No codes...but feels like fuel pressure or spark hesitation. Help!

[lowpost99]

My 01 Chevy Tahoe LT is pretty well maintained by me. I've got a history of problems with L460e tranny rebuilds going out frequently (meaning I've bought 4 rebuilds over 19 years). I experience an issue while cruising up inclines at around 50mph and 1k-1.5k RPM that feels like a jerky, hesitation that continues until I give it gas and accelerate to above 2KRPM and above 55MPH. Doesn't occur at other speed ranges or when accelerating only when attempting to maintain even speed and then encountering a hill. I've had this issue for years and it has stayed with the truck, across transmission swaps and I've been told there was nothing wrong with the tranny. I've cleaned the MAF and the trottle body. Sometimes a cleaning seems to clear this issue for a few weeks but it comes back very quickly. Any ideas appreaciated.

 

[SnowDrifter]

Well, have you checked fuel pressure?

When you look at live data, what happens? Any spark retard, misfires, knock triggers, or changes in air/fuel?

Does it happen in all gears or just 4th? What's the torque converter lockup doing?

 

[lowpost99]

I haven't done any of those tests due to lack of knowledge/diagnostic equipment. I'll youtube the fuel pressure testing and I'll rent a gauge from Advance. Wondering if you could point me in the right direction as what code reader would do those other tests.

 

[Bigshawn]

Could be one of the coil packs, plugs or wires. I have a 01 yukon slt with 319,000 miles and still has the stock tranny but back to your problem i would hook up a obd scanner and see if one of your cylinders are misfiring that would be the easiest and cheapest way in my opinion.

 

[OneofFew]

It could be a number of things. I would check for a faulty MAF, coked over O2 sensors, vacuum leaks. Of course the other replies are good advice. I do find it suspect that you have had to replace so many transmissions. Maybe some issue is causing it to not go into TCC lockup? wild speculation. Maybe a faulty temperature sensor is telling the computer that the transmission is cold and adjust shifting and TCC accordingly.... Best to get a good scanner and do some investigating, but a good look around the engine would likely find some issues. Check for a coked up throttle body also. Egr low flow?

 

[burgess101307]

I've got a similar problem with my 05 Yukon XL 172,000k. Mine is at low rpm from take off or in park. I have a OBD2 tool and noticed that only 1 O2 was bad. So far I've replaced the EVAP purge valve and solenoid, and just did new plugs and wires. Like yours, no light but stumbles. I too have cleaned my MAF and throttle body. Going to do a vacuum leak test soon.

 

[lowpost99]

Anyone know how to test/replace the trottle position sensor? I've also heard someone replaced something called a MAP sensor, and someone else found a bad ground wire for the crankshaft sensor. Any advice on where I can find these items in the engine bay and how to check/replace them is welcomed!

 

[SnowDrifter]

Start checking whats ready been posted. Just because someone else found a solution doesn't mean it sill solve your problem. If you're uncomfortable doing diagnostics, give it to the dealer/shop and pay the ~$100 diag fee. You'll drive yourself nuts throwing parts at it on a guess and check basis