audimafiaoso

This is the problem, after about 10 minutes [warm up] the idle is varying up and down between 1200 and 1600 rpm.

This is what I have done to the car so far.

New ISV.

All new vacuum hoses, plus the the rubber manifold that connects to the valve cover.

Changed the valve cover gasket.

New injector holders and seals.

New injectors,this was another problem they were streaming.

New coolant temp sensor.{Black} and has proper voltage.

Checked and adjusted the idle switch now I can hear the 'click'

Tested the full throttle switch it's ok

Do these 87 Quattros have the double idle speed control relay ? VDO, like the 84s-85s

Maybe the relay is hidden somewhere,and I just can't find it?

The car was sitting for about 10 years so im doing just about everything.

One more thing if I disconnect the idle, full throttle switch [3prong plug on the throttle body]the car stops hunting, but the idle stays high.

{Scratches head}






Thanks in Advance!!!

SteveAngry

It is located under the drivers side kick panel.

Simply open the access panel lower left of the steering wheel and look in there.

Steve
Michigan

dwengi

SJM has a procedure for dialing in the duty cycle on the ISV using the idle screw - and it is recommended that you do this before adjusting CO. I just have mine cranked almost all the way in to prevent wandering idle.

You may also want to hook a meter up to o2 sensor and see if the voltage is bouncing around a lot. i.e. disconnect the ISV and let it idle at a constant speed - 02 voltage should be more or less steady.

Avant Sport

Mine would wander after warm up with the ISV hooked up. I disconnected the ISV wiring and adjusted the idle screw, drove it this way for over a year. The problem was on very cold starts I would have to baby the throttle for about 1 minute to keep it from idling at 500 rpm or less. I replaced the ISV temp sensor, hooked up the ISV wiring and cranked the idle screw all the way in. Voila. Starts up great cold and holds a good warm-up idle and whem warm doesn't have the run-away idle. Tested the ISV temp sensor before I replaced it and it was way out of specs at room temperature. IIRC, it was supposed to be 1000 ohms at 70F, mine read like 20,000 ohm.

RussB

The troubleshooting pages on sjmautotechnik.com contain all the info that's needed to get an MC1 or MC2 engine humming perfectly under all conditions. Thermistors ("temperature sensors") slowly drift out of spec over many heat cycles and years and must be replaced when they're out of spec. ("Garbage in; garbage out." comes to mind.)

Once I was certain that all of the sensors were within spec, the idle speed and idle mixture adjustment procedures on the same site, while tedious to follow, resulted in my 88's MC1 engine's transformation from a mess to a sweet purring kitten.

Avant Sport

<ul><li><a href="http://www.sjmautotechnik.com/trouble_shooting/10vcoolt.html#coolt">http://www.sjmautotechnik.com/trouble_shooting/10vcoolt.html#coolt</a</li></ul>

audimafiaoso

There is a double wide relay under the map shelf the but it is used for the window/moonroof 443-959-257-B No VDO relay

Allthe way down on the drivers side left there is the knock sensor ignition control unit.

Thanks for the Response

audimafiaoso

The engine is a NF, and is not equipped with the sensors you speak of.
Just the Multi function temp sensor in [smj pic] for the temp gauge in the dash.

Thanks for the help!!

Im going to try to change the Jetronic unit under the pass kick panel.

So im off to the Junk yard.
Only an 80 mile hike, but the guy has about 10 Audis at anyone time.

If that doesn't work [Can I get lucky just one time] it's back to the DMM and testing.

audimafiaoso

Thanks for the help!!

boxerfan

Hook a duty Cycle meter to the CO connector (2 pin connector near the ISV).

Shoot for the needle waving wround the 50% mark and keep adjusting the idle to the recommended RPM as the CO is altered.

There is more to this proceedure. You need to clamp off some hoses and iirc disconnect the ISV. The motor needs to be warm too.