Injector/Fuel issues (Stock harness issue)
11-02-04, 09:46 PM
#1
Injector/Fuel issues (Stock harness issue)
Preface:
Running an N332 rtek 1.7 ECU
720 CC secondaries
no emissions
walbro fuel pump
ALL 87 wiring harness
Two weeks ago I finally finished my project (that had been sitting for 7 months) and went to start it. Zero fuel pressure (with a 1 year old walbro). Replaced walbro. Good Fuel pressure now. Now the injectors are not firing. The car has 115 compression on front and rear rotors. It was rebuilt by kevin landers 5000 miles ago. Plugs are bone dry. Will injectors fail if they are run with 0 fuel pressure? My next step is to pull the injectors and test the ohms on 'em. I just can't understand why this is happening. The only other thing that stands out, is that I've got a cream colored wire with red stripes on it with a (non stock) spade connector on it
It's running off the same wire that runs to the ground on the top of the manifold. I don't remember seeing this on my other harness (I replaced the harness with a better looking one since the old one melted from the turbo heat.)
WTF.
Running an N332 rtek 1.7 ECU
720 CC secondaries
no emissions
walbro fuel pump
ALL 87 wiring harness
Two weeks ago I finally finished my project (that had been sitting for 7 months) and went to start it. Zero fuel pressure (with a 1 year old walbro). Replaced walbro. Good Fuel pressure now. Now the injectors are not firing. The car has 115 compression on front and rear rotors. It was rebuilt by kevin landers 5000 miles ago. Plugs are bone dry. Will injectors fail if they are run with 0 fuel pressure? My next step is to pull the injectors and test the ohms on 'em. I just can't understand why this is happening. The only other thing that stands out, is that I've got a cream colored wire with red stripes on it with a (non stock) spade connector on it
It's running off the same wire that runs to the ground on the top of the manifold. I don't remember seeing this on my other harness (I replaced the harness with a better looking one since the old one melted from the turbo heat.)WTF.
11-02-04, 10:30 PM
#2
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Check and see if they are getting a signal to turn on before suspecting the injectors.
Injectors can stick shut if left sitting for a time, especially if allowed to dry out or if moisture is present in the fuel.
I have had to spent an hour or more getting some of them working again that were stuck, and even then some didn't pull thru.
Good luck,
Gordon
WitchHunter Performance
Fuel injector cleaning & flow testing service
Injectors can stick shut if left sitting for a time, especially if allowed to dry out or if moisture is present in the fuel.
I have had to spent an hour or more getting some of them working again that were stuck, and even then some didn't pull thru.
Good luck,
Gordon
WitchHunter Performance
Fuel injector cleaning & flow testing service
11-02-04, 10:33 PM
#3
Originally Posted by switch
Check and see if they are getting a signal to turn on before suspecting the injectors.
Injectors can stick shut if left sitting for a time, especially if allowed to dry out or if moisture is present in the fuel.
I have had to spent an hour or more getting some of them working again that were stuck, and even then some didn't pull thru.
Good luck,
Gordon
WitchHunter Performance
Fuel injector cleaning & flow testing service
Injectors can stick shut if left sitting for a time, especially if allowed to dry out or if moisture is present in the fuel.
I have had to spent an hour or more getting some of them working again that were stuck, and even then some didn't pull thru.
Good luck,
Gordon
WitchHunter Performance
Fuel injector cleaning & flow testing service
11-03-04, 10:07 AM
#5
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No, that just tests the coils. The only way to test them is to wire them into the fuel rail so they don't pop out under pressure, jumper the fuel pump relay (yellow two pin connector), turn the ignition to on and then pulse power into two prongs on the inject. When it gets power it should spray fuel. Don't give the injector power for to long might burn the coil only quick bursts.
Last edited by Kingofl337; 11-03-04 at 10:20 AM.
11-04-04, 07:51 PM
#6
OK, verified that the injectors are working, they are the correct (2ohm) impedence. Hooked up power and they were clickin and passing fluid. I am sure the problem resides in the ECU or wiring harness. Is it possible this could be caused by a bad CAS as well? Is there anything else that the ECU uses as input to fire the injectors that it may not be getting a signal from?
