Yukon throttle response

[Cartier16]

Hey everyone new to the forum this will be my first post. Recently purchased an 03 Yukon Denali. I use to own an 05 Tahoe ppv and I’m wondering why this truck don’t get going. It runs but when I want to really pick up the speed or push this 6.0 it doesn't want to. I clean the maf sensor and the entire intake out. Cleaned out the throttle body and did a sea foam treatment so far in it but when I push down the pedal to ramp up the engine my rpm’s don’t move much for the amount the pedal is. I’m wondering if the fuel filter could be clogged or the cats. I use to own a mopar with a Hemi so I’m use to that Hemi kick but my 5.3 Tahoe was in far worse condition and it would move more when I wanted it too. Planning on doing a fuel filter and all new plugs and wires but what else could be causing this? The fuel economy gauge won’t even change much when I’m pushing down on the pedal and if I just dump it it’ll take off about the same as it would if I were doing 1/4 throttle. Any advice, experience or input would be very helpful thank you.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I cannot personally help you with your question; however, other members on this Forum that are much more knowledgeable than me will chime in.

 

[Cartier16]

Thank you very much

 

[OR VietVet]

Welcome to the forum from Oregon. Recommend this filter: https://www.rockauto.com/en/moreinfo.php?pk=360047&cc=1420568&pt=6200&jsn=885.

You need to know fuel pressure at idle and when accel. I like a mechanical gauge attached and with a long enough extension to run out back of hood and taped to w/s and watch while driving. What does the transmission fluid look like? Is the problem maybe it not kicking in to passing gear? Age and condition of plugs and wires? May be related to throttle sensor or pedal pressure sensor at the throttle pedal. Needs the Tech 2 attached and monitor it. Maybe fuel pressure regulator problem? CEL on?

More Information for ACDELCO 2134668

Monitor vacuum and see if has clogged cats and check for exhaust pressure at back of cats. MAF could be bad and cleaning will not help.

Is it a "drive by wire" set up or does it have an accel cable? I am unsure about that. My 02 had cable and my 05 is DBW.

 

[rockola1971]

I would be interested in seeing if there are any check engine codes. Is the CEL on? Does it flash when this horrible throttle response happens? How does the engine idle?

There is no such thing as a "passing gear". What many refer to as a passing gear is just the transmission downshifting into a lower gear. So if you are cruising down the interstate in OD (4th gear) and you have to stomp on it to get past a semi then your transmission is just downshifting into 3rd gear and once your foot backs off the throttle then the tranny will shift back up to OD(4th gear). You could also do the same scenario in town cruising in 3rd gear and stomping on it and it downshifts to 2nd gear.

 

[Cartier16]

No cel. There is no misfire it just appears that the gas volume and throttle response don’t line up. I don’t think it can be the throttle sensor more so fuel delivery problem

 

[Jonesy92]

I chased my issue for months. Finally bought a fuel gauge and a the -n1 fitting for the fuel rail. I was seeing only 17lbs. I could drive it anywhere, but upon towing, hard acceleration, or being cold outside, it would backfire through the intake, or would move up 500rpms, as if I wasn’t slamming the throttle. In N, it would rev, but not under a load. New fuel filter, and I got 25pounds at the rail. Replaced the fuel pump at 1am this morning, and I’m now seeing the 48-52psi at idle.

 

[OR VietVet]

I chased my issue for months. Finally bought a fuel gauge and a the -n1 fitting for the fuel rail. I was seeing only 17lbs. I could drive it anywhere, but upon towing, hard acceleration, or being cold outside, it would backfire through the intake, or would move up 500rpms, as if I wasn’t slamming the throttle. In N, it would rev, but not under a load. New fuel filter, and I got 25pounds at the rail. Replaced the fuel pump at 1am this morning, and I’m now seeing the 48-52psi at idle.

Yep, basics first at all times before throwing money at problems. Great that the fuel pump and filter fixed the problem.

 

[Jonesy92]

Yep, basics first at all times before throwing money at problems. Great that the fuel pump and filter fixed the problem.

Yeah, I started with the filter, as first inspection it was falling apart. Hated the screw-on style filter, so I went with the push-on. Drove it for a while(as it was my only vehicle, and not having a second would not work), and babied it. Bought a new car for the wife, and finally set time aside to replace the pump, clean the tank. And pressurize it to make sure it wasn’t leaking anywhere, and held pressure.
Finally this morning at 2am, I fired her up. Finally sounding, and running like it’s supposed to.
03 Tahoe, 311k, original engine and trans. Alternated upgrade, intake gasket, air intake, and ball joints have been the only things I’ve have to replace, besides routine maintenance.

 

[Cartier16]

Awesome man that’s exactly where I wanted to start fuel filters are cheap and easy. Got 170k miles and it’s the original pump. The sending unit is bad so it’s alternate from a full tank to a empty tank sometimes during idle. I hope I can make that pump work for a could thousand more miles because I do not have the time to take on that task.