'84 stalls right after start....
10-17-2009, 01:50 AM
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'84 stalls right after start....
so the $250 928 automatic with 4.7 & lh jet brian picked up sure it living up to its value. ive searched thr forum and found nothing like this.
i got the engine to run after wiring in a new ignition switch to the hacked colum, but she wouldnt run well or accelerate with the throttle, just bog down, also the AFM had to but propped out a bit for it to idle. later it wouldnt start at all, it seems the timing belt was so loose that it jumped timing so all this time the engine had just been running on 4 cylinders thus not making a steady suction to allow the AFM to work.
after i replaced the failed timing belt tensioner the compression was back to normal. so now the car will start but only run for a second or two, then sometimes it can be started right back up for just a second and other times it wont. how ever if you manually feed it a steady diet of brake clean it will keep running, so that means the injectors are not firing, ignition is good. manually proping the AFM flapper open does not help. also i found it seems the coldstart injector is the only injector that is sending fuel at all. unpluging it results in an engine that will never start without fuel manually dumped down the intake.
so im suspecting the ECU is not working after cranking, i have no blown fuses, i have a solid 12v on fuse 12-16, the fuel pump relay is clicking and i can hear it run before cranking, during and after. i have a constant 35psi of puel pressure. is there good place i can jump 12v to power the injectors/computer constantly to narrow down my problem? thanks
i got the engine to run after wiring in a new ignition switch to the hacked colum, but she wouldnt run well or accelerate with the throttle, just bog down, also the AFM had to but propped out a bit for it to idle. later it wouldnt start at all, it seems the timing belt was so loose that it jumped timing so all this time the engine had just been running on 4 cylinders thus not making a steady suction to allow the AFM to work.
after i replaced the failed timing belt tensioner the compression was back to normal. so now the car will start but only run for a second or two, then sometimes it can be started right back up for just a second and other times it wont. how ever if you manually feed it a steady diet of brake clean it will keep running, so that means the injectors are not firing, ignition is good. manually proping the AFM flapper open does not help. also i found it seems the coldstart injector is the only injector that is sending fuel at all. unpluging it results in an engine that will never start without fuel manually dumped down the intake.
so im suspecting the ECU is not working after cranking, i have no blown fuses, i have a solid 12v on fuse 12-16, the fuel pump relay is clicking and i can hear it run before cranking, during and after. i have a constant 35psi of puel pressure. is there good place i can jump 12v to power the injectors/computer constantly to narrow down my problem? thanks
10-17-2009, 06:01 AM
#2
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Yes. Remove the fuel injection relay. Jumper with a three-ended wire or two jumper wires.
30 to 87 to 87a
This will bypass the fuel injection relay. Relays can click and not make contact inside. The electromagnet snaps the rocker points into postion, but points are dirty or burned like in an old car distributor and therefore make partial or intermittent or no electrical contact. In some cases voltages then are reduced and if a relay feeds another relay various intermittency problems precipitate.
ECUs on these don't seem to fail very often by everybody's account here. Be sure that the little branch hot wire at the battery + post is clean, because it feeds the ecu.
The other thing that will decomission all injectors is a single short anywhere in the injector wires that lead to the injectors. They batch fire simultaneously and are on the same circuit. They sometimes short in the little wires leading to one of the injectors, at the plug. I bought a Lisle noid light that can be plugged into one of the injector leads to ascertain if its a problem.
There are a couple hard-to-reach ground wires for the injector harness located under the passenger side cam cover, also, that need to be clean for the system to work.
Another thing that makes them run terrible or not at all is a bad tempII sensor. They go bad.
Another reason for intermittency is bad grounds throughout the car. Be sure they are clean. Takes a few hours but is very important.
I've woken up several cars that were in deep slumber. These days I do grounds and CE panel cleaning, fuse and relay replace, before even cranking them. Regarding the color coded plugs at the base of the CE panel, I have learned to take a little pick or screwdriver and back-probe/press every single wire connection into place after removal, especially in the fuel injection plug area, plug X, I think. (This week that has been identified as the remaining run/no run problem with my 85 --- non-seated connectors within non-seated plugs. Doubt its your issue, but check)
Also, use the key to unlock both doors and the hatch. That way as you troubleshoot you know the start-interrupt feature of the alarm system is not an issue.
Did you post pictures of the car? Get a membership if needed, but its a whole lot easier and more fun to see the pictures of what we are working on.
I love stories of rescuing free 928'. Glad you are getting it running. Lots of them are parked due to these frustrations, sometimes after some trashing and disrespect, but they are solid runners if touched just right.
30 to 87 to 87a
This will bypass the fuel injection relay. Relays can click and not make contact inside. The electromagnet snaps the rocker points into postion, but points are dirty or burned like in an old car distributor and therefore make partial or intermittent or no electrical contact. In some cases voltages then are reduced and if a relay feeds another relay various intermittency problems precipitate.
ECUs on these don't seem to fail very often by everybody's account here. Be sure that the little branch hot wire at the battery + post is clean, because it feeds the ecu.
The other thing that will decomission all injectors is a single short anywhere in the injector wires that lead to the injectors. They batch fire simultaneously and are on the same circuit. They sometimes short in the little wires leading to one of the injectors, at the plug. I bought a Lisle noid light that can be plugged into one of the injector leads to ascertain if its a problem.
There are a couple hard-to-reach ground wires for the injector harness located under the passenger side cam cover, also, that need to be clean for the system to work.
Another thing that makes them run terrible or not at all is a bad tempII sensor. They go bad.
Another reason for intermittency is bad grounds throughout the car. Be sure they are clean. Takes a few hours but is very important.
I've woken up several cars that were in deep slumber. These days I do grounds and CE panel cleaning, fuse and relay replace, before even cranking them. Regarding the color coded plugs at the base of the CE panel, I have learned to take a little pick or screwdriver and back-probe/press every single wire connection into place after removal, especially in the fuel injection plug area, plug X, I think. (This week that has been identified as the remaining run/no run problem with my 85 --- non-seated connectors within non-seated plugs. Doubt its your issue, but check)
Also, use the key to unlock both doors and the hatch. That way as you troubleshoot you know the start-interrupt feature of the alarm system is not an issue.
Did you post pictures of the car? Get a membership if needed, but its a whole lot easier and more fun to see the pictures of what we are working on.
I love stories of rescuing free 928'. Glad you are getting it running. Lots of them are parked due to these frustrations, sometimes after some trashing and disrespect, but they are solid runners if touched just right.
Last edited by Landseer; 10-17-2009 at 06:22 AM.
10-17-2009, 06:10 AM
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thanks ill try those ideas, this car is a vandalism victim, i have no keys at all, weve been stripping the interior (its becoming a race car) maybe an iterior ground is to blame. ill see
10-17-2009, 06:24 AM
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Yes. I have to go look at my panel to see what wires we finally jumped.
On mine, we removed the alarm module located up inside the dash pad behind / above the glove compartment. But also jumpered a pair of wires on the Z plug.
Interior grounds are above CE panel on firewall, also, above the pedals, behind the pod, for instruments.
On mine, we removed the alarm module located up inside the dash pad behind / above the glove compartment. But also jumpered a pair of wires on the Z plug.
Interior grounds are above CE panel on firewall, also, above the pedals, behind the pod, for instruments.
10-17-2009, 06:33 AM
#6
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Z4 to Z6 with a jumper on the panel (wire with two female connectors), shown by Xs below.
O X
O O
O X
Z plug is the short one. It is located out-of-sequence alphabetically on the panel. Look for three heavy read wires connected at the lower mid point of the panel with single white connectors. Z plug is the short plug located beneath them. The plug itself can be left disconnected. Pull the alarm module also. Leave the alarm relay.
O X
O O
O X
Z plug is the short one. It is located out-of-sequence alphabetically on the panel. Look for three heavy read wires connected at the lower mid point of the panel with single white connectors. Z plug is the short plug located beneath them. The plug itself can be left disconnected. Pull the alarm module also. Leave the alarm relay.