I also tested the fuel relay, and solenoid resistor, both were within spec.
I also tested the fuel relay, and solenoid resistor, both were within spec.
Last edited by F1blueRx7; 11-04-04 at 07:54 PM.
11-04-04, 08:50 PM
#7
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At this point, to verify the harness and CAS inputs, you might as well get down to the ECU and start checking voltages. Should have battery voltage (12) at each injector "input" to the ECU with key on (ECU plugs on, also). The voltage should drop a bit while cranking, though good luck on trying to decipher whether the voltage is falling due to the starter draw, or the injectors actually firing...Needless to say, if one is falling much more than another, the one not falling as much (or at all) may be bad...This scenario could be due to a bad ECU, also...If both don't fall at all, check that rear rotor housing ground (resistance from the ECU pins, if you wish).
As for the CAS, you can either remove the plug (big one), and read the two coil circuits with a meter for resistance (should be around 150 ohms each circuit), or check the inputs for voltage (probably a little less than 1v) while cranking (plug ON)...
As for the CAS, you can either remove the plug (big one), and read the two coil circuits with a meter for resistance (should be around 150 ohms each circuit), or check the inputs for voltage (probably a little less than 1v) while cranking (plug ON)...
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11-04-04, 09:48 PM
#9
Originally Posted by WAYNE88N/A
At this point, to verify the harness and CAS inputs, you might as well get down to the ECU and start checking voltages. Should have battery voltage (12) at each injector "input" to the ECU with key on (ECU plugs on, also). The voltage should drop a bit while cranking, though good luck on trying to decipher whether the voltage is falling due to the starter draw, or the injectors actually firing...Needless to say, if one is falling much more than another, the one not falling as much (or at all) may be bad...This scenario could be due to a bad ECU, also...If both don't fall at all, check that rear rotor housing ground (resistance from the ECU pins, if you wish).
As for the CAS, you can either remove the plug (big one), and read the two coil circuits with a meter for resistance (should be around 150 ohms each circuit), or check the inputs for voltage (probably a little less than 1v) while cranking (plug ON)...
As for the CAS, you can either remove the plug (big one), and read the two coil circuits with a meter for resistance (should be around 150 ohms each circuit), or check the inputs for voltage (probably a little less than 1v) while cranking (plug ON)...
here is my diagram... just tell me I've got it right...
THANKS WAYNE! you rock.
11-04-04, 10:01 PM
#10
Lives on the Forum
Hey, that's kinda cool, I've never used the harness diagrams like that before. Just remember that the plugs on the harness sides might be mirror-imaged when looking at the backs of them while installed on the ECU. Of course, if you verify wire colors before you poke, you'll be OK. And, you might find it easier to use a small piece of hard wire, like a paper clip, instead of the actual meter lead when backprobing the ECU with the positive lead...And if you're doing all of this by yourself, having clips to hold the ground on/wire in/etc. will help immensely...
11-05-04, 01:35 AM
#11
Holy **** I AM AN IDIOT. I forgot the ECU case WAS the ECU ground. I had it unbolted going through testing everything. Henrik (the pocketlogger guy that does the Rtek7 upgrades) Pointed this out to me. I'm going to replace everything and check and see if this was the issue. Hours of pouring over FSM, checking resitances, conspiracy theories and it boils down to this. Man I feel stupid.
11-05-04, 03:03 AM
#12
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Sorry, but the ECU case is a ground for ...nothing. You can put the ECU on a piece of rubber and the thing will work just plenty good fine and never miss a tick. Right now I'm driving my 87 turboii arond with it not bolted to anything. Just sort of hanging around......like a hanging chad. (election season humor).
11-05-04, 09:16 AM
#14
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Perhaps a solder joint that is slightly broken on the circuit board and when the ECU is bolted down the break in the solder joint closes together???
Maybe when you get it bolted down and running right you can press down on the ECU with you hand to see if the engine starts to sputter or whatever the bad symptoms are. It sounds like a bad solder joint. Just guessing. Don't know.
Maybe when you get it bolted down and running right you can press down on the ECU with you hand to see if the engine starts to sputter or whatever the bad symptoms are. It sounds like a bad solder joint. Just guessing. Don't know.
