Need a tuner for a mild '93 corvette

[jay72]

Heres a log file.
Seems better at low to mid range, stronger acceleration.
WOT is slower, wideband shows 11.1:1
I did lower the idle a little, changed tcc lock/unlock.

I'm thinking of switching to heated 02's.

[Fast355]

Heres a log file.
Seems better at low to mid range, stronger acceleration.
WOT is slower, wideband shows 11.1:1
I did lower the idle a little, changed tcc lock/unlock.

I'm thinking of switching to heated 02's.

I fattened the VE table at WOT higher RPM up to what I felt was safe for a startup tune and left the PE fuel multipliers stock.. That being said with the air/fuel at 11.1 to 1 it can lean out quite a bit and still be safe. Can probably find another 20hp in leaning it out to a safe level. I will look over the log and send you one with the PE fuel multiplier set for about 12.5 around peak torque at 4,000 and about 13.2 at peak HP about 5,800. Once you log that and let me know what the wideband is reading the VE tables can be worked a little. I retarded the timing a couple of degrees up top as well as I didn't want to go crazy without knowing the WOT air/fuel ratio. Lean + Timing = BOOOM!

[jay72]

I fattened the VE table at WOT higher RPM up to what I felt was safe for a startup tune and left the PE fuel multipliers stock.. That being said with the air/fuel at 11.1 to 1 it can lean out quite a bit and still be safe. Can probably find another 20hp in leaning it out to a safe level. I will look over the log and send you one with the PE fuel multiplier set for about 12.5 around peak torque at 4,000 and about 13.2 at peak HP about 5,800. Once you log that and let me know what the wideband is reading the VE tables can be worked a little. I retarded the timing a couple of degrees up top as well as I didn't want to go crazy without knowing the WOT air/fuel ratio. Lean + Timing = BOOOM!

I do appreciate your help. It helps to see what changes you make and what happens, I can learn from that.

[Fast355]

I do appreciate your help. It helps to see what changes you make and what happens, I can learn from that.

Repost the newest .bin with your idle/tcc changes.

Also your 02s should be heated on the LT1 IIRC.

[Fast355]

You will either have to paste in your idle and TCC changes or paste in my new VE tables and PE% change tables. I used the BLM histogram and averaged both banks to help dial in the idle/low speed VE table. The PE% change was commanding a PE air/fuel ratio of around 11.2:1 at WOT. I leaned it out to 12.5 around peak torque and 13:1 up top. I also noticed your trans seems to shift early on the 2-3 shift at WOT. Under 5,000 rpm. The 93 F-car I messed with would shift at 5,600-5,800 on the money. Are you sure the TV cable is adjusted properly? Also check to make sure the correct governor is installed. Finally the 700r4s are bad about a condition where the throttle valve spring gets weak called short spring syndrome. SSD or an improperly adjusted TV cable could cause transmission failure much sooner than it should. Has it always shifted that early?

[jay72]

You will either have to paste in your idle and TCC changes or paste in my new VE tables and PE% change tables. I used the BLM histogram and averaged both banks to help dial in the idle/low speed VE table. The PE% change was commanding a PE air/fuel ratio of around 11.2:1 at WOT. I leaned it out to 12.5 around peak torque and 13:1 up top. I also noticed your trans seems to shift early on the 2-3 shift at WOT. Under 5,000 rpm. The 93 F-car I messed with would shift at 5,600-5,800 on the money. Are you sure the TV cable is adjusted properly? Also check to make sure the correct governor is installed. Finally the 700r4s are bad about a condition where the throttle valve spring gets weak called short spring syndrome. SSD or an improperly adjusted TV cable could cause transmission failure much sooner than it should. Has it always shifted that early?

The transmission has always shifted too early in my opinion. It is the original trans with the vin stamped on it, it was rebuilt at some point before I got the car, I've had it out and went through it, installed a transgo 2&3 kit, modified the governor weights, etc. I've built a few 700R4's usually modify the governor to get the shift points set, but on this car getting the cover back on is a nightmare and I haven't finished tuning the governor.

[Fast355]

The transmission has always shifted too early in my opinion. It is the original trans with the vin stamped on it, it was rebuilt at some point before I got the car, I've had it out and went through it, installed a transgo 2&3 kit, modified the governor weights, etc. I've built a few 700R4's usually modify the governor to get the shift points set, but on this car getting the cover back on is a nightmare and I haven't finished tuning the governor.

Roger that! Honestly for that very reason I put a 4L60E into the 90 TBI F-car I was working on and used a 95 TBI truck computer to run it.

[jay72]

Repost the newest .bin with your idle/tcc changes.

Also your 02s should be heated on the LT1 IIRC.

They are factory one wire sensors, I replaced them approx 2500 miles ago.

[Fast355]

They are factory one wire sensors, I replaced them approx 2500 miles ago.

I guess I am just so accustom to playing with the last of the TBI and later LT1s that have factory heated sensors.

You do have a weird BLM split that could be numerous things. You could have a small exhaust leak before or near the 02 sensor or perhaps a vacuum leak at the injector O-rings. I saw BLM value splits of up to 10 on the Left and Right bank at any given time. It was still running a bit rich at part throttle, 108 BLM in places with the Integrator bottomed out at 70ish but I like to limit what the PCM can pull, unlike whoever set the minimum BLM to 80 in your other .BIN. A couple more datalogs and revisions should smooth that out.

[bybyc5]

Not sure if the 93 Corvette is the same as the 93 Z28, but my son's 93 had single wire O2's.

[Fast355]

Not sure if the 93 Corvette is the same as the 93 Z28, but my son's 93 had single wire O2's.

Probably so, did not realize GM kept the sensors unheated that long. The TBI/CPI trucks switched in 91-93ish depending on application. Then again my brother has a 99ish Sunfire with the 2.2 and it has a single wire 02.

Generally speaking the single wire should be ok in a shorty header, but it could never hurt to have a heated sensor with the cooler exhaust temps from all the additional surface are and thinner metal.

I noticed that the Vette does not appear to use the a/c temperature input. The OP might add a wire from his 0-5 volt output on his wideband and input it into the A/C Evaporator temperature pin used of the F-body version of the PCM. Then post up the transfer function included with the wideband instructions to convert voltage to AFR. It would give the datalog wideband air/fuel mixture capability.

[bybyc5]

Agreed, My 93 K1500 16168625 has not only a single wire O2 stock....but one O2 at that, on the driver side. GM cuts corners where ever they can I guess. Heck, my K1500 doesn't even use an air intake temp sensor. One of the main reasons I am switching to the 16197427 and run $0D is to add an IAT sensor and a MAF, however the truck runs great as it is now.

Keith