95 Tahoe intermittent TPS

[WyomingTahoe]

I recently have noticed a more severe decline in power with my Tahoe. The problem has been occurring for quite awhile, but nothing major has happened. Now, I'm beginning to have issues such as the transmission hesitates to shift at WOT, and won't go above some speeds. This doesn't happen all the time however, and when I tested the TPS I got a smooth voltage reading from .6v to 4.5v. It has 50,000 miles on the new engine, transmission hasn't been replaced, and the vehicle has total 199,500 miles on it. The O2 sensor, MAP sensor, Temp sensors are all new. Everything else I can find suggests the TPS, but when I tested it, it worked fine. I just don't want to drop $40 on a sensor I don't need. Anyone got anything else I could try?

 

[Jungle Rooster]

Is there any chance the timing chain has come loose? I understand that chains are less likely to loosen over time compared to belts, but I've read that the chains have been known to need replacement if they've somehow come loose. There's information online about how to check that.

 

[WyomingTahoe]

I doubt it. The engine has less than 40,000 miles on it, and if it was the timing chain I would know of a consistent issue. Since the issue is not consistent, I don't think that could be the issue. However, I will check to make sure.

 

[lesterl]

Have you pulled any codes?

 

[WyomingTahoe]

I tested the computer, and got no codes in response. Back in the summer of 2015 I was having several issues, all caused by a vacuum elbow on the MAP sensor, but during that I only got codes for transmission (shift solenoids), MAP sensor, O2 sensor. All of the codes haven't appeared since July, so I doubt its the solenoids. The MAP and O2 sensors are new so I don't see them being the issue. The computer seems to think that the car is fine, but I can easily tell its not.

 

[lesterl]

Wonder if the converter isn't plugging up?

Can you use a timing light and make shure your timing is dead on and not moving around?

Use the timing light to examine the injector spray pattern, is it clean and smooth?

 

[WyomingTahoe]

The catalytic converter was brand new last summer so it shouldn't be plugged up. I don't have a timing light where I'm at. Can you borrow one at O'Reilly's or one of the other stores? I'll have to check the spray as well. It was fine a couple months ago when I checked it, and the problem started before then so I kind of doubt that it is the issue.

 

[Sanderson]

95 tahoe tps

Don't know if this will help you or not but I've got a 95 LS 2WD with 220,000 miles. New GM crate engine ~80,000 miles ago. Original transmission & fluid looks good. I've also replaced the TPS twice due to transmission hunting between OD & 3rd. Only happens when it is cold outside (in the 30's or below) and/or there is a headwind putting the engine under more load while in OD. Replacing the TPS cured the problem, at least for awhile.
I recently noticed the transmission acting funny when I put it into 3rd instead of "D" like I normally do - and have done since 1995. Leads me to believe there may really be a transmission issue causing the problem - maybe some varnish build-up over the years.....

 

[WyomingTahoe]

Turns out I had multiple things wrong. TPS and IAC had both failed. Replaced both of the them and car runs much better. Seems that problem is solved. Now moving on to the next. Lol.

 

[Sanderson]

IAC????

Sanderson

 

[WyomingTahoe]

Intake Air Controller. It reduces air flow for cold engines so they warm up faster. Mine was stuck so that it was always running rich.

 

[lesterl]

Idle Air Control valve (sets the idle by bypassing air around the throttle plate.)