LQ4 into a 3rd Gen/1972 Nova
Thread Starter
Joined: May 2007
Posts: 1,806
Likes: 46
From: Vancouver BC, Canada
Beer tomorrow night? Pick up PCM then. I'll zip over to the garage tonight and pick up my old harness for you to pillage. Text me if tmrw works for you
Thread Starter
Joined: May 2007
Posts: 1,806
Likes: 46
From: Vancouver BC, Canada
Wow looks like I forgot about this thread.
LOQ72NOVA.. the holed piece is the shock cross-member for my Glink rear suspension.
Small update, car still isn't running:
- got a 2nd "known good" (Mark heard it running in a van) PCM & plugged that in with zero tuning, car did identical wide-open injector pulse width no start
- measured continuity of all grounds on harness, all good
- inspected all grounding points, sanded fresh
- measured voltages/grounds for all harness wires @ PCM w/ harness connected to PCM (that sucked)
- cross-checked above w/ wiring diagram, appeared that all sensors needing 5V were getting it, ref grnd getting it, appropriate 12V all present.
- inspected HPtuners scans for PID inputs & behaviours when cranking, it appears that following sensors with scanner inputs were all good: MAP, IAT, ECT, RPM, O2's
- only sensor I couldn't check was VSS
- started unplugging each sensor one-by-one to see what, if anything, affected the scan
- got to TAC module, stupidly unplugged that, turns out that BRICKS the PCM if power is given to the PCM without TAC module connected.. oops
- when tried to start after reconnecting TAC, get a P0606 "internal PCM fault" DTC, as well as a P0207 (if my memory is correct) "TAC module error"
- remembered that at some point something physically fried the PCM (un-soldered connections, charred bits), so I'm thinking that charge could've back-traced its way into the TAC module as well, giving it some faulty reading that wasn't indicated by either a measured pin voltage or Throttle Position on the scanner.
New "tested" TAC module & PCM on the way, hopefully that sheds some new progress... so I see this is why they invented beer!
LOQ72NOVA.. the holed piece is the shock cross-member for my Glink rear suspension.
Small update, car still isn't running:
- got a 2nd "known good" (Mark heard it running in a van) PCM & plugged that in with zero tuning, car did identical wide-open injector pulse width no start
- measured continuity of all grounds on harness, all good
- inspected all grounding points, sanded fresh
- measured voltages/grounds for all harness wires @ PCM w/ harness connected to PCM (that sucked)
- cross-checked above w/ wiring diagram, appeared that all sensors needing 5V were getting it, ref grnd getting it, appropriate 12V all present.
- inspected HPtuners scans for PID inputs & behaviours when cranking, it appears that following sensors with scanner inputs were all good: MAP, IAT, ECT, RPM, O2's
- only sensor I couldn't check was VSS
- started unplugging each sensor one-by-one to see what, if anything, affected the scan
- got to TAC module, stupidly unplugged that, turns out that BRICKS the PCM if power is given to the PCM without TAC module connected.. oops
- when tried to start after reconnecting TAC, get a P0606 "internal PCM fault" DTC, as well as a P0207 (if my memory is correct) "TAC module error"
- remembered that at some point something physically fried the PCM (un-soldered connections, charred bits), so I'm thinking that charge could've back-traced its way into the TAC module as well, giving it some faulty reading that wasn't indicated by either a measured pin voltage or Throttle Position on the scanner.
New "tested" TAC module & PCM on the way, hopefully that sheds some new progress... so I see this is why they invented beer!
You get the new parts?
Did they fix your issues?
Any other updates?
How did the cycle turn out?
Sorry for all of the questions but you have us all on the edge of our seats waiting!
Did they fix your issues?
Any other updates?
How did the cycle turn out?
Sorry for all of the questions but you have us all on the edge of our seats waiting!
Thread Starter
Joined: May 2007
Posts: 1,806
Likes: 46
From: Vancouver BC, Canada
New PCM works.. haven't bricked it yet. New TAC module (from '06 Sierra) hooks up but doesn't acknowledge my '05 DBW pedal signal and thus doesn't actuate the TB. Switched back to original TAC module with new PCM, TB responds normally. Stock tune on 3rd PCM does identical problem (rich commanded AFR).. so it's a sensor or wire issue. I believe I may have found the problem tho. TAC module/DBW pedal control the throttlebody properly, as in TB butterfly is barely cracked open at 0% pedal, and opens fully at WOT, however both Throttle Position Sensors on the TB read 1.17V/1.03V at closed, and 3.53V/3.50V at WOT.. so there's definitely something screwy with the position sensors. Kindof very strange for both to be bad. Wonder if something physical in the rotating sensor bit got screwed causing both sensor pickups to be offset/bad. Voltages were measured against both a known-good ground as well as the reference low voltage lines, and the 5V reference power lines measure a good 5V.
Getting real tired of this car's ****, it's getting costly with 2 new PCM's, 2 sets of HPTuner credits for the their VIN's, as well as a (apparently unnecessary) new TAC module, and now a new throttlebody. Everybody fingers crossed this does the trick.
Getting real tired of this car's ****, it's getting costly with 2 new PCM's, 2 sets of HPTuner credits for the their VIN's, as well as a (apparently unnecessary) new TAC module, and now a new throttlebody. Everybody fingers crossed this does the trick.
Wow man I hadn't read your thread in a while. I had no idea you were going through these problems. WTF dude. You are just not blessed with good luck. I hope you have found the source of your issues with the TPS. That earlier post showing the "soldered" ground terminal and the screwed up PCM internals made me cringe. With all the wires I've soldered, crimped, and pinned lately, I'm bound to have similar problems somewhere.
