1989 964 Stalling immediately upon start up - Please help.

[JSny]

Hello, just bought a 964, and this is my first post. Thank you for reading this and any help is appreciated. Please let me know if you can help, as I have spent about 8 hrs online searching and in my garage, trying to find a solution.

Issue: After changing the spark plugs the vehicle stalls immediately after start-up. It starts very quickly & easily and seems fine for a second or two. I double and triple checked all of the plugs wire routing, wiring connections and vacuum lines.

I found one vacuum line disconnected within a "T", but I don’t know where it goes.
Picture 1: Vacuum line T in question - Is near the throttle linkage


Picture 2: Fuel Pressure Regulator connected to T - under the throttle body - I think


Picture 3: Not sure what valve this is, it's connected to the T and is in front of the intake manifold on the driver side:


Is this my issue?

Thank you!

[Justin@Athens]

Make sure there is a vacuum line connected to the back side of the airbox. It may be your problem. There is a small vacuum reservoir that resides back there that maintains pressure, if not connected, it does sometimes produce the symptom you describe.

You might also check to make sure your idle microswitch is working. When the throttle linkage returns all the way to the rest position, you should hear a small click. YOu might also make sure the plug for it is in good condition, I had an issue recently where one of the wires actually came loose inside the insulation and caused me some grief.

[JSny]

Thank you Justin, I will check the micro switch tonight and double check the airbox vacuum line.

Any other suggestions are welcome.

[JSny]

I checked the microswitch, it makes a small click when depressed. Also, the vacuum line on back of the airbox is connected.

I love this car and enjoying working it.

I have successfully finished a few projects with parts I purchased at Pelican: Spoiler Wall, central locking prop rod, hood and trunk struts, spark plugs. I have a valve cover kit for the valve adjustment once I get this thing running again. Thanks.

[JSny]

Please let me know what other ideas you might have: From reading other posts I hear discussion of the MAF, CHT, DME & O2 sensor. How to I check these? Could they be the issue? Thanks

[Justin@Athens]

AFM most likely doesn't need to be messed with, as the car was running ok before. You have obviously inadvertently disturbed something to cause this situation. My guess is also that you have a vacuum leak somewhere and you were on the right track to begin with. I don't know where that T-connection leads though. On my car it is a straight line from the valve in pic#3 to a port directly under the ISV. No T connection present on my car.

[JSny]

Thanks Justin. I have spent another 3 hours working on it tonight. No luck. From searching this site, I did the following: 1. Inspected the ISV, it looked clean inside (& it was replaced 4k miles ago, from previous owner). 2. Made sure the idle microswitch is making contact with the linkage. It is with engine off. 3. Disconnected each coil, then started vehicle. It ran a little longer with the upper connected, but only for a few seconds, then stalled. 4. Cleaned battery terminals. The little terminal connected to the positive has some corrosion on it, but it measured 0 resistance with a ohm meter. I am charging the battery now, as it ran down to 12.0 V from so many attempts to start. I am learning much about the car, but need to get this thing running.

I will try to connect pic#3 to the ISV, just as a test. If anybody has any other ideas, please let me know. Thanks so much.

[JSny]

Justin, you were right, I found where the vacuum hose went. Unfortunately, after connecting it, it still stalls. AHHH! I really appreciate the input. It helped me stay determined to find where it went. BTW: There is a vacuum nipple on my car, about 75 mm below the idle microswitch, the vacuum line connected there. At least we figured that out.

I disconnected the O2 sensor and tried starting it, it still stalled. Cleaned the ISV electrical terminals with spray cleaner, still stalled. I found all of these checks here.

What to check next?

[Justin@Athens]

Use a 9v battery to test the ISV. Just apply the battery to the terminals for a second, you should hear the unit click. As soon as you remove the battery, it will go back to rest. Do not hold battery power to the unit, as it is not designed to operate with constant power present.

Its probably not the coils, as your car should run on just one distributor--albeit down on power.

You might check for a good connection at the back of the AFM. Inspect the electrical plugs to all these things we are discussing, pulling back the little rubber boots to look for loose connections.

If you put your foot in the gas does it run? Is this solely an idle problem?

[JSny]

Thanks:
1. I tested the ISV with a 9V battery. I heard the click, so that seems fine.
2. It's not just an idle issue, as I tried to start it and gave it full throttle, it died quickly.
3. I will check the AFM connector/wires tomorrow after work. I got a late start today.
4. I started checking the connectors, so far no broken wire or terminal push out.
5. I also jumpered the DME, no issue found.
6. I triple checked the plug wires, went through each underneath the car and above. They all seem to be fine. I did find the #1 plug wire, seems broken at the 90 degree turn into the valve cover. The rubber boot is fine, but I can feel that it seems separated inside. I don't think this would make it stall though.
7. I check resistance from the neg terminal to the body attachment point, it was about .4 ohms. Seems ok.
8. I removed the blower motor and checked each electrical connections behind it, un-connecting and reconnecting. No issue.
I don't want to give up yet. I will continue to check the connections and the AFM tomorrow. Appreciate all of the advice!

