desolateboosted
15+ Year Contributor
- 192
- 5
- Jan 20, 2005
-
Twin City,
Minnesota
Ok car is a 92 Talon AWD. This is a buddy's car thats just been through a rebuild.
Car tries to start but dies immediately. It will catch, but dies immediately. I've been trying to diagnose this with everything (swapping out parts, de-modding, tracing some wires, checking fuses, relays) only to come to a dead end. Right now car is demodified to stock like specs (450cc injectors, stock cams).
Things that have been swapped out:
----------------------------------------
-2 CAS's (confirmed working from running car)
-2 Coil Packs (confirmed working from running car)
-3 sets of injectors (confirmed working from running car)
-2 ECUs, one with dsmlink (I have two more can also try later)
-Transistor pack (confirmed working from running car)
-MPI/fuel relay inside the car I believe (confirmed working from running car)
-Injector Resistor Pack (confirmed working from running car)
-Swapped out cams (De-modded from BC288s to stock)
-Swapped out Infinity Q45 throttlebody to stock (rewired stock TPS correctly)
-Redid Timing Belt 3x
-Getting Fuel pressure (can see on gauge)
-Getting Spark on all four
-Compression test yields around ~120 (New motor hasn't had a chance to idle or drive)
-checked for intake manifold leaks, no open ended hoses or ports. All looks sealed up.
Here's where I've narrowed the problem down to. If I reset the key all the way off then turn it back to the "on" position. Then take out the CAS and spin it by hand I can hear all the injectors tick for about 3-4 revolutions then completely shut off. If I continue rotating the CAS, everything becomes silent and the only thing you can hear is the coil pack sending pulses of spark. To make sure it was really the injectors ticking I hooked up a spare injector to each of the injector plugs and verified it.
Once it you get past a few rotations of turning the CAS, the injectors shut off. I can sort of "reset" the test by rotating the key in the ignition back all the way off then back to the "on" position. Once that occurs re-spinning the CAS will get the injectors to pulse again for a few short rotations before shutting off again.
I wanted to double check that behavior so I tried the same test on a running dsm to find out that the injectors will not stop pulsing until you stop rotating the CAS. Obviously that's how it should be!
I believe I have all the requirements to get this car running, but why do the injectors stop pusling after a few rotations of the CAS?
(It also explains why the car catches when trying to start it, but never stays running.)
Additionally on the exhaust manifold, only two runners get warm (runners 2 & 3) if the car catches and tries to run. ??! I'm not too worried about that right now since the car won't even stay running, but it's something I wanted to note. It probably has something to do with the injectors shutting off?
I believe if the ECU sees too high of a TPS position it will shut off the injectors to protect the engine? However, the stock throttlebody I swapped in is confirmed working from a running dsm.
One more thing to note is if the coolant temp sensor somehow is not functioning or connected the car will not run? How much will that be a factor in this?
Is there something I'm missing? Something I haven't checked?
This car is all decked out ready to go. Built motor, built tranny, twindisk, twin walbro, cams, JMF drag maniold, GT4088!
Help get this running!
Car tries to start but dies immediately. It will catch, but dies immediately. I've been trying to diagnose this with everything (swapping out parts, de-modding, tracing some wires, checking fuses, relays) only to come to a dead end. Right now car is demodified to stock like specs (450cc injectors, stock cams).
Things that have been swapped out:
----------------------------------------
-2 CAS's (confirmed working from running car)
-2 Coil Packs (confirmed working from running car)
-3 sets of injectors (confirmed working from running car)
-2 ECUs, one with dsmlink (I have two more can also try later)
-Transistor pack (confirmed working from running car)
-MPI/fuel relay inside the car I believe (confirmed working from running car)
-Injector Resistor Pack (confirmed working from running car)
-Swapped out cams (De-modded from BC288s to stock)
-Swapped out Infinity Q45 throttlebody to stock (rewired stock TPS correctly)
-Redid Timing Belt 3x
-Getting Fuel pressure (can see on gauge)
-Getting Spark on all four
-Compression test yields around ~120 (New motor hasn't had a chance to idle or drive)
-checked for intake manifold leaks, no open ended hoses or ports. All looks sealed up.
Here's where I've narrowed the problem down to. If I reset the key all the way off then turn it back to the "on" position. Then take out the CAS and spin it by hand I can hear all the injectors tick for about 3-4 revolutions then completely shut off. If I continue rotating the CAS, everything becomes silent and the only thing you can hear is the coil pack sending pulses of spark. To make sure it was really the injectors ticking I hooked up a spare injector to each of the injector plugs and verified it.
Once it you get past a few rotations of turning the CAS, the injectors shut off. I can sort of "reset" the test by rotating the key in the ignition back all the way off then back to the "on" position. Once that occurs re-spinning the CAS will get the injectors to pulse again for a few short rotations before shutting off again.
I wanted to double check that behavior so I tried the same test on a running dsm to find out that the injectors will not stop pulsing until you stop rotating the CAS. Obviously that's how it should be!
I believe I have all the requirements to get this car running, but why do the injectors stop pusling after a few rotations of the CAS?
(It also explains why the car catches when trying to start it, but never stays running.)
Additionally on the exhaust manifold, only two runners get warm (runners 2 & 3) if the car catches and tries to run. ??! I'm not too worried about that right now since the car won't even stay running, but it's something I wanted to note. It probably has something to do with the injectors shutting off?
I believe if the ECU sees too high of a TPS position it will shut off the injectors to protect the engine? However, the stock throttlebody I swapped in is confirmed working from a running dsm.
One more thing to note is if the coolant temp sensor somehow is not functioning or connected the car will not run? How much will that be a factor in this?
Is there something I'm missing? Something I haven't checked?
This car is all decked out ready to go. Built motor, built tranny, twindisk, twin walbro, cams, JMF drag maniold, GT4088!
Help get this running!
