounds like the ISV is indeed working, but the feedback from it

And am I right to assume that there is no vacuum leak, since when I disconnect electrical connection to ISV, when I stop, rpm does not drop low to ~600 rpm and then up to ~900 and then to normal 750 as it does with ISV connected.

Nedavno Steve Sears pise:

| And the "Haynes" manual?.......ugggh! When you read "Assembly is the | reverse of removal" you'll realize why the Bentley Manual is worth the | extra$ for those who actually do work on their car.

You are right! Just got my Haynes. Not much to help me solve my problem. There is no information where is located ISV Control Unit for my car. I wanted to test it according to:

but when I removed driver side parcel shelf I could not find it. There were only few relay's and connectors.

Anyone knows location of ISV Control Unit on 5-cyl. 1989 Audi 100?

Bentley says that it should be in the aux relay panel (by drivers left knee under dash on left hand drive cars). It looks like a relay but is double the width of a normal relay. Bottom row of relays.

Nedavno Tony pise:

| Bentley says that it should be in the aux relay panel (by drivers left | knee under dash on left hand drive cars). It looks like a relay but is | double the width of a normal relay. Bottom row of relays. | > | > Anyone knows location of ISV Control Unit on 5-cyl. 1989 Audi 100?

I looked there, only 4-5 wire connectors and 2-3 relays, none of them wider than normal. I will look again soon (to cold now).

Or is it different on European models? Anyone from Europe?

Yvan, You might want to look close to the relays you have found, in my 1987 5ktq there are a set of relays accessable by a cover, but there are also some relays mounted beside them. Cheers! Steve Sears

1987 Audi 5kTQ 1980 Audi 5k

Nedavno Steve Sears pise:

| You might want to look close to the relays you have found, in my 1987 | 5ktq there are a set of relays accessable by a cover, but there are | also some relays mounted beside them.

I took some pictures:

Black box that I outlined with red color is Bosch car alarm. Nothing looks like ISV Control Unit. Am I looking at right place? Look at first two photos.

That is where you should find it.

Like I mentioned before, that is where it should be. I remember someone commenting on the Audiworld form (T44 / V8) that some years controlled the ISV from the ECU but I am not sure if that is correct and what years it would involve. You may want to ask the question there as well.

T> Nedavno Steve Sears pise:

Nedavno Tony pise:

| That is where you should find it. | | Like I mentioned before, that is where it should be. I remember | someone commenting on the Audiworld form (T44 / V8) that some years | controlled the ISV from the ECU but I am not sure if that is correct | and what years it would involve. You may want to ask the question | there as well.

I will, thanks.

Nedavno Steve Sears pise:

| You might want to look close to the relays you have found, in my 1987 | 5ktq there are a set of relays accessable by a cover, but there are | also some relays mounted beside them.

I found ISV control unit. It is integrated with fuel injection control unit, and is under right side kick panel, and ISV is connected to it. I checked connection and it is OK. Ignition control unit is under left side kick panel, and idle and full throttle switches are connected to it (and the connection is OK, and switches work as they should).

Since I did not knew how to fix my idle problem proper way I decided to do the only way I knew. I cut the wire from fuel injection control unit to ISV just in front of fuel injection control unit, and then used rear fog light switch on the dash for connecting and disconnecting ISV.

Hire is how it now works: I switch ISV on, start the car, and drive for a while until engine warms up to ~50 degrees Celsius. I then hit the switch, and disconnect ISV, and engine revs nicely around 800 rpm. No stalling - hesitating then. Not the best solution, but it works.

I was wondering if I could do some damage by disconnecting ISV while engine is running?

Am I right to assume that there is no vacuum leak if engine does not stall with ISV disconnected?

And since idle switch works, and its connection to ignition control unit is OK, as is ISV - fuel injection control unit connection, perhaps ISV is my problem. On the other hand I cleaned ISV with carburetor cleaner (I should use throttle body cleaner as I learned later), and checked it with 9V battery, it seemed OK to me. And I did put another ISV (but not from NF engine, it was slightly different), and my problem did not go away:-(

Anyway I temporarily solved my stalling/idle problem.