11-05-04, 03:47 PM
#15
Ok Bolted the ECU down, Still same issue. Measured voltage at the ECU on the primary injectors is 12VDC, at the injector itself .... a slightly different story... If I ground the black wire of the multimeter to the bell housing, I get good voltage, If I test the two wires together I get some really wierd fluctuating results, this is with the key in the ON position. Should I just reground the B/Y Wires right to a solid ground on the chassis? Also, Where can I find good injector grommets to replace the stock ones? I got some Pepboys ones and they do not seal correctly and it's leaking a small amount of fuel.
I also checked the resistance at the CAS, it was 153 ohms which is in spec.
I also checked the resistance at the CAS, it was 153 ohms which is in spec.
11-05-04, 04:42 PM
#16
Originally Posted by f1blueRx7
Ok Bolted the ECU down, Still same issue. Measured voltage at the ECU on the primary injectors is 12VDC, at the injector itself .... a slightly different story... If I ground the black wire of the multimeter to the bell housing, I get good voltage, If I test the two wires together I get some really wierd fluctuating results, this is with the key in the ON position. Should I just reground the B/Y Wires right to a solid ground on the chassis? Also, Where can I find good injector grommets to replace the stock ones? I got some Pepboys ones and they do not seal correctly and it's leaking a small amount of fuel.
I also checked the resistance at the CAS, it was 153 ohms which is in spec.
I also checked the resistance at the CAS, it was 153 ohms which is in spec.
This is kind of strange because when you run from the cas, through the front harness, to the emissions harness, and RIGHT to the injector. Bypassing the ECU. All the ECU is doing is Providing 12v and the cas signal from the front harness is making the link. If you look at the E.G.I Control unit plugs in the diagram. There are no B/Y wires.
Can anyone tell me where the B/Y wires are getting their signal from so I can run new wires to that point and verify this is the issue?
In the mean time I'm going to radioshack and building an LED with a resistor to simulate the injector firing. (thanks to swivel for this advice)
11-05-04, 11:02 PM
#18
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The black/yellow wire supplies 12v to the injecotr coils.
The ECU makes the injectors pulse by applying and removing a ground on the other wire to the injectors. It does this on/off in milliseconds.
The CAS wires go from the cas to the ECU. The ECU uses that cas signal to pulse the injectors by putting a ground on the injectors.
So? What's the problem?
The ECU makes the injectors pulse by applying and removing a ground on the other wire to the injectors. It does this on/off in milliseconds.
The CAS wires go from the cas to the ECU. The ECU uses that cas signal to pulse the injectors by putting a ground on the injectors.
So? What's the problem?
11-06-04, 06:55 AM
#19
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Have you tried swapping in the stock E-Prom in the ECU? I would imagine you socketed your ECU when you changed chips?
To answer your question with the picture. You can do it but you would need a resistor to get the impediance back up for the ECU. You probably would want to cut the wire on both ends and splice the wire in as a replacement. You should really try and find another ECU to test with before you go crazy.
To answer your question with the picture. You can do it but you would need a resistor to get the impediance back up for the ECU. You probably would want to cut the wire on both ends and splice the wire in as a replacement. You should really try and find another ECU to test with before you go crazy.
Last edited by Kingofl337; 11-06-04 at 06:59 AM.
11-06-04, 08:10 AM
#20
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Originally Posted by f1blueRx7
A picture is worth a couple words...
And, do you now know how the injectors work???? And that you'd NEVER ground the black/yellow wire any more than you'd ground the positve wire on your battery? Say YES.
11-06-04, 10:49 AM
#21
Originally Posted by HAILERS
Something is screwy here. You said the injectors are 2 ohm resistance. Then you post a jpg of a car that has high resistance injectors. So? Which is it? IF its a early 87 the proper diagram is the one I'm posting with this post.
And, do you now know how the injectors work???? And that you'd NEVER ground the black/yellow wire any more than you'd ground the positve wire on your battery? Say YES.
And, do you now know how the injectors work???? And that you'd NEVER ground the black/yellow wire any more than you'd ground the positve wire on your battery? Say YES.
