924Board.org

[RobG]

I seem to have developed an issue with stalling. Last summer I had a catalytic converter (generic) from NAPA welded in, and the problem, as well as I can recall, began about that time. It wasn't too bad, though, so I left it. Over the last few months, the problem has become worse, with the car hardly able to idle without assistance, and often stalling.

In recap, the symptoms include:
1. Low idle, when starting cold OR hot.
2. Idles rough when at factory spec (840+-40) rev, and can't maintain that spec. w/o assistance, leading to eventual stall most of the time.
3. Exhaust tone is different than before, i.e. louder when idling. (May not be related).
4. Runs fine at speed.

To address this problem, I've:
1. Replaced most of the vacuum hoses with the kit from Lindsey racing. The hoses under the intake manifold aren't the same diameter.
2. Checked and verified gap of spark plugs.
3. Replaced spark plug wires. Wire #1 (corresponding to cylinder 1) was corroded on the distributor cap and the connector broke off of the wire.
4. Replaced cracked distributor cap with new, and replaced rotor.

I'm kind of at a loss of what the issue could be. Nothing else that affects the ignition was changed AFAIK over the past year.

It seems that the spark part of the equation is ok.
Vacuum ?
Fuel? This seems like the most likely culprit, though at speed the engine runs and accelerates smoothly. Wouldn't this indicate a healthy fuel delivery system?
Is it possible that an overly constrictive catalytic converter could cause these symptoms?

Any suggestions?
Thanks!
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1987 924S
#1066

[Llamaguy]

just a thought, did you get the vacuum hose that connects underneath the intake boot? This has fallen off my car before and caused similar problems.
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1987 924S Guards Red
1997 Suzuki Tl1000 Supersport

[924guy]

almost sounds like an 02 sensor issue to me... possibly they didnt reconnect it when you had the exhaust work done, or its in need of replacemnt?
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Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
Performance by Pasha

[RobG]

924guy - of all the things that it could be, i had completely looked over that ... i'll give it a check. i think i've been too busy dreaming of worst case scenarios!

llamaguy - i've been through the vacuum lines over and over, and while there were some connections under the intake manifold I couldn't see, I felt around as best I could and all seemed to be fine.

thanks for the suggestions!
feel free to post others if any come to mind....
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1987 924S
#1066

[Paul]

Check the grounds under the heater control valve.

Check for bad intake gaskets on one or more cylinders.

Check for low compression in one or more cylinders.

Hook up a vacuum gauge and make sure the needle is not flicking back and forth wildly.

Unplug 1 injector at a time and verify that the car runs worse.

Unplug 1 spark plug at a time and verify that the car runs worse.

(for both of these tests, shut the car off, then disconnect and restart)

Check the throttle position switch for proper operation.

Check the idle control valve and the hoses that attach to it.

[Mavfan]

Maybe the fuel pump relay, because my 924s is sitting in my garage awaiting a new one that i'm purchasing today, and had pretty much the same issues, minus the ones you were unsure about. (she stalled 3 times in the past 6 months, then 2 days ago she stalled, stalled again, and so i took her home coasting and stalling, thankfully i hadn't gotten very far. i thought it was the fuel pump, but some guys here said that it might just be the fuel pump relay, soo i'm saving about $150, check out my post)
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Black 1988 924S SE
Red 1985.5 944

http://mavfan72.tripod.com/
http://www.cardomain.com/id/mavfan

Video:
http://video.google.com/videoplay?docid=-5193982457901018136

[RobG]

Thanks for the suggestions! I've been methodically going through each, but have yet to find the problem. I'm moving at a snail's pace, but consistently.
I've ruled out some things, the last was the ground under the heater control valve. What a PITA that was without pulling anything out!

Thanks again, I'll be sure to post if and when I isolate the problem.
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1987 924S
#1066

[RobG]

In removing the connectors from the fuel injectors to check if one is not operating, it seems the engine speed did not noticeably change when one was removed, signifying that it isn't operating properly.
The problem I'm encountering is that the idle is so unsteady anyway, it is hard to be 100% sure that I've made the correct "diagnosis".
To return the injectors (might as well do all) to new condition, it seems there are two possibilities:

1. Buy new injectors
2. Clean out the old injectors.

From what I've been able to gather, cleaning the injectors with a solvent is possible? I've got a compressor and solvent.... Will soaking and forcing solvent through the injectors produce "clean" injectors?

