3.6 conversion idle problem/ECU help

[ssfrancis]

It's been a little while but no solution.
Ive checked and rechecked all plugs, tightened intake bolts/clamps, cleaned and measured all grounds, swapped DME relays (gets quite hot).

I pulled the lead to each coil independantly and it idles normal with either unplugged. But idles high (2-3k) when both coils are plugged in.
Any thoughts?
If not I think it's time to send my ecu out for a check

[ischmitz]

Did you ever get the CEL to work? It should come on with the ignition in ON and the engine not running just like the oil and alternator light. This is the self-test to ensure the bulb works. If not make sure one side of the bulb sees +12V and the other side goes to the correct DME pin.

With the CEL working you can flash out fault codes and the CEL will come on if for example the ICV isn't working due to an open or short.

The fact that you had issues from day one leads me to believe you could have a fault in your setup. Maybe something as simple as a mis-adjusted throttle cable. Try detaching the throttle cable from the throttle body to eliminate any chance of a tight cable causing the throttle to stay open.

Along the same line maybe someone mis-adjusted the lower throttle stop and the throttle pate simply stays open to wide. You might have to remove the throttle body to be able to inspect that.

Next, you really need access to a Hammer or PST-2 and hook it up to the DME:

- check what the DME "sees" from the TPS. This is what selects the idle program once the throttle closes all the way.

- check the ICV function to ensure it can move its full range

- Read the O2 sensor value


Good luck,
Ingo

[ssfrancis]

Ingo-
Thanks again for your help!

Ive tried to unhook the throttle cable. no change I'm pretty sure it is properly adjusted.

I did get the CEL light hooked up. seems to function properly. Stays on when key is in run position. A couple seconds after starting the engine it turns off.
I get no CEL light while running, ever, and it wont read any codes when depress (5sec) then let off accelerator while the key is on 'run'.

I did hook up an o-scope to the ICV and it looked to be an even square signal.... if I have time I'll try it again tonight and take a picture.

One strange thing is that it is sometimes intermittent. For instance I started it this morning and it settled to a 900-1k idle. After it warmed up at normal idle I turned it off, then immediately back on, and it went back to high idle at 2k then crept up to 3k. weird.

This engine only has ~6k miles on it, so I'm beginning to think it must be something ECU or install related. I did go through the entire harness while the car was running squeezing and manipulating the bundle to see if there was possibly a frayed wire. I found no change. If its not the ECU I'll putt the whole harness and go through it... Would it be throwing a code if there was a short?
Thoughts?

[h.wong]

hello,

check your wire harness to see if it has the recalled harness ... (alt+injectors, etc.)

all my insulation on all wires was frayed .. but car still ran.. then barely when i

discovered the frayed wires. you also need to swap chips.. before having the

ECU checked. good luck..

cheers,
harry

almost bought your engine.. you beat me by 30 minutes..

[ssfrancis]

Thanks for pointing me toward the recalled harness issue, I'd never heard of that and will look at the engine harness in detail.

I haven't had a chance to swap in a stock chip, but everyone keeps telling me it impossible to be causing my issues.

I literally replied 3 minutes after that add was posted. I just happen to be looking at the classifieds

[ssfrancis]

Ding ding!!! We may have a winner!
Started exploring the engine harness and found this:


The car this engine came from supposedly crashed at the dealer, I bet the harness recall was never done. I have a new replacement on order and will report back!


Sent from my iPhone using Tapatalk

[h.wong]

get recalled wire harness from Sunset porsche .. a little over $100....under
the recall ... questions..? give me a buzz...

Harry
626 379-7252

[ssfrancis]

Harry- thanks.
When you replaced your harness did you drop the engine?

Its not a big deal to take it out again... I'd just rather not waste my fresh oil!

[h.wong]

Yes ... i did drop the engine. .. in a 914/6 .. but it is doable on a
an early car 911...because the alternator is up front.. or just use
a clean 5 gal bucket and re use the oil...good luck! in a 993 the engine
compartment has too much stuff to take off ... and is more difficult to drop.
Hopefully you have the bare minimum.. are you running A/C..?

[ssfrancis]

So I spent the weekend changing the engine wiring harness..... Took two days, did some clean up around the engine and installed a single pulley setup
Just got it together, started her up.....and..... No change. I tried the idle adaptation, no change.