[JSny]

Please confirm rear coil and the left distributor (closer to left/drivers side quarter panel) are connected, and the front coil and the right distributor (closer to the fan) are connected. Thanks

[iamtheari]

I think which coil is connected to which distributor shouldn't make a difference. I would try starting it with maybe 10% throttle. I had idle hunting issues a couple years ago (final diagnosis was overfilled oil; I did a good cleaning of the ISV and throttle body and removed some oil and it was fine) and remember that trying to keep it running with full throttle seemed to stall it just as fast as no throttle.

Failing that, my understanding of internal combustion engines is that there are four things needed for them to run: lubrication, air, fuel, and spark. It sounds like you have already basically eliminated three of those as potential problems (or at least as the main culprit). Can you find someone able to test your fuel pressure?

[JSny]

Thanks -Here's the list of things I worked on tonight:
1. Tried starting with 10% throttle. No go, worse than with foot off the gas.
2. Checked the AFM connector and wiring. not easy to get too, but not the issue. Actually, I nicked the insulation and taped it for tonight. I need to put some heat shrink on it. Insulation seems brittle there.
3. Measured resistance at the Idle microswitch: .5 ohm. I also measured the microswitch on the opposite side of the throttle, it measured .5 ohms as well. I think less than 6 ohms (some say 10 ohms) or less from what I read here. Both were infinity when WOT.
4. The zinc plated bracket that holds the throttle cable (down about 4 inches from the idle microswitch) was extremely loose. One of the screws fell out. I tightened this and thought I found the issue, but no. Same issue. Ran for about 2 seconds and stalled.
5. I checked the Fuel pressure reg, by pulling the vacuum line to see if fuel was present, read that here. If fuel present, the reg is bad. No issue.
6. Checked several more connectors, looking both the male and female terminals - no issues found.
7. I don't know of a way to check the fuel pressure. I don't thing there is Schrader valve on these cars, which is an easy way to check. Any ideas on this?
I am running out of ideas. Thanks for your input.

[Justin@Athens]

okay let's go back to the basics here. perhaps you have inadvertently installed the wrong spark plugs.or possibly you were sent the wrong plugs or they were not gapped properly. you might also double check or triple check all the wires to the injectors themselves.

[JSny]

I like the basics I checked the plug wires. No issue found. I found the firing order online and each wire is marked with the cylinder #, love that. I traced each to the corresponding cylinder, including the grommet pass through. I got underneath the car and made sure each matched the cylinder number. I thought this could be it, as "stepping back", this is the work that I did on the vehicle. The vehicle ran before I worked on it, so I think it's safe to say, I did something to it, but what?

Describing the issue: It seems to run smooth for about 2 seconds. It starts every time in about 2 seconds, but then the dash lights up with tell tails, a solid chime sounds and the engine dies.

Could it be fuel, as Ari suggested? I don't have a pressure tester. Wonder if I can squirt fuel or starter fluid in the air box as my son starts it? If it wants to keep running longer, its the fuel?

I just got this vehicle, but feel i am learning so much about it. That's pretty cool, but it would be nice to drive it

THANKS

[bazar01]

Do you have a spare DME relay?
If not, just make a triple jumper and jumper the DME relay for testing purposes.
This will keep the fuel pump running and ignition components powered during test.

What exactly are the components that were disturbed during the spark plug and wire replacement?

[JSny]

On the DME, I used the paper clip method to jump it. Is that ok? I tried to start it and no difference. Started, then stalled..... Turned ignition off, pulled the key, then pulled the relay out of the fuse box. I heard a click in the general area of the pass side, near front, after the relay (w/jumper) was pulled. Not sure if this was the fuel pump or what?

Changed the spark plugs and removed:
Drivers side upper: blower motor & inlet tube to blower motor, disconnected connectors, plug wires at spark plugs & spark plugs.
Pass side upper: ac compressor (just moved it out of the way), air filter cover and air filter, plug wires and plugs.
Drivers side lower: cat converter, shields, pulled O2 grommet, silver heat shield against valve cover, plug wires and plugs.
Pass side lower: exhaust, heat shield against valve cover, plug wires and plugs.
BTW: I didn't disconnect the battery when i changed the plugs. I probably should have.

Since I am confessing everything, I took the fan belt off and adjusted, by adding shims, as it needed tightening, as I planned on adjusting the valves soon. Need to turn the vehicle over manually via the fan nut, to achieve TDC. The first time I tried this, the vehicle was in gear and the vehicle moved forward. I put it in neutral after this. I never started the valve adjust. glad I didn't. Thanks.

[Justin@Athens]

Well you can spray some starting fluid in the face of the airbox, and just see. It probably will run longer no matter what, as that is just going to be super rich. You might also use some kind of non metallic object to hold the AFM barn door open slightly if you are concerned the AFM has failed.

I actually think you are probably getting too much air somehow, but I don't know where.

[JSny]

Thanks. I tried the starting fluid. No go. No difference. It started and stalled quickly. Not sure what that means. I pulled the air filter cover, air filter and put a plastic rod to hold the flapper door open, then sprayed starting fluid.

[porterdog]

Hiya! Want me to bring my Hammer over? I'm waiting on a new cable but I think it would be here by next Tuesday, which is the day I'm always in Canton...

Best to shoot me a PM as I'm not on here all that often.