I'd hate to buy new injectors, only to find out I had been wrong, though I have found an online company that sells them for around $60 each:
http://www.fuelinjectorsdirect.com/
This seems to be the cheapest I could find. Do they get any cheaper?
Thanks!
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1987 924S
#1066

[Paul]

You cannot assume it's the injector yet. All you have done so far is determine which cylinder isn't pulling it's load.

You need to also check to see if removing the plug wire on that cylinder makes any difference.

Then make sure a vacuum check does not result in a wildly swinging needle.

Then do a compression check.

If these tests are ok, then replace the injector.

[RobG]

paul,
thanks for the continued help. When i changed out the wires the first thing I did was try the test you mentioned, after realizing that new wires didn't address the problem. As was the case with the fuel injectors, the poor idle of the vehicle made it hard to diagnose whether the removal of each respective wire had an impact. It seemed that it did, but I can't be sure, so I'm going to throw in new spark plugs, even though the old ones seem fine, just so I know i've replaced all the suspect electrical parts. Then I'll be able to move on from there.
Thanks
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1987 924S
#1066

[Slam]

Hiya, RobG,

Had my 83 944 do the same thing to me after a shop welded in some exhaust stuff - similar scenario to yours. I ended up having to swap out the TPS switch. My only guess was that voltage spikes from welding fried it. Haynes recommends disconennecting the battery before welding anything. Try unplugging your TPS and restart the car to see if the symtoms change.

HTH

Slam
1983 944 - mine
1982 931 - hers
1985 944 - parts
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'88 944 Auto - may or may not resurrect

[RobG]

The inevitable finally happened ... the car will no longer start. In looking at it this weekend, it appears that the ignition coil is not producing spark. I tested it by removing the wire to the distributor and trying to get the spark to arc to the body (not mine!). Nada, except for a flicker as soon as I stopped cranking the engine.
I tested the coil as per haynes, and primary resistance checked out. Terminal 4 was crammed with "rosin" (?) and i couldn't get a good connection, so secondary resistance is unknown. The coil is getting power, though it only registers if you ground to the body, not to the negative terminal on the coil. Does that sound right? If you can't tell I'm kind of a novice to electrical testing.
I tried using an ignition coil from a car that runs, and the conditions were the same.
So, it appears that the issue is either with the DME or the reference sensors. Anything else I'm missing?
As for the reference sensors ... any good way to test them?

I'm hoping that this development is the terminus of the issue with stalling, rather than a whole new alchoholism-inspiring set of problems!
Thanks for your advice!
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1987 924S
#1066

[RobG]

To answer my own question (and to help any others out), a good write up on reference sensors can be found here:

http://www.clarks-garage.com/shop-manual/ign-02.htm

Update:

Sometime before I purchased my 924S there had been an engine fire. The previous owner had some soldering done to reconnect wires, and a liberal application of electrical tape ... and the car acted as it should. Last summer when I first noticed the rough idle i inspected the taped connectors for the speed and reference sensors at the bracket. Turns out the connectors were gone, and solder barely held together the two ends of wire. I resoldered the wires but it didn't seem to do much, so I assumed the problem lay elsewhere.

The idling problem became worse, eventually leading to a no-start with no spark. I replaced/checked every single ignition component (plugs, cap, rotor, plugwires, coil, DME, ignition switch), all grounds, and was about to start the multimeter olympics with the DME connector.

While researching this, I found the above link for testing the reference and speed sensors. Realizing that there were three pins on the connectors (remember that I'd never seen a connector), I was confused as to where the third wire was. Some extra searching revealed that the shielding on the wiring actually acts as a third wire, I believe providing grounding for the sensors. Who knew?

Well, the shielding is all torn up on mine and splicing doesn't seem like an option, so I'm going the new-used harness route to replace this section, and hopefully get the car back into shape. I'm sure I'm going in over my head ... and before I do, does this seem like a sensible diagnosis ... and if so, will I regret getting into this project? I'm really in no rush to get the car back on the road, so adequate time isn't an issue (however the timing belt clock is always ticking!).

On this subject, I've got a harness, if I want it, in "really good" condition with reference and speed sensors attached, for $175. It's from an '83 944. I know the DME's for an 87 924S and an '83 944 are different, but I should be able to make it work, at least for the portion I need, right?

Any advice?
Anyone have a '87 924S wiring harness?

Thanks!
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1987 924S
#1066