01' 6.0l low power, detonation.

[davemonkey]

Sorry if this has been covered ad nauseum, but i was unable to find answers searching old forums.

I have a 2001 GMC 2500 HD 4x4 w/ the 6.0l, it has 160,000 miles on it. I have a few issues:

1. Under load ( pulling a 1000 lb trailer uphill into a 30 mph headwind) at WOT at about 4-4500 rpm I get severe detonation noises, SES light and dtc p0101 and p0301. The SES turns off after a bit. I was thinking low fuel pressure or knock sensor??

2. Accelerating under light load at about half throttle I hear what sounds like lifter noise from about 2500-3500 RPM.

3. Lack of power. In general I don't feel that I am seeing the 300 advertised hp from my truck. I can't spin the tires unless it is wet (TM??) and acceleration event epty is pretty dissapointing. I realize that this is a big heavy truck, but my old 94 K2500 w/ a 5.7/NV 4500 will out run it.

In the last 5000 miles (since I have had the truck) I have replaced the plugs, wires, fuel filter, installed a K&N panel filter and a freer flowing muffler. I am not looking for a race truck, but would like it to perform to it's potential. Oh yeah the tires are 285/75/16. Sorry for the long post, but I am trying to provide the most info I can to get an accurate answer. Thanks for any input.

[burnthefurnitur]

I'm not sure about the SES light and codes its throwing, but do you have the factory tune on it? If the guy before you put a tune on it, running stock octane fuel could cause the pinging at WOT. One way to combat that could be to get the CPU re-flashed at the dealer. Also, a lot depends on the rear axle ratio. I have not had a problem like this, but the 285 75r16 tires are significantly larger than the stock ones and that could have something to do with your power issue. If the stock tire is 245 75r16 then you're other tires are 2 inches larger and being as much larger as they are it will slow you down a lot. In addition, the WOT problem has to do with torque management most likely. When you hit WOT, the computer pulls back the timing advance to help save the drivetrain from strain and the hope was for GM to lessen warranty claims on powertrain. This is why for example right after it shifts into second gear, it falls flat on its face. The reason your 94 smokes this truck is because I do not think it has torque management since it has a standard transmission. I'm not sure which year they began torque management but i believe it was post 94. Hope this helps you out some, but ask any questions you want.

[davemonkey]

I am unsure about a tune, but this all happened running 91 octane fuel.

[tpitcher]

Q's......

Have you decarbonized it...?? (Seafoam inthe power brake booster ot GM Dealer...)

How many miles on the O2 Sensors...??

Did you disconnect the battery cable foe 10 minutes and drive it kinda hard after that to relearn the PCM...??

[tpitcher]

Also...

Run a bottle of Amsoil P.I. in the gas... That'll clean 'er up good.

[davemonkey]

Just got some seafoam and rislone today. No idea on the O2 sensors. Will the pcm relear get gid of an aftermarkt tune. I reset the dtc's w/ my scanner. What is the P.I.?

[davemonkey]

Just seafoamed the truck ( 1/2 in the vacuum, 1/2 in the tank). SOP says there is some improvement, but I still set a DTC for a misfire on #3. Thinking about swapping coil; packs w/ an other cylinder. Or maybe a bad injector? All in all the seafoam seems to be the bomb. I will try it again next oil change.

[tpitcher]

The Seafoam helps a lot in the injection system - glad you did it.

How many gallons was in the tank to how many ounces of Seafoam added to the gas...?

Amsoil P.I. is a powerful injector/fuel system cleaner - better than seafpam & Techron. It cleans like a white tornado!! 5% better gas mileage at least.....

[tpitcher]

O2 Sensors - how many miles have you put on the truck??

O2 Sensors usually last 100k. Gas mileage WILL suffer if they are old or sluggish......

[davemonkey]

To my knowledge the o2 sensors have not been changed. Wouldn't they throw a code if they were going bad? I had about 10 gal. in the tank when I added 8 oz of the seafoam, is that too much?

[davemonkey]

Is the amsoil PI a once in a while thing or every tank? How pricy is it? Also would a diablo sport programmer w/ 87 octane tune be able to tweak any of the detonation problems or would it just magnify them?

[tpitcher]

Amsoil PI is a once and a while thing - like Techron, only way better.

Wow - original O2 Sensors? If really bad, a code, yes. BUT they get sluggish and affect the mileage & performance. Do a little research. You may wanna change them...

I have the 5.3L engine & have the detonation. It got all cleaned up, got my mileage back and got my performance back - thanks to the P.I.

Get a bottle, run it full strength+ & report back.....

[burnthefurnitur]

Originally Posted by davemonkey

Also would a diablo sport programmer w/ 87 octane tune be able to tweak any of the detonation problems or would it just magnify them?

