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EFI Gurus, I need your help! EFI Trouble Diagnosis
- Thread starter luderchris
- Start date
Sounds like you probably lost spark, but visually check to make sure. After that you need to check to see if the coil is getting a ground pulse. The same wire you had the tach hooked to should pulse a ground signal while cranking.
chuzie
Bronco Guru
- Joined
- Jul 21, 2006
- Messages
- 2,701
Pull a wire at plug and see if it arcs to something metal while cranking. I shouldn't have to tell you not to hold it! Report back and we can go from there.
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luderchris
Bronco Guru
Ok. Checked for spark and nada. No spark.
Just picked up a new coil to try. Pep Boys said I can return the coil if it isn't the issue.
If the coil isn't the issue, what should I check on the distributor/TFI module?
Just picked up a new coil to try. Pep Boys said I can return the coil if it isn't the issue.
If the coil isn't the issue, what should I check on the distributor/TFI module?
chuzie
Bronco Guru
- Joined
- Jul 21, 2006
- Messages
- 2,701
If the new coil doesn't work run through the following below (courtesy of jrichker at stangnet).
No spark, possible failed items in order of their probability:
A.) MSD or Crane ignition box if so equipped
B.) PIP sensor in distributor. The PIP sensor supplies the timing pulse to trigger the TFI and injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed. See paragraph 5A – Using a noid light will tell if the PIP is working by flashing when the engine is cranking.
C.) TFI module: use a test light to check the TFI module. Place one lead of the test light on the red/green wire on the ignition coil connector and the other lead on the dark green/yellow wire on the ignition coil connector. If the TFI is working properly, the test light will flash when the engine is cranked using the ignition switch.
D.) Coil
E.) No EEC or computer power - EEC or computer relay failure
86-93 models only: EEC relay next to computer - look for 12 volts at the fuel injector red wires.
94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
Both 86-93 and 94-95 models: No 12 volts with the ignition switch in the run position on the fuel injector red wires. The relay has failed or there is no power coming from the ignition switch. Make sure that there is 12 volts on the red/green wire on the coil before replacing the relay.
F.) No EEC or computer power - fuse or fuse link failure
86-93 models only: Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid. Look for a 20 gauge blue fuse link connected to 2 black/orange 14 gauge wires.
94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire. No 12 volts, blown fuse link or faulty ignition switch. Remove the plastic from around the ignition switch and look for 12 volts on the red/green wire on the ignition switch with it in the Run position. No 12 volts and the ignition switch is faulty. If 12 volts is present in the Run position at the ignition switch but not at the coil, then the fuse or fuse link is blown.
Note: fuses or fuse links blow for a reason. Don’t replace either a fuse or fuse link with one with a larger rating than stock. Doing so invites an electrical fire.
Ignition fuse links may be replaced with an inline fuse holder and 5 amp fuse for troubleshooting purposes.
94-95 models only: Check inside fuse panel for fuse #18 blown – 20 amp fuse
H.) Missing or loose computer power ground. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness
I.) Computer.
J.) Bad or missing secondary power ground. It is located between the back of the intake manifold and the driver's side firewall. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges.
K.) Engine fires briefly, but dies immediately when the key is released to the Run position. Crank the engine & when it fires off, pull the small push on connector (red wire) off the starter relay (Looks like it is stuck on a screw). Hold the switch in the crank position: if it continues to run there is a problem with either the ignition switch or TFI module. Check for 12 volts at the red/green wire on the coil with the switch in the Run position. Good 12 volts, then replace the TFI. No 12 volts, replace the ignition switch.
No spark, possible failed items in order of their probability:
A.) MSD or Crane ignition box if so equipped
B.) PIP sensor in distributor. The PIP sensor supplies the timing pulse to trigger the TFI and injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed. See paragraph 5A – Using a noid light will tell if the PIP is working by flashing when the engine is cranking.
C.) TFI module: use a test light to check the TFI module. Place one lead of the test light on the red/green wire on the ignition coil connector and the other lead on the dark green/yellow wire on the ignition coil connector. If the TFI is working properly, the test light will flash when the engine is cranked using the ignition switch.
D.) Coil
E.) No EEC or computer power - EEC or computer relay failure
86-93 models only: EEC relay next to computer - look for 12 volts at the fuel injector red wires.
94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
Both 86-93 and 94-95 models: No 12 volts with the ignition switch in the run position on the fuel injector red wires. The relay has failed or there is no power coming from the ignition switch. Make sure that there is 12 volts on the red/green wire on the coil before replacing the relay.
F.) No EEC or computer power - fuse or fuse link failure
86-93 models only: Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid. Look for a 20 gauge blue fuse link connected to 2 black/orange 14 gauge wires.
