Some power loss and bad mileage???

v10power · 01-31-2003, 01:03 AM

I have a 99 automatic with 44600 or so miles and I am getting less than 200 per tank also. I feel the car should also be running alot stronget than it is. There is a slight odor occasionally in the car and I have no clue as to where it is coming from. I have also noticed that in cold temps the car ALWAYS has steam coming out of the tailpipes, is this normal? The smoke has no real color or odor it's just the steam you always get ehen the car is still cold, but it never goes away. I did calculate mileage today and I am at 13.5 and that was really bieng nice to it the whole tank!! I have a borla cat back but everything else is stock as I have only had the car a month or so. Should I put in some injector cleaner? Please help here guys, my buddies only know Grand Nationals and have no clue with LS1's.

RamAirBird2k2 · 01-31-2003, 08:04 AM

So what does the odor smell like, is it gas, coolant, oil, what?
Got access to a compression check gage, do a comp check, see if any of the cylinders show low.
Autotap it, see what the ECM sees, it may be backing off the timing in response to detonation.
There's alot of things that "could" be wrong, but we need as much info as you can give
Could be a simple fix, or could be a high $$$ complex one, some basic diagnostic tests will help determine, or at least narrow down the choices

v10power · 02-01-2003, 06:32 AM

Sorry for the vague post. The odor is not very easy to desribe. It's not a gas or sulfer smell it actually smells like someone is farting through my heater vents. I have only noticed a few times but everytime the heater was on. The main problem that I am worried about is the constant steam coming from the tailpipes. You know the steam that every car has when it's first started on a cold day? Well this never stops, I drove 80 miles and when I got off the highway I looked in my rearview and the damn thing was still smoking/steaming whatever you want to call it! I don't think it's a head gasket because the smoke has no color or odor, I have keeps a close eye on the oil and it doesn't seem to be using any and the smoke like I mentioned isn't blue. I did notice that the oil pressure gauge moves higher as the rpms do, nothing drastic but If I am at WOT it will move almost 20psi. The power has loss a bit and oddly enough the car has goten noticibly quieter, a friend of mine today saw it again for the first time sinse I got it and he noticed how much quieter it is. When I first start the car it is VERY rich and you can smell the gas when you stand the exhaust but this goes away in less than 5 minutes. I can't think of anything else to include that can help you determine my problem, all I know is that I have 2 weeks left on my warrentee and the stealership said that there is nothing wrong and that it's supposed to steam like that. I know he is full of crap but having little or no knowledge of this car I need you guy to give me a heads up on what I should tell him to check. If you would like to discuss this with me in an easier fashion you can email me at v10power@comcast.net or you can aol istant message me, my aol name is importkillerrr. THANKS ALOT, you guys rule, I spend hours at night just looking at your rides drooling!!

bsmith · 02-01-2003, 03:28 PM

Have you ever changed the thermostat? If it is sticking open, the car never actually gets up to operating temperature. If the car isnt up to temp, then the mileage is going to be bad. Our cars are pretty well known for having inaccurate temp gauges. I would try something cheap and easy like this before going to the dealer.

v10power · 02-02-2003, 12:22 AM

I never changed the thermostat but I don't see how that's the problem, the car heats up fine not just judging by the gauge but also by the heat output from the heater. If the car never warmed up properly due to a stuck thermo. the heat wouldn't get hot either.

6speedZ28 · 02-02-2003, 12:35 AM

I put a 160 thermostat in my car and the mileage dropped a sh!t ton....but the heater still pumps out hot air. Maybe like said above your thermo is stuck open. Whats your temp guage read?

v10power · 02-02-2003, 12:49 AM

Temp gauge is running around 200 - 210 or so. The thermo is not stuck wide open, the thermo on my dodge ram is stuck wide open and that thing never gets over 130 degrees and that a v10.

v10power · 02-02-2003, 12:54 AM

didn't mean to come across like an a$$ in that last post, it kinda reads that way but it wasn't meant intentionally.

RamAirBird2k2 · 02-02-2003, 02:06 PM

First make sure all this has been documented, that way if you have problems after the warranty is out you can show this was a problem that occured during the warranty period, and still be covered
Second go to a different dealer. The one you're currently going to sounds like they A. don't care, or B. aren't capable of diagnosing the problem.
It almost sounds like a leak in the head gasket, just enough to introduce water into the combustion chamber. I would have them run a compression check on all cylinders to see if the leak can be located.
Also check the temp sensor, the one that provides info to the ECM
Get the dealer,(the new one) to scan the ECM to see what it sees, your power loss may come from retarded timing due to detonation.
Check the plugs (are they stock) despite what the book says 100,000 miles is way too long between plug changes, plus the plugs can tell you alot about what's going on inside the engine
Check the coolant, with 44k on the car the coolant (dexcool) can turn to something the consistancy of wallpaper paste (not good to cool a car with) Dexcool should be changed @ 30k BTW
Check the plug wires see if you can see any arcing (best done at night with the hood open, look for a greenish glow from the wires)
Good luck

AL SS590 M6 · 02-03-2003, 01:43 AM

What fuel are you running? 92 octane or better I hope!
Some that are new to the LS1 arena don't realize that they are a premium only car.
Like one other guy said. Get the computer scanned. Is there someone close by that you know that has Autotap? Due to the huge inaccurassy of the stock gauges the only way to really tell what is going on is a scan tool.
As far as the oil pressure goes. 10-20 at hot idle, 45-55 at hot cruise, 50-60 at hot WOT is what I see in both of mine.

Cream · 02-03-2003, 11:34 AM

Smells like someone is farting through the heater vents, loss of power. loss of gas milage and quiet exhaust

Just a guess here but sense no one else mentioned it I would consider something wrong with your catalytic converter(s). Don't know how you would go about checking it, but all of the symptoms above could be traced backed to a bad/clogged cat.

Michael

bsmith · 02-03-2003, 12:02 PM

I had a cat go bad in my 00Z, and it was throwing codes for it.