Reduced engine power....anyone have a stick of dynamite??

[John Bragg]

So it's been about 2 1/2 years now dealing with this issue. I've posted about it in the past. Replaced the entire throttle body, mass air flow sensor, and the sensor at the accelerator pedal. Not to mention fuel pump and complete fuel line system in the entire vehicle. I have checked the wiring at the throttle body tug test checked for broken wires and even unpinned them and removed the factory braid they had at the plug. As a last resort I installed a new ECM last night. Drove it and sure as shit reduced engine power. The issue doesn't happen in the cold at all winter is a treat in that aspect. However warm weather gets the bug going. After the ECM now the reduced engine power comes on and it idles at 1500 rpm which I didn't do before, and obviously idle is a loose term the engine is running like shit when this is going on. Plan B is a stick of dynamite I have owned Chrysler products most of my life GM always seemed like a good vehicle. Guess they proved me wrong. Should probably get back to what I know and trust.

 

[swathdiver]

So it's been about 2 1/2 years now dealing with this issue. I've posted about it in the past. Replaced the entire throttle body, mass air flow sensor, and the sensor at the accelerator pedal. Not to mention fuel pump and complete fuel line system in the entire vehicle. I have checked the wiring at the throttle body tug test checked for broken wires and even unpinned them and removed the factory braid they had at the plug. As a last resort I installed a new ECM last night. Drove it and sure as shit reduced engine power. The issue doesn't happen in the cold at all winter is a treat in that aspect. However warm weather gets the bug going. After the ECM now the reduced engine power comes on and it idles at 1500 rpm which I didn't do before, and obviously idle is a loose term the engine is running like shit when this is going on. Plan B is a stick of dynamite I have owned Chrysler products most of my life GM always seemed like a good vehicle. Guess they proved me wrong. Should probably get back to what I know and trust.

What kind of diagnostic tools do you have John? This sounds like a problem where a bi-directional scan tool, like the Tech-2, is a necessity to run proper tests and see what's going on inside.

 

[John Bragg]

What kind of diagnostic tools do you have John? This sounds like a problem where a bi-directional scan tool, like the Tech-2, is a necessity to run proper tests and see what's going on inside.

All I have is a basic code reader and with the troubles this has caused me I don't think there is another GM in my future so I don't see the point in spending hundreds of dollars on a scan tool specific for GM I appreciate the advice tho I priced the up a while back and didn't seem like a solid investment since I don't own many GM products and don't plan on owning more

 

[swathdiver]

All I have is a basic code reader and with the troubles this has caused me I don't think there is another GM in my future so I don't see the point in spending hundreds of dollars on a scan tool specific for GM I appreciate the advice tho I priced the up a while back and didn't seem like a solid investment since I don't own many GM products and don't plan on owning more

Well, the thing is John, you're throwing parts at it and wasting money without that scan tool. Granted, a Tech-2 is not ideal in your situation but something that can cross brands would be ideal for your stable. The Tech-2 is $350. How much have you spent and the problem is not solved? Mine has paid for itself over and over and over. I bet you could sell it here on this forum for nearly as much as you paid for it afterwards.

 

[asand]

Not a gm problem, but mechanic problem. Just like you can't change a head gasket with a screwdriver, you need the proper diagnostic tool.

What codes DO you get?

 

[John Bragg]

Been getting the same codes from the jump P2135 P1515 P0120. The throttle body I changed due to a roughness to the operation by hand I read online of those having and issue with that. The mass air flow sensor my scan tool life feed did show an issue with it being erratic. Yet these same issues continue. During the cold winter's I never have a problem as soon as warm weather starts the issue comes back. That is why I thought maybe the heat was causing some expansion or something in the ECM making for a bad connection or something somewhere. Obviously that was incorrect too. I feel like it's down to the wiring harness somewhere and that is going to be a serious excursion and a lot of time to find and repair I don't have a backup vehicle and can't be down for days or weeks to pinpoint the issue assuming that's the problem. Perhaps trying to find a deal on the tech2 will be worth it. Otherwise I guess it will become a driveway decoration

 

[JetBlackNali]

Had a similar problem. But mine got worse when the weather got cold. Trying to accelerate on to freeway in snow and damned reduced power. SCARY. I would clear codes, fire the truck and it would be good for a couple days. Got so good clearing the code I could still be rolling, clear code, fire the truck and be on my way.Always happened at the most inopportune time.
Tried tps (cheapest part first), then a throttle body, still no good. Called a buddy with a better scanner than mine. Ended up the throttle body was no good. Replaced again and has been great.

Was the throttle body new gm ? Or offshore cheapy? Through the years have had many a bad part right out of the box. For my old K5 blazer we went through 5 right front calipers before we got a good one from the parts store. All reman (only thing available), all junk. Piston wouldn't retract, bad bores.

I figure if it lasted this long I don't mind buying the pricier part. I would try another throttle body. 9/10 reduced engine power seem to point to the throttle body.

 

[John Bragg]

Yes I put a genuine GM throttle body on it

 

[Brisolle]

Yes I put a genuine GM throttle body on it

Hi:

I have a 2004 Yukon xl Denali. Went through same nightmare as you. Changed all these parts and discovered on some forum or YouTube to look at a ground wire behind the engine and ground wires under driver’s side door where it meets the fender. (There are two wires there). I loosened the nuts on all three, cleaned with sand paper and wire brush, sprayed some wd40 and put everything back together. Haven’t had reduced power yet and it’s been almost a year. I felt real dumb that it took that long to fix it but professional mechanics could not fix it either. It worked for me. Hope it works for you. Good luck.

 

[John Bragg]

Thanks I appreciate the info I'll give it a shot it can't hurt