I have heard good and bad things about the Diablo sport. Basically detonation is occuring because the fuel is igniting in the cylinder before the spark plug sparks. The way that these programmers and tunes make power is by advancing the timing. This just makes it more prone to detonation. For example, I ran an 87 octane tune on my truck with 89 octane gas and it still pinged, especially with a load on the engine around 4000-4500 rpms. I would stay away from programmers frankly. Also, do you have any idea what your rear axle ratio is? In the glove box there should be a sticker with codes, i think it ought to either be GT4 or GT5 or something like that, maybe GU6, but if its too low with those big 285 tires, that could play a roll in your truck seeming sluggish.

[97Silverado]

1. Just an FYI but you can't seafoam through the brake booster on a 6.0L powered HD. There isn't one.

2. OP, you mentioned you have 285s. Have you reprogrammed for the different tire size?

3. The DiabloSport is a great programmer for that setup. I run it on my '01HD.

[grayblazer]

Not being able to spin the tires on dry ground is a standard trait on these trucks because of the engine calibraiton (mostly torque management). I have an '03 and my dad had an '02 (2500HD, 6.0L auto, 4.10 gears) that were bought new and neither would let you spin the spins from a take off on dry ground. An older 200 HP 350 truck would light the tires up almost on demand, but the 6.0L trucks would blow them away otherwise...just make sure you are equating tire spin = faster.

The O2 sensors probably could use replaced, but I doubt they have anything to do with the misfire codes you are seeing and those codes need to be taken care of first before slapping other parts on it. Was this happening before you installed the new plugs? If not then it points to something that happened during the install. Bad plugs (just because they are new doesn't guarantee they are good). Did you check the gap? Did you make sure the connections were good? The coil packs or wires could be going bad (not applicable if it's a coil on plug...I feel dumb as I can't remember for sure right off hand). I recently worked on a car with the same codes and issues and found one of the connectors from the coil pack severely corroded and causing the issues.

[tdoyle]

at WOT at about 4-4500 rpm I get severe detonation noises, SES light and dtc p0101 and p0301. The SES turns off after a bit.

Not trying to be a smartass, but have you looked up these codes and tried to correct the problems causing them? 0101 is a MAF problem and 0301 is cylinder 1 misfire. Clean or replace the MAF and check all the connections, make sure your plug wires are good and you don't have a bad coil to #1. Check the #1 plug and see if its fouled. You could have a bad plug wire...unusual, but we've all seen weirder things. Odds are decent that 160k you could use a pair of front O2 sensors anyway, though they may not be the culprits...spend the money and get the GM ones.

Contrary to other's here I think your truck should be able to spin the tires on dry ground. I have an 00 2500 6.0, totally stock, no tune on it and I have no trouble smoking the rear end...the tires will spin freely and for a good 50' or so from a dead stop on clean, dry pavement. My truck accelerates acceptably, but its neither fast, nor quick...its a solid 3 tons empty and that kind of mass is no joke to get moving.

[davemonkey]

Thanks for all of the help, this is a great forum. I was a little stumped at first about which vacuume line to use when I remembered that I have hydroboost so I ended up using the vacuume line off of the fuel pressure regulator. And I haven't reprogrammed for the tire size, I thought that just affected the speedo so I just checked my speeds via GPS and go from there. I am not looking to hot rod around burning off my tires, but i just thought from past experience that a vehicle w/ this much advertised HP would have a little more punch (thanks TM ). BTW I have 4.10 gears, the HD w/ the 6.0 didn't come any other way... I think. As far as the plugs and such go they were installed by a mechanic as part of the deal when I bought the truck. I usually do my own wrenching, but couldn't pass up a free tune up. The wires were replaced at that time. The MAF sensor code appears to be a one time thing. I'm trying to run down the #3 misfire. I will take a look at the coil connector. I am kind of leaning towards the #3 injector causing a lean condition in that cylinder. I am also curious about the knock sensors. I have heard alot about problems w/ them. When they go bad do they just stop working or do they retard the timing all of the time? I am out of town until Friday so I will have to check all of this then.
BTW many years ago I was an ASE master techat a GM dealer so the mechanical stuff is clear, but the newer control systems are creating a steep learning curve. Thanks again for all of the help. I will try to contribute when I can.

[burnthefurnitur]

Originally Posted by 97Silverado

3. The DiabloSport is a great programmer for that setup. I run it on my '01HD.

Hey sorry I didnt mean to say its not a good programmer, I just meant if its detonating already, until the problem is found out, it might not be good to put a programmer on. Please correct me if I'm wrong, but I've been told that one way programmers make power is by advancing timing? Plus I believe that you can do a little with torque management with the diablo sport.

[davemonkey]

That's what I was thinking as well, but I was kind of hoping that I could tell my wife that the programmer would fix the problem :)

[grayblazer]

Just noticed that you have a CAI (sorry, not familiar with the slang for stuff like that) and a code for the MAF. Considering the MAF was messed with when installing the CAI I would definitely take a look at it. However you did mentioned maybe it was a one time code?? On most diagnostics it will give you a "count" which is basically the number of times the DTC was triggered.