Big Dog Posted August 21, 2009 Posted August 21, 2009 I am having an issue with an 88 car. The engine starts and runs for several seconds and then shuts off. It will restart and do the same thing, over and over. I have heard of this happening but don't know why it happened and am hoping to get some help on how to diagnose the problem. How to I test the spark to determine if it is being interupted after several seconds? Can I simply remove a spark plug, ground it and look to see if it is working as the engine dies? How do I check the injectors to see if they are shutting off? Is there a wire/circute that takes over after the initial start to keep the car running? I can't fine anything on the wiring diagrams to tell me. Could there be something from an alarm circute that is causing the car to stop like this or would an alarm wire stop the car from starting at all? I have never had a 944 street car so I don't know. In looking at the wiring harness coming from the ECU, I see a blue wire coming out of the big connector that is not on my diagram. Any idea what it is? Nationals are coming and thanks for the expert help Big Dog Quote
944-Spec#94 Posted August 21, 2009 Posted August 21, 2009 Jim, Not sure if this is you issue, but my ignition switch failed years ago. I could "start" the car, but as soon as I let off the starter the car would die. What happen is the ignition switch only worked in the "start" position, but when in "run" mode it fail and shut off the car. When the car dies do you still have electric power in the car? Have you swapped the DME relay? Since it is a street car it could be and afermarket alarm causing issues. Those can be hard to fix since they are all different. Quote
JerryW Posted August 21, 2009 Posted August 21, 2009 Also had this problem with my son's 84. We ended up swapping out the DME to solve the problem. Never did work out exactly what the problem was though. Actually - should say it was a similar problem. Quote
Cheap_Thrills Posted August 21, 2009 Posted August 21, 2009 So many things it could be, I'm never right when forum troubleshooting but here's my .02.... Coolant temp sensor? confuses the DME into flooding with fuel. Test by disconnecting and jumper the plug. Speed or reference sensor? If your factory tach is still there, I think it's supposed to bounce when you crank it if they're working. Fuel pressure regulator? http://www.clarks-garage.com/shop-manual/fuel-07.htm" onclick="window.open(this.href);return false; Did you test the AFM? http://www.clarks-garage.com/shop-manual/elect-22.htm" onclick="window.open(this.href);return false; When you had your gas tank off, did you replace the filter? Did you check your fuel pressure at the rail? For troubleshooting, can you run a hot wire straight from the battery to the coil and /or fuel pump on these cars to bypass sensors, then run it to see if it's fuel or spark related? I've done it on other cars, not sure about the 944. Quote
Big Dog Posted August 22, 2009 Author Posted August 22, 2009 OK, solved the problem with lots of help and advice from Hal Dunn and others. It turns out that the feed from the mass air flow was broken. This is the blue/green wire going to the ECU. After connecting it back up, the car fired immediately and continued to run great. Thanks again for all the ideas and help. 944 racers are great at helping each other. That is why I chose to race in this series. Jim Quote
JerryW Posted August 22, 2009 Posted August 22, 2009 Great - now you need to make it to Thunderhill by the 8:30 drivers meeting ! Quote
Cheap_Thrills Posted August 23, 2009 Posted August 23, 2009 OK, solved the problem with lots of help and advice from Hal Dunn and others. It turns out that the feed from the mass air flow was broken. This is the blue/green wire going to the ECU. After connecting it back up, the car fired immediately and continued to run great. Thanks again for all the ideas and help. 944 racers are great at helping each other. That is why I chose to race in this series. Jim wow I actually kind of got it right for once. I figured if I scatter-shotted enough possibilities I'd hit something. Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.