New Rear is in, what a difference

J

Jsup

Member
Went out for a couple hours with the new gears. Now, forget the typical "seat of pants" because that's just a bullshit measurement anyway. I went from D36-3.07 to D44-3.73

Let's stick to FACTUAL stuff.

I felt the tune has been a bit off. The car stumbled and bucked off the line, it stumbled and bucked at highway speed,(50-60) it popped lean. Something I have been fighting with the tune for a bit.

Now, believe it or not, the new rear solved the stumbling problem off the line, that shows the value of setting up the right engine with the right gears. Also, the lean popping has almost disappeared. There is no more bucking and stumbling at highway speeds either.

The car ran almost like a factory car. Well, not EXACTLY, but a lot like it. Smoother, more driveable. I never thought the rear would cure all the other problems. Unbelievable.

Still some work to do on the tune, but much more driveable.

Keep in mind the original L98 was happy to run at 1500 RPMs highway gears. The cam was set up for that, the intake. NOW the new motor likes to run 2200 RPMs and better. The new gears let it do that.

That's the value of considering the right combination for the drivetrain. If not matched up, it won't run right. So the switch did pretty much what I wanted it to do.

Wanted to say thanks to Grumpy who said from day 1 I needed more gear.

Couple more small items and I'm done. I'm going to convert the AC to 134 to make my life easier. The trans needs a new harness to work with the ECU, (the new trans doesn't have the lockup with the ECU since it's the wrong harness), and dress up the tune a bit.
 
jsup, thanks for posting this!



Im impressed!

can I believe my ears!!! :mrgreen:


there's actually guys on the site who both read and actually use the years of EXPERIENCE posted in some of the threads Ive posted it almost makes the work worth it! :lol:

makes me feel really good that on occasion the posts help guys

btw the rate the engine can now accelerate is partly masking the lean popping, and engine bucking conditions, get it tuned correctly and you'll see FURTHER increased power , and the car will pull harder

my sence of humor is not for everyone, but I hope you understand the post was mostly aimed at bringing a smile to those reading thru it!, and NOT designed to do anything else

thank you for posting that ITS VERY MUCH APPRECIATED :mrgreen:

http://www.tomsdifferentials.com/tomp.htm
 
Big_G said:
Now get it to the track for some real data!
Click to expand...

Need to fix the torque converter issue, it does not lock up right because I need the new harness that works with the ECU. Then finish the tune.

Someone offered me a set of slicks....I'll try it.

Not long, I'm thinking September in the cooler weather!
 
Big_G said:
Now get it to the track for some real data!
Click to expand...


practice launching and get the tire pressure adjusted so you get an equally dark, full tire width patch of black rubber on the pavement,too little air pressure usually makes the outer edges darker, to much air presure usually tends to make the center of the tire marks darker

gearratiochart.gif
 
grumpyvette said:
Big_G said:
Now get it to the track for some real data!
Click to expand...


practice launching and get the tire pressure adjusted so you get an equally dark, full tire width patch of black rubber on the pavement,
Click to expand...


The car needs an alignment. I understand that if the alignment is adjusted in a certain way, it will provide better traction.

Do you know what that is?
 
grumpyvette said:
jsup, thanks for posting this!



Im impressed!

can I believe my ears!!! :mrgreen:


there's actually guys on the site who both read and actually use the years of EXPERIENCE posted in some of the threads Ive posted it almost makes the work worth it! :lol:

makes me feel really good that on occasion the posts help guys

btw the rate the engine can now accelerate is partly masking the lean popping, and engine bucking conditions, get it tuned correctly and you'll see FURTHER increased power , and the car will pull harder

my sence of humor is not for everyone, but I hope you understand the post was mostly aimed at bringing a smile to those reading thru it!, and NOT designed to do anything else

thank you for posting that ITS VERY MUCH APPRECIATED :mrgreen:
Click to expand...

It only goes lean on the passenger side, or at least did. There are no vacuum leaks. No header leaks. No exhaust leaks that I could find.

Any thoughts? I switched the injectors from left to right. next step is to switch the harness from right to left see if the problem moves.

It's much better than it has been.
 
grumpyvette said:
check your fuses, and voltage on each bank, and verify there's no restriction in the fuel rails of bad connectors, or grounds

info in the linked info or sub links should help

viewtopic.php?f=32&t=596


viewtopic.php?f=55&t=635
Click to expand...

Here's the thing. It is only at light throttle, say 12% tps at 2400-3500 rpms

If I go say 30% TPS, no problem.

If I go WOT I get AFR of 10 on each side, which is as low as the device will read. So the fuel output seems to be there.
 
that info tends to point to sensor readings effecting the pulse duration, maybe your o2 sensors or heat sensors are giving the control unit bad data and thus the pulse duration is being changed by the computer, to compensate for that data error, why not swap the left o2 sensor or sensors to the right side and right to left or replace the o2 sensor(DEPENDS ON THE YEARS as some years had one, two or four o2 sensors)if you do so and the problem moves or disappears with the sensor swap,or replacement, you know its a defective sensor causing the problem
 
grumpyvette said:
that info tends to point to sensor readings effecting the pulse duration, maybe your o2 sensors or heat sensors are giving the control unit bad data and thus the pulse duration is being changed by the computer, to compensate for that data error, why not swap the left o2 sensor or sensors to the right side and right to left or replace the o2 sensor(DEPENDS ON THE YEARS as some years had one, two or four o2 sensors)if you do so and the problem moves or disappears with the sensor swap,or replacement, you know its a defective sensor causing the problem
Click to expand...

The next step, now that it seems to have almost totally cleared up, is to move the O2 senosr, there's only one, from the driver's side, to the passenger side.

I have been through 3 sensors. I think a swap is in order.

More information:

When I had the popping, the passenger side would go lean at the same time we got the popping.

WHILE the popping and lean condition were happening on the passenger side, the driver's side was trying to pull fuel OUT.

I had two different widebands in the car, one on each side, and on a dyno. They verified what I thought. The driver's side was good, and the passenger side was lean...

Of course the red one is the wideband on the passenger side, the one on the screen is the driver's screen.

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