Hvyhitr

I just bought a 03 SL55. Going from a fully built Z06 to something a bit more street friendly. So far I love the car but it does have a couple of issues. First off its a high miler, 94k. I dont keep a car long and she made me a buy a cheaper one to see if I would like it. As of now I can see a upgrade in the future, sl65, sl63.

Anyhow here is what the car is doing.

If you try and floor it it is going into somesort of limp mode. It will not throw a check engine lite all the time when it does it. The two times it did I came up gas pedal senor malfunction. I did the reset on the ecu/tb and had no effect. Is this a common problem or do I just have a bad gas pedal? All I have to do is shut off the car and restart it and it resets in untill I floor it again.

The other problem is the car seems to have a heavy vibration around the 2500-3500 rpm range. It isnt gear specific and does seem to smooth out with higher speed within the same rpm range.

I have noticed the car does seem to tach pretty high at 80mph. Right in the 2000-2500 rpm range. Is this normal on these cars?

Thanks for the help!

aluthman

Not too sure about your gas pedal issue, but I think I might be able to help with the other two. Your description of the vibration would point me to one of two things. I would check the motor and tranny mounts to make sure they are in good shape, as mine were completely shot when I bought my SL55 and it had a similar issue. Another possibility could be driveshaft U-joints. I know this is an apples and oranges comparison, but when the u-joints went out on my truck it developed a noticeable vibration (more of a shake actually), that only occurred in a certain speed range, mainly 30-45 mph. Pay close attention next time it happens to see if it's based on engine speed or vehicle speed. you could also just rev the engine in neutral and see if it occurs as long as it happens before the limiter kicks (3k rpm maybe in neutral? don't remember). And as far as the seemingly high rpms at speed, thats normal. It's going to tach a bit higher than a 6-spd Z06 at cruise speeds. I came from an '02 MN6 vette before I bought mine and noticed the same thing. I guess 5th gear isn't as much of an overdrive as the vettes have.

allenjdmb

my bet is that it's the trans mount. Very high failure item on these cars. On the other hand, with 94k, surely it's already done. Yes, these cars came with the 5 speed and it is a touch shorter than some other cars. Of course, comiing from a Corvette, it's going to seem way higher than the really tall gearbox ratios in it.
Just a complete guess on the drivablity issue, MAF sensor. Even if they have been replaced, they fail again.

Hvyhitr

Thanks guys. I was kind of guessing mounts or u joints also. Ill get it on the hoist tomorrow and see whats up. Will check out the maf also.

deliman

I have an 05 SL55 with 77K miles. For sure the Tranny Mount should be replaced. As well as check the Motor Mounts. Sounds like the IC pump is in need of replacement if its falling on its nose when you push it when its hot. Also I dont think the Supercharged SL has an MAF sensor from what I recall.

I would suggest getting it to a Dealer for an inspection. Then once you get the list of issues nailed down you can go with an Independent Repair shop.

The big thing with these older SL`s is usually always the Intercooler Pump. IC Pump. When the intake Air temperature gets to high the supercharger is not engaged and you feel the power loss. And it wont throw a code or a CE Light either. Get a late rev pump or go to the Johnson CM30 pump.