DirtyDaveW

I'm having a very odd issue with my fuel injection system.
History

• Car started out with 60# mototrons, ran great.
• In 2011, I decided to go to low impedance, larger injectors. Bought package deal of Acceleronics 95# inj and the driver box.
• Installed the box and injectors. Worked perfect right off the bat. Restated the injector size to my tune and the car ran fantastic.
• Around June of 2012, I was driving in Upstate NY and hit a hellacious pothole. I'm surprised the air bags didn't go off. Immediately, the car ran like crap. I pulled over and popped the hood as the engine struggled to stay running. I thought, for whatever reason, the harness to the Acceleronics box might have gotten jarred by the pothole strike. I wiggled the plug from the box to the injectors and nothing happened. I then unplugged it, killing the motor. I plugged it back in but then noticed the ground lead on the LTCC coils for the drivers side had came undone. Supposing it had been the pothole that knocked off the last thread of the bolt holding/grounding the coils, I smiled as I thought, "Easy fix!" and put the bolt back in.
• After tightening the bolt, I got back in the car and tried to start it. It struggled as I had to clear flood it (planting the gas petal while cranking) and immediately a huge plume of white gasoline steam started coming out the tailpipes. I swear, If there was a match back there, it would have exploded like Napalm. I had to keep the RPM's above 2K to keep it running.
• I got her home, then surmised the box must've gotten fried when I unplugged it when it was running. I contacted Jeff Stevens, the guy that makes/sells them. He said he doubted that was the issue but he said to send it to him anyway and he'd check it out.
• Jeff got it, took it apart and said it looked like one chip might've been affected. He repaired it and sent it back for the cost of shipment. I put it on the car. Same white cloud. Took it back off and put in my mototrons. Ran perfect.
• Fast forward to last month. I decided to just buy another brand new box since 'surely the old box is causing this'. Well, put the new box on. Same white cloud of gas. Take the box off, runs great…
• I told Jeff that it was like with the box on, the injectors just locked wide open. He described the circuitry of the box and said he couldn't see how it could do that.
• I decided to do some in-depth testing. With voltmeter set to 12v range, I had key on, engine off, probed one of the injector connectors I'd pulled of cylinder #4. 12 volts was found.
• Installing a noid light, without the Acceronics box in the circuit, Key on, engine off. The noid light was off. Starting the engine, the noid light pulsated as the injector command was issued.
• Installing a noid light, WITH the Acceronics box in the circuit, Key on, engine off. The noid light was ON. Starting the engine, the noid light STAYED ON the whole time.
• Give that the 12 is applied all the time and the pintle is closed unless the PCM pulls the circuit to ground, it is strange that merely introducing the box was causeing it to go to ground.
• I thought, "Maybe the PCM is fried?". Having 2 other PCM's, I plugged in each of them and repeated the above test with the Noid light. Exact same results. Put the original PCM back in.
• I thought, "Maybe the wiring harness is shorted someway?". I have an additional 'red connector' for the PCM so I found the wire for Injector #4, stripped the end for a connector and left all the others unconnected. I pulled up the PCM, took off the Red connector on my harness and just put the one wired substitute red connector in it's place. I then ran that one wire over the engine compartment to injector #4 and tested the noid light. Damn it.. still works the same way. Noid light off w/o box, noid light on all the time with the box.
• Just to be sure that it would do the same thing with a real injector it was doing to the noid, I pulled out one of the now unused #95 and tried it in the harness while holding the injector in my hand so I could feel if it was clicking. It was off when I put it in the stock harness before starting and would click with the motor idling. Putting the box in the circuit, it would click open immediately upon 'key on' and stay open the whole time with the engine running (and flooding the motor in the process)

This is what is so crazy… Why would it start doing this after a year of running fine from just hitting a pothole? And why does it run fine on the stock harness but either one of the low impedance boxes, one of which was brand new, causes the injectors to lock wide open? I've tried both sets of injectors (60# and 95#) and it does the same with both. You guys have any ideas?
Thanks!
Dave

DirtyDaveW

Well.. My good friend Brian Grimal (aka 'Brains') came up with a test plan for me and I went thru it. Looks like he may have isolated the issue.
Here's his test plan...
BTW "VF" = "Versa Fueler"..

