TCU and 4L80e quesitons

[Cameron@TCI]

One more question. How important is the geometery of the cable setup on the TPS? I'm using a Quadrajet that was not designed for use with a kick down cable. I added the stud to attach the cable for the TPS to the throttle linkage, just ahead of the hole where the return spring is connected.

The geometry is important, but what is most important is that you have about .5 volts at an idle, and that the TPS gives you a clean sweep to 4.5-5 volts at WOT.

If the TPS is reading slow or never getting above a certain % it could cause some oddities.

Thanks,

[Cameron@TCI]

Also check and replace the EPC solenoid.

Thanks,

[critter]

Thanks for the information.

[Cameron@TCI]

Let me know what you find out when you test the force motor and EPC.

Thanks,

[critter]

I made some progress today. I'd taken a break from this project because I tend to screw up more when I'm tired of it all.

After airing up the flat tire I realized that I should recalibrate the speed after putting the new wheels and tires on. They are slightly shorter. While I was at it I installed that profile that TCI sent and I'd upped the line pressure by 10 percent. Then I recalibrated the TPS for good measure.

I took it for a drive and watched the pressure gauge. The pressures were more in the 120 psi range when driving now and the "shift" was firm but not harsh. I say "shift" because it would make the 1-2 shift as you'd expect. However, I never could get it to make the 2-3 shift unless I let off the gas. It seemed that I needed to be above about 30mph for the 2-3 shift to kick in. I could then cruise in 3rd unless the speed dropped below that 30mph mark again. So I'd take it above 30mph, release the gas briefly and then cruise. See what I mean?

I went into the shift point tables and tried dropping the upshift point on the table by 10 percent but it didn't seem to help any. I fiddled around with some other ideas but nothing seemed to help.

I think I'm on the verge of having this worked out if I can work through this upshift problem. I'm sure I'll need to do some minor tweaking after that but I'd sure like to get it all the way through the gears, up and and down one time! Any thoughts?

I made some progress today. I'd taken a break from this project because I tend to screw up more when I'm tired of it all.

After airing up the flat tire I realized that I should recalibrate the speed after putting the new wheels and tires on. They are slightly shorter. While I was at it I installed that profile that TCI sent and I'd upped the line pressure by 10 percent. Then I recalibrated the TPS for good measure.

I took it for a drive and watched the pressure gauge. The pressures were more in the 120 psi range when driving now and the "shift" was firm but not harsh. I say "shift" because it would make the 1-2 shift as you'd expect. However, I never could get it to make the 2-3 shift unless I let off the gas. It seemed that I needed to be above about 30mph for the 2-3 shift to kick in. I could then cruise in 3rd unless the speed dropped below that 30mph mark again. So I'd take it above 30mph, release the gas briefly and then cruise. See what I mean?

I went into the shift point tables and tried dropping the upshift point on the table by 10 percent but it didn't seem to help any. I fiddled around with some other ideas but nothing seemed to help.

I think I'm on the verge of having this worked out if I can work through this upshift problem. I'm sure I'll need to do some minor tweaking after that but I'd sure like to get it all the way through the gears, up and and down one time! Any thoughts?

can you please take a datalog at a consistent 20-30 percent throttle for 0-40mph. Also send your phone number or give me a call. thanks

[critter]

Russ, can it be done with the rear up on jackstands or do I need to be on the road? It's hard to drive and watch all the gauges at the same time.

Russ, can it be done with the rear up on jackstands or do I need to be on the road? It's hard to drive and watch all the gauges at the same time.

No need to watch gauges just have to select datalog and start it and drive the car down the road and back. Can not be done on jack stands. Also when you said you changes the line pressure what did you change it to? because i had it turned up pretty high and did not want you to change any thing while we were testing it.

[critter]

I emailed you what I gathered yesterday with that refined profile you sent. I mis-spoke about the line pressure adjustment it seems. I think this is the one you sent me, unaltered. I loaded the one where I adjusted pressure but went back and overwrote it before driving it. I'll attemp to drive it again and datalog one more time tonight, after work.

[critter]

OOps!

Russ came over and we spent the morning tuning. He couldn't figure out why the thing needed so much throttle position to achieve a shift. Then he asked me about the carb. When I said Quadrajet the light went on. The small primaries require a lot of throttle position to achieve the same amount of "go" from the car. They don't tune much for Qjets. There you go.

I drove, he worked the computer and by the end of the morning he had it shifting pretty nicely. He had to pull the shift points WAY down because of the carb and torque of the motor. Then he said we needed to run it WOT a few times just to see what we had.

I still had the pressure gauge tapped into the transmission. On the second WOT it spun until 30mph (data logs are cool) and then hooked. It started hunting between gears so he had me get out of it. When I did, the pressure spiked and WOOSH! The pressure blew that hose off the fitting that went into the transmission. AT fluid hit the exhaust and we had quite a smoke show going.

The good news was that I was out of it when it let go and we just coasted down to the foot of the hill. I don't think I really hurt anything. I called AAA and had the roll back operator dump it back in the garage. I'll crawl under there, pull the remains of that fitting and plug it now that I know we're in pretty good shape on the tune. The I'll fill it back up with fluid and go again.

it's always something.


My snail trail:



The offending gauge:



I'll have a mess to clean up under the car:



Russell Culver from TCI was still tuning on it after the incident. Thanks Russ!:



At least I had time to make a photo of the car with the new wheels and tires while I waited: