Why is my C5 slow?
 

At the track today, I did the 1/4 mile in 15.1 sec. with the car loaded with full tank of gas (I weigh 230lbs). It's all stock '98 coupe with 49,000 miles. What are some areas I can look into? Change the air filter? Check/change the spark plugs? What else?

Thanks all.

what was your 60':eek:

I would guess a fuel problem

Somethings terribly wrong.. what were your #'s...please post all of them

15.1,15.2,15.4,15.1

not sure about 60 times, but that part seems OK, my top end is where I lost - top speed always 91mph.

How can I check the right fuel delivery?

What other things can I check?

Holy crap! did the car always feel this slow? When did it feel like it lost power.

Need 60 foot times.

I just got it. What should the 1/4 times be like? low to mid 13's? Top speed - should be in the 100's right? What can I check to help me locate the problem(s)?

A bone stock MN6 w/ the 345 hp LS1 should run low 13's @ 106ish mph. For reference I piloted my mom's bone stock '99 MN6 to a 13.1 @ 107.

What is your 60 ft? Stick or auto trans? Where do you live? My bone stock auto 2004 went 12.92 @ 107

Thanks guys, I can see that somethings wrong. I live in El Paso, TX and was told that this stock Auto Vette belonged to some doctor before he traded it in w/49,000 mi.

What steps do I take to check out problem areas. I think it might be the fuel or air delivery - change filters? Sorry, I didn't get 60' times, but I seemed to do well there. The other cars would pass me after we got half way down the 1/4 mile course.

Thanks

We still need to know what your 60" times were. Also, did you run the car in 3rd gear since it is an automatic? If you ran it in 4th, that is part of the problem. You also likely have the 2.73 rear end and not the optional 3.15 available for automatics.

If your 60' times are too high, this will also explain some of the low mph.

Do you have heavy aftermarket wheels on the car? Is there added weight such as subwoofer box? Full tank of gas also doesn't help.

The DA or outside temperature also is a factor. Elevation is also a factor but not likely in Texas.

wheel are stock. Temp out side was around 50F.

I used overdrive. Should I use 3rd all the way down?

I had the traction control on. Should I turn it off?

Also, how can I check the transmittion oil? I think I saw leaks on the driveway before I left to the drag races? This alone might be the cause - no?

put the competitive driving mode on.....hold the T/C button down for 8 sec....while ur stopped.....and i leave it in drive....??.......it seems the be the fastest when i do that....ive never ran down a real track b4....go to a private closed road and practice....u will be able to feel the car urself...u dont need a clock telling u good luck:thumbs: :thumbs:

Yes, use drive all the way down the 1/4. Turn the traction control off.

The tranny fluid level is not simple to check. It is easier on a lift since the tranny is in the rear of the car.

I will turn the traction control off next time (I can't believe I didn't think of that there!). Could this make that big of a difference?

What else can I check? Fuel/Air filters? Should I have a shop check it out? Will a diagnostic test tell me anything or do they have to do a dyno on it? About how much is that (incl. vette tax!)?

Fuel filter! S/B replaced at 30K.:cheers:

There has to be something wrong. I've left the traction control on while bracket racing and I still cut 2.1xx 60s in 85 degree heat and went 13.6 letting off. I also have 2.73 gears and was still stock when I went 12.92 @ 107. There might be something going on there with your car.

Make sure you're pushing the pedal all the way down :lol:

It doesn't matter what his 60' times are, what gear he was in, what driving mode he was in, etc. If he's only trapping 91 mph he's WAY down on power. Like something on the order of 100 rwhp down. The car needs attention from a good Corvette mechanic. If it otherwise runs well (not rough or smoking) it has to be something relatively simple. That or somebody swapped in a L-48 while he wasn't looking!

I bet this guy is going to get the cheapest 100 rwhp boost on record. :)

Have a dyno run with A/F ratio reading done and get back to us. ;)

When I first bought my car it was very slow.The car sat for along time and had some bad gas and the plugs were toast(pucks fell off on 3).Do a tune up and put some fuel injector cleaner through it and beat the hell out of it on the highway for the full tank of gas.(run the tank very low to get all the old gas out.)The DR before you probably babied the car and now it is carboned up.JER

:leaving:

There are two final drive ratios in the auto cars. Which one is in your car? :bigears That could explaine a lot

The air filter is the first thing to check. It's easy to get to, and you'll never make power if it's toast. You can find these for under $10 at any auto parts store. :thumbs:

time for a tune up

change your oil, fuel-air filters, spark plugs, spark plug wires, add an exhaust to help a little. good luck!

Hi jah -

Change out the fuel filter, make sure the air filter is not clogged -

Make sure there is not restriction in the exhaust pipes.

With 50k miles, it's not like it sat all the time.

I vote you have a fuel system issue - if you are not equipped to check it out yourself, it's time for a trip to a qualified tuner/mechanic.

best regards -

mqqn

check yr air flow,that things like a ramjet,the faster it goes the more air it uses.....it also depends on the factory path for air,anything bent on the bottom stops it up.....

