Looking for "oompf" my vette surely had once

[KREX 725]

The other day I had an opportunity to take a ride in a 2003 50th anniversary convertible with less than 8,000 miles on it. Obviously it drove like a dream and it really pointed out just how "loose" my '95 auto couple feels.

Everything on my '95 is stock. Are there any obvious things I could start with that might make it feel a bit tighter? I know the shocks need replacing and a balancing job wouldn't hurt, but the engine itself just doesn't feel immediately responsive. When I step on the peddle, it seems to take a quick second before it kicks in. I realize the C4 is notorioius for its rattles and such, but I imagine something "tighter" and more responsive has to be out there.

I apologize for all of my non-mechanic descriptions here, but I'm hoping for some general replacements for a '95 automatic coupe with 80,000 miles on it. I still love my "admiral" but I think it deserves a little TLC to get back on track.

Any thoughts or suggestions would be greatly appreciated! Thanks!

 

[Jeb]

Plugs.

Plug Wires.

Adjust the TPS. That will probably cure the slight delay between your foot and the launch. (I would probably do this one first because it's a freebie and you might be able to save the money on the rest).

You've already mentioned shocks.

Are the tires old? Sometimes new shoes will perk up an otherwise sloppy handling car a bit.

Timing?

Once you're done with the above, let us know how it feels.

 

[C4Tom]

Yes, start with a tune-up.

Can't adjust the timing on the Opti-spark LT-1.

Get a K&N open box filter. Have the transmission gone over by a good shop(ask around locally).

Like Jeb said, bad or wrong tires can make it feel sloppy.

Get the new shocks on before getting an alignment.

 

[John Robinson]

92 or better

Yup it will be sluggish if you run regular in it. When I bought mine the dealer gave me a free tank of gas. You guessed it he put in regular. The next tank I put in premuim and after a few miles the car felt like it had been transformed. The throttle was more responsive. No more sluggish off the line starts and best of all the average milage per tank went up about 3 MPG. I don't know if you are using reg or not but if you are before doing anything else take the cheap route and run a couple tanks of premium in your car and let us know what that does for your problem. I in particular would be interested if you have the same results as I did. Sometimes we fail to do the easy or cheap things because we are convinced that if it's a problem with a Corvette it has to be complicated and expensive. My 93 auto had 67K on it when I bought it and it now has 81K. It still has the original plug wires plugs etc. I have replaced a water pump. Fixed the dimmer switch myself and put new brakes on the front. I sent the radio to Doctor Don and replaced a blown radiator hose in the last two years. The car still engages the ASR on upshifts from 1st to 2nd to 3rd. Please let us know what the outcome of your problem is. That is the only way we can all gain from this site.

 

[B17Crew]

While you’re going over your ’95, I’d give the throttle body a good cleaning. Probably not a cause for your hesitation, but a task that should not be overlooked. I’d also install a new fuel filter too.

B17Crew

 

[KREX 725]

Yup it will be sluggish if you run regular in it. When I bought mine the dealer gave me a free tank of gas. You guessed it he put in regular. The next tank I put in premuim and after a few miles the car felt like it had been transformed. The throttle was more responsive. No more sluggish off the line starts and best of all the average milage per tank went up about 3 MPG. I don't know if you are using reg or not but if you are before doing anything else take the cheap route and run a couple tanks of premium in your car and let us know what that does for your problem. I in particular would be interested if you have the same results as I did. Sometimes we fail to do the easy or cheap things because we are convinced that if it's a problem with a Corvette it has to be complicated and expensive. My 93 auto had 67K on it when I bought it and it now has 81K. It still has the original plug wires plugs etc. I have replaced a water pump. Fixed the dimmer switch myself and put new brakes on the front. I sent the radio to Doctor Don and replaced a blown radiator hose in the last two years. The car still engages the ASR on upshifts from 1st to 2nd to 3rd. Please let us know what the outcome of your problem is. That is the only way we can all gain from this site.

Always the premium gas for "the Admiral." I read enough posts on here about going the cheap route that I never even tried.

I was hoping some of the sluggishness could be explained away by the cold weather this time of year, but it warmed up this past week and it was still feeling a bit down. I'll be doing the new shocks this week and then I'll move on to the engine itself. I'll check the wires, plugs, etc. to see if they're still original and their condition.

Thanks for all of the replies thus far!

 

[Rogue]

Tuneup!

New spark plugs, ignition wires, especially after 80k miles. New air filter & fuel filter would be nice too. Clean the FI with a flush job.

New shocks definitely at 80k miles. Have you replaced the brake fluid and brake hoses? Broke hoses need to be replaced every 4 years. Every 2 years too for your coolant.

As for squeeks and rattles, don't drive without the top. Tighten ALL interior screws/bolts. Replace weather stripping around rear hatch and side windows. Lube all hinges. Remove all loose junk inside the car especially coins, or anything else that can rattle (if any). How are your side mirrors? Rattling? The mirror trunions can sometimes loosen over time and start rattling. It is extremely irritating because you hear it everytime up until you shut the door too!

