LT4 LT4 Engine Problems?

[B17Crew]

Chris, if you are still interested in the LT4, I’d drive a few more to compare trannys. The one you drove may have been in need a fluid change. Tuna made a good point; changing the transmission fluid can make a difference. I noticed a change in my tranny when I changed the fluid too. Shifting was noticeable smoother.

Before I bought my LT4, I test drove a LT4 Collectors Edition that had a very smooth shifter... but alas, the previous owner was rough on the interior items, needed new seats, carpet... etc. The ZF is not a snick-snick transmission, it’s a little more heavy handed than that.

Sixth gear -- shouldn’t be used below 65 mph. According to Gordon Killebrews book Top 50 Questions from Corvette Owners and Dealers.

Good luck on your search!

B17Crew

 

[LT4BUD]

The car simply has a dead feeling in 6th, even though you are getting great economy etc etc etc. The problem is especially noticeable on freeways around the city, where there is often a need for pretty sharp acceleration even when at freeway speeds, and a need to quickly slow down then speed back up.
Chris Kennedy
Houston, Texas

I quess we all have are different driving styles....but certainly one of the great things about the LT4 is its ability to run smoothly even down around 1000rpm and still rev easily to red line.....6th gear = 30+mpg.....I like...acceleration....lets see 108 or so mph in 3rd gear around 13 seconds flat

I wonder how many cars could beat an LT4 in 6th gear at 60mph.....BTW you can always downshift if want to accelerate...DEAD FEELING????????

You can always go to 4.10 gears...I did....but I still don't understand the problem with 6th gear, it is for cruising not racing....I used it regular even below 45 mph....LT4 is just fantastic

 

[Vettelt193]

6th gear 'is what it is'. The 6 speed corvettes have a double over-drive. ("drive" is usually considered to be 1:1 ratio, that is what 4th gear is. 5th is .75:1 and 6th is .5:1).

It is a good thing overall, because if you want to go to 4:10 gears (which is what I think the car is built for) you don't lose much gas mileage because of the huge overdrive. If you do a lot of highway driving, keep the stock gears and get great gas mileage. If the car has a 'dead' feeling, you may have shifted too soon... keeping the RPM's too low, especially in town, isn't good for the engine because of increased cylinder pressures.

The shifter on the ZF is a pretty good one too... definitely drive another one, I haven't driven one that isn't precise

 

[JEFNLSA]

I quess we all have are different driving styles....but certainly one of the great things about the LT4 is its ability to run smoothly even down around 1000rpm and still rev easily to red line.....6th gear = 30+mpg.....I like...acceleration....lets see 108 or so mph in 3rd gear around 13 seconds flat

I wonder how many cars could beat an LT4 in 6th gear at 60mph.....BTW you can always downshift if want to accelerate...DEAD FEELING????????

LT4 is just fantastic

My sentiments exactly....
I commute in freeway traffic everyday and I keep it in 5th unless I hit a good open stretch, 65mph or above, where 6th applies. For aggressive/controlled driving, I'm shifting all the time. I'd love to go to 4:10's someday but the 3:45's are more than adequate for my needs. I sure wouldn't want to have the 3:07's that some of the 6spd's have.
Before I even drove a Vette, I knew that I wanted the LT4 and now that I own one I know I was right. For the extra money (LT4) it was well worth it.
What a motor!!!

 

[Hib Halverson]

1-4 skip shift is bypassed by unplugging the wire hanging on the bottom of the tranny... takes 5 minutes.
(snip).

This is not correct.
The LT4 has OBD2 emissions controls and will set a code if you simply unplug the skip-shift solenoid. You have to install one of the "skip shift" eliminator products which "fools" the ECM into "believing" the solinoid is connected.

On 89-95, you can simply unplug the solenoid.

 

[Wake]

This is not correct.
The LT4 has OBD2 emissions controls and will set a code if you simply unplug the skip-shift solenoid. You have to install one of the "skip shift" eliminator products which "fools" the ECM into "believing" the solinoid is connected.

On 89-95, you can simply unplug the solenoid.

Are you sure about that??? I didn't think it was connected to the emission system... I unplugged mine on my 96 and didn't set any codes... I've also heard from a few other LT4 owners that didn't have that problem either...

Is there a Pxxx code for it???

 

[LT4BUD]

Not sure about this, so I am going out on thin ice, but I think on OBD2 it is possible for the ECM to be reprogrammed to ignore unplugging the skip shift or maybe even defeat the skip shift with it still plugged in ..........

Some people out there made a lot of money if all you had to do was unplug the connector....so all the ads said & I am pretty sure just unplugging the connector on a stock LT4 will set a code

I bought & installed a skip shift elimintator plug for my LT4....

 

[Roadster Guy]

Richard Newton in his book says no can do on a 96!

Are you sure about that??? I didn't think it was connected to the emission system... I unplugged mine on my 96 and didn't set any codes... I've also heard from a few other LT4 owners that didn't have that problem either...

Is there a Pxxx code for it???

According to Richard Newton in his book "101 Projects for your Corvette" on Page 84, Hib is right.

On the 1996 (not prior years) you can't simply unplug it...you have to install one of the shift eliminator products to fool the ECM or you will get a service emissions warning light (SES).

 

[wx briefer]

With the plug in CAGS eliminator, one still has the dash warning for 1st to 4th shift instruction. However, with the LT1 edit, one simply deselects the CAGS and that solves the whole problem, shift solenoid AND dash instructions. I bought the eliminator before buying the LT1 edit. Anyone want my CAGS eliminator for $10?

 

[Greg@NASA]

Thanks, Greg. Yeah, I noticed about 40 mph per 1000/rpm, too. In fifth gear, about what mph per 1000 do you see?

/s/ Chris Kennedy

Houston, Texas

Chris, about 33 mph per 1,000 rpm.I go to San Antonio a couple times a year, 6th gear is great on long open spaces, and downshifting is fun , but there is enough torque to pull.

Greg

 

[Vettelt193]

With the plug in CAGS eliminator, one still has the dash warning for 1st to 4th shift instruction. However, with the LT1 edit, one simply deselects the CAGS and that solves the whole problem, shift solenoid AND dash instructions. I bought the eliminator before buying the LT1 edit. Anyone want my CAGS eliminator for $10?

I may... do you still have it? I can let you know tomorrow