tech help

[Commuta_Busa]

ok guys I've hit a road block. Here's my situation. Inj #4 doesn't wanna flow any fuel after startup.

On the initial startup signal when the ecu tells all four injectors to shoot fuel at the same time they all work including inj #4. After that crank rotation the ecu switches to multiport port injection meaning it shoots the fuel before the intake stroke for each cylinder. At this moment is when the #4 injector stops flowing fuel.
The ecu will not allow the engine to run if it's not getting a signal from more than one failed injector. I pulled the #3 inj and the engine still started. This tells me the ecu doesn't view inj#4 as having some kind of failure.

I checked the wiring and there's no short.
I checked to see if it got 12v and they all do.
I checked the continuity from the injector to the ecu and it's within spec of the other injectors.
I also swapped the harness between #3 & #4 which causes the #3 inj to follow the same pattern. This tells me it's not the injector itself.

It's not a tipover, kickstand, neutral, safety issue because the engine does run.
I thought the ecu might have failed but when I swap in another ecu it still does the same thing.
If it were some kind of soft rev limit it would effect two injectors and not just one.

Does anyone have any thoughts? What could possibly cause only the #4 injector to stop working after the initial start?

 

[m_ridgeway]

what tuner are you using?

 

[Commuta_Busa]

I pulled the power commander off and no change.
Also, verified there was no trim set for only the #4 cylinder.
Even if it was trimmed -5 max the injector would still shoot some fuel.
I use the ecu flasher too that's why I swapped ecu's to see if that would make a change but it didn't.

 

[m_ridgeway]

I pulled the power commander off and no change.
Also, verified there was no trim set for only the #4 cylinder.
Even if it was trimmed -5 max the injector would still shoot some fuel.
I use the ecu flasher too that's why I swapped ecu's to see if that would make a change but it didn't.

think the PC injector harness could be damaged? try checking contuinity on the harness?

 

[Commuta_Busa]

I checked continuity also the injector works during the initial start injection.

 

[Johnnycheese]

I have the same problem on #3 on Gary's turbo bike after we left Loring last year and I still can't find it, and I have replaced everything yes EVERYTHING

 

[Commuta_Busa]

that's where I'm at. Looks like Loring is going to be a wash for me. JC, can you pm me your number I would like to talk to you tomorrow about it. It's almost midight here and I done.

I have the same problem on #3 on Gary's turbo bike after we left Loring last year and I still can't find it, and I have replaced everything yes EVERYTHING

I just hot wired 12v directly to it and hot wired only two inches from the ECU directly to the injector and it has no change. It's just weird that it the inj fires for the initial start but then wont fire again. The problem follows the harness but even hot wiring it directly has no effect.

 

[bobber]

Something doesnt sound right,You swapped the harness from inj#3 with #4 and if I read your post right[ then inj 3 isnt working? correct?}and if you unplugged the PC and went with another ECU , Youd think that wouldve made a change.The only other factor is the harness itself running from the PC to the ijectors harness unless when you swapped out the ECU you ran a new harness to the injection connector and a different harness from the connectors to the injectors themselves.. If you ran a new harness form the ECU to the Inj harness plug in ,then that only leaves the short harness that runs to the Injectors themselfs. But your smart enough that youve probually have already done that.
There isnt anything left that I can see unless theres a hidden factor that bleeds into the monitoring system or sensor. How did you come across that it was failing anyway ?

 

[m_ridgeway]

that's where I'm at. Looks like Loring is going to be a wash for me. JC, can you pm me your number I would like to talk to you tomorrow about it. It's almost midight here and I done.



I just hot wired 12v directly to it and hot wired only two inches from the ECU directly to the injector and it has no change. It's just weird that it the inj fires for the initial start but then wont fire again. The problem follows the harness but even hot wiring it directly has no effect.

is there any way the ecu flash couldve affected injector timing? did you flash the other ecu or try it stock? if it was stock that would elimate that problem.

sorry bout your luck, i have the same feeling right now with mine, chasing a gremlin gets old fast.

 

[bobber]

Dont know what ECU you swapped out . Might want to try a stock ecu [if thats not what you used] and run the new harness all the way [ including the fuel injector harness to get your answer. Something doesnt sound right. You say it made a change from 4 to 3 when you switched thd leads around, That alone leads me to believe its either in one of the 2 harness's or the ECU has an issue . but the weird thing is; you had the same problem after swapping the ECU out . No secoundarys ? best wishes,,let us know what you find.

 

[Commuta_Busa]

Ok guys here's everything I've done to diagnose this:

1. checked continuity at the injector (within spec/passed)
2. checked to see if the injector is grounding (passed)
3. checked for voltage on the harness at the injector (passed)
4. checked continuity from the injector harness connection and the ecu connector (passed)
5. checked for ecu faults/error codes (passed)
6. checked voltage at the ecu pin (passed)
7. checked to see if it might have been a soft rev limit problem but the #1 injector is functioning normal.

now for the all of the different swapping and the results:
1. removed power commander. (no change in symptoms)
2. swapped harness at the injector between #3 and #4 resulted in #4 working properly and #3 failing. (this leads you to believe it's harness related, injector works fine)
3. hot wired 12v directly to the injector and hot wired a new wire lead 3 inches away from the ecu to the injector. (no change in symptoms)
4. swapped to a bone stock ecu. (no change in symptoms)
5. removed connection to the #1 injector and bike would still start. (if the ecu recognized qty.2 injectors not connected/failed then the ecu will not allow the engine to start)
6. disconnected cam sensor. (no change in symptoms)


problem:
What is odd is that during initial startup all four injectors shoot fuel. After this then the #4 injector doesn't function. The engine will run and rev but cyl #4 isn't doing anything (no fuel = no power).
Tonight I'll swap the injector with another one I have and see if there's any change.