Your car is over 10 years old and has 80k miles. The powertrain is good to run a long time. But time and mileage will wear out many of your body and interior parts. So replacing some of the plastics, rubber, as well as tightening all the bolts and screws will help tremendously. The sad fact too is that the C4's body flexes a lot, especially without the targa top. You may want to look into fitting your car with R&D Racing's front subframe brace and rear brace, which are suppose to stiffen up the body structure of the C4. This of course, after you've done the basics above.

 

[John Robinson]

I should have mentioned

When I got my 93 coupe it had been sitting for a while so I bought a can of white spray lube and hit all the bump pads for the doors and hood etc. Then I removed the top and coated all the rubber surfaces generiously with spray silicone. ( A good quality not WD40) As suggested coat everything that can squeek or move against something else. Doing this took most of the noise out off the body flexing. Dont' forget to get under the car and spray all the rubber bushings etc. I think you will find a few dollars spent on lubricants will answear a lot off your concerns. If not at least you have had the fun of getting up close and personnel with your vette. ;worship

 

[KREX 725]

All great ideas! Thanks again!

I might just have to use some vacation days at work in order to find enough quality time with the vette!

Plus, I think I've just talked the little lady into making a trek down to Bowling Green, KY at the end of the month. I definitely don't want to drive down in her Taurus... :L

 

[John Robinson]

On tje right track

Don't forget to put some fuel injector cleaner in before you go to BG. One more thought on the sluggish running. Could you have gotten a bad tank of gas? I have and usually whatever I am driving or riding will run like a dead possum. The upside of that is some dry gas and running the bad gas out will fix the problem. I generally go to the busiest station around on the theory that they are pumping more prem. than a low volume station. If you have'nt guessed by now gas is an obsession for this old F---

 

[RoadReady]

Tuneup! New spark plugs, ignition wires, especially after 80k miles. New air filter & fuel filter would be nice too. Clean the FI with a flush job. New shocks definitely at 80k miles. Have you replaced the brake fluid and brake hoses? Broke hoses need to be replaced every 4 years. Every 2 years too for your coolant.... The powertrain is good to run a long time. But time and mileage will wear out many of your body and interior parts. So replacing some of the plastics, rubber, as well as tightening all the bolts and screws will help tremendously. The sad fact too is that the C4's body flexes a lot, especially without the targa top.

Always premium gas and clean the throttle body, non runflat tires, add the subframe brace and the shock tower brace, and bolt in the top brace when the top is off. It will be a different car!!!

The C5s take 1-1/2 tank for the system to completely reset after low-test or bad gas, and I think I remember that the C4s are same but could be wrong.

 

[B17Crew]

These are all great suggestions... looks like you’ll have some C4 bonding time in the near future!

B17Crew

 

[Lucs_Vette]

given some of the advice here .. i'd like to tune mine up too (1985).. planning on doing the plugs, wires, ... etc and the TPS. Does anyone have any info on what i can do to clean the TPS, parts that should be changed .. etc?

anything would be helpful

 

[Jeb]

given some of the advice here .. i'd like to tune mine up too (1985).. planning on doing the plugs, wires, ... etc and the TPS. Does anyone have any info on what i can do to clean the TPS, parts that should be changed .. etc?

anything would be helpful

Here ya go. It's pretty straightforward.

http://www.geocities.com/jgkov/IACService.html

As a bonus, you can dig back into that site for a lot of other goodies.

 

[6speeder]

http://www.badasscars.com/techtips.html

 

[wildbill486]

I got this out of the badass link.

"Remember this, a correctly timed engine produces the most horsepower. An engine with timing too late (retarded) will have a low idle vacuum, have slow throttle response, feel like a turd at low RPMs and will run hotter than normal."

Could be something as simple as an advance weight hanging up.

 

[aboatguy]

I got this out of the badass link.

"Remember this, a correctly timed engine produces the most horsepower. An engine with timing too late (retarded) will have a low idle vacuum, have slow throttle response, feel like a turd at low RPMs and will run hotter than normal."

Could be something as simple as an advance weight hanging up.

Not on a 1995 LT1. It does not have a mechanical advance; the timing is controlled by computer, input from the OPTISPARK and other sensors. If the knock sensors are reading knock (real or false) timing may be retarded and cause the symptoms described. If it were my car I would run my datalogger and see whats really going on.
Mike

 

[wildbill486]

shows how much I know.

On the risk of a hijack, I pulled my car outa my gf's garage Sunday and drove it home and this is what I woke up to this morning.

 

[Pseudomind]

What happened to your car? A shaving cream convention in town? What is that stuff on it? :L Drive on!

 

[KREX 725]

Okay I have new KYB shocks on the way, as well as a set of new Magnaflows (thanks to Jeff's soundclip and advice). When I get those thrown on, they're also going to hook the vette up to the computer and see if anything else is acting up. They're also going to take a look at the plugs, wires, etc. I have a good and HONEST shop whose manager is a previous C4 vert owner, so I know I'm in good hands.

I know it'll never be the same as a 2003 with 7,000 miles, but with a few add-on's, turns of a wrench, and dabs of oil I think I'm on the right track. Thanks again for everyone's suggestions and tips!