New member from NWFL

[Alissa Marie]

Stumbled across the forum in hopes of figuring out the issues with my 2005 Tahoe Z71. On the verge of trading her in and really don't want to because I love this truck. I have had the truck roughly for a little over a year. In the past 6 months, EVERYTHING has been going wrong with it. Engine problems, transmission problems, suspension problems, braking problems, fuel problems, only to find out that whoever owned the vehicle before me never did any tune ups or maintenance. I have put over 2k in parts into this truck in the past 6 months and it's still having an intermittent problem. Before I discuss the problem, I will go ahead and list the new parts that have been installed in the past three months.

Torque Converter
Starter
Water Pump
New Spark Plugs and Wires
Knock Sensors
Knock Sensor Harness
Manifold Gaskets
Throttle Body
Blend door Accuator
Blower Motor Resistor
Brake pads
Brake Rotors
Control Arms
Ball Joints
Idle Arm and Pitman

and STILL having this one intermittent issue. I press on the gas pedal and it has severe loss of power, hestiation upon accelerating even at low speeds, it idles completely normal, no over heating, no codes being thrown out. Odd thing about this problem, the more I run the truck, the better it clears up, but once it sits for more than an hour, it does it again. Also it is running rich, very strong gas smell coming from it. Any ideas on what it could be please let me know. I would take it to a mechanic, but I have done all these "fixes" based on mechanics opinions and it still is not fixed yet. I am at a loss.

 

[Tonyrodz]

Welcome to the forum. What kind of wires and plugs did you install? Some guys have really good luck staying with ac delco products. Were they gapped correctly? Are you sure no codes are stored? Does anything come up in the display under the PRNDL display? A very common issue is the "reduced engine power", but I don't think you're having that issue, yet. Are you blowing black smoke from the tailpipe? Are you using a lot of gas? More then you think you should be?

 

[Alissa Marie]

Welcome to the forum. What kind of wires and plugs did you install? Some guys have really good luck staying with ac delco products. Were they gapped correctly? Are you sure no codes are stored? Does anything come up in the display under the PRNDL display? A very common issue is the "reduced engine power", but I don't think you're having that issue, yet. Are you blowing black smoke from the tailpipe? Are you using a lot of gas? More then you think you should be?

Definitely using more gas, I only use AC Delco parts, no black smoke from the tail pipe. Nothing in the digital display. All wires and plugs were installed correctly. There's no issues with it starting at all, no hesitation what so ever when it starts. Only when the pressure is applied to the gas pedal in drive AND reverse.

 

[Tonyrodz]

I wonder if you might have clogged cats. How many miles does it have?

 

[Alissa Marie]

189,000

 

[Tonyrodz]

189,000

I'm not a mechanic by any means, but maybe you can try to get your cats checked out. Hopefully someone else will chime in.

 

[PG01]

Welcome

 

[swathdiver]

Do you have a scanner? I would definitely check the exhaust side and also suspect a fuel problem of some sort.

 

[iamdub]

Welcome to the forum! Looks like a clean truck and that hood ornament is a beauty! It sucks that the PO didn't take care of it and you're left cleaning the mess. Let's hope you're about finished playing catch-up with the maintenance and repairs.

It's strange that you're not getting any codes when it's running rich, but not totally inexplicable. There are numerous possible causes for the hesitation and rich mixture. We can all throw out guesses and you could throw all kinds of parts at it in hopes something fixes it, but my recommendation is to scan your PCM with scanner that can display a live data stream. This would eliminate a good bit of the possibilities. It could be an actual failed part(s) or a failed sensor making the PCM respond accordingly to a condition that doesn't actually exist. The PCM is just operating within it's set parameters, so it doesn't "see" a problem which gives it no reason to set an SES light/store a code.

Reading a live data stream will show you what all the sensors are telling the PCM and what the PCM is telling the controlled components to do in response (injector duty cycle, IAC/throttle position, etc.) An experienced and knowledgeable eye would be able to see something out of whack among this data that would help point you to the culprit.

 

[about20ninj45]

What's your stft percentage at when you compare the two under acceleration?