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· efil4aggin
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Discussion Starter · #21 ·
i lost several cilinders about a year ago ,but it moved and was different cilinders ... took the grounds off both heads sanded the head a little and put them back on...the left side ground is on the back of the head ,a ratchet wrench works best .
I did the grounds as well. That left side one is easy to do (with all things considered) using a box end 13 with a ratchet on one side.
Funny thing I noticed last night, after all the starting of the car, to check if what I had done fixed it ...I no longer have a check engine light. Whatever was causing the CEL, it must not be present in the past 3 starts (think that's how many the computer must see to clear a CEL) Car still only runs on the first 4 cylinders though, LOL.
Going to marinate on some ideas/thoughts for the rest of the week. If I'm still drawing a blank, I'm going to look into trading it in. Not something I relish doing but it's becoming too costly to keep sitting in my garage (damn rental car is costing me over $700 a month!).
 

· Suffering Fools
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Did you test the injectors with teh PCM firing them?

Pull the fuel rail out and put some blue shop towels under the injectors. Unplug the coil packs and try to start the car for a couple seconds and see if the towels are wet under all the injectors.
 

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Did you test the injectors with teh PCM firing them?

Pull the fuel rail out and put some blue shop towels under the injectors. Unplug the coil packs and try to start the car for a couple seconds and see if the towels are wet under all the injectors.
I agree on this test. I once had an older Mustang that seemingly had pulse to the injectors but would not start. Ended up swapping out the ECM and it started just fine. Granted, it was different vehicle with a completely different electrical system, but the experience may be similar in this case.
 

· Was Here
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:popcorn2: rental for a month at $ or take the car to fix for $ :bomb:
 

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I'm going to look into trading it in. Not something I relish doing but it's becoming too costly to keep sitting in my garage (damn rental car is costing me over $700 a month!).[/QUOTE said:
There are plenty of good mechanics around H-town that know LS motors. If you trade in your GTO you will get hosed and $700 will be peanuts. Buying a new car is always, always a bad investment. We buy new cars for emotional reasons. Bite the bullet and bring it in. If you drive it for another year or two you will be money ahead.
 

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at this point, its wiring or ECM I think. A high resistance in the injector ckts (power or ground) Is the most likely. An O-scope on the injector circuit would reveal this.

because of the programing involved, its not feasible to just swap in a Known-good ECM.

So the final test is to power atnd ground each injector briefly using the ECM connector. This will test the injectors and all wires simultaneously, leaving only the ECM out. You'll have to hot wire the fuel pump at the relay to get fuel pressure. No big there.
 

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Yep, since you drive an 05, to swap the ECM you need a dealer with a Tech II to synch up all the modules (PIM?, etc). But id bet money thats what it is. I dont have a wiring diagram in front of me, but its hard to imagine a wiring fault only effecting two half banks. Common grounds per bank and all that.
 

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Yep, since you drive an 05, to swap the ECM you need a dealer with a Tech II to synch up all the modules (PIM?, etc). But id bet money thats what it is. I dont have a wiring diagram in front of me, but its hard to imagine a wiring fault only effecting two half banks. Common grounds per bank and all that.
Ive honestly never seen something like this. Ive seen plenty of stupid shit that shouldnt happen. but not this.

Things that are new and different excite me. this gets a bonus for being really fucking weird.

If the injectors fire when being powered at teh ECM connector, and the ECM powers and grounds are good, Its 99.999% certain its the ECM at fault. that missing .001% is from the fact that nothing is ever certain, and not doing the tests myself. Trust but verify and all that.
 

· efil4aggin
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Discussion Starter · #29 ·
Once I again I owe THANKS!

Yep, since you drive an 05, to swap the ECM you need a dealer with a Tech II to synch up all the modules (PIM?, etc). But id bet money thats what it is.
Hmm, never knew that about the computer swap (having to use the Tech II for more than CPS and CKPS programming). That kind of blows ... I've got a thing or 2 left to try (will look into powering the injectors as KTG suggested ... though I swear all the injectors are receiving a neg pulse from the computer).
Curious, does anyone know the going rate for an ECM in these cars and what's a TECHII re-write generally run? I'm guessing none of this can be done with HPT? I ask because my car currently has a "Tune By Chuck" (was done a few years back when I installed the cam, UDP, LT's and Svede intake) and I'm going to need to see him again as well I guess.

I dont have a wiring diagram in front of me, but its hard to imagine a wiring fault only effecting two half banks. Common grounds per bank and all that.
I have, for the most part, a complete service manual on file
http://www.mediafire.com/?5q4xnwtum6kgspd

I scoured that thing for hours while working in Woodward Ok. last month (not much to do when sitting in a hotel room). The injector/coil wiring is per bank (pretty simple layout). Nothing correlates on why only the back 4 won't fire.

Ive honestly never seen something like this. Ive seen plenty of stupid shit that shouldnt happen. but not this.
Wow, that makes me even less enthused about finding the issue. I respect the fact that you're an actual Technician (that diagnoses these things regularly I take it). Yet you take the time out to come chat about cars on here (that would be akin to me being on Wind Turbine sites discussing parameters ... which I never do, LOL).
I'm going to take some measurements to/from the computer to each injector plug > < computer pin. I highly doubt 4 just all of a sudden had an increase in resistance. But I do want to say I crossed all my "t's and dotted my i's.

