dcsst28

That is really interesting. It sounds like we have the same problem. I did not understand some of the things he mentioned, though. For example, what does he mean by the ISV temperature switch? I did not know it had one. Also, when he references the cold start injector, does he mean that it remains open?

My car has one microswitch; it is the one for full-throttle. I pushed it while the car was idling, and the idle increased. I'm assuming it works, because it is supposed to enrich the mixture when activated.

About the throttle set screw, here's the deal... I actually already turned it a bit, because my book made a reference to it. It did not do much at all. I put it back in the position it was in before I altered it.

So, I ordered an ISV from Force 5 Automotive; they said it came from a running vehicle, so hopefully it is good. It was only $20.00, so if nothing else, I'll have a spare. I hope that is the problem, because that is an easy fix.

socalclimber

You have a coolant temperature sensor (CTS), usually on the cyl head or on upper radiator hose outlet flang on cyl head. This is one of the inputs to the ECU (see overview pic of KE-Jetronic). These usually don't cost that much. Look for part number on it and google it.

Don't know how much of role CTS plays with ISV (maybe increased idle speed during warm-up).

Have you blocked off ISV with plastic or clamped ISV hose shut to see if that drops idle speed? Or see if your used part solves it when it arrives?

Set screw: you said it looked tampered with. Make sure throttle butterfly is not being held open by it. Back off screw until it's doesn't touch stop, then screw in until it just touches stop + 1/2 turn, then tighten little nut.

Microswitch: remove electrical connector harness, is there two prongs or three? Sometimes idle microswitch is underneath throttle body and not really visible. If there's three prongs, you have an idle switch as well, and it's probably underneath.

There are test procedures for both CTS and microswitches (that I might be able to find). Keep us posted.

dcsst28

Okay, I know what you are talking about now when you mention CTS.

No I have not blocked ISV with plastic yet, nor have I clamped the ISV hose shut. I won't be able to work on the car until Friday. I live in another state during the week.

I know the microswitch swings back and forth loosely until the throttle is opened all the way and the switch is closed. I will check if there are two or three prongs. I would appreciate the procedures for testing those items.

I will work on the car on Friday, and I will report back my results.

Thanks.

jh0104

Hey about the full throttle switch- if u push it in while the car idles it should want to die out, not increase in idle iirc.

Unplug cts on block side of coolant hose while at idle, its the bottom one iirc. If idle changes then cts is good.

Sounds funny to ask this one, but do you have a fuse in your ecu spot in your fuse box? Its an unlabeled fuse that is mistaken for a spare. I can post a picture if you want.

The best way to test and clean an isv is by connecting it to a 9v battery and activating the actuator while spraying carb cleaner into the thing.

Pull the air box apart, look under airbox lid where the metering plate is, is it all gunked up? Move it up and down and spray it with brake and parts cleaner.

Since its already idling high i would adjust the idle screw on the intake manifold all the way to the right,if the idle doesnt decrease but the car wants to die then i would imagine ignition timing could be advanced. If thats the case then unscrew the nut holding the distributer and rotate it clockwise. this basically retards timing so if it was advanced, maybe this will lower engine speed. Test this and see if its smoothed out.

About the hard starting- csv's rarely go bad. I think you can unplug it and crank the car to see if fuel sprays? Also, might be a silly question but, is it cold where you live? Are you using heavy weight oil such as 20-50? How old is your battery? Changed fuel filter recently?

And like everyone else said- check for massive airleaks ;-)



Oh yea! Run 91 or higher octane, it really is worth the money and im convinced it IS the right octane for these.

jh0104

Ecu fuse- check to see if its even there buddy

dcsst28

Well, there must be a problem with the throttle switch, then. The idle definitely increased.

I will test the CTS on Friday when I'm home. I'll unplug the wire harness like you said to see what happens.

I do not remember if I have a fuse there, but I will know on Friday. I'll let you know as soon as I find out.

Cleaning the ISV sounds pretty simple; I can do that. I know that the cylinder rotates for a second or two, then it shuts off for a second. Then it rotates again, and shuts off again. It does this continuously. I do not know if that is the expected behavior of the device.

I will pull the air box apart, but I have a heck of a time getting to it. Rog pointed out before that if I remove that piece of metal in the corner (basically a triangle), then I could get to it much more easily. I did not want to cut it out at first, but the more I think about it the better it sounds. I am not exactly sure what kind of tool to use to do that. I will have to ask Rog how he did it.

I already turned the idle screw all the way to the right. Actually, it was already turned as far as it could go; it looks like someone else has done it in the past. I'll definitely check to see if the timing is advanced. I'll probably do that first.

So, I will pull the CSV and see if fuel sprays when I try starting the engine. It actually is very cold where I live. I do not know the weight of oil that is being used now. It is whatever the dealer put in the engine before I bought it. I have 10w40 to put in when I change it. I believe that is what it calls for. The battery is brand new. The old one died after letting it sit for over a year. I haven't changed the fuel filter, but I do not think that has anything to do with it. I did a pressure test of the fuel injection system, and everything checks out. The system pressure is 5.4 bar, which is right where it's supposed to be. If the fuel filter was clogged, then that value would be lower, right?

