CashDudeHomie

iTrader: (5)

Hey guys I'm having a weird problem with my truck. I floored it today and from 60-75mph, which is the top of my second gear, the truck is pulling back power to where I can actually feel it. It feels like if I was letting the gas off the slightest bit and pushing it back to the floor. It will do this about once a second 3-4 times before it shifts to third. It scared the crap out of me but I repeated twice and got the same result. It also did this the other day but I didn't think much of it until now. Does anyone know what this could be. I'm running the 6.0 on a 5.3 Hypertech tune. Thanks in advance guys.

900Z1

Sounds like TQ Management

1LowTahoe

My Tahoe does the same thing sometimes. Mine does it around 80 mph thou. I go WOT and it like it slows down around 80 mph and then it regains power ... I swear i see the mph gauge drop like 2-3 miles back and then it goes up again.

Is this also TM?

CashDudeHomie

iTrader: (5)

It's not TM and it doesn't slow down, it just stops pulling as hard then pulls again like surging. I might just be low on gas since my gauge is broken. I'm about to go to town and see how many gallons it holds. Tahoe your problem sounds similar.

speedy02

iTrader: (2)

You could be seeing a little knock retard.. I loged a run with HP Tuners with the Hypertech tune in..I was running lean up top and getting some KR*..
It could be in the tuning..

01Blackerado

iTrader: (4)

You're joking right

Cashdude, it almost sounds like your losing power somewhere, I mean fuel or spark wise!! Check your sparkplugs first, then if they're ok make sure you're using 93 octane gas and check the fuel filter!! If you havent been using 93 then that might be it and you might want to use some fuel injector cleaner if that was the case also!!

If for some reason none of the above are it then the next thing id check is tranny!! Is the hypertech setup for firmer shifts??

CashDudeHomie

iTrader: (5)

Now that I think about it, I'm still on the stock 6.0 plugs so I need to get those POS's out of there. Also I put 22 gallons (always 93 octane) in so I was almost empty (gauge doesn't work) but I can't rule out the tuning or KR because both times this has happened it has been above 70 degrees outside and when I filled up and tested it was in the 50's. I'm probably past due for a filter change and new plug wires as well Does knock retard come on and off like this and feel like surging? I just hope it isn't the fuel pump. And thanks speedy, if a 5.3 would run lean up top, I'm guessing a 6.0 would be worse because doesn't WOT use a pre-set & non-adjusting fuel table? And thanks Blackerado, you motivated me to do some routine maintenance this weekend.

ludicrist2500hd

Get hptuners and remove the tqmangement all I can say is wow..... they realy only let me have my 310hp in the middle of the power band and no where else ...

marc_w

Stock settings for KR have it pretty slow to recover, so I don't think it would feel like surging... It honestly takes like, 10 seconds for a big hit to trail off to where timing is fully restored.

WOT does use a pre-set and non-learning fuel table... for the most part. If you're running lean at part throttle, and the truck is adding fuel (which would be seen as positive LTFT values in tuning/scanning software), then some part of learned fueling WILL be added in on top of the base (non learning) WOT fueling table.

If you're rich at part throttle, then you simply run off of that hard-coded table when you got WOT... the learned data is only there to come in if you're running lean.

The whole rich/lean thing at part throttle is a little confusing. We're always running at 14.7:1 no matter what (assuming we're in closed loop) - it's the initial programming that will reflect if we're technically "programmed lean" or "programmed rich" which would show the positive or negative fuel trims, which would then reflect any possible changes to WOT fueling.

Anway... that was a bit of a tangent... sorry.

I initally want to say it's screwey WOT fueling problems... assuming plugs and fuel filters and things are all up to date. I believe surging IS a sign of being lean... at least at part throttle (in non fuel injected or closed loop vehicles).

Steve Bryant

iTrader: (1)

I'd almost guarantee that it's knock retard. Now the source, I can't say for sure. You need to log some data like AFR, KR, Timing, injector duty cycle, etc. It could be something as simple as a piece of carbon in the the combustion chamber that's big enough to start pre-ignition problems and is setting off a chain reaction of KR at high MAP levels. Torque Management would act in a similar way by pulling timing to "manage (AKA reduce) torque" but it's set up at a much higher value than you'll see with your level of modifications.

Steve