Pirate 4x4 banner

1 - 13 of 13 Posts

·
Registered
Joined
·
779 Posts
Discussion Starter #1
Need help from the guru's on this one.
Basically the engine will no longer run - injectors are staying open, flooding the intake and killing the motor.
Truck set up - 84 4x4 w/ 87 EFI system, stand alone harness, no EGR or any SMOG equipment. Do have an O2 sensor. Fuel pump is a Bosche, all lines fuel tight.
TPS, AFM are all good and correcly adjusted. Inlet ducting is air tight. Timing is correct, cam 2' ahead, valve lash correct.
Engine ran good during a 30 minute break in run. Started several time after, ran and idled fine. Took it out for a run and it hauled ass. About a mile later the 5 amp fuse I had running the injector resistor blew (too small, needed to be a 10a) Swapped in a 10a fuse and it was running just fine again. Then about 3 miles later it just died.
*******What we have double & trippled checked:********
First thing I did was pull the codes - it was a 1 - system normal.
TPS - operatin & adjustment
AFM- operation & readings
All wiring connections, all grounds
Swapped in an other coil, ignitor, AFM, cap, rotor, wires, plugs.
Resistor, all relays, all fuses, fuel pump, distributor, injector resistance, etc.
Pulled the upper intake, found the lower intake flooded w/ fuel. Swapped in some known good injectors. And yes these are the correct injuectors.
Cleared all codes and rechecked.
********
What is occuring is that the injectors are not pulsing, but instead staying open and dumping fuel. If I disconnect the resistor they will close. Even with a seperate distributer wired in and the shaft turned, they still will not pulse.
Thought it was an ECU, but every time I check it there is only a 1 code. Doubt it is a wiring issue, and it did run just fine.
So what else am is missing here?????
 

·
Registered
Joined
·
4,463 Posts
BlueCoyote3 said:
Need help from the guru's on this one.
Basically the engine will no longer run - injectors are staying open, flooding the intake and killing the motor.
Truck set up - 84 4x4 w/ 87 EFI system, stand alone harness, no EGR or any SMOG equipment. Do have an O2 sensor. Fuel pump is a Bosche, all lines fuel tight.
TPS, AFM are all good and correcly adjusted. Inlet ducting is air tight. Timing is correct, cam 2' ahead, valve lash correct.
Engine ran good during a 30 minute break in run. Started several time after, ran and idled fine. Took it out for a run and it hauled ass. About a mile later the 5 amp fuse I had running the injector resistor blew (too small, needed to be a 10a) Swapped in a 10a fuse and it was running just fine again. Then about 3 miles later it just died.
*******What we have double & trippled checked:********
First thing I did was pull the codes - it was a 1 - system normal.
TPS - operatin & adjustment
AFM- operation & readings
All wiring connections, all grounds
Swapped in an other coil, ignitor, AFM, cap, rotor, wires, plugs.
Resistor, all relays, all fuses, fuel pump, distributor, injector resistance, etc.
Pulled the upper intake, found the lower intake flooded w/ fuel. Swapped in some known good injectors. And yes these are the correct injuectors.
Cleared all codes and rechecked.
********
What is occuring is that the injectors are not pulsing, but instead staying open and dumping fuel. If I disconnect the resistor they will close. Even with a seperate distributer wired in and the shaft turned, they still will not pulse.
Thought it was an ECU, but every time I check it there is only a 1 code. Doubt it is a wiring issue, and it did run just fine.
So what else am is missing here?????
if I ahd to bet money, I'd say the resistor or the ecu is to blame.
 

·
Registered
Joined
·
261 Posts
the ecu grounds the injectors to fire them. check for a short to ground between the injectors and the ecu. otherwise try a different ecu
wiring diagram split in half for clarity as the emanual wont allow to save as a pic, i had to screenshot it large for clarity.



print them out and tape together.
 

·
Registered
Joined
·
779 Posts
Discussion Starter #5
WR250 - thanks for the diagram. Bit easier to read the the book versoin, but all the wireing is correct per this diagram as well. PM me if you have any spare ECU's - I am also in the Hi Dez

4RnrRick - Stand alone harness - this is a 90 harness mated to an 87 motor that is installed in an 84 truck. Since this is a race vehicle, and does not have 1 single bit of OEM wiring. I spent hours on POR researching, reviewing diagrams, posts, etc along with hours mating the harness to the truck. Same process when installing EFI into a buggy. All wires were rung out prior to connection, all sensor thoroghly checked and adjusted. It has over an hour run time prior to the test drive - ran great, only a 12 code (KNOCK) due to no connectoin.