I've looked for air leaks. I do not know where else to look. I could see one of those tiny vacuum tubes leaking, but the boot that connects the mixture control unit to the manifold seems pretty solid. I haven't seen the underside yet.

I will use premium gas after I rebuild the engine; that is my ultimate goal. I want everything to be working before I do that, though. This way I'll know if something doesn't work when I'm done, it is my fault.

jh0104

Yea, the fuel filter is just to clean things up a bit and help her tune up a bit, along with a cap,rotor,button,plugs and wires. They will all improve starting/running/idling. Remember, our cars are pretty old and will NEED lots of TLC.
Your isv is working fine if it is actuating intermintently, it should be cleaned as general maintance. Uncrew idle adj screw all the way out and shoot lots of parts cleaner in there and spray and wipe screw.

The airbox is not so bad, the part the rog showed it cut out is a great idea, a sawzall should do the trick.
To get it out you just need to angle the back side opposite the "imaginary triangle" up and away, carefull not to disturb/rub those wires, u can unscrew ground and move it out of your way. Now just pry the front corner of the box lid out by popping it past that metal triangle.
Once thats done, look under the lid. Mine was so gunked up, it would get stuck and my idle would sit around 2700-3000 lol!
Clean it with parts cleaner, moving it up and down gently as i spray.

I asked about oil weight because i run 50w no matter how cold it is, takes a few cranks to get it curculated then it fires up. Takes me about 10 minutea to get the oil up to temp and viscous again.

Are you actuating full throttle switch and revs get high? wouldnt that mean that somewhere along the communication lines, the fpr/dpr are doing the wrong thing?? Could o2 sensor be bad? I never had one go bad and never did dpr tuning so i dont know how much of a role they play in idle and enrichment modes.

Maybe cleaning and degunking the metering plate will help! Like i said before, mine was getting stuck and my idle would hover at damn near 3k!

And fyi, if idle air screw was "closed" aka all the way tight; and your timing is advanced enough to cause a 3k idle, it would stall with idle air tightened. If your advance was that far, you would need lots more air to keep the engine chuggin.

dcsst28

Yeah, I'm trying to give it as much TLC as possible. I already replaced the distributor cap and rotor, the plugs, and the plug wires.

Well if the ISV is working, then I bought one for no reason. Oh well, I was hoping that would be the problem.

I will do my best to get the lid of the air box off, and I will check out what lies underneath.

I thought that if the full throttle switch was closed, then the DPR would cause a larger pressure drop outside the slits in the fuel distributor, so that more fuel would flow to the injectors and enrich the mixture. That is not correct?

Yeah, mine DOES hover at 3000 rpms. It is so loud, and it sounds like the engine is going to blow up.

So, it sounds like the timing is not advanced on my engine. Another downer, because that means I still have to search for the problem.

I'll get to it on Friday, and I'll report results.

socalclimber

That is correct, the full throttle switch enriches mixture by increasing current to actuator (DPR). This usually increases idle speed, esp. if there are vacuum leaks because it richens up the mixture. If system is running rich already (which wouldn't be good), let's say near the rich limit, closing full throttle switch could over-richen things and cause a lower idle, but I suspect not. I very much doubt you have a problem with full throttle switch.

I always suggest troubleshooting to determine a cause first, then replace parts. Disconnect full throttle switch connector, connect an Ohm meter to full throttle switch contacts, close switch. If you get continuity, it's fine.

Idle micro-switch is more likely to be a problem, if you have one. If you have a 3-prong connector at throttle body, you also have an idle micro-switch. Again, if so, test with ohm meter to see if you have continuity when throttle closed. This lets ECU know that throttle is closed. Idle micro switch, if you have one, is sometimes underneath throttle body and not immediately visible.

For timing, you NEED to connect a timing light and see where you're at, adjust as necessary.

I don't think you have ruled out the ISV yet? Also, do check that throttle is closed all the way.

Mixture: the only easy way to see where you are with mixture is to connect a volt-ohm-amp meter (in amp mode) inline between DPR and DPR connector and see where you are current-wise from the ECU. This will also tell you how oxygen sensor is doing in closed-loop mode, and how ECU responds to temp sensor. Accuator current is in mA. If you are at one of the mixture limits, called lean limit or rich limit, the accuator current will tell you that. You want to be in the middle, usually 8-12mA or so (you need Bentley manual to check specs for your car). If you are near one of the mixture limits on either end, lean or rich, system can't compensate enough, and could hunt on idle also.

More info on measuring DPR current here:
http://www.humanspeakers.com/audi/timing2.htm
(I made my own harness, but you can buy them as well)

If you don't have the manual and tools to test properly, you are really flying blind.

dcsst28

I'm getting pretty frustrated. I'm trying to test the current to the DPR, but everytime I disconnect the wire harness the engine dies. It doesn't seem to even run in "limp home" mode. Maybe I need to let it warm up a bit. When I connect the multimeter in series with the DPR, the engine still dies; then I am unable to start the engine with the multimeter connected. I do not understand this, because I'm completing the circuit.

I'm going to test timing now. Will report in a bit.