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Electrical stuff is not my cup of tea and as of latley we have some problems. I have a Fast ECU that I have taken the injector harness and added on to it so I can run 16 injectors many folks have done this and the injectors are run parallel. We have a Digital 7 ign box also. Here is what we have take car to dyno and it will not rev over 7k and has a noticable miss but we keep messing with it. Go to track and the car is bucking pretty bad and hesitating so I cut it hoping to get some data and the computer did not record. Second pass same thing but I get some data the car is reving to 7k and will not rev past that (no there is not a rev limiter on in the ECU or Digital 7 I checked many times) I start looking for obvious problems and the only thing I can come up with is the crank trigger is gapped at .025 so I put it at .080 and LOw and behold the car is a monster it revs to 8800 and pulls like a rapped date. Next pass (final round) the car has the same miss 7k rpms and the crank trigger is still .080 !????? I pull the plugs and all are jet black except #2 cylinder it is smoked white with sighn's of detonation. I take the car to the Chassis dyno the next day new plugs new cap rotor plug wires and on the dyno it will not rev past 5000 this time and is really bucking and acting up I even put my single set of 160 lbs injectors in and put the old map in and no change 17psi of boost and only 400hp???? This time i brought it home and all plugs are black and #2 again is lean with more detonation. Cranking compression is 110 all cylinders and #2 is 60 so we have hurt that piston. This morning I changed to a new ECU, and new Dig 7 box hoping to figure this out before we change the piston and hurt another one. Any help is appreciated. Chris Derrick the mud duck :smt017
 

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I'm sure Sparky will answer this one when he gets a chance but I'll try to keep you busy until then. :-D

I saw where Travis told you to get a noid light. You can get them at most auto parts stores. The light plugs into the injector socket. It will flash when you crank the motor and let you know if that injector is firing. You can use a regular ol trailer light and just stick it in the injector socket. I have used a test light before too.

Here's what you want to know. The big wire going to the injector should always have 12v when the ecu and ignition have power. I'm pretty sure it's a red wire. You'll be able to tell because this wire is bigger diameter of the two going to the injector. Make sure you have 12v at this wire when the power is on.

The ecu completes ground to fire the injectors. That's why you want to put some kind of 12v light across the terminals to see if it fires. Maybe check a hole that you know is working then check the problem child. If you find the injector is not firing you might be grounding out the harness somehwere or the injector driver in the ecu might be screwed. Sparky can probably tell you what else to check. Hope this helps. I HATE ELECTRICAL PROBLEMS!!! :evil:
 

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While you're at it, check to make sure none of the pins on your ecu connector are bent or pushed out. Also, if you have a engine harness with a disconnect plug check those pins to make sure they are not bent, pushed out, or shorting out against eachother. Did I mention I hate electrical stuff? :evil:
 

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Well, Jim is on the right track as for checking injectors. Jim is also correct that the Red wire should have constant power when Ignition is on. While the engine is running and whatever you use for a noid light, at an idle this light should blink at a steady rate, as engine RPM increases, this blink should be more rapid.

If either injector on #2 is dead, I would suggest using some kind of DVOM (Digital Volt Ohm Meter).
Check for Resistance (in Ohm Mode) From Injector #2 (Brown wire) to Injector 10 pin connector, (Pin H) on Injector harness side, you should have a resistance value somewhere between.003 and .007 ohm resistance.
Then check resistance from the 10 pin connector, main harness side, Pin H will be a purple wire on the main harness back to the ECU, ECU pin #S1. Again you should have a similar reading.
If you have no reading at all, there is a break somewhere between the ECU and Injector Connector, but by checking for resistance, should help you isolate where this is. If everything checks out, you could have a bad Injector Driver on the board of the ECU.

As for the engine not revving up issue, have you put a Timing light on the engine and revved the engine up? The timing on the balancer should coordinate with what you have in the FAST Spark Table, if you are using any part of the FAST to retard timing (N20 enable) or the Digital 7 for any type of timing retard, don’t forget to take this into account. If the timing on the balancer is off in left field and does not coordinate with the FAST Spark Table, a couple of things can be done.
1.) Try switching the wires on the crank trigger and run above procedure again, if this does not fix the problem.
2.) Replace the Crank trigger. I like to run the gap between .050 and .080.
Wire color means nothing, so try the wires one way then the other. I.e. Purple to Red, Green to Black and vice versa.

I thought further about your post and added the following, some of which is just thinking out loud.
What puzzles me is, you have one lean plug and seven fat plugs. A lean plug would indicate lack of fuel, too much timing or a combination of both and the exact opposite for the other seven plugs. Both fuel and spark are controlled by the Crank Trigger, which also relates to possibly why the engine won’t rev up as well.
Are you doing anything to Cylinder #2 that you’re not doing to the others, any individual timing and/or fuel management in this cylinder? Does any of the data show what the timing is at, or what the air fuel is?

If you get an opportunity, please give me a call (810) 229-9688.
 

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Am I the only one that thinks that the dead cylinder might be effecting the ability of this engine to rev?

Yes I'm sure there is a cause to this, that was not the cylinder itself, but you see where I'm going with this?
 

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If you have a 7531 msd turn the slew rev limit off for now and make sure you're not hitting the time based rev limit. Oh yea, if all this stuff fixes your problem give me the leave if we ever race eachother. :)
 

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Six,
I don’t necessarily think Cyl #2 is dead. Chris stated that the plug was lean and detonated. There is some fuel and fire in the hole, if the Cyl was dead, it would not hurt the piston, cranking compression, etc. Yes I feel a mistuned Cyl will affect an engines ability to rev, but I don't think it would affect how high the engine can rev.
 

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Discussion Starter #8
Jim Monson said:
I'm sure Sparky will answer this one when he gets a chance but I'll try to keep you busy until then. :-D

I saw where Travis told you to get a noid light. You can get them at most auto parts stores. The light plugs into the injector socket. It will flash when you crank the motor and let you know if that injector is firing. You can use a regular ol trailer light and just stick it in the injector socket. I have used a test light before too.

Here's what you want to know. The big wire going to the injector should always have 12v when the ecu and ignition have power. I'm pretty sure it's a red wire. You'll be able to tell because this wire is bigger diameter of the two going to the injector. Make sure you have 12v at this wire when the power is on.


Hey Jim thanks and I checked em all 16 and they are fine. what else? DUCK
The ecu completes ground to fire the injectors. That's why you want to put some kind of 12v light across the terminals to see if it fires. Maybe check a hole that you know is working then check the problem child. If you find the injector is not firing you might be grounding out the harness somehwere or the injector driver in the ecu might be screwed. Sparky can probably tell you what else to check. Hope this helps. I HATE ELECTRICAL PROBLEMS!!! :evil:
 

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Discussion Starter #9
Sparky said:
Well, Jim is on the right track as for checking injectors. Jim is also correct that the Red wire should have constant power when Ignition is on. While the engine is running and whatever you use for a noid light, at an idle this light should blink at a steady rate, as engine RPM increases, this blink should be more rapid.

If either injector on #2 is dead, I would suggest using some kind of DVOM (Digital Volt Ohm Meter).
Check for Resistance (in Ohm Mode) From Injector #2 (Brown wire) to Injector 10 pin connector, (Pin H) on Injector harness side, you should have a resistance value somewhere between.003 and .007 ohm resistance.
Then check resistance from the 10 pin connector, main harness side, Pin H will be a purple wire on the main harness back to the ECU, ECU pin #S1. Again you should have a similar reading.
If you have no reading at all, there is a break somewhere between the ECU and Injector Connector, but by checking for resistance, should help you isolate where this is. If everything checks out, you could have a bad Injector Driver on the board of the ECU.

As for the engine not revving up issue, have you put a Timing light on the engine and revved the engine up? The timing on the balancer should coordinate with what you have in the FAST Spark Table, if you are using any part of the FAST to retard timing (N20 enable) or the Digital 7 for any type of timing retard, don’t forget to take this into account. If the timing on the balancer is off in left field and does not coordinate with the FAST Spark Table, a couple of things can be done.
1.) Try switching the wires on the crank trigger and run above procedure again, if this does not fix the problem.
2.) Replace the Crank trigger. I like to run the gap between .050 and .080.
Wire color means nothing, so try the wires one way then the other. I.e. Purple to Red, Green to Black and vice versa.

I thought further about your post and added the following, some of which is just thinking out loud.
What puzzles me is, you have one lean plug and seven fat plugs. A lean plug would indicate lack of fuel, too much timing or a combination of both and the exact opposite for the other seven plugs. Both fuel and spark are controlled by the Crank Trigger, which also relates to possibly why the engine won’t rev up as well.
Are you doing anything to Cylinder #2 that you’re not doing to the others, any individual timing and/or fuel management in this cylinder? Does any of the data show what the timing is at, or what the air fuel is?

If you get an opportunity, please give me a call (810) 229-9688.
Mike I will give you a call in the am thanks for the advice. I have the slew off, I have no rev limiters on, I have checked the timing at idle where it is 36 degrees and it shows 36 on light but I have not reved it up and checked it, I used a trailer light and made two male adapters to stick into each plug on the injector harness I turned on the ign and cranked with it in each plug and all of them lighted up fine. I have tried two fast boxes and for some reason don't think they are both bad but I have seen funnier things happen so I have another good box and O2 in car now. I also put on a new dig 7 box, and new coil have not started it yet. I ohmed the injectors and they all ohm .002 on the 160lb injectors I have a set of 50's that ohmed .005 ?? I have another crank trigger wheel and eye but they are old units how can I check them to see if they are good or bad can I ohm them also? As for piston #2 it is down 45-50 on compression so it is hurt but I have been beating on it pretty hard on dyno trying to get it to run. I wish I knew how to open these fast boxes up and check stuff my self. Mike If I can't figure it out I will bring it up first thing and wait on your door step like petty did untill its done how about that! At one time I had a set of 160 injectors and a set of 50lb injectors what if the 50 units were high impedence and the 160 was low or vise versa could this have hurt the ecu? How do I know if the 50's are low or high precsion turbo sold them to me and they are supposed to be correct but you know how that goes? The funny thing is this thing at 3100lbs ran 168mph first pass down track but was way lean due to fuel system issues and was 160% duty cycle and 13.5 AF ratio with the 160's and the 50lbers in come on fellas shoot away got any more ideas? duck
 

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If you have the time and money I would definately drop that thing off on Sparky's door step. That way you can eliminate electrical problems from the mix all together. Plus you get to see a man work on your car in a pink bunny suit. :smt005
 

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Discussion Starter #11
Hey Sparky thanks for the help along with all of you for handing out ideas. I found the problem and don't care to share it with any of you! :oops: Sparky if you tell I will come through this computer and shock you! :smt005 lmao!
 

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Discussion Starter #14
Ok lets just say it had nothing to do with wires! Thats all your getting. :-D
 

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I could guess all day long, but it'll be much quicker and easier for you to just tell us, now. ;) :p

IBfuelfilterwasclogged
 

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Discussion Starter #16
No six it was not fuel filter but here is a hint, all cylinders were black (plugs) all but #2 it was clean and white. Remember I had a miss and it was not electrical! Damn I am stupid! DUCK :roll:
 
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