Idles good drives ok til 3200-up rpm
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johnplogii
Senior citizen
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- Aug 13, 2005
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Can you monitor fuel pressure while it is missing under accelleration? If that checks good and you have swapped the coil pack AND ignition module with a known good one, I would lean towards valve springs or flat cam.
Also trace the positive cable off battery.... going to the starter..... My car had a bad engine mount on the drivers side.... and allowed the engine to rock over alot under hard acceleration.... and the batt cable got too close to the underside of the pass header.... and it melted the insulation..... it would short out only during hard acceleration.... then when the engine would rock back from the backfire.....cause no voltage from the short..... it would un-short itself.... and pick right back up where it left off.
I like to have never found that one. Have seen it on at least one other car since.
I like to have never found that one. Have seen it on at least one other car since.
johnplogii
Senior citizen
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- Aug 13, 2005
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My car did that too but it would pop once loud then completely fall on its face then recover.
I do need to hook fp gauge to windshield and drive as my cold fp setting varies by 3-4 psi. So i set it at cold idle and by warmup it is at 45. It is an early walbro. I did get some small drops of on circuit board of T+ box and they cleaned right off, then rinsed with electronic cleaner/alcohol. My MAF counts aree low even with a few seconds of wot. They are 133 (after adj for chip) so that doesnt sound right , even if motor cant eat that much air due to breaking up? Will check batt cable. Wish i had a tr freind to swithc parts from...i done trust my old shelved parts like modue...they can become bad from bad luck.
Thanks
Thanks
meanchicken
gallo vicioso
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- Oct 6, 2007
- Messages
- 5,254
If you're sure the CE light is lighting, then it's electrical.
Before you replace more parts, try to isolate an actual issue.
Make sure the base of the ign module is bolted down tight to the intake; make sure the screws holding the ign module to the base are tight; check the ground bolt at the back of the passenger side head...you can get a good look at it from under the car if needed; check the battery cables to be sure they are tight...just disconnect them and scrub off the terminals and cables with a wire brush for good measure...then reconnect good and tight; make sure the down pipe is not hitting your pos battery cable at the frame rail; check the ground cable at the turbo braket/block and make sure it's clean and tight....check all grounds....
Make sure the wiring harness off of your ign module is not chafing and shorting to that back intak bolt on the drivers side....been there...
Coil packs do go bad, so the simpe check is with a voltmeter looking for about 12K Ohm across each terminal set front to back, but if you can get a Caspers coil pack tester, it will tell you things that the ohm check can't.
Before you replace more parts, try to isolate an actual issue.
Make sure the base of the ign module is bolted down tight to the intake; make sure the screws holding the ign module to the base are tight; check the ground bolt at the back of the passenger side head...you can get a good look at it from under the car if needed; check the battery cables to be sure they are tight...just disconnect them and scrub off the terminals and cables with a wire brush for good measure...then reconnect good and tight; make sure the down pipe is not hitting your pos battery cable at the frame rail; check the ground cable at the turbo braket/block and make sure it's clean and tight....check all grounds....
Make sure the wiring harness off of your ign module is not chafing and shorting to that back intak bolt on the drivers side....been there...
Coil packs do go bad, so the simpe check is with a voltmeter looking for about 12K Ohm across each terminal set front to back, but if you can get a Caspers coil pack tester, it will tell you things that the ohm check can't.
The pass head ground terminals are hell to keep from twisting on the last trun of the bolt. A few engine jobs will break the wires from the terminals.
Re ign ground to block. I am missing the rear brace bolt, but no big deal as ohmic value is same 0.5 from any point on engine to ground.
Re ign ground to block. I am missing the rear brace bolt, but no big deal as ohmic value is same 0.5 from any point on engine to ground.
- Joined
- May 28, 2001
- Messages
- 16,603
Check end play on the crank....If the thrust is "tango uniform", then the crank sensor may be getting out of the ring far enuf to cause the problem...
Just found this on an LSX engine w/ the wheel on the crank.
Just found this on an LSX engine w/ the wheel on the crank.