Things that are new and different excite me. this gets a bonus for being really smurfing weird.
Well I propose a trade and sign with ya. You can have this one and I'll take your running one ... No questions asked :)

If the injectors fire when being powered at teh ECM connector, and the ECM powers and grounds are good, Its 99.999% certain its the ECM at fault. that missing .001% is from the fact that nothing is ever certain, and not doing the tests myself. Trust but verify and all that.
I've checked the injector wiring with two different sources. Once with a noid light. Secondly with a computer safe test light. It's simply a 12v powered test light with resistors and LED's. Attach it to positive it lights red. Attach it to negative it lights green. The fact that it has LED's allows it to be used like a noid light to read the negative pulse from the computer to the injectors. The non firing ones all have positive from battery and are getting a pulse from the computer.
For the coils, they are all firing which I verified with my spark tester that goes in line between the coil and plug.
Since i haven't actually measured ohm's between the injector clips and the computer plug, I'm going to do as you suggested (because it takes less than 3 volts to energize a LED so there could possibly be a high resistance. It would allow my Test Light to flash pulses but maybe the voltage is too low to open the injector correctly).
Oh yeah ... On buy a NEW car ... Not an emo purchase by me.
NEVER have i owned a "new" car (Dave Ramsey and Tom Martino fan here). My GTO was purchased by me August of 06 with 11K on the clock for $21.5K (financed out at 24.5) I owe next to nothing on the car at this point and it has less than 55K on the odometer.
If I am forced to trade it off, I'd purchase a Vette (07-09 is in my price and payment range) or a 330i Beemer (fun little twin turbo inline 6 and the 07-08 can be had for under 27k with low miles).
I'm really not trying to come off as a know it all or as being better then anyone at anything (though I am better then anyone that doesn't put forth efforts!). I realize how much I don't know every day I live (age does that to you, LOL). BUT I can do the basic math and if the repairs starting approaching the $3k mark (including rental car at this point) I'd be money ahead to trade it in. Would I get the full value of it, NOPE but I'd easily get 8K into the trade (have you seen what GTO's are selling for right now ... seems they went up in value for some reason). I was without a car note for 9 years before I bought the GTO and had kinda looked forward to being that way again for a while. But, the best laid plans of Men and Mice ...
Anyhow, no more doom and gloom thoughts (sell car/buy another one) ... I'm going to think positive and hope I discover something this weekend :D
 

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(because it takes less than 3 volts to energize a LED so there could possibly be a high resistance. It would allow my Test Light to flash pulses but maybe the voltage is too low to open the injector correctly).
This right here is my major line of thought. been burned by that before. Which is why Im such a huge fan of voltage drops as a testing method. I almost never look at ohms, relay coils, and various component tests on the bench is it. On the car, on active circuits, one can build a very good picture of whats going on with voltage drops.

Also, I was talking with a coworker this AM, and aside from the stuff we are already looking at, he suggested the possibility (though slim) of a fractured cam that still turns. It broke, but is out of time just enough to fuck up firing.
 

· Suffering Fools
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I was just asking because I was curious. I wasn't trying to help troubleshoot.
 

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Also, I was talking with a coworker this AM, and aside from the stuff we are already looking at, he suggested the possibility (though slim) of a fractured cam that still turns. It broke, but is out of time just enough to smurf up firing.
I think this is highly unlikely. If the valve events were out of time, he would likely have backfiring, popping, etc. that would be occurring on those cylinders. I think a broken cam can be completely ruled out.
 

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I think this is highly unlikely. If the valve events were out of time, he would likely have backfiring, popping, etc. that would be occurring on those cylinders. I think a broken cam can be completely ruled out.
Agreed. Just demonstrating the current proximity to level 5 WTF in which we find ourselves.

FWIW, old Mercury Villagers with the free-wheeling VG30E will break the crank but still pump the #3 & #6 piston just fine, albeit 30* or so off.
 

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Have you checked your muffler bearings? I'm just asking because I am curious. I am not trying to help troubleshoot.

Gerry
 

· Suffering Fools
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Have you checked your muffler bearings? I'm just asking because I am curious. I am not trying to help troubleshoot.

Gerry
Don't make fun.
 

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Intermittent CEL can be caused by a vacuum leak.


Also, shot in the dark here, But I had a Crown Vic that has a 'limp home' mode in the ECM that shuts down fuel to the rear 4 cylinders in the event of an overheat to help reduce engine temperatures.

GTO have anything like this?
 

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Intermittent CEL can be caused by a vacuum leak.


Also, shot in the dark here, But I had a Crown Vic that has a 'limp home' mode in the ECM that shuts down fuel to the rear 4 cylinders in the event of an overheat to help reduce engine temperatures.

GTO have anything like this?

No, it doesnt have a limp home based on ECT. Also, ford doesnt shut down a certain 4, its any four. It only does it for a few revs per set.
 
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