Okay, try this. Set the meter to DC volts.
1. Pull the fuel pump relay, crank the car and let it use up any fuel pressure still in the rail so we don’t wash down the cylinders with fuel during testing. Turn the ignition back off.
2. Connect the VF to +12V and ground only, and connect your meter’s red wire to +12V
3. Probing with the black wire from the meter, verify the INPUTS on the VF show 0V (or very close to it).
4. Probing with the black wire from the meter, verify the OUTPUTS on the VF show 0V (or very close to it).
5. Plug the VF into the fuel injectors. Leave the inputs unplugged. Repeat #3 and #4, they should still both read 0V, and the injectors should stay closed.
6. Turn the ignition on to power up the PCM, then verify the PCM’s injectors lines are showing 0V, or really anything other than 12V (the output will likely float when not commanded to ground)
7. Now plug the VF into the PCM. Repeat #3 and #4, they should both still read 0V.

Based on the troubles you’re having, 12V is going to show up on the meter somewhere between step 3 and 7:
If it’s either #3 or #4, the box is bad.
If it’s #5, and the input measures 0V, the box is at fault. If the input measures 12V, it’s still the boxes fault; the pull-up resistors aren’t pulling the inputs high - thus turning on the injectors full time.
If it’s not until #6, the PCM is possibly overpowering the pull-up resistors in the VF.
If #6 was OK and you don’t see 12V until step #7, the problem is in the wiring between the PCM and the VF.
=========================================
My responses were for the two Versa Fueler boxes I have.
Box1 = Old/Original VersaFueler
Box2 = My new VersaFueler

Test3 = "Probing with the black wire from the meter, verify the INPUTS on the VF show 0V (or very close to it)."
Box1 = 12 volts.. (uh oh..not good)
Box2 = 0 volts

Test4 = "Probing with the black wire from the meter, verify the OUTPUTS on the VF show 0V (or very close to it)."
Box1 = 12 volts.. (welp, box 1 is definitely affected and is going in for repair)
Box2 = 0 volts

Test5 = "Plug the VF into the fuel injectors. Leave the inputs unplugged. Repeat #3 and #4, they should still both read 0V, and the injectors should stay closed."
Box1 = No longer testing since it's obviously toasted.
Box2 = 0 volts

Test6 = "Turn the ignition on to power up the PCM, then verify the PCM’s injectors lines are showing 0V, or really anything other than 12V (the output will likely float when not commanded to ground)"
Box1 = No longer testing since it's obviously toasted.
Box2 = 0.35 volts


Test7 = "Now plug the VF into the PCM. Repeat #3 and #4, they should both still read 0V."
Box1 = No longer testing since it's obviously toasted.
Box2 = 8.35 volts <-- not good. It should still be zero or near it.

So, box 1 being shipped back to Jeff at Versafueler for repairs. Box 2, I *think* is okay, it's just my injector wiring from the "RED" connector on my PCM that must have a short to ground of some level on one of the 8 injector wires. I have a spare "RED" connector that I'm going to wire off of and put new wires to each injector clip.

DirtyDaveW

Tested everything again and again. Can't locate an issue. Sending both boxes back to Jeff at VersaFueler/Acceleronics to have him look at the boxes. I don't think it's the boxes though. I thing the wiring hates me ....

At any rate, I'm punting and I ordered a set of these high impedance injectors...
https://www.texas-speed.com/p-3976-b...injectors.aspx

DirtyDaveW

Got the data sheets on the Bocsh 127# fuel injectors if anyone wants to see them.