Fuel injector service and tuning...

**Bob Savage** · 08-19-2008, 03:30 PM

I've got a 98 WS-6, bought it new, and outside of using some Redline injector cleaner, haven't gone to a service shop or dealer to have my injectors/ports serviced and cleaned. Is this a critical maintenance item?

Also, and I was going to post this in the tuning section, but without going into the whole long story of why my car was there in the first place... I ended up with my car at a Chevy dealership after a fuel pump failed on me. When I picked the car up they said they had "updated my computer."

I noticed that the car seemed to have a little more pep, but I also noticed that my fuel economy went out the window. Whereas I used to get about 25-28 MPG on the highway, I'm now down to 20 MPG. I've had the car smogged since and it again passed with flying colors so I have no concerns there, but I want my fuel economy back!

Any ideas on why this is happening and/or how I can get it "fixed?"

Thanks

**KING Z28 HAWK** · 08-19-2008, 03:34 PM

Give them a call and ask them what all did they do

**Bob Savage** · 08-19-2008, 04:40 PM

Originally Posted by KING Z28 HAWK

Give them a call and ask them what all did they do

Unfortunately I didn't realize the gas mileage thing until some time later. This is a dealership I would not return to and I'm doubting they would remember or have the details of what they did, at least my receipt wasn't very specific.

**Frost** · 08-20-2008, 02:04 PM

Originally Posted by KING Z28 HAWK

Give them a call and ask them what all did they do

they flashed his PCM with the latest OS and cal data available for his year/VIN via their TechII I'd imagine.

**Bob Savage** · 08-21-2008, 07:17 AM

Originally Posted by Frost

they flashed his PCM with the latest OS and cal data available for his year/VIN via their TechII I'd imagine.

That's what I figure they did too, I'm just surprised that my mileage went down so much.

How could/would I go about finding somewhere to flash it back to the stock code?

Also, any input on the injector maintenance question?

Thanks

**Frost** · 08-22-2008, 06:35 AM

O2s are running the show for closed loop fueling, so they are suspect as soon as mileage is mentioned.

Is there some issue that you are having (mileage not withstanding) that makes you concerned about your injectors?

**Bob Savage** · 08-22-2008, 08:47 AM

Originally Posted by Frost

O2s are running the show for closed loop fueling, so they are suspect as soon as mileage is mentioned.

Is there some issue that you are having (mileage not withstanding) that makes you concerned about your injectors?

Nope, there are no concerns other than the mileage, but I'm really not looking at the injectors for the major part of the mileage problem because I believe this change occured after the computer code update.

The car is performing well other than the mileage.

There is one other oddity that now occurs since the fuel pump was replaced. My fuel gage does not appear to be completely accurate any longer. It shows slightly above full when I fill the tank but it *quickly* drops about 1/8'th below full within about 5-10 miles. When on empty I can generally only get about 13-13.5 gallons before the tank is full so I suspect the reading is lower than the actual fuel available.

**Frost** · 08-22-2008, 12:48 PM

Originally Posted by Bob Savage

Nope, there are no concerns other than the mileage, but I'm really not looking at the injectors for the major part of the mileage problem because I believe this change occured after the computer code update.

The car is performing well other than the mileage.

There is one other oddity that now occurs since the fuel pump was replaced. My fuel gage does not appear to be completely accurate any longer. It shows slightly above full when I fill the tank but it *quickly* drops about 1/8'th below full within about 5-10 miles. When on empty I can generally only get about 13-13.5 gallons before the tank is full so I suspect the reading is lower than the actual fuel available.

they could have bent the float for the sender's wire; it's easy to do. there is little in a cal update that should affect mileage; it'd have to be a switchpoint change and that is highly unlikely.

**Bob Savage** · 08-22-2008, 01:04 PM

Originally Posted by Frost

they could have bent the float for the sender's wire; it's easy to do. there is little in a cal update that should affect mileage; it'd have to be a switchpoint change and that is highly unlikely.

Well that stinks... where would you suggest I start in my quest to get my 7 MPG back?

**lloydb3** · 08-22-2008, 01:45 PM

Do not do the injector cleaning/fuel injection service at a dealership. When I was wrenching we used to call it the "Wallet Flush"! You can get the same stuff at your local parts store and do it yourself.

**Bob Savage** · 08-22-2008, 07:08 PM

Originally Posted by lloydb3

Do not do the injector cleaning/fuel injection service at a dealership. When I was wrenching we used to call it the "Wallet Flush"! You can get the same stuff at your local parts store and do it yourself.

That's the info I'm looking for. So the Redline stuff is good enough?