dave6666
Enthusiast
Battery tenders are usually not good for "charging" a battery. More for helping keep a fully charged battery, fully charged.
Problem with my GTS (feels like she missing spark/fuel)
- Thread starter Dom426h
- Start date
Battery tenders are usually not good for "charging" a battery. More for helping keep a fully charged battery, fully charged.
Try Partsrack, ViperPartsLarry and/or call the Wizard for advice on which controller is better for you.
Brake Dust
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- Oct 19, 2008
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Ok, got it back and after a few days of driving I haven't seen it do the same problem (where the throttle seems to completely become unresponsive). It has also not died on me while idling at a light either (which is was doing a bit), but I have felt it drop to very low RPMs just for a half second or so before recovering (probably a load up problem as I'm still tuning).
It also seems to be responding to the VEC1 tuning with a lot more accuracy than before. Before when tuning it was hard to tell a difference at times, but it was very noticeable this time around. And at 80mph in 5th on the highway the tone and feel of the engine was different, seemed more consistent and smoother on the RPMs.
I did feel a slight sputter of fuel once or twice when taking off from a stop light (around 2-3krpm in second or third gears), almost as if it was spewing fuel non-stop into the cylinder, but it only lasted a quick moment. And that still could be tuning.
So something definetely got fixed (I would guess cam sensor because of all the other reports). It's good enough for me now so I'm dropping her off at the paint shop tomorrow!
The saga continues in search of injector #7 ground signal...
A member on the board was kind enough to ship over a spare PCM to help with diagnosing. Thanks Ellow!
Recent Diagnosing:
I plugged the PCM in and the injector 7 ground signal is still missing. I've traced it all the way to the PCM connector, and have tested the resistance across the connector and it seems to have connection. I have tested the ground at the fuel injector connector and it's giving a ground when the car is turned off. It seems like the wire is fine.
I did wiggle the connectors and pushed the wire into it more and got a wide open ground on the injector for awhile. It disappeared after 10 more minutes of testing wires. The injector stuck open while my friend was doing a leak down on the motor. That's strange.
Spark notes: Injector 7 ground wire stays open - never any ground.
Swapped in another PCM. Still having problem. Wiring has been checked out.
Possible causes:
Cam or Crank sensor - these 2 sensors are used by the PCM to decide when to open the injectors
Bad ground - poor grounding for entire car? I have heard this causes strange problems
Need to dump PCM memory? - It should dump memory when I switch out PCMs anyways. Unlikely
Need to clear codes for it to run properly? - I have cleared codes some when running it. Unlikely
Is there anything else that could cause this problem of the ground signal disappearing?
A member on the board was kind enough to ship over a spare PCM to help with diagnosing. Thanks Ellow!
Recent Diagnosing:
I plugged the PCM in and the injector 7 ground signal is still missing. I've traced it all the way to the PCM connector, and have tested the resistance across the connector and it seems to have connection. I have tested the ground at the fuel injector connector and it's giving a ground when the car is turned off. It seems like the wire is fine.
I did wiggle the connectors and pushed the wire into it more and got a wide open ground on the injector for awhile. It disappeared after 10 more minutes of testing wires. The injector stuck open while my friend was doing a leak down on the motor. That's strange.
Spark notes: Injector 7 ground wire stays open - never any ground.
Swapped in another PCM. Still having problem. Wiring has been checked out.
Possible causes:
Cam or Crank sensor - these 2 sensors are used by the PCM to decide when to open the injectors
Bad ground - poor grounding for entire car? I have heard this causes strange problems
Need to dump PCM memory? - It should dump memory when I switch out PCMs anyways. Unlikely
Need to clear codes for it to run properly? - I have cleared codes some when running it. Unlikely
Is there anything else that could cause this problem of the ground signal disappearing?
Through testing the wire through its entire path I am ready to move on to the next possibility. I have tested for a ground right after the PCM connector and did not get a ground at that point. Then tested the resistance from that point to the pin in the connector, closed connection so the wire is there.