Belonged to some doctor before you got it?? Hmmmm....that there may be the crux of the problem...:willy:

You think your car is slow 'cause you don't really believe "there's always someone faster"... once you accept this concept.. you'll be happy with your ride :D

I'd be looking behind the gas pedal for the brick that the old doctor put behind there!

Everyone is quick to blame the car......

But by what he posted (left the car in OD and left traction control on), I seriously doubt he even knows how to properly launch an A4.

If I were him, I would do a forum search on the proper launch technique.

Just for quick reference though, next time you go to the track:

1. Place the car in competition mode (you'll be happy you did).

2. Put the car in 3rd gear.... Let it do the shifting for you.

3. Put your left foot on the brake and hold the gas pedal down until the tachometer is holding around 1500 RPMs. If the wheels are slipping, then back off a little on the gas.... If they're not, then appliy a little more gas until just before the wheels spin.... DON'T SMOKE THE TIRES!!!

4. When the last yellow light lites, let off the brake and at the same time, push down the gas pedal..... Don't stomp it, but firmly press it all the way down. If you do it right, you won't "red light".

5. Hold on and pay attention to the road and the car, don't look at the other guy or the speedometer..... As you pass the finish line let off the gas and slowly apply the brakes, don't slam them on.

If you do that, I bet your track times will improve..... If not, then check out the car.

Good luck.......:cheers:

Not with a 15 second 1/4.:thumbs:

:iagree: I don't see how any of these other variables could result in consistent 91mph trap speeds. Unless you're at half throttle down the strip, the car is down on power. Check/change air and fuel filters and plugs. If that fails, go get on a dyno and see what the A/F and timing look like.

BTW-is "jah" you initials or are you a Rastaman?

Dang dude, my 84 is faster than that, my 84 60ft times are 1.95-1.98 and I always beat a stock C5 in the 60, your 60 should be I would think around 2.00 give or take a few. but don't quote me.:thumbs:

I have done all of the above things wrong at one point in time. I have launched a stock A4 w/TC ON, it doesn't radically alter the 60' times (maybe you loose a 1/10th). I have also run it in OD. If the car is put to WOT, the car should still shift properly (even if you are slow).

His MPH is way too low for it to be driving technique. The only times I had seen my MPH that low was if I got out of it during the launch because of serious traction issues. (i.e fishtailing etc)

I think you said you're in el paso... altitude's a bitch, so you're always going to be slow...... but not that slow.

I didn't see too many symptoms listed other than it's slow times/speeds; any CEL's?

I'd look at:

cats
plugs
wires
af
fuel filter

I'd recommend getting a tune up (plugs, filters, etc) and then if that doesn't get you back up to normal, see about getting a dyno tune.

:iagree: Definatly get a tune and go to a closed road (or one with no cars on it at the time :lol: ) and work on your launch. If things dont improve, there is something wrong you just havent figured out yet.
Good Luck!

You Might want to look in a mirrorand be sure who you see looks like a race cars driver.

Just curious but what tranny do you have - an auto ? :ack:

Used to own a '98 coupe A4 and I could get more out of it by manual shift right at the redline.

Otherwise, if you have a 6-spd and your clutch is slipping then the run times will suffer. :(

Get a tune up and try again!:beatdeadhorse:

Tried that with a 98 auto-no go, engine falls flat. If you turn off the traction control only you can power brake and get the response you want but not in Competition Mode- Been told that is a design flaw for 98s

New air filter and plugs is a good start. I would also have the catalytic converters checked to see if they could be going bad and possiblly clogged.

There's definitely something wrong, and no matter how poor your driving, you 91mph trap speed is way too low. It's about 15mph slower than it should be. You track results are equivalent to a 200hp V6 Camaro.

I don't know how mechanically inclined you are, but I would agree that taking your car to an experienced, Corvette mechanic/specialist. Prior to that, the one simple thing you can do is check to see how dirty/clogged your air filter is, because if it's limiting airflow to the engine, it can affect power output.

Maybe the doc drove the car like a snail for all them years, and the computer is trained to his snail like driving.

Just a thought! Was it a California car? Maybe the Cat converters are clogged? Seems like every California car I've seen goes through Cats. early.

Troll.

Just like every other thread you started. *yawn*

Try tking your foot off the brake...if that doesn't work check the washer fluid, it might nedd topping off...:lol:

Slow
 

PULL IN THE ANCHOR :thumbs:

:iagree:

:iagree: Just looked at his other threads too.

I thought he may be racing at 6000 ft altitude or something :lol:

Let someone else that has experience in the 1/4 mile drive your car and see if they get close to the same ET. That will tell you if it's the driver or the car. If it's the car, then I would go do a Dyno pull and have them scan it while doing a pull. There is about a million things that can cause you to lose power.

oh i wish i was at the track when u were racin a 15.1 sec C5. i can see some kid with a turbo honda runnin 14's thinkin he just smoked a c5 :lol:

hold the traction control button down until cmpetitive driving mode pops up on the dash for some reason its a hidden feature

Clean your MAF

:iagree: :iagree:

this guy dont make sense..... he starts treads just to attract attention....