Hello,

I have an idle problem ('86 5000CD QT) that was intermittent but is becoming more regular. Some idle adjustments a couple of months
ago made the problem "go away" but then the problem started appearing again gradually.

The car starts no problem when hot or cold (also has had fuel accumulator removed) but won't start for a couple of minutes if the
hot engine dies when it fails to idle. The engine tries to adjust the idling and most of the time succeeds but for the last two
days, when the engine is hot and operating, when I let go of the gas it dies and then I can't start it for a couple of minutes. If
the engine dies when I'm moving I put it in gear and it starts again no problem. Then today I drove the car for a couple of hours
and the problem only occurred once. Other than that, the engine idles very smoothly and I never sense a loss of power. I've gone
over the various threads and haven't found a solution yet. I've cleaned the idle stabilization valve (engine dies when I disconnect
cable) and the injectors seem fine (I've run injector cleaner already). All the various ignition parts have been replaced. All
filters have been replaced. We have what we call AirCare here in British Columbia and it passed like a new car (so said the
mechanic) with 0 CO and everything else WELL below average. So it's probably not the oxygen sensor.

Any ideas what it could be? Electrical connection? (but if so, the car does start fine when put in gear when moving....)

Other than, it's quite an amazing car for something 20 years old.

Thanks for any help,
cp

 

It sounds like you are familiar with the ISV system and have established that it
is functioning correctly. Therefore my guess is that you have a vacuum leak that
is somewhat intermittent (those are the most fun).

Have you tried the T44Q back yard vacuum test?
- Engine idling: pull oil dip stick - engine should falter and begin to run rough.
- Replace dip stick.
- Remove oil filler cap - engine should die.

If not you have a vacuum leak.

First place to look is the Michelenman hose (front of intake manifold). You need
to remove it to check carefully for cracks on the bottom side. After that check
the crankcase breather. After that check all other possible lines. Don't forget
the decel valve in the passenger fender hidden behind the fuel distributor. If
the decel is the problem it can be disconnected with little effect on
driveability and plug the line.

cp wrote:
> Hello,
>
> I have an idle problem ('86 5000CD QT) that was intermittent but is becoming more regular. Some idle adjustments a couple of months
> ago made the problem "go away" but then the problem started appearing again gradually.
>
> The car starts no problem when hot or cold (also has had fuel accumulator removed) but won't start for a couple of minutes if the
> hot engine dies when it fails to idle. The engine tries to adjust the idling and most of the time succeeds but for the last two
> days, when the engine is hot and operating, when I let go of the gas it dies and then I can't start it for a couple of minutes. If
> the engine dies when I'm moving I put it in gear and it starts again no problem. Then today I drove the car for a couple of hours
> and the problem only occurred once. Other than that, the engine idles very smoothly and I never sense a loss of power. I've gone
> over the various threads and haven't found a solution yet. I've cleaned the idle stabilization valve (engine dies when I disconnect
> cable) and the injectors seem fine (I've run injector cleaner already). All the various ignition parts have been replaced. All
> filters have been replaced. We have what we call AirCare here in British Columbia and it passed like a new car (so said the
> mechanic) with 0 CO and everything else WELL below average. So it's probably not the oxygen sensor.
>
> Any ideas what it could be? Electrical connection? (but if so, the car does start fine when put in gear when moving....)
>
> Other than, it's quite an amazing car for something 20 years old.
>
> Thanks for any help,
> cp
>
>

 

It sounds like you are familiar with the ISV system and have established that it
is functioning correctly. Therefore my guess is that you have a vacuum leak that
is somewhat intermittent (those are the most fun).

Have you tried the T44Q back yard vacuum test?
- Engine idling: pull oil dip stick - engine should falter and begin to run rough.
- Replace dip stick.
- Remove oil filler cap - engine should die.

If not you have a vacuum leak.

First place to look is the Michelenman hose (front of intake manifold). You need
to remove it to check carefully for cracks on the bottom side. After that check
the crankcase breather. After that check all other possible lines. Don't forget
the decel valve in the passenger fender hidden behind the fuel distributor. If
the decel is the problem it can be disconnected with little effect on
driveability and plug the line.

cp wrote:
> Hello,
>
> I have an idle problem ('86 5000CD QT) that was intermittent but is becoming more regular. Some idle adjustments a couple of months
> ago made the problem "go away" but then the problem started appearing again gradually.
>
> The car starts no problem when hot or cold (also has had fuel accumulator removed) but won't start for a couple of minutes if the
> hot engine dies when it fails to idle. The engine tries to adjust the idling and most of the time succeeds but for the last two
> days, when the engine is hot and operating, when I let go of the gas it dies and then I can't start it for a couple of minutes. If
> the engine dies when I'm moving I put it in gear and it starts again no problem. Then today I drove the car for a couple of hours
> and the problem only occurred once. Other than that, the engine idles very smoothly and I never sense a loss of power. I've gone
> over the various threads and haven't found a solution yet. I've cleaned the idle stabilization valve (engine dies when I disconnect
> cable) and the injectors seem fine (I've run injector cleaner already). All the various ignition parts have been replaced. All
> filters have been replaced. We have what we call AirCare here in British Columbia and it passed like a new car (so said the
> mechanic) with 0 CO and everything else WELL below average. So it's probably not the oxygen sensor.
>
> Any ideas what it could be? Electrical connection? (but if so, the car does start fine when put in gear when moving....)
>
> Other than, it's quite an amazing car for something 20 years old.
>
> Thanks for any help,
> cp
>
>

 

It sounds like you are familiar with the ISV system and have established that it
is functioning correctly. Therefore my guess is that you have a vacuum leak that
is somewhat intermittent (those are the most fun).

