Ok, I was finally able to get back to this problem with some equipment to test it.

I got an OBD1 reader and was able to get some info.

These are the reading I got with the car wrmed up. As you can see idle is pretty high

http://forums.pelicanparts.com/uploa...1177512098.gif


Now, look what happened when I disconnected the ISV

EDIT: PLEASE SEE NEW PIC BELOW


The car will still start with the ISV disconnected, but I guess this is because is was already at working temp. I dont think it will start without the ISV when cold.

So, does this means the problem is the ISV???

What do expert think about the other info on the pics?...I noticed the MAF voltage also decreases when the ISV is disconnected, but I have no idea what this means.

Also, ignition time at idle seems to be high 6degr vs. 3degr for the reference. Is there anything wrong there?

Thanks in advance for your help

Assuming that you blocked off the ISV port to the engine, I'm guessing your ISV adds zero air, since the target idle is below 1200.

(Disconnecting the ISV does not limit it from passing air through it.) You must physically block the port that allows air to enter the engine.

With that assumptoin in mind, I'd guess one of two things:
1. your throttle is not closing.
2. you have a vacuum leak.

I also have a '95 DME.

I don't think the timing is a great clue, though I know the computer uses timing to keep the idle steady. retarding timing slows the engine and advancing would speed it up a bit. So it actually uses the ISV and timing to steady the idle speed.

One question I'd have is: can target idle speed be modified within the chip itself? If so, maybe someone set it for 1200 so as to avoid the stalling issue that some have had with the 3.6 conversion? I know Loren and Steve Wong would know this, probably Bill, too.

Doug

Thanks for your reply DW SD,

Nop, I didn't block the port to the engine.

But, I am not sure I undertand,... if the ISV adds zero air, why does idle drop when I disconnected the cable to the ISV?

I didn't write clearly enough. From the looks of your reader charts, there was no change in speed 1200 to 1200?

I think the ISV has a rotating ball valve which adjusts very quickly. When you disconnect power and it stops moving, it is random how much air may pass through. Even though it is disconnected, it still allows air to pass. So..... I think you need to make sure no air is passing through it to see its real effect on idle speed.

SORRY , I selected the wrong second pic. Here it goeshttp://forums.pelicanparts.com/uploa...1177521637.gif

With the ISV disconnected, is the idle stable or does it hunt badly? The answer may narrow down from this list:

I'd guess one of four things:
1. bad ISV
2. chip is set to target idle rpm of 1200 (to avoid stalling issue). (I do not know if the chip can be programmed with a target idle speed. I suspect it can.)
3. vacuum leak bumps up idle speed and ISV cannot close down enough to compensate.
4. throttle plate is stuck slightly open - allowing more air and increased speed.

with no ISV idle is steady

This is with a brand new chip sent by Timmins. I will check with him what should be the target idle speed.

Anyway to check the throtle plate without taking the engine out???

Neither of my 993 engines will idle hot or cold w/o the ISV connected.

Idle is supposed to be controlled by the chip, but it can be affected by rotating the inner core of the ISV relative to the outer case. The inner and outer parts are pinned by 3 x allen head screws buried in epoxy.

When I swapped the engines this past winter I also replaced both chips, so I don't know if the resulting good idle currently exhibited is a result of chips or vac leaks that were corrected.

Bill,

I already tried to adjust idle by rotating the ISV.

With my previous chip idle would go down when adjusting but then the engine will not start .

With this chip idle seems no to be affected that much by slight rotations of the ISV...and the engine would not start either if I take the ISV from the original setup.

There seems to be no vac leaks. I tested several times with propane and starting fluid and I was not able to find any leaks.

something not yet offered. I have a 993 Vram flashed in Germany by cyntex. I just finished reinstallign my motor and trans after some lifter work ( dont ask =P).

Crawl under the car and look at the jacket on the throttle cable where it meets the body of the car. The body may ( mine does ) have a "nipple" welded on to locate the throttle cable jacket. If the jacket is not seated correctly, the idle will increase.

For me the nipple bent off durign removal, ultimately changing throttle cable assembly length.

Mario, did you find a solution?

NOIP!
I still trying to find the reason for this. I though about exchanging the ISV to see if that{s the problem but iti is too $$$ for just trying

I haven{t had too much time to dig into this lately.

I keep trying to solve an idling problem with my 3.6 Vario engine.

Idle start right, at about 900RPM but one i press the gas it remains high at about 1300 RPM. I already check for vacuum leaks and there seem not to be any. I measure vacuum at idle and it is steady at about 12.5 Hg. Is this right?

I have changed all the intake rubber boots, just in case.
I also exchange the TPS switch, but still the same problem.

Is there any reliable way to check the ISV? It is too expensive to change without being certain that this is the cause for the problem. I already cleaned it, and it seems to be working.

Any more ideas what could be wrong here?

This is the vaccum I get at the intake manifold at idle. Is it correct?


Thanks


http://forums.pelicanparts.com/uploa...1188147910.jpg

Bump. I'm bringing an old thread back from the dead...

Mario did you ever get your high idle resolved on your '97 Euro Vario engine?

I recently purchased an '88 911 with the same Timmin's supplied '97 Euro Vario engine and Cyntex chip. My car idles at the same 1200 RPM.

I spend the weekend looking for vacuum leaks and didn't find anything significant.

Please let me know. Thank you in advance for any help you can provide!

Hi Kaefer

I was never able to really solve it. I was able to control it a bit by doing the trick on the ISV valve. I need to check the file, but there is a procedure by which you can adjust a bit the idle there.

I ended solving it but in a different way. I installed a Supercharger kit and then I was able to play with the programing of the piggyback ECU, but thats a different story...quite happy with the SC, though!!!

I will try to search for the ISV valve solution I mentioned, but aparently the high RPM is du to the low weight flywheel.

One more thing. Sorry, but my memory is playing tricks. I also replced the Cyntex chip provided by Timmins for a chip of Steve Wong and that adressed the issue, if I recall correctly

Mario,

Thank you for your reply. I did try the "adjust the ISV' trick however the computer quickly adjusted the idle back to 1200 RPM.

Interestingly I also have a Steve Wong chip but that chip makes the car idle at 1400 RPM. This was the chip that was installed in the DME when I purchased it and after looking for vacuum leaks I decided to install the Cyntex chip to see what it did. Cyntex = 1200 RPM idle and Wong = 1400 RPM idle.

I've got to be missing something. I'll contact Timmins and Wong and see what their thoughts are.

Thanks again. I bet your car is a BEAST with a supercharged 3.6 euro Vario engine!!!

Scott, I have exactly the same problem.
96 V-Ram ROW OBD1 engine and absolutely no vacuum leak anywhere.
- With Steve Wong cheap: 1400 RPM
- With Stock chip: 1300 RPM
- If i disconnect the O2 Sensor (ROW and only one O2 Sensor) : 1000 RPM

ISV Trick wont work for me. the ECU kicks it back to 1400 no matter how I rotate or disconnect the ISV.
The only differences to a regular 993 are
- No AC
- Not all vacuum connections are needed
- Maybe (I am guessing) the engine or ECU are from a TIP car and have diff programming ?!?!

Does anybody know that the Idle RPM can just be set to 800 in the ECU/Chip?