That leaves two possibilities:
1 The connector is not making connection with the PCM pin - eliminated by confirming wire has a solid ground when car is turned off
2 No ground signal from the PCM
#2 boggles my mind because I just swapped in another PCM to eliminate the PCM as a possibility.
Tom F&L GoR
Enthusiast
Red,
I haven't re-read everything, so apologies if any of this is a repeat. It's also a little hard to tell what you mean by seeing a ground.
The injector always receives 12V when key is on, but only opens to allow fuel when the PCM completes the circuit and provides the ground. So if you had one injector "stuck open" then you might have had 12V going to it and the other wire grounded. So something was working?
I would suggest switching the injector 7 plug with #5 or #9. The injection timing won't be sequential, but so what? Before sequential injection, systems simply fired "left bank" then "right bank" and sometimes the fuel went through an open valve, sometimes puddled on the back of the valve, etc. (I'm trying to convince you it will do no harm.) Once you switched it, see where the problem goes. That should help diagnose whether is it wiring, PCM or injector and answer the mind boggling question.
Since the injector isn't firing (and flooding) when running, why not try to measure if the PCM is providing a ground at all while the engine is running? A digital meter will read funny, but hopefully you can distinguish that from a full open condition. With all the electronic gizmos in the PCM I don't know that a ground signal when off is a good data point. Maybe the ASD that provides the 12V is switched to ground when key is off and you're measuring ground via the input side.
The other thing I'm sure you've done is measure voltage across the injector while engine is running. With a digital meter it should jump around, but at least you know it is getting power. Do this on a "good injector" and then your #7.
Hope this helps. Good luck.
I haven't re-read everything, so apologies if any of this is a repeat. It's also a little hard to tell what you mean by seeing a ground.
The injector always receives 12V when key is on, but only opens to allow fuel when the PCM completes the circuit and provides the ground. So if you had one injector "stuck open" then you might have had 12V going to it and the other wire grounded. So something was working?
I would suggest switching the injector 7 plug with #5 or #9. The injection timing won't be sequential, but so what? Before sequential injection, systems simply fired "left bank" then "right bank" and sometimes the fuel went through an open valve, sometimes puddled on the back of the valve, etc. (I'm trying to convince you it will do no harm.) Once you switched it, see where the problem goes. That should help diagnose whether is it wiring, PCM or injector and answer the mind boggling question.
Since the injector isn't firing (and flooding) when running, why not try to measure if the PCM is providing a ground at all while the engine is running? A digital meter will read funny, but hopefully you can distinguish that from a full open condition. With all the electronic gizmos in the PCM I don't know that a ground signal when off is a good data point. Maybe the ASD that provides the 12V is switched to ground when key is off and you're measuring ground via the input side.
The other thing I'm sure you've done is measure voltage across the injector while engine is running. With a digital meter it should jump around, but at least you know it is getting power. Do this on a "good injector" and then your #7.
Hope this helps. Good luck.
Hey Tom,
I've checked the system between injector #7 and #9 and the lack of a ground signal to #7 is causing the problem. The 12v signal to both is fine. I've picked up the ground off #9 and it's easy enough to understand what's happening with a digital multimeter. The constant ground on #7 injector ground wire only lasted a few minutes. I'm going to check into that more now. It has commonly not gotten any ground signal.
Good idea on switching the injector plugs. I'll try that between #7 and #9 then can ensure that injector #7 is operating fine by reading exhaust manifold temps. There's still the prob of no ground signal.
The two possible causes I have in my mind are:
1. Still a loss of connection somewhere - likely in the PCM connector. Will check with my fancy otoscope
2. Poor grounding - I've remember reading that poor grounding will cause wacky problems. Will check the stock grounds and the 2 extra that are advised when installing a Roe.
Diagnosing last night:
The ground from the engine to the frame seems fine. Read 2 ohm across it.
