Slowhawk

iTrader: (12)

I've tuned many F-body's but this is the first Vette.
The problem at hand.Installed a TR224 on 112.Did the ussual tuning ie idle,timing ect.
The problem I'm having is hot start and when you rev it the idle drops to 200-400rpm then goes back up.It did die on me once.
This could be fixed on a F-body by drilling the TB but I know not to drill the TB on the Vette.
Would the fix be the Idle air table??
Other than this problem the car runs great.

C5kid

iTrader: (12)

did you try an idle relearn w/ it? that is how you handle alot of idle problems w/ C5's

here are the directions

Just remember to do a idle relearn. Turn the key on but don't star the engine. Remove the number 16 & 23 fuses from the underhood fuse box. Turn the key off. Replace the number 16 & 23 fuses. Start the car and let it run @ 175 degrees or warmer for 5 minutes. Shut down the engine for at least 30 seconds, then drive the car for about 30 miles at varying speeds. If you do this kind of low bugget mods you will feel a big difference in the seat of your pants, and ET's. Good luck have fun.

Slowhawk

iTrader: (12)

I'm under the impression it is not an idle relearn problem.
The car idles perfect.Just for 4 seconds on hot start and when the revs come down it surges a couple times then catches itself and idles perfect again.
Looks like the revs just need to come down slower,I've already played with the followers with no results.

Bink

Good advice. Here's the "Idle Relearn" from a C5 manual compliments of Patches :
Automatic Transmission:
1 Turn off the ignition

2 Restore the PCM battery feed

3 Turn Off the AC controls

4 Set the parking brake and block the drive wheels

5 Start the engine

6 Allow the engine coolant temperature to reach 176 degrees F

7 Shift the transmission selector into the drive range

8 Allow the engine to idle for 5 minutes

9 Turn on the AC controls (Omit for 2000-01 model)

10 Allow the engine to idle for 5 minutes (Omit for 2000-01 model)

11 Shift the transmission selector into Park

12 Allow the engine to idle for 5 minutes (Omit for 2000-01 model)

13 Turn off the AC controls (Omit for 2000-01 model)

14 Allow the engine to idle for 5 minutes

15 Turn off the engine for 15 seconds


Manual Transmission:

1 Turn Off the ignition

2 Restore the PCM battery feed

3 Turn Off the AC controls

4 Set the parking brake and block the drive wheels

5 Transmission in neutral

6 Start the engine

7 Allow the engine coolant temperature to reach 176 degrees F

8 Turn on the AC controls (Omit for 2000-01 model)

9 Allow the engine to idle for 5 minutes (Omit for 2000-01 model)

10 Turn off the AC controls (Omit for 2000-01 model)

11 Allow the engine to idle for 5 minutes

12 Turn off the engine for 15 seconds

Good Luck.
joel

Bink

On my car, with a big cam, it will plummet thru idle - if I don't do an idle relearn. Idle relearn sets the idle throttle position to provide proper airflow at idle RPM. You can see this if you scan TPS during relearn. I assume it sets the target RPM and decay accordingly. FWIW.
joel

Slowhawk

iTrader: (12)

Thanks,I did the relearn and now its great.

c5ls1vette

iTrader: (6)

How come you do not drill a hole in the throttle body of a corvette, alot of people on the corvette forum drill one.
Please enlighten me, I am just trying to learn.

thanks,

66ImpalaLT1

I have never drilled a hole with my T1 cam (221,.558,112) and I only have a slight surge in open loop with the air conditioning on. Adding timing at idle really helped my car.

Bink

C5 is Fly-by-Wire. Computer adjusts the throttle for idle airflow. A spring, wound on the shaft of the TB motor actually prevents the blade from closing completely-leaves a gap of 2-3 mm. Spring acts as a mechanical damper.anyhow, drilling the blade allows unmetered air to enter and, theorectically, throws off the computers analysis/adjustments.
Hope this helps some .Maybe one of the Gurus can Chime in??
joel

MNC5

I've run a few very large cams 240+ duration in my corvettes and never had to drill the TB. If the idle is bouncing around, you missed something with your tuning. Check all the tables for smooth transitions from one cell to another @ idle