 

[Commuta_Busa]

bumpty bump...

 

[bobber]

Swapping the inj#4 sounds like a good idea. Then you know its not the issue. Perhaps swapping out the inj harness with connector might help.Thats where My vibes are leading me to look because of the swapping out of inj#4 with #3 resulted in #3 failure. While running a continuity on wireing/wireing harnesses and elements ect , These tests help; But Ive seen cases where under a load,it would fail resulting in a false positive. You Might wanna consider swapping that out too. Im just going by the 3 and 4 swapping only to find # 3 dying . sounds like its up front somewhere. or the connector pins may be unstable. Or a slight break in the harness wireing not showing up on the continuity test but fails under the true load. Hot water heater elements and such were nortoreous for that gremlin effect,,,nerve racking..my 2 cents
I hope you have a friends harness to borrow for the DX.

 

[prayer warrior]

Ok guys here's everything I've done to diagnose this:

1. checked continuity at the injector (within spec/passed)
2. checked to see if the injector is grounding (passed)
3. checked for voltage on the harness at the injector (passed)
4. checked continuity from the injector harness connection and the ecu connector (passed)
5. checked for ecu faults/error codes (passed)
6. checked voltage at the ecu pin (passed)
7. checked to see if it might have been a soft rev limit problem but the #1 injector is functioning normal.

now for the all of the different swapping and the results:
1. removed power commander. (no change in symptoms)
2. swapped harness at the injector between #3 and #4 resulted in #4 working properly and #3 failing. (this leads you to believe it's harness related, injector works fine)
3. hot wired 12v directly to the injector and hot wired a new wire lead 3 inches away from the ecu to the injector. (no change in symptoms)
4. swapped to a bone stock ecu. (no change in symptoms)
5. removed connection to the #1 injector and bike would still start. (if the ecu recognized qty.2 injectors not connected/failed then the ecu will not allow the engine to start)
6. disconnected cam sensor. (no change in symptoms)


problem:
What is odd is that during initial startup all four injectors shoot fuel. After this then the #4 injector doesn't function. The engine will run and rev but cyl #4 isn't doing anything (no fuel = no power).
Tonight I'll swap the injector with another one I have and see if there's any change.

swap the injector see how it goes, next step check your CDI box look for any little bumps I am guessing that's what it is! you have done a lot right things to troubleshoot that.

 

[Commuta_Busa]

Last night I bypassed the harness, no change. It's as if the ecu is picking up some kind of signal from something else and bassed on that will not fire the #4 inj. Even swapping in a bone stock ECU has the same effect. These ecu's aren't that smart so now it comes down to little stupid things. Swap the injector and play with the pin connector at the ecu.

Either way I had to cancel my Loring trip. Now I've got to wait another whole year until 2011 :down:

I wanted to get some new connectors so I can just build my own harness for the Injectors from scratch but the connectors on backorder (17 weeks out)! Unless you wanna buy 7000 of them. Greg (smith-a-busa) didn't want to buy the 6950 some odd ones I would have for sale.

It's funny though, the injector harness is one of the few last remaing bits of the OE harness that's original. I never messed with it because of the connection it has with a power commander. Once I'm able to get new connectors and the housings I'll just clean up the wirring and build a new harness.

 

[Commuta_Busa]

CDI as in my ignition? I get plenty of spark just no fuel. I'm not sure what you mean about "bumps" either...

swap the injector see how it goes, next step check your CDI box look for any little bumps I am guessing that's what it is! you have done a lot right things to troubleshoot that.

 

[kjcili]

Put a noid light on that harness, and make sure its pulsing. having power and ground and continuity are all good, but if the ecu is not pulsing the injector you either have a crank trigger problem or the ecu is poop.

 

[m_ridgeway]

that sucks you gotta cancel the trip over this. let us know what you figure out...

 

[bobber]

Let us know what you find. I thought that by swapping out the ECU all the way[ harnesses and connectors ] to the injectors would solve the issue,Im sorry you missed your meet. Who knows; you may find it by 2nite. too bad you dont have axces to inj to ECU complete switch out; harneesses/connectors/the whole 9 yards.

 

[Ketchmi]

I recently had almost the same problem on an older Porsche. Measure the resistance between the positive wire to the injector and the ground trigger wire from the ECU. Even a small short in the injector wiring will take enough current to keep the injector from firing. When I finally found it, it was corrosion inbetween the wires to the tune of about 70 ohms. You wouldn't think that would be enough to keep an injector from firing but it certainly did. Since that Porsche uses batch fire, it killed all the injectors and the car wouldn't start. It (944 Turbo) fired two injectors at a time but it killed all of them. It had me stumped for a while, I had the proper ground pulse coming out of the ECU and had a good 12vdc supply but the injectors just wouldn't fire.

Good luck!