wbzautocustomiz
Want my GN to go 11's one day
- Joined
- Feb 11, 2007
- Messages
- 468
update: 2 weeks of work and still aint right
Update; All scanmaster #'s in specs, New plugs and wires, coils at towers ohm out in specs 11k-13k, cam sensor dialed in and cap good,Installed caspers ground stretcher kit , cleaned scraped wire brushed re-grounded all grounds added a few extras from ign module, gas tank, chassis to battery, did walboro 340 upgrade, adjusted fuel pressure between 42-45psi line off, re-wired hot wire and replaced with a new relay, etc. etc. etc. just havent done anything with crank sensor yet but will do. It is definitly my check engine light that flickers when car breaks up at 3200-3800 rpms I did install aftermarket stereo and alarm removed all that and STILL BREAKS UP AND BACKFIRES! This is so messed up that that i have considered swapping to a old school engine and trans like small block with carbareter so all I need is gas and fire dont get me wrong I love the 231 turbo but she sending me through alot right now car is all together and pretty just wont run good like she looks. Thanks, one fustrated TR guy
Update; All scanmaster #'s in specs, New plugs and wires, coils at towers ohm out in specs 11k-13k, cam sensor dialed in and cap good,Installed caspers ground stretcher kit , cleaned scraped wire brushed re-grounded all grounds added a few extras from ign module, gas tank, chassis to battery, did walboro 340 upgrade, adjusted fuel pressure between 42-45psi line off, re-wired hot wire and replaced with a new relay, etc. etc. etc. just havent done anything with crank sensor yet but will do. It is definitly my check engine light that flickers when car breaks up at 3200-3800 rpms I did install aftermarket stereo and alarm removed all that and STILL BREAKS UP AND BACKFIRES! This is so messed up that that i have considered swapping to a old school engine and trans like small block with carbareter so all I need is gas and fire dont get me wrong I love the 231 turbo but she sending me through alot right now car is all together and pretty just wont run good like she looks. Thanks, one fustrated TR guy
Just to add some more info re: tps sensor. You need to check it under load, not with car at idle. If you can play back the scan tool readings, make sure the tps voltage readings continue to rise as you accelerate. You might have a drop out where volts go to zero and then pick up again. I had a faulty tps sensor and it caused a backfire-even blew off the up pipe!
Hang in man, consider that i can fix all my freinds cars and my other 7, but its always something on "satan" (my gn's nickname). Im the guy who buys a gm car with 130 k miles and drive it 120k more. I have waited 3.5 years for just a set of heads to be done. Best shop in town cut my exh seats so it smoked with new rebuild. Then they took over a year before i pulled them from them. Then another shop ruined them. They were nicely ported. Khai took 9 months and 3 sets of heads (ruined my 79k original set)before scraping up some from ?? that gave un-even cc's and were milled to hell and he wont call me about other problems with the deal. Are you there Khai? How long should my patience last, forever!!! Before that, Precision Machine machine shop knocked over my crank after it was polished, then charged me to cut it. Then resized rods to 3.5 thou. And charged me to clean pistons that werent usable with pin bore wear. Im very scared of their align bore on this motor, and as Chuck suggested, it may be thrust bearing causing my present problem.
So i get running after waitng 3.5 years on other's screw ups, then it gives 2 good punches before doing this. I too should get rid of it, but either way it has to be figured out. If i had had this luck on other cars, Id be riding a horse. Sorry for rant.
Can the chain part stores check our modules/coils? I know in the past they havent been able to so i doubt it.
So i get running after waitng 3.5 years on other's screw ups, then it gives 2 good punches before doing this. I too should get rid of it, but either way it has to be figured out. If i had had this luck on other cars, Id be riding a horse. Sorry for rant.
Can the chain part stores check our modules/coils? I know in the past they havent been able to so i doubt it.
wbzautocustomiz
Want my GN to go 11's one day
- Joined
- Feb 11, 2007
- Messages
- 468
I have to check but my readings at a glance shows 4.66-4.68 on scantool have to check playback and report back but,expecting snow again
- Joined
- Feb 18, 2006
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- 10,084
You guys should take a close look at the crank sensor. Check crank end play like Chuck mentioned. Also, make sure balancer is tight. Make sure sensor is tight and not making contact with the ring. Check each blade on the wheel as it passes through the sensor. Make sure non of them are bent. Replace ring, sensor and bracket if needed. If you do replace the sensor, make sure it's a ac delco from a reputable distributer like nos4gn.com
This is a real critical part and can cause all kinds of headaches if not right.
This is a real critical part and can cause all kinds of headaches if not right.
- Joined
- Feb 18, 2006
- Messages
- 10,084
Roger that. Chip and ECM need to be ruled out.
wbzautocustomiz
Want my GN to go 11's one day
- Joined
- Feb 11, 2007
- Messages
- 468
Crank sensor
Crank bolt tight no play that I can detect and ordered a crank sensor from caspers already just waitin to put on and I have read up on crank sensor adjustment with the "ring" etc. but i wish there was more info on exactly where to place shim etc. just a vague instruction an "how to" I am having trouble adapting to all this stuff on my TR Thanks again guys
Crank bolt tight no play that I can detect and ordered a crank sensor from caspers already just waitin to put on and I have read up on crank sensor adjustment with the "ring" etc. but i wish there was more info on exactly where to place shim etc. just a vague instruction an "how to" I am having trouble adapting to all this stuff on my TR Thanks again guys
Its fixed. It took trying 3 coils to defeat it. I had tried one with good tower ohms...same exact result. Then found one with bad tower ohmage that i had from a junkyard on an Olds. It worked , and funny thing, after warmed up, the open ohmage went to 135k ohms. I still am wary about the code 42. Wonder whats next.
Thanks, and good luck to wbzautcustomsz.
Thanks, and good luck to wbzautcustomsz.
