Hey everyone, I'm new here, as I just bought my first Vette about 3 weeks ago. I have an issue that I hope someone would be able to help me find the cause of, though it's a little weird for me to describe, so bear with me.


First off, about my car. It's a 1999 Torch Red manual transmission coupe with 46,000 miles (when I bought it, I'm already up to about 48,000). I am by no means mechanically inclined, and everything I know about Vettes (which isn't much) I've learned from YouTube and general internet browsing. All I really know about my car is what the salesman told me about it, and what I've looked around and found out. Only thing he told me as far as mods is the Blackwing air intake and a B&B exhaust. I don't think either of those would be relevant to my issue, but figured I'd mention them incase.


So now on to my issue. When I get up to cruising speeds in 6th gear, and I let off the gas and coast (either with cruise control letting off due to a hill or just manually to slow down), I get a weird thing that I can only describe as a jerk or stutter. The best way to describe the feel of it is that it's as if I was applying and releasing the brakes. I have done a little experimenting with it, and it doesn't happen when I shift it to neutral and let it coast or when I push the clutch in, so it seems to be related to the engine braking. It is less noticeable if I leave it in 5th instead of 6th, but I think that's just because the engine braking slows it down much faster. Sometimes it's more subtle than others, but it happens consistently.


My father in law thought it might just be the fuel filter (which I doubted), but we changed it this weekend, and it's still doing it. I'm pretty much at a loss at what this could be, so if anyone has any ideas, I'd love to hear them.

 

See if you have any codes stored.. Use your DIC to get your codes I attached info on how to do it

 

what speeds ??? might be going too slow and bogging ???? 6th is best above 70 plus IMO !!!!

 

Being able to pull up these codes is super cool. I went through them, but none of them seem relevant to this particular issue, but here they are anyway incase I missed something or looked up something wrong:

• 10-PCM
  • NO CODES
• 28-TCS
  • NO CODES
• 38-RTD
  • NO CODES
• 40-BCM
  • NO CODES
• 58-SDM
  • NO CODES
• 60-IPC
  • U1160 H
• 80-RADIO
  • NO CODES
• 99-HVAC
  • B0367 H
• A0-LDCM
  • B2252 H
  • B2282 H
  • B2284 H
  • U1064 H
• A1-RDCM
  • B2253 H
  • B2283 H
  • B2285 H
  • U1064 H
• A6-SCM
  • B2860 H
  • U1255 H
• B0-RFA
  • U1096 H
  • U1064 H
  • U1016 H

So from what I can tell, B2860 may explain why my telescoping steering isn't working, U1255 may have something to do with the 3 loose wires I found under my driver's seat this weekend, but all the rest I have no real idea on. Do any of these codes stand out as a possible cause of this? If not, should I be worried about any of these?

 

It's definitely more noticeable at ~60 & up. And it definitely still happens at 70 & up too, so I don't think that would be the issue.

But since you bring it up, this is my first 6 speed. All the other manuals I've owned have been 5 speed or under. Plus it's been over 15 years since my last one. Should I really only be using 6th for 70+?? I've been using it as my cruising gear, so for everything around 55 and up. It handles it great, and feels like the right gear for it, but I guess I could be using it wrong.

 

A friend at work just said the same thing. I'm going to try driving a bit with AHS off, and for a bit in Competitive Driving Mode on the way home from work today and see if that has any change on it.

 

If it's what I'm thinking of then I think it might be a normal thing for the car to do. I'm thinking what Pounder is referring to as it seems like the rpm's are to slow for the gear your in. Drive it the way you normally do but instead of 6th try 5th and see how it reacts. Or try downshifting into 5th instead of letting the 6th gear do the work.

 

Yeah I saw that the telescoping steering is tied up in the seat controls under the driver's seat (for whatever reason, I'm not a designer so what do I know), so that's actually what had me looking under there this weekend hoping to just find a loose connection that I could jiggle and have it start working. Unfortunately I found 3 loose wires instead, so I'm gonna have to see if I can figure out what wires they are, where they came from, and if I can get them back together. I'll attach a pic, just incase anyone has any ideas about them.


As for the RPM, I'd say it's around 1,750-2,000 EDIT: Was definitely not 1,750-2,000. Probably closer to 1,250-1,500. or I so I guess. I haven't paid a ton of attention to where it was at when it happens, but once I THINK I saw that the tach in the HUD had a small spike when it happened, and I believe it was around 2,000. I may have imagined that spike, and I've been trying to watch for it but haven't seen it anymore. I'll try and watch the tach on the way home from work to see if I can catch the exact number it happens at.

 

It could be possible I suppose. When it's stronger than usual, it definitely doesn't feel normal. Even when it's a little more subtle it seems off, but I'll drive for a stretch in 5th on the way home today and see how that goes (I've got a long list of things to do on the way home today, LOL).

 

Oh wow, I'm definitely overusing mine if that's the case. I pretty much push it to 6th once I hit cruising speeds. Looks like I may have to adjust my driving habits. Now I wish I would have asked about it a couple weeks ago before I got used to driving this way.

 

This has enough technical jargon in it to sell me on it. LOL. I guess I definitely need adjust my driving habits. This explains how my 20 year old sports car gets 33 miles per gallon!

Thanks to everyone for the help.

 

It was driving me crazy, so I went and got my book to see what they recommend for shifting speeds. It says to shift from 5th to 6th at 50mph, and to downshift if rpm drops below 900. So it sounds like I've been driving it right according to the manual. But I'm still going to assume that this normal because the explanation was so good, and just ignore it unless it gets much worse.

 

Maybe the car has a cam?

 

you do know 5th and 6th are overdrive ????

 

Well, yeah. Does that conflict with anything I've said here? I use 6th when I get to my cruising speed, and then set my cruise control. When I go down a hill and the cruise lets up to slow down, the car jerks (or stutters, or something else that's probably more accurate that I can't come up with). Unless I'm missing something, that's what overdrive is for.

 

Just drop down a gear or two and see if it happens again. You’re bogging the engine down.

 

So here's a weird status update. I took a buddy at work for a ride to show off the car, and tried to force it to happen to show him what I was talking about. I was only able to get it to happen once, and it was pretty slight. So now I'm wondering if the fuel filter somehow helped (though I still don't know how or why it would).

On the way home I took everyone's advice and drove 90% of the drive without going over 5th gear (I refused to set my cruise to 75 in 5th gear on the interstate). It was still slightly there, but as I said, it's way less noticable in 5th (my reasoning is that the engine braking in 5th slows it down faster so it doesn't have as much of a chance to happen, but again what do I know).

So now my plan for in the morning is to drive to work as I usually do, and see if it still happens, or if it really is reduced. If it is reduced, apparently I got a magic fuel filter and that helped it somehow. If it is back to doing it as it's been doing for the last few weeks, then it's maybe normal, I somehow use 6th gear incorrectly/ too often, or I'm just imagining things.

I'll post a status update tomorrow morning. Thanks for all the help.

 

Moved to C5 Tech.

 

So here's my update after driving to work this morning.

It seems to still be happening, even in 5th (just not as bad or as noticable). But it does seem to be happening less. I'm going to operate under the impression that it's normal, and not worry about it unless it gets worse.

Thanks everyone for the input and help. I really appreciate it.

 

It happens at different points. Sometimes as soon as I let off the gas, and again further down the rpms. So usually between 1300 and 1100 or so when it happens in 6th I would say.