Testing operation of Idle Valve? Other DME questions

[Stutzdriver]

Ok, here is the story. My 84 Targa ran OK but the idle was at about 1000-1050 RPM. So I warm it up, jump the terminals as pe the published procedure and set the idle at 800 but the dash tach. It idles really well and all seemed well. Went to start form cold and I get 2-3 seconds of start up and it dies, over and over. Give it some throttle and it starts but won't idle.

I checked the CO setting on the air flow unit and it was screwed out 4+ turns, so I set it back to the 2 turns from fully screwed in. I also need to check the O2 sensor but it looks fairly new.

I do a search here and find the values for the CHT sensor and that it should be a 2 wire (replace the single wire unit if its still there) I have the 2-wire and it tests within the published parameters.

Ok next is the idle control valve which I pull and clean per some suggestions. I hook it up and watch the operation but don't really know what I'm looking for...Can someone describe the operation of the valve (what should I see it do) and a testing procedure/values? I did a search but nothing comes up.....

[DRACO A5OG]

Wow, let's deal with initial High Idle, 1000-1050RPMs is way too high.

Before you adjusted it, did you try to find out why the idle was so high?

Check for loose vacuum lines in the back to and from the Fuel Pressure Regulator and the passenger side diaphragm which also looks like the FPR. My buddy had high idle issues on his 86 and we found these lines were disconnected.

Check the idle switch at the throttle body and the throttle throw to insure it is adjusted properly ( at rest the switch should be engaged, once you lift off you should hear or feel a "click" ) and the switch is actually clicking on/off.

On a related note, let's make sure you are getting full throttle. Ask a helper to press the pedal down to the floor ( make sure there is nothing in the way ) then check the throttle to see if there is any slack ( there shouldn't be any if it is adjusted too tight ). adjust at bell housing. I would start from zero, loosen it to insure the idle switch is engaging then adjust to insure full throttle, if this is an issue.

Jumpered Base Idle setting must be done when the car is warm, lights off. Is your car chipped or OEM, if OEM your base idle should be 780RPMs, if chipped 880RPMs. Adjusting it cold will throw it off, because O2 sensor will increase idle and AFR until it is up to running temps

Adjusting the CO at the AFM blind like that is not recommended. You need a LM1 or LM2 to properly adjust the AFR when car is warmed to proper levels. If you can borrow one that would be good but at least use the O2 sensor and DVM to ball park your proper AFR. You run the risk of running too rich or thin.

As far as the ICV, after removal, you quickly shake the ICV in a twisting motion to see if you can feel the component inside is moving freely without binding. While it is off the car read the OHMs to insure it is within tolerances.

[Stutzdriver]

Fuel pressure checks fine
Full throttle is adjusted correctly
Idle switch is adjusted correctly
All hoses and connections are solid and connected
I checked the manifold to head connections and they are tight and have no detectable leaks

The ICV moves freely and when energized by plugging it in it seems to close approximately 1/2 way and clicks? What are the valued I'm looking for on which pins of the 3?

I do not have a Bentley Manual (yet), the car came with a (so far) semi-worthless Haynes manual....

[Dave Colangelo]

The only other thing I will add to Draco's suggestions is to check your injectors. It sounds like you are getting good flow as the car starts and runs but you may have some gunk build up or need some new injector seals. I often overlook these when trouble shooting issues like this only to find that a bottle of injector cleaner or a decent flush will solve the problem.

Regards
Dave

[Stutzdriver]

Actually the last tank of fuel had a double shot of Techron. I did this because the car had been driven less than 400 miles in the 2 years previous to my buying it and I knew there would be some build up of crap. It did run much better after the first tankful with the Techron last summer, this was the second. BTW this is a 51,000 mile car

[Stutzdriver]

Got a PM with the correct information on testing the ICV, Center terminal to either of the outer = 20-30 ohms---outside terminal to outside terminal= 40-60 ohms

I'll test tonight to see where mine falls!

[PabloX]

Stutzdriver, could you send me the information in that PM?

I'm having a similar problem. Idle when warm is about 1000rpm. I'm also getting the idle bounce symptom.