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10-17-2009, 10:58 PM
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ok i got her going, it was the 10 ga wire next to the battery + terminal, i cant beleive thts where the power input is, why not off the starter or alternator? so it doesnt run perfectly, not that im was expecting that, but she does drive! ill get the video up
10-17-2009, 11:20 PM
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has a bit of studder but that may be to low fuel pressure and general lack of running for years
http://s31.photobucket.com/albums/c3...t=CIMG2826.flv
http://s31.photobucket.com/albums/c3...t=CIMG2826.flv
10-18-2009, 12:05 AM
#11
Race Car
L-Jet uses a Inj for cold start, it will start but will not run if either of the following are having issues..
Check your green wire.
Use a Noid lamp on one of the injectors see if it flashes.
Check your green wire.
Use a Noid lamp on one of the injectors see if it flashes.
10-18-2009, 08:13 AM
#13
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Nice work. Nice. Car sounds pretty good in the video clip. Looks solid. You could refurb that interior if you wanted to drive it rather than race it.
The LH Jet cars use a magnetic position sensor on a toothed ring near the flywheel.
The L Jet cars like yours and mine don't.
They use a pickup inside the distributor.
The signal is run on a coaxial cable from the base of the distributor to the right fender where there is a module to process/distribute the position signal.
The coaxial cable is in a green sheath, hence "green wire"
Its ends are proprietary shape / uncommon and are often brittle.
The wire is sometimes damaged because it runs right across the top front edge of the block.
Some folks have experienced problems with it.
Also, it is reported by Jim Bailey that a batch of incorrectly assembled green wires were shipped a few years ago, but the result I think is a complete non=run situation.
My guess is that your wire is ok now that the car is running. Maybe Tampa knows of failure mode where it can run rough with a bad green wire, I don't know.
The LH Jet cars use a magnetic position sensor on a toothed ring near the flywheel.
The L Jet cars like yours and mine don't.
They use a pickup inside the distributor.
The signal is run on a coaxial cable from the base of the distributor to the right fender where there is a module to process/distribute the position signal.
The coaxial cable is in a green sheath, hence "green wire"
Its ends are proprietary shape / uncommon and are often brittle.
The wire is sometimes damaged because it runs right across the top front edge of the block.
Some folks have experienced problems with it.
Also, it is reported by Jim Bailey that a batch of incorrectly assembled green wires were shipped a few years ago, but the result I think is a complete non=run situation.
My guess is that your wire is ok now that the car is running. Maybe Tampa knows of failure mode where it can run rough with a bad green wire, I don't know.
10-18-2009, 09:36 AM
#14
Race Car
On my 82/Gts the injector style connector on the green wire was corroded and was causing intermittent issues. But as you know its not just one thing with age its a cumulation of several things that cause problems. The WSM will walk you through the trouble shooting step by step but you actually need to read it first. Once you know what checks out then search for how to repair what doesn't.
Back to basics
Can be rented or purchased at local auto parts store.
Check you cam timing, crank at 0 cams notch lined up with line (free just look)
Spark check with timing lamp does it flash
Inj firing check with noid lamp does it flash
Fuel check with FP gage 32-39 Lbs
Green wire you can ohm it out for continuity or shorts.
Vacuum leak, after you do the testing for the main things look for lines or boots torn or disconnected, especially the intake boot.
Back to basics
Can be rented or purchased at local auto parts store.
Check you cam timing, crank at 0 cams notch lined up with line (free just look)
Spark check with timing lamp does it flash
Inj firing check with noid lamp does it flash
Fuel check with FP gage 32-39 Lbs
Green wire you can ohm it out for continuity or shorts.
Vacuum leak, after you do the testing for the main things look for lines or boots torn or disconnected, especially the intake boot.
10-18-2009, 11:22 PM
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yeah the wiring is decent in most areas, needs some cleaning. this car isnt worth repairing wht interior, we have much more fun plans in mind for it. anyone want some decent black interior pieces?