87 924S no start. Where's the DME relay?
03-21-2013, 05:18 PM
#61
Three Wheelin'
Thread Starter
Question on tach bounce. When I did it, the tach bounces after you turn the key off. NOT on turning the key to power on and not when cranking. ONLY when finished cranking and turning the key off. It's a very tiny bounce. I assumed that is the bounce everyone mentioned to look for. Is it not? Should it bounce on cranking?
Also shop confirmed the ingiton is supplying power off and on and they don't suspect the ignition is the issue.
Also shop confirmed the ingiton is supplying power off and on and they don't suspect the ignition is the issue.
03-21-2013, 10:06 PM
#62
Rennlist Member
Sorry to hear the bad news - you just can't catch a break on this car! The shop had it running with the new DME for a little while, right?
When you crank the engine, you should see the tach needle jump up to register the rpm (so it should bounce at least several hundred rpm, i.e. a noticeable amount). It sounds like you aren't getting that. My guess is the tiny bounce you see when turning the key off is just the tach losing power.
If they put new ref sensors in and there is no tach bounce on cranking, then I believe the problem could be one of 2 things:
1) The ref sensors aren't gapped properly from the flywheel. I believe Clark's Garage has the exact specs, but the tolerances for the distance between the sensor and the teeth of the trigger wheel are pretty tight.
2) The signal from the sensors isn't being transmitted to the DME because of a bad connection. If this is the case, the no-start condition is often intermittent and you may even be able to jiggle the connectors located at the back of the intake manifold to make the problem go away temporarily (unless the connectors aren't clicked all the way in, in which case clicking them in should solve the connection issue because the problem is really that the sensors aren't fully plugged in). I believe there's a kit to replace the connectors and wiring for the reference sensors, which could solve a problem of poor connections.
There are a ton of other threads on here about reference sensor problems, so you can get more info from searching around, but hopefully this is a helpful start.
When you crank the engine, you should see the tach needle jump up to register the rpm (so it should bounce at least several hundred rpm, i.e. a noticeable amount). It sounds like you aren't getting that. My guess is the tiny bounce you see when turning the key off is just the tach losing power.
If they put new ref sensors in and there is no tach bounce on cranking, then I believe the problem could be one of 2 things:
1) The ref sensors aren't gapped properly from the flywheel. I believe Clark's Garage has the exact specs, but the tolerances for the distance between the sensor and the teeth of the trigger wheel are pretty tight.
2) The signal from the sensors isn't being transmitted to the DME because of a bad connection. If this is the case, the no-start condition is often intermittent and you may even be able to jiggle the connectors located at the back of the intake manifold to make the problem go away temporarily (unless the connectors aren't clicked all the way in, in which case clicking them in should solve the connection issue because the problem is really that the sensors aren't fully plugged in). I believe there's a kit to replace the connectors and wiring for the reference sensors, which could solve a problem of poor connections.
There are a ton of other threads on here about reference sensor problems, so you can get more info from searching around, but hopefully this is a helpful start.
03-22-2013, 10:44 AM
#63
Three Wheelin'
Thread Starter
Good news. The shop just realized the speed ref sensors were not clicked all the way in from previous diagnostics. The car is running perfectly now! What a relief.
03-22-2013, 12:38 PM
#65
Three Wheelin'
Thread Starter
Not sure. I'll swap the old DME back when i get the car back and see for myself. Doesn't hurt to have a spare too. Or I could attempt to return the new one. I'm just happy to have my car coming back after a month in the shop!
03-22-2013, 09:53 PM
#69
Rennlist Member