The odd thing is that I had replaced the O2 sensor last year which seemed to solve the idle bounce, but now that symptom is back.

[techman1]

Pablo,

A test of the idle valve (will sometimes id a bad one), is to give the idle valve a couple light bops with a small hammer/wrench while the car is idling high. If it drops, you are temporarily unsticking the idle valve. If that happens, do a search on cleaning the idle valve.

[PabloX]

Originally Posted by techman1

Pablo,

A test of the idle valve (will sometimes id a bad one), is to give the idle valve a couple light bops with a small hammer/wrench while the car is idling high. If it drops, you are temporarily unsticking the idle valve. If that happens, do a search on cleaning the idle valve.

Thanks! I'll give that a try. I'm noticing also that the idle oscillation happens when the car's warm only.

[techman1]

That is one of the symptoms of a stuck idle valve. Could be other things, but usually the ICV.

[PabloX]

Originally Posted by techman1

That is one of the symptoms of a stuck idle valve. Could be other things, but usually the ICV.

I'm sure it's never been touched. I may just take it out and attempt to clean it.

[cabmandone]

Stutzdriver,
Come on down/over to Delphos OH. We'll drink some homebrew and play Porsche mechanic. My car idles a bit high too. Maybe we can both solve our problem or have a few beers trying

[PabloX]

Originally Posted by cabmando

Stutzdriver,
Come on down/over to Delphos OH. We'll drink some homebrew and play Porsche mechanic. My car idles a bit high too. Maybe we can both solve our problem or have a few beers trying

I'm glad you put an or instead of an and there.

[rick-l]

I did not know you could set the idle speed on these cars.

CO content yes but not idle speed.


EDIT: never mind I did not realize this was a turbo with a CIS.

[Stutzdriver]

To bring this full circle, BOTH the Closed Throttle microswitch and the Throttle Open/Closed Sensor were bad. The Open/Closed only worked on the FULL OPEN position, nothing at the closed, the microswitch was broken internally with no fixing that...

I sourced a Closed Idle Switch and the Throttle Open/Closed Position switch her on the forum (thanks Cory/Tippy). They came in today's USPS and I will install tonight, adjust the CO and the Idle....Can't wait to drive the car with it all working correctly!

More tomorrow....

[Stutzdriver]

Updated:

Installed the micro-switch and the TPS full open sensor and the car fired right up, cold idle worked (1100 RPM) and settled right down to 800 RPM...Drove the car about 10-15 miles and warmed it up, ran like a champ. Set the CO using the O2 sensor, car shut off and started fine, idled good. Replacing the cracked hoses and tightening the intake runners, checking all the other connections along with the now functioning throttle closed micro-switch made this car run MUCH better...

Went into the garage this morning and tried a cold start, NO START. DME relay clicks, car cranks and cranks, NO START....I had to leave for work so I couldn't do any more until tonight. I have the Rennlist and Pelican forums No Start check list and I'll work through that tonight.

Frustrating but If it will start ok it ran SOOOO much better.

[rick-l]

Originally Posted by Stutzdriver

So I warm it up, jump the terminals as pe the published procedure and set the idle at 800 but the dash tach. .

OK so it is a DME car. What did you adjust to set this?

[Stutzdriver]

UPDATE:

Last night I went through the entire DME check/test procedure. Everything works as far as power to the DME (relay is good and works on 1 relay but not the other) but it doesn't close to kick in the fuel pump or create spark at the plugs. Pull the DME 35 pin connector and stare testing with an Ohm meter. The reference sensor is fine, the speed sensor is dead so no signal to trigger the fuel pump on or spark. The speed sensor shows no ohm reading at all and no voltage created when cranking.

Looked up the part number for the Porsche part (911-606-215-01) at $158.25 from Pelican (ouch)

Found the BMW part number for the duplicate part with a slightly LONGER connector wire (1/2" so I am told) 12-14-1-708-619.

I have a great relationship with the local BMW parts manager, called him and I'll have 2 sensors here tomorrow at $55.00 each so tonight's project will be to remove the old ones and be ready for the parts delivery at about noon tomorrow, then we should be good to go!

[DRACO A5OG]

Very Cool. Let us know.