Here's the surprise. The ground wire near the #7 injector connector is grounding out. Or possibly making contact with the positive wire. It's a solid ground when the car is turned off. I was thinking all the ground signal wires gave a ground when the car is off, they actually stay open. I found this out by testing off #9 injector ground signal wire. When the car is running I'll get .41V with + on PDC post and - on ground signal wire.
The fuel rail on the Roe traps the connector and I can't pull it out to fix the wiring. I'm going to pull the fuel rail tomorrow and fix that.
The PCM still wasn't giving a ground signal the other day when I was checking it and the wire was NOT grounded out at that time. This ground out may not be the end of the tunnel...
The ground from the engine to the frame seems fine. Read 2 ohm across it.
Here's the surprise. The ground wire near the #7 injector connector is grounding out. Or possibly making contact with the positive wire. It's a solid ground when the car is turned off. I was thinking all the ground signal wires gave a ground when the car is off, they actually stay open. I found this out by testing off #9 injector ground signal wire. When the car is running I'll get .41V with + on PDC post and - on ground signal wire.
The fuel rail on the Roe traps the connector and I can't pull it out to fix the wiring. I'm going to pull the fuel rail tomorrow and fix that.
The PCM still wasn't giving a ground signal the other day when I was checking it and the wire was NOT grounded out at that time. This ground out may not be the end of the tunnel...
PROBLEM SOLVED
Pulled out #7 injector connector, removed surrounding electrical tape and found the constant and ground signal wires were making a connection. Both wires had soldered connections, BUT only one was insulated with shrink wrap. The exposed soldered connection wore through the other's insulation and made connection. I fixed the wiring and the injector fired fine. It also improved the overall running of the engine. When the constant bridged across the ground signal it seems to kill the entire system. Fixed the one wire and the engine moved from what felt like 250hp back to 600hp. I made my tires pay for their laziness at the autox!
The root cause of the problem of only insulation on 50% of the connections remains on the remaining 9 injector connectors. It is impossible to remove the injector connectors without breaking them while the fuel rail is in place. I broke #7 connector and replaced it with a smaller one that still clips in. When I have the fuel rail off I will fix the remaining connections.
Pulled out #7 injector connector, removed surrounding electrical tape and found the constant and ground signal wires were making a connection. Both wires had soldered connections, BUT only one was insulated with shrink wrap. The exposed soldered connection wore through the other's insulation and made connection. I fixed the wiring and the injector fired fine. It also improved the overall running of the engine. When the constant bridged across the ground signal it seems to kill the entire system. Fixed the one wire and the engine moved from what felt like 250hp back to 600hp. I made my tires pay for their laziness at the autox!
The root cause of the problem of only insulation on 50% of the connections remains on the remaining 9 injector connectors. It is impossible to remove the injector connectors without breaking them while the fuel rail is in place. I broke #7 connector and replaced it with a smaller one that still clips in. When I have the fuel rail off I will fix the remaining connections.
Tom F&L GoR
Enthusiast
Excellent! Funny how a problem gets so complicated and in the end is so simple. Kudos for your patience, too.
Thanks Tom! Feels great to have the GTS back with real Viper power.
It's not completely over. The constant that fed through the ground signal wire burned out #7 fuel injector driver in the PCM. The PCM is also staying open loop at all times (not a problem b/c it's still running close to stoich at cruise, WOT it is already open loop that I've tuned for). I got #7 injector to fire by wiring it into #8 injector's driver - same spot in firing order. This means #8 driver is driving two injectors. I will pull out the PCM and take a look at it to see if there is anything apparant that got damaged (broken solder, blown up capacitor, not really sure b/c I haven't worked electronics before). Otherwise, I'll replace the PCM.
I wanted to wire in #7 injector to see if the problem was fixed before tossing in another PCM and possibly burning it out. I am unsure about the durability of the circuit running two injectors, will fix soon.
