Tow/Haul

sealevel · April 17, 2004

I want to, seriously, thank the members who reply to my questions and give me such valuable information.

Here's one of more to come. When I press the tow/haul switch the only change that occurs is the light on the cluster turns on. I use to notice a rpm change or lower gear. What can I do to fix the problem?

PewterC3 · April 17, 2004

You don't notice harder(firmer) shifts?

sealevel · April 17, 2004

Shifts are ok. Before my 60,000 mile tune up I was easily doing 2nd and 3rd gear churps when I stepped on the gas. Now she seems to fan out bad up to 4500+ rpm. She seems to kick into overdrive to easily after lettting off the gas, leaving a long whined up to get moving again. Use to cruise 75mph at 1500rpm and tap the gas no more than 1/4 of an inch and take off, currently 2000rpm at 65mph. She feels like if I was going up a hill that if I didn't keep giving a little more gas that she'd slow to a stop. Don't know what else to mention. Maybe, I noticed when going into park she idles about 150rpm higher. While in park and idle I get major voltage drop while rolling up window, or turning steering wheel to the left. battery checked, alternator checked, and today I'm checking for vacume leaks, electrical grounds, and cleaning my Amsoil air filter(I believe it was in upside down and had way to much oil put on it. Oh yeah, I about passed out when the parts store told me how much a oxygen sensor cost AND I HAVE FOUR OF THEM! I'd rather get wester's and disable the system if possable, It would be cheaper.

Late

PewterC3 · April 17, 2004

The big change in RPM sounds like it's not locking the torque convertor at cruise unless you changed tire/wheel size.

The over oiled filter could be a performance problem. If you oiled the MAF it will make a big difference. Get some plastics safe electronic cleaner and spray the MAF clean...but don't wipe!

sealevel · April 17, 2004

Thanks for the hook up on the cleaner. Yep, I have oil in the bottom of the filter housing. I just scrubbed gently my TB and I guess I'm going to try and get into the intake. I found a injector that is loose. I can rotate it quiet a bit, hopefully I can remove the one injector and not have to take off the entire fuel rail? Also, is the EVAP Purge valve suppose to be loose? The bolt that fastens it down seems to be as tight as it will go, and the valve seems loose to me? Also the MAP sensor is loose?

sealevel · April 17, 2004

No wheel size change on the truck.

teamjnz · April 18, 2004

What size is your engine? I have the 6.0 with 73K on the odometer. I cruise at 65MPH @ 2000RPM in overdrive. (14 MPG) RPO numbers say I have 3.73 gears. I also have a 99' Suburban with the 5.7l. Cruising at 65 I am @1800RPM with 3.73 gears.

I would love to cruise at 75 and be turning 1500RPM.

teamjnz

robsawatsky · April 18, 2004

75 MPH at 1500 RPM sure ain't a 3.73 rear end.

The 4L60E and 4L80E transmissions between the 1500 'burb and the 2500 truck have different overdrive ratios so they'll always cruise at different RPMs with the same size tires.

I can imagine my tranny shifting at the slightest hill or headwind if it was geared for 75 MPH at 1500 RPM.