It appears the ECU is keeping the injuectors grounded, not letting them pulse, yet the ECU gives a 1 code (system normal).
 

·
Registered
Joined
·
4,463 Posts
you do know that the 94 injectrs/resistor/ecu MUST work together. you can't mix/match with the 87 stuff. they work off of different impedences
 

·
Registered
Joined
·
535 Posts
it's really only one of 3 things.

Bad ECU
bad injector resistor
bad wiring.

my guess is its the ECU, even though it checks fine, it doesn't check everything, and it's not a real thourogh test.

this is about where you get the multimeter out and trace it down.

unplug all 4 injector connections, and test the 2 sides on 1 of the plugs. one lead (the blue or yellow) should be +12V when the ignition is on. the other lead(white, or white/red?) will probably be grounded out. it shouldn't be.

if you get ground at that lead, then unplug the ECU entirely, and then check at that lead. if your ground went away, then it's the ECU. if the ground is still there, then unplug the injector resistor, and check both wires going into the injector resistor to find out where the ground is.
 

·
Registered
Joined
·
535 Posts
btw, i've seen this happen. in my case, it was a error on my part, when re-assembling an ECU after taking it apart to paint it, i forgot a piece of plastic that separated a transistor from the body ground, causing the whole case to ground out, and causing the injectors to stay all the way open.

the other time i saw this was with an SDS setup, a ground lead inside the ECU was shorted out, also causing the injectors to stay open.
 

·
Registered
Joined
·
2,062 Posts
NAPA has a cool tester called a logic probe. You have to order it. If the engine runs at all, start it up and test the two wires going into the injector. One should show a red light and the other should show blinking red and green. If one is red and the other is green and you've checked your wiring then you have an ecu problem. One of the chips that drives the injectors is shorted out. There are a few of causes for this: Either you are using too low of an impedance injector, you have a short in the wiring somewhere, or the capacitors inside your ecu can leak and cause shorts. I can tell you step by step how to test your ecu caps. Just email me. Good luck.
 

·
Registered
Joined
·
398 Posts
Do all 4 injectors stay open, or is it just one or two injectors?

Exactly which injectors remain open?

If you unplug the wiring harness to the injectors that stay open, do they close?

=======================================

Your ECM provides the ground for each pair of injectors when it decides to turn them on. You may have a short to ground on the wire between the fuel injector and ECM. That would cause the fuel injectors to stay open.

Try this:

1. Disconnect the ECM
2. Clamp the aligator clip of a test light to battery positive
3. Disconnect your fuel injector harness wiring
4. Use your test light to probe the white wire on the #2/#4 injector
5. Use your test light to probe the white wire with the red strip on the #1/#3 injector
6. If the test light turns on, you have a short to ground

(ps. don't forget to test the test light is working properly)
 

·
Registered
Joined
·
779 Posts
Discussion Starter #12 (Edited)
Found The Problem

penguinofdoom said:
btw, i've seen this happen. in my case, it was a error on my part, when re-assembling an ECU after taking it apart to paint it, i forgot a piece of plastic that separated a transistor from the body ground, causing the whole case to ground out, and causing the injectors to stay all the way open.

the other time i saw this was with an SDS setup, a ground lead inside the ECU was shorted out, also causing the injectors to stay open.
This was just about what happened. :D

Found the problem this afternoow after about 2 hours of quality DVM time. Where the #10 terminal wire was soldered to the PC board inside the ECU, the tail was a bit long. It was close to or touching the plastic, and arced through to the metal case, resulting in a direct ground. Put it back together with 3 rows of foam tape to prevent it from re-occuring. Truck is running fine again with no codes.

Suggest that anyone running a Toyota ECU do the foam tape mod to the ECU. The forces of hi speed dez running, dropping hard off a rock, etc, can cause the PC board or the cover to flex, causeing this problem. In my case the truck died after flying some 2' whoops.
 

·
Registered
Joined
·
535 Posts
awesome, glad you found it, i heard you had a race coming up too.

good luck in the race! show 'em the power of the 22re. :D
 
1 - 13 of 13 Posts
Top