My truck is running real poor. HELP

[badbowtie]

Hi Guys, I need some advice here. This might get a little long. My Suburban has been running progressively worse lately and all of a sudden the check engine light came on. The engine started to bogg down but kept going at a normal pace. As long as you don't floor it it keeps going. I took it to my local mechanic for repairs. They checked the knock sensors, O2 sensors, fuel pump, switched coils around, nothing has worked. I have a Hypertech tuning on the engine. My Sub was broken into back in August and they took my programmer. I am stuck in performance mode so I can't go back to stock. My mechanic says he can't do much more because of my tuning. Should I have the dealer flash my PCM back to stock and go from there or can I get Nelson to flash me a stock PCM if I agree to get the performance tuning when the problems are fixed. I do not know which codes the PCM threw. What should I do???

[stumpy]

Does it backfire through the intake, and bog down when you give it a little to much gas, when you pass that sweet spot that it is in to keep going.

If so, your injectors are dirty. Get them purged and cleaned. Our 2000 van with the 5.7L did that. Felt real bad, bogged, misfiring, all that. Dirty injectors.

[chrisj6]

It could just be the hypertech. Did they change the fuel filter? That could be what it is. If you