92SilverSHO

iTrader: (3)

I had my car tuned a few years ago and it was fine. For the past few years however gas mileage has been taking a hit and the smell of fuel more pronounced. Its pretty bad now that the car is running really rich. I haven't had anyone touch the computer. Is the tune still in the car?

LS6427

iTrader: (2)

My PCM was dying years ago, like 5-6 years ago. I had no idea it was the PCM. But it gave my MAF the boot....took it out of the loop. I could unplug the MAF and it would start and run the same. So I kept it unplugged for years.

About 1 year ago I replaced that original PCM finally and had my tuner download the IDENTICAL tune from back in 2002 into the new PCM....I simply hooked it up, plugged the PCM in, re-plugged my MAF in.....Started the engine and bam, it was like a new engine was installed.

So you may have a PCM that is on its way out. From what I was told...NO, a tune cannot change if the PCM is healthy.

.

rabbit320

iTrader: (11)

im newb @ tuning but i think the tune isnt changed, but the sensors may age, more carbon buildup on parts, plugs, etc begin to throw off what info is being sent to the computer to control the tune; therefore no changing the tune but making it not as accurate as it once was.

check o2 sensors first for mpg's...

Bluestreak

The tune programmed into the PCM can't change. But... over time, adaptive strategies in the PCM will adjust how your car reacts to sensors as they age. If your car has significant mileage on it, the PCM could be nearing the limits of the ability to compensate for aging parts and sensors.

92SilverSHO

iTrader: (3)

Well i have a new set of Denso o2 sensors waiting to go in, but im kind of nervous since my car isn't throwing an o2 sensor code. Wouldn't it throw a code if the mileage was that bad. Im talking almost single digits in city driving with a grandma foot and short shifting.

I say nervous because some cars with headers, don't get the o2 to heat up and constantly throw codes since they are placed farther down the pipe. I remember people were using the corvette o2s with the longer harness to avoid it but it only worked on some cars.

z28241

iTrader: (13)

How often do u drive it? BTW having that ORY could have something to do with that fuel smell.

01ssreda4

iTrader: (96)

I'd say a tune up is in order, including the O2s.

92SilverSHO

iTrader: (3)

Well the plugs were changed when the headers went on which is when the car was dynotuned. I change the oil and coolant regularly and all maintenance. PCV valve has never been changed, fuel filter was changed a few year ago. The car has around 60,000 miles on it and only gets driven for about 6-7 months out of the year which i only put on maybe 5-6k miles a year.

Yeah i know the ORY would make it smell more but for the first couple years it didn't really smell that bad at all, and now my car burns more gas car than my buddies ls2 stroker and my other buddies 396 LT1 stroker.

Bluestreak

I think you're looking at something a bit beyond a normal maintenance item being neglected. Mine has 58k and I can get 25 +/- highway mileage... 17+ if I'm nice to it around town. Sounds like you need to investigate some more. See if you can find someone with a decent scan tool... then go run around town. Pull some movies and analyze the data. If you're running that rich and burning more gas than a 396, something should stick out to provide a clue as to why.

MUSTANGBRKR02

iTrader: (91)

Your MAF may be reading low and need to be changed. I would agree though that a full tune up is in order as it is not that expensive.

No a PCM can't lose its tune.