I didn't realize that diagram was high IMP. It's the only wiring diagram I have in my copy of the FSM for a turbo car. I have the online version of the S4 FSM, which is probably from a High imp 88 car.
11-06-04, 10:53 AM
#22
Originally Posted by HAILERS
The black/yellow wire supplies 12v to the injecotr coils.
Originally Posted by HAILERS
The ECU makes the injectors pulse by applying and removing a ground on the other wire to the injectors. It does this on/off in milliseconds.
Originally Posted by HAILERS
The CAS wires go from the cas to the ECU. The ECU uses that cas signal to pulse the injectors by putting a ground on the injectors.
So? What's the problem?
So? What's the problem?
11-06-04, 01:48 PM
#23
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I'm still not sure what type car you have. Theres one way to find out. Pull the air filter/afm out of the car. Look directly below it. If its a low impedence car you will see an aluminum covered resistor package with one large plug on it, mounted on the fender.. IF you have a high impedence car you will not have that item. It would be mounted on the fender with two bolts.
A car with high impedence injectors will have one wire at EACH injector that is Black/Yellow and no solenoid resistor package under the afm/air filter. Sooooo....if you have the black/yellow wires at each injector plug....and no solenoid resistor package.....the injectors should be about 11-13 ohms each.
If you pull the plug off the ECU, pins 3E is the front primary and pin 3C is the rear primary. IF you leave the plug off and put your meter on the PLUG side of 3E and 3C....you should see battery voltage and it should be a steady reading. That is if the injector plugs are attached and the key is to ON.
A car with high impedence injectors will have one wire at EACH injector that is Black/Yellow and no solenoid resistor package under the afm/air filter. Sooooo....if you have the black/yellow wires at each injector plug....and no solenoid resistor package.....the injectors should be about 11-13 ohms each.
If you pull the plug off the ECU, pins 3E is the front primary and pin 3C is the rear primary. IF you leave the plug off and put your meter on the PLUG side of 3E and 3C....you should see battery voltage and it should be a steady reading. That is if the injector plugs are attached and the key is to ON.
11-06-04, 10:55 PM
#24
Originally Posted by HAILERS
I'm still not sure what type car you have. Theres one way to find out. Pull the air filter/afm out of the car. Look directly below it. If its a low impedence car you will see an aluminum covered resistor package with one large plug on it, mounted on the fender.. IF you have a high impedence car you will not have that item. It would be mounted on the fender with two bolts.
A car with high impedence injectors will have one wire at EACH injector that is Black/Yellow and no solenoid resistor package under the afm/air filter. Sooooo....if you have the black/yellow wires at each injector plug....and no solenoid resistor package.....the injectors should be about 11-13 ohms each.
If you pull the plug off the ECU, pins 3E is the front primary and pin 3C is the rear primary. IF you leave the plug off and put your meter on the PLUG side of 3E and 3C....you should see battery voltage and it should be a steady reading. That is if the injector plugs are attached and the key is to ON.
A car with high impedence injectors will have one wire at EACH injector that is Black/Yellow and no solenoid resistor package under the afm/air filter. Sooooo....if you have the black/yellow wires at each injector plug....and no solenoid resistor package.....the injectors should be about 11-13 ohms each.
If you pull the plug off the ECU, pins 3E is the front primary and pin 3C is the rear primary. IF you leave the plug off and put your meter on the PLUG side of 3E and 3C....you should see battery voltage and it should be a steady reading. That is if the injector plugs are attached and the key is to ON.
Last edited by F1blueRx7; 11-06-04 at 10:59 PM.
11-06-04, 11:00 PM
#25
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The Black/Yellow that feeds the Solenoid Resistor???? Battery voltage...approx 12v.
The Black/Yellow comes from the Main Relay and a Black/Green wire at the Main Relay feeds that B/Y when the Main Relay closes. It (B/G), originates from the 40amp fuse in the engine bay.
The Black/Yellow comes from the Main Relay and a Black/Green wire at the Main Relay feeds that B/Y when the Main Relay closes. It (B/G), originates from the 40amp fuse in the engine bay.
Last edited by HAILERS; 11-06-04 at 11:05 PM.