94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire. No 12 volts, blown fuse link or faulty ignition switch. Remove the plastic from around the ignition switch and look for 12 volts on the red/green wire on the ignition switch with it in the Run position. No 12 volts and the ignition switch is faulty. If 12 volts is present in the Run position at the ignition switch but not at the coil, then the fuse or fuse link is blown.
Note: fuses or fuse links blow for a reason. Don’t replace either a fuse or fuse link with one with a larger rating than stock. Doing so invites an electrical fire.
Ignition fuse links may be replaced with an inline fuse holder and 5 amp fuse for troubleshooting purposes.
94-95 models only: Check inside fuse panel for fuse #18 blown – 20 amp fuse
H.) Missing or loose computer power ground. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness
I.) Computer.
J.) Bad or missing secondary power ground. It is located between the back of the intake manifold and the driver's side firewall. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges.
K.) Engine fires briefly, but dies immediately when the key is released to the Run position. Crank the engine & when it fires off, pull the small push on connector (red wire) off the starter relay (Looks like it is stuck on a screw). Hold the switch in the crank position: if it continues to run there is a problem with either the ignition switch or TFI module. Check for 12 volts at the red/green wire on the coil with the switch in the Run position. Good 12 volts, then replace the TFI. No 12 volts, replace the ignition switch.
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luderchris
Bronco Guru
Ok. Tried the new coil. Still won't start, but the new coil doesn't even get warm when we crank it over. The original coil got quite hot. Not sure why that would be.
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luderchris
Bronco Guru
No. Still no spark.
Just checked the TFI module from part C above, and the test light only dims, it does not flash when cranking over.
Just checked the TFI module from part C above, and the test light only dims, it does not flash when cranking over.
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luderchris
Bronco Guru
Plug wire. No spark.
rjlougee
Bronco Guru
- Joined
- Dec 26, 2001
- Messages
- 1,959
A stock '97 F250 would have a roller cam in it and the dizzy would be set up for an external TFI module. If you're running an A9x EEC, you either rewired in the external TFI module or swapped the dizzy to an earlier version integrated TFI dizzy. Which one?
1. If you did swap the dizzy, did you also swap the gear off the bottom? If not, and you may want to check this anyway, is the rotor still rotating as you crank the engine?
2. If not, and you wired in the remote TFI, I think there's a wiring issue there, which would also account for the hot coil.
3. Maybe some combination of the two.
HTH, Joe
1. If you did swap the dizzy, did you also swap the gear off the bottom? If not, and you may want to check this anyway, is the rotor still rotating as you crank the engine?
2. If not, and you wired in the remote TFI, I think there's a wiring issue there, which would also account for the hot coil.
3. Maybe some combination of the two.
HTH, Joe
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luderchris
Bronco Guru
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luderchris
Bronco Guru
BOOM!!! Replaced the TFI module and it started right up!
Thanks for all your help guys. I'll know later this week whether my stumble over 3000 RPMs is better, but my cold start issue (would stall out until warm) is fixed now too.
Thanks for all your help guys. I'll know later this week whether my stumble over 3000 RPMs is better, but my cold start issue (would stall out until warm) is fixed now too.
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luderchris
Bronco Guru
Haha. Hopefully I won't have too many, but I am sure it won't be my last.
Thanks again to you chuzie, and everyone else, for your input and help. Much appreciated!
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luderchris
Bronco Guru
Ok. Well now that I have the truck running, I'd like to get it running well! Not the case right now. Chuzie, you jinxed me!
It will idle, but erratically. I tried to drive it and it is bucking and popping and stumbling all over.
I ran the codes.
KOEO
31, 81, 82, 85, 84
KOER
The first problem is that it identified the engine as a 6 cylinder every time I ran the test (code 6). The rest if the codes were-
13, 31, 46 (I ran this a few times, and one time I got a 91)
I then did the cylinder balance test. The first time I ran it it gave me a 70, 10, 30. The second time it have me a 60.
Any help in figuring out wtf is going on is much appreciated! Thanks in advance guys.
It will idle, but erratically. I tried to drive it and it is bucking and popping and stumbling all over.
I ran the codes.
KOEO
31, 81, 82, 85, 84
KOER
The first problem is that it identified the engine as a 6 cylinder every time I ran the test (code 6). The rest if the codes were-
13, 31, 46 (I ran this a few times, and one time I got a 91)
I then did the cylinder balance test. The first time I ran it it gave me a 70, 10, 30. The second time it have me a 60.
Any help in figuring out wtf is going on is much appreciated! Thanks in advance guys.
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