Have you tried the T44Q back yard vacuum test?
- Engine idling: pull oil dip stick - engine should falter and begin to run rough.
- Replace dip stick.
- Remove oil filler cap - engine should die.

If not you have a vacuum leak.

First place to look is the Michelenman hose (front of intake manifold). You need
to remove it to check carefully for cracks on the bottom side. After that check
the crankcase breather. After that check all other possible lines. Don't forget
the decel valve in the passenger fender hidden behind the fuel distributor. If
the decel is the problem it can be disconnected with little effect on
driveability and plug the line.

cp wrote:
> Hello,
>
> I have an idle problem ('86 5000CD QT) that was intermittent but is becoming more regular. Some idle adjustments a couple of months
> ago made the problem "go away" but then the problem started appearing again gradually.
>
> The car starts no problem when hot or cold (also has had fuel accumulator removed) but won't start for a couple of minutes if the
> hot engine dies when it fails to idle. The engine tries to adjust the idling and most of the time succeeds but for the last two
> days, when the engine is hot and operating, when I let go of the gas it dies and then I can't start it for a couple of minutes. If
> the engine dies when I'm moving I put it in gear and it starts again no problem. Then today I drove the car for a couple of hours
> and the problem only occurred once. Other than that, the engine idles very smoothly and I never sense a loss of power. I've gone
> over the various threads and haven't found a solution yet. I've cleaned the idle stabilization valve (engine dies when I disconnect
> cable) and the injectors seem fine (I've run injector cleaner already). All the various ignition parts have been replaced. All
> filters have been replaced. We have what we call AirCare here in British Columbia and it passed like a new car (so said the
> mechanic) with 0 CO and everything else WELL below average. So it's probably not the oxygen sensor.
>
> Any ideas what it could be? Electrical connection? (but if so, the car does start fine when put in gear when moving....)
>
> Other than, it's quite an amazing car for something 20 years old.
>
> Thanks for any help,
> cp
>
>

 

Hi Tony,

> Have you tried the T44Q back yard vacuum test?

Yes

> - Engine idling: pull oil dip stick - engine should falter and begin to run rough.

Yes

> - Replace dip stick.
> - Remove oil filler cap - engine should die.

Yes

> First place to look is the Michelenman hose (front of intake manifold). You need to remove it to check carefully for cracks on the
> bottom side. After that check the crankcase breather. After that check all other possible lines. Don't forget the decel valve in
> the passenger fender hidden behind the fuel distributor. If the decel is the problem it can be disconnected with little effect on
> driveability and plug the line.

I will check those, I noticed one of the lines was plugged. Also, when I squeeze what you call the Michelin Man hose the engine
falters or dies if squeezed stronger, that's normal, right? (it's being choked of air?)

Thank you very much Tony for your help, it gives me something to go at. I took it to a known Audi fuel injection expert and he
couldn't figure it out, I suppose if I threw money at it then he could probably solve, but the car is basically worthless (market
wise), so I guess I'll try to figure it out myself, it's more fun that way. =)

cp

 

Hi Tony,

> Have you tried the T44Q back yard vacuum test?

Yes

> - Engine idling: pull oil dip stick - engine should falter and begin to run rough.

Yes

> - Replace dip stick.
> - Remove oil filler cap - engine should die.

Yes

> First place to look is the Michelenman hose (front of intake manifold). You need to remove it to check carefully for cracks on the
> bottom side. After that check the crankcase breather. After that check all other possible lines. Don't forget the decel valve in
> the passenger fender hidden behind the fuel distributor. If the decel is the problem it can be disconnected with little effect on
> driveability and plug the line.

I will check those, I noticed one of the lines was plugged. Also, when I squeeze what you call the Michelin Man hose the engine
falters or dies if squeezed stronger, that's normal, right? (it's being choked of air?)

Thank you very much Tony for your help, it gives me something to go at. I took it to a known Audi fuel injection expert and he
couldn't figure it out, I suppose if I threw money at it then he could probably solve, but the car is basically worthless (market
wise), so I guess I'll try to figure it out myself, it's more fun that way. =)

cp

 

Hi Tony,

> Have you tried the T44Q back yard vacuum test?

Yes

> - Engine idling: pull oil dip stick - engine should falter and begin to run rough.

Yes

> - Replace dip stick.
> - Remove oil filler cap - engine should die.

Yes

> First place to look is the Michelenman hose (front of intake manifold). You need to remove it to check carefully for cracks on the
> bottom side. After that check the crankcase breather. After that check all other possible lines. Don't forget the decel valve in
> the passenger fender hidden behind the fuel distributor. If the decel is the problem it can be disconnected with little effect on
> driveability and plug the line.

I will check those, I noticed one of the lines was plugged. Also, when I squeeze what you call the Michelin Man hose the engine
falters or dies if squeezed stronger, that's normal, right? (it's being choked of air?)

Thank you very much Tony for your help, it gives me something to go at. I took it to a known Audi fuel injection expert and he
couldn't figure it out, I suppose if I threw money at it then he could probably solve, but the car is basically worthless (market
wise), so I guess I'll try to figure it out myself, it's more fun that way. =)

cp

 

Also,

> It sounds like you are familiar with the ISV system and have established that it is functioning correctly.

Not too familliar. In this case, how would I know that the ISV is OK? (engine dies when unplugged?.....)

cp

 

Also,

> It sounds like you are familiar with the ISV system and have established that it is functioning correctly.

Not too familliar. In this case, how would I know that the ISV is OK? (engine dies when unplugged?.....)

cp

 

Also,

> It sounds like you are familiar with the ISV system and have established that it is functioning correctly.

Not too familliar. In this case, how would I know that the ISV is OK? (engine dies when unplugged?.....)

cp