Still breaking up and backfiring
I'm going to run it with no boost and see what happens also going to try it with a smaller pulley depending on the results with no boost.
Thanks for all the ideas hopefully the problem will finally turn up we'll have it well documented for others.
Interesting would you say the car did the same thing where it lost all power at high rpms and then proceeded to sputter die and backfire. If so I'll replace the injectors ASAP of course I'll have to probably retune it.
Yea no kidding about the crank I can't imagine the stress this is putting on my engine trying to diagnose this.
As for the + draw..What does the batt voltage show on the logs?? [I don't have HPT]
Batt in the trunk? How are the cables run? Using the body as a ground?
Can you set up a pid to log fuel psi?
Last edited by Old Geezer; Aug 1, 2010 at 06:34 AM.
Someone had devised a way to test wheel run out thru the sensor hole, comes to mind.
A bore scope could allow a look, w/o disassembling the engine?
Off the cuff: Does the t-400 have the converter circuit modified to control psi?
Excessive psi will push the verter off the support, and can trash the thrust brg.[Many v-sicks Buicks suffered this fate!]

Could it be, the thrust is worn enuf to allow the crank sensor wheel to move far enuf to cause the signal loss?
We logged fuel psi by using a oil pressure gauge and a hp tuners PID it was doing like it should.
Excessive psi will push the verter off the support, and can trash the thrust brg.[Many v-sicks Buicks suffered this fate!]

Could it be, the thrust is worn enuf to allow the crank sensor wheel to move far enuf to cause the signal loss?
You lost me a little bit there I'll try my best to answer I don't know much about different types of converters and transmissions. I installed my converted and took it on and off a few times it doesn't have anything hooked up to it or the transmission it's all mechanical (hope that answers what your asking).
Last edited by laughatrice; Aug 1, 2010 at 09:24 PM.
We logged fuel psi by using a oil pressure gauge and a hp tuners PID it was doing like it should.
Excessive psi will push the verter off the support, and can trash the thrust brg.[Many v-sicks Buicks suffered this fate!]

Could it be, the thrust is worn enuf to allow the crank sensor wheel to move far enuf to cause the signal loss?
You lost me a little bit there I'll try my best to answer I don't know much about different types of converters and transmissions. I installed my converted and took it on and off a few times it doesn't have anything hooked up to it or the transmission it's all mechanical (hope that answers what your asking).
If I'm following you correctly you mean excessive pressure inside the converter causing it to move away from the transmission towards the thrust brg causing damage. I'm not sure I assume if I pulled the transmission this would be fairly obvious where the converter meets the engine. I have a spacer in between my converter and the crank converter needed it for an LS1. The clearance was right though when I checked. This is the first thing that actually pertains to when all this started I had just changed out the converter first time I ran it after I swapped it so it caught my attention.
Check the crank end play. If it's way too much, the crank sensor / wheel may be out of line enuf to cause this problem..
http://www.turbobuick.com/forums/tra...s-big-ls2.html
Camarod may have a good point. I think that 12.5v is low. When under boost, the load on the plugs/coils/wiring goes up. [hi cyl psi.] I'd want to see at least 13.2+.
I took my voltmeter through the fusebox and got pretty consistent readings some of the fuses were a few tenth's lower than other but I don't think too significant.
Check your pigtails and make sure that they are making good contact on your sensors. I just discovered this problem with my TPS today. It has driven me batshit crazy for the last couple months trying to figure out what was going on. Totally intermittent.
The Best V8 Stories One Small Block at Time
Couple observations while driving around it only seems to do it when the engine becomes unloaded during wheel spin. It's like the PCM can't keep up with rapid changes of engine load, RPM and boost. If the car is rolling about 40mph or so and I go WOT it seems to be fine and just pull on along it's only at low MPH usually. Any thoughts?
Any ideas to where this is orginating from I'm still doing the trial and error method but I'm hoping this is my problem it doesn't sound normal to me.
Just checking things since I've already replaced the crank sensor should I replace the cam sensor too. I know it's generally associated with starting issues but fine once running but if it was intermittent could it cause issues up high?
If this isn't it I'm going down the crank reluctor wheel and crankshaft end play route but that's a big job.
I started thinking the reluctor wheel is screwed up so I started checking out my transmission to block connection and the damn dowel pins for the tranny have fallen out I'm not sure if this is causing some flex in there when the engine torques over but it's not good so I'm going to replace those.
It's not a big job. Just bar the balancer back and forth. If it moves more than a "RCH", the thrust is gone.
How in hell did the dowel pins get gone??? Have you knocked them out, before, and they were loose?
No pins, and the trans will move around! The bolts are not a register for the trans case.
It's not a big job. Just bar the balancer back and forth. If it moves more than a "RCH", the thrust is gone.
How in hell did the dowel pins get gone??? Have you knocked them out, before, and they were loose?
No pins, and the trans will move around! The bolts are not a register for the trans case.
Drill a hole from the edge of the block, into the dowel pin bore. Tap it for a set screw. Install the dowels w/ locktite, run the set screws in, and U R done...