So I'm back to the drawing board. If I unplug the icv it idles great. If i plug it it it idles around 3k..... I think I'm going to explode.


Sent from my iPhone using Tapatalk

[shahram]

Somehow I could bet it is one of the sensors or one of the hoses running to the engine.
It could be the CHT or a bad O2 sensor or even the flywheel sensor (bad or needs adjustement).
Just one more suggestions, take a hose clamp pliers and clamp the hoses which are conected to the engine one after next one, such as break booster hose, breather hoses... and see if that changes anything.

[ischmitz]

Time for a Hammer or PST-2 or other diagnostics tool to tell you what the sensors "see" and what the ECU commands to the ICV, timing, and injectors.

And remind me. When you say w/o ICV it idles closer to where it needs to be I assume you block off the intake hole it leaves behind, correct. Then as others said maybe another massive vacuum leak on the intake.

Ingo

[ssfrancis]

I'm going to throw in the towel and admit defeat. I'll find a local shop to get a Dx... which really eats me up inside. I take pride in working on my own cars, but this computer crap is just too much.

When I say I unplug the ICV I mean just that. I leave it in place and unplug it. With it plugged in it idles anywhere from 3-4k rpm and creeps up. With it in place and unplugged it will idle At ~1k for about 15 seconds, then go up to 2k rpm for 5 seconds then back to ~1k idle for 15 seconds....I have no clue how that is being controlled, could the ecu be changing the timing?

Is it possible that the bad engine harness messed up the ECU?

Once again, I'm 99.9% sure I do not have an air leak.

[ischmitz]

The TPS tells the DME it's time to idle. The ignition and timing maps are switched and the ICV is an adjustable bypass to the throttle plate. It introduces metered air into the engine.

You could have a bad TPS for example where the DME never "gets the memo" to idle. All that is why a diagnosis with the Hammer/PST-2 would be my next move.

Best,
Ingo

[ssfrancis]

I did check the TPS and its is working with in tolerance, but you are very right that I have no clue if the ECU is getting the memo.

I'll find a Hammer and hopefully get this over with and I'll report back.
Thanks again for all the help.

[0396]

This S--t is way above my pay grade . Good luck with your search

[ssfrancis]

More questions...
Does the Hammer require a OBD-1/2 plug to talk tot he ECU?

I found thsi thread:
[URL="http://forums.pelicanparts.com/porsche-911-technical-forum/150218-how-use-obdii-diagnostic-port-3-6-transplant.html"]

But I'm still a little unclear on how exactly to do this. Any advise is greatly appriciated.

Lastly, is the Durametric reader any good?
Can it get values for each sensor?

If so I may just buy it for $300, a shop is going to charge me at least $100 to use the Hammer.

[ischmitz]

Any tester needs at least four wires: GND, +12V, K-line, L-line to function. The most economic way to realize this is to install an OBD port connector. This will allow a shop or tester out of the box to hook right up. Porsche started with a custom 19 pin connector but these are hard to come by and expensive. For later 993 the switched over to 16-pin OBD.

I made my own custom cable for my Hammer and matching custom port (LEMO) because I had these connectors lying around.

In addition to these four signals the Porsche testers use RPM, KNOCK, and CEL. But I don't think a Durametric uses these.

Others may chime in on what the Durametric can and cannot do. Or check their website. It has pretty good information. I never tried one.

Ingo

[ssfrancis]

I was able to find a install an OBD-II style plug and had a local shop with a durametric pull the codes.
I got:
16 Throttle Potentiometer

34 Hall Sensor

Although I checked the TPS and it seemed OK, I wonder if that is the problem. That would explain why I cant get the ECU to flash out the codes.
I read around the Hall Sensor and I hope that just goes away on its own!

[ischmitz]

The TPS not working prevents the DME to enter its idle routine. The hall sensor not working will retard ignition by 6 degrees and leave power on the table. Neither will go away on its own.

I bet these faults are due to broken wires right at the respective connector. Ohm it out from each pin of the 55-pin to the correct pin on the TPS or HALL connector.

The fault memory should tell you whether each fault is permanent or intermittent.

Ingo