Hobbyracer75

I recently bought this truck to tow my race car. I have exhausted myself on searching for answers. So here's the deal.
I feel as tho this truck should be able to pull a lot better. Fully loaded, ready to head to the track I'm towing close to 8000-9000 pounds. In overdrive with tow/haul on, it can't carry a steady speed on flat ground running 70mph. Take it out of OD, and pull in 3rd, it will stay steady at 70, until a slight hill, and it falls to 60mph (not using cruse control) - if I do, it shifts into 2nd and revs into the 4000- 5000 range.
The check engine light comes on when starting off, and happens right at the 1-2 shift. Code is always p0101. That's all that comes up. After the third drive cycle it clears itself.

Maybe I've got spoiled to my dads cummins pulling this load, but my old 5.3 suburban could pull this load better than this. What am I missing?

I have replaced, air filter, fuel filter, and spark plugs. Removed the stock muffler and installed a dumped flowmaster, and cleaned the MAF sensor.

TXsilverado

iTrader: (19)

does the 1500HD have dual exhaust like the 2500HD? I've considered dumping my dual for a single 3" setup. i love the way my stock exhaust sounds with a huge DI/DO magnaflow back there though.

GMC93

Check to see if the plastic intake tube is seated all the way on the throttle body and also check to see if the hose clamps are tight on the maf aswell.

2002_Z28_Six_Speed

iTrader: (20)

What have you done to fix the maf issues?

Hobbyracer75

All I have done is cleaned it. But has not helped. Resurching it, there is more than just the MAF that will set that code. I have inspected the boot, tube, and sprayed brake cleaner on the intake/gaskets to see if anything is leaking past.

Thanking maybe the cats or muffler is cloged up (why I replaced the muffler), going to take it to the exhaust shop and have the cats replaced soon. Other than that, I'll just start throwing sensors at it. Starting with the MAF, then the MAP, O2 sensors, knock sensors with new intake gaskets( gaskets have been replaced before) and so on.

I did notice the throttle baby is pretty nasty, will cleaning it do anything? And may do the coolent bypass while there.

1FastBrick

iTrader: (17)

P0101 is a faulty Mass airflow sensor or damaged circuit. The description reads Mass Air Flow (MAF) Circuit Range/Performance Problem. So its either the sensor or the wiring. Look at this for more help---> P0101 Trouble Code - Mass Air Flow (MAF) Circuit Range/Performance Problem

This will make it run like poop! period, End of story. Start with this code first.

Cleaning the throttle body will help. The more crap that builds up, the more of a restriction it creates. A little seafoam treatment will help too!

01WS6/tamu

iTrader: (36)

Cats are stopped up.
Under heavy throttle the PCM is not seeing the airflow across the MAF it is expecting to see because the exhaust is restricted and not flowing enough and slowing down airflow through the MAF. The hotter the cats get the worse the problem gets.
Knock out the cats tune out the MIL and it will run like a complete different truck. I've seen this exact problem with many of these trucks that are used like yours.

The last truck like yours we had in GM had discontinued the cats or one side of the cat if my memory serves me right. Gut cats and move on is what I would do. But if you are hell bent on having cats then you need to spend the money and get the correct GM cats if they are avail still or the 50 state magnaflow cats designed for your truck. Average run of the mill cats are pure junk and when installed on a vehicle that is used for heavy towing for extended periods of time will turn into melted down lumps in no time at all.

Hobbyracer75

So, if I gut the cats what will happen without a tune? I live fairly remotely, and the closest town that MIGHT have a tuner is an hour away. (Waco tx.) I'm sure there is someone in Houston that can tune it but that's about 2.5 hours to the north side of Houston.

I went out and checked the voltage coming to the MAF(good voltage), but my meter won't read hertz, so couldn't check that. (My good meters are sent out for calibration).
I also read that the fuel pressure regulator could be leaking into the vacuum line and cause these issues, will check that tomarrow.
Also what does the MAP sensor do, doesn't it work with the MAF to tell the comp what's going on?

I have a bad habit of reading to much online, and taking myself in all kinds of directions on what if's, and this might do this.... I drive myself crazy!!

2002_Z28_Six_Speed

iTrader: (20)

It will throw a MIL and your readiness checks will not complete. If you don't care about looking at a MIL and you don't have emissions testing then who cares. There is no drawback powerwise. I believe the PCM has a cat protection mode that sometimes dumps extra fuel to help cool the cats when it calculates that they may be getting too hot. That could be disabled to prevent you from running too rich. That is about it. I guess you could say that a gutted cat might not flow as well as a straight pipe. But how much of a loss could that be?

Do you have a thermal gun to check the cat temperature with? You can get them cheap at harbor freight. If the stoppage is bad enough it might be apparent by just looking under the vehicle.

1994Vmax

iTrader: (4)

Realistically what are you expecting out it for stock? That sounds about like every one of those trucks I have owned when they were stock pulling that kind of weight. If it's got 3.73's in the back it's rated to tow like 8000 lbs maybe.... and there is a reason for that. The 4X4's with 3.73's are only rated to two 7900 lbs. Sure the truck can handle damn near twice that weight but it's not gonna do all that great pulling it.

I mean fix your code and take the advice to check the cat's but don't expect a miracle of improvement with that trailer behind it. My old 05 I have is the strongest one I have ever driven.... even when it was stock. But honestly it's such a dog now compared to anything else I own even when towing. And that's with an air intake setup ( stock NNBS box with the fender trimmed to match, filter and MIT tube), flo pro muffler, E fans and a custom tune. It's still slow lol. And my truck is running 4.10 gears to boot. The convertor in the 4L80E is such a piece of garbage.... coupled with that high first gear..... yeah it's not fast.

For reference I have had the P0101 code here and there among ownership of like 6 of these trucks.... and not once did I ever get a noticeable performance loss. I would replace the MAF, clear the PCM and it would never return.... but drove about the same. The worst MAF problem trucks I have driven never actually threw a code. But then the fuel trims were all over hell, the transmission didn't shift right and it was down on power. The last one pinged so bad tuned you thought it would explode.... and even on the stock tune it pinged. When I datalogged you could see that the MAF response was not even close to what it should be. And not once did that truck toss a code.... and neither did my own 04 before it with similar symptoms.

If you want power tune the truck. GM's stock tune in an LQ4 is so bad it's not even funny.