How did you measure the TPS voltages? Is this what the PCM/HPT reports or did you probe it with a DMM? If you probed it, where and how?
You deserve to have a running car at this point.
How did you measure the TPS voltages? Is this what the PCM/HPT reports or did you probe it with a DMM? If you probed it, where and how?
You deserve to have a running car at this point.
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Thread Starter
Joined: May 2007
Posts: 1,806
Likes: 46
From: Vancouver BC, Canada
Clint.. I probed with a DMM. I took apart the TB plug, removed the individual pins I wanted to probe, and for each one jammed a piece of 20ga stainless mig wire in between the waterproof rubber grommet and the metal pin crimp, then re-installed the pins, and reassembled plug, and plugged into TB, so I could read the line voltages with TB powered on, but without needing to strip any wiring to do so.
And yes, I do deserve to have a running car at this point. Haven't been this frustrated/pissed off at it before. Pissed away the whole summer's worth of driving over a (likely small) problem that is still not 100% known.
I haven't considered TBC because that would require many changes, and up until this point I hadn't figured it was anything related to the TB setup.
And yes, I do deserve to have a running car at this point. Haven't been this frustrated/pissed off at it before. Pissed away the whole summer's worth of driving over a (likely small) problem that is still not 100% known.
I haven't considered TBC because that would require many changes, and up until this point I hadn't figured it was anything related to the TB setup.
Joe, what's new with the car? We're finally about to enter beautiful season, you're more than welcome to trailer her down here for the winter, get the kinks worked out, and drive the sh*t outta her on some open desert roads.
Can I borrow your transmission? Thread Starter
Joined: May 2007
Posts: 1,806
Likes: 46
From: Vancouver BC, Canada
Nothing new with the car. A while back I probed all the harness pins and recorded the voltages or grounds for all 160 harness-PCM pin connections. This past weekend I started labeling what each measured reading actually corresponds to on the wiring diagram, so I can see what voltage was meant for what sensor, etc, but then gave up. I've reached the limit of the minimal-teardown diagnosing I can do... time to pull the full harness and inspect each wire, inch-by-inch. There's something physically screwy, and all the sensors I confirmed work by reading them on the computer. This'll end up being a fall/winter project. I'm now focusing on getting my motorbike back on the road to enjoy what little nice weather we likely have left.
Be great if there was a spare harness laying around that someone was not using so you could plug it all in for a test...maybe put some light at the end of the tunnel.
If you can wait a few months, I might pull mine off my car and switch over to a 06' truck harness with a flex fuel sensor and E38 ECM.
If you can wait a few months, I might pull mine off my car and switch over to a 06' truck harness with a flex fuel sensor and E38 ECM.
Thread Starter
Joined: May 2007
Posts: 1,806
Likes: 46
From: Vancouver BC, Canada
It would be great if I had an extra harness, that's actually a really good idea. Is yours a mod'd stock or aftermarket harness? I could bench test a different harness in the engine bay (does that make it hood-testing? haha) if it's just as simple as a constant 12V, switched 12V, and chassis ground, then I'd try that before I'd de-loom it and strip it all apart. At the same time, there's something screwy with my harness and to fix and re-use it, I still have to pull the whole thing to inspect it.
My old stock harness has been pillaged to bits, but maybe I'll wait for you to pull yours. This thing isn't going to be driven until this is fixed, and there's no longer a big rush because the weather will be **** for the next bunch of months. I'll look into the shipping cost both ways if you can PM me you location. If it's not too bad I might just do that. But we'll be in touch regarding it.
My old stock harness has been pillaged to bits, but maybe I'll wait for you to pull yours. This thing isn't going to be driven until this is fixed, and there's no longer a big rush because the weather will be **** for the next bunch of months. I'll look into the shipping cost both ways if you can PM me you location. If it's not too bad I might just do that. But we'll be in touch regarding it.
It would be great if I had an extra harness, that's actually a really good idea. Is yours a mod'd stock or aftermarket harness? I could bench test a different harness in the engine bay (does that make it hood-testing? haha) if it's just as simple as a constant 12V, switched 12V, and chassis ground, then I'd try that before I'd de-loom it and strip it all apart. At the same time, there's something screwy with my harness and to fix and re-use it, I still have to pull the whole thing to inspect it.
My old stock harness has been pillaged to bits, but maybe I'll wait for you to pull yours. This thing isn't going to be driven until this is fixed, and there's no longer a big rush because the weather will be **** for the next bunch of months. I'll look into the shipping cost both ways if you can PM me you location. If it's not too bad I might just do that. But we'll be in touch regarding it.
My old stock harness has been pillaged to bits, but maybe I'll wait for you to pull yours. This thing isn't going to be driven until this is fixed, and there's no longer a big rush because the weather will be **** for the next bunch of months. I'll look into the shipping cost both ways if you can PM me you location. If it's not too bad I might just do that. But we'll be in touch regarding it.
My harness is a Speartech 2002 ls1 camaro harness.
Thread Starter
Joined: May 2007
Posts: 1,806
Likes: 46
From: Vancouver BC, Canada
I haven't ripped anything out yet so I'll have to check if at cranking the TB is just barely cracked open AKA idle, or if it is opened a fair amount for increased airflow, I can't remember. If it's just idle or barely cracked, I could leave DBW TB in place or hold it slightly open. I'm just wondering what happens on the PCM side when it doesn't get a complete circuit from the servo, only gets a TPS signal. That's if the '02 LS plug even connects to my DBW TB.. which I highly doubt it would. Likely still have to connect an LS1 TB, maybe see if I can borrow an LS1 one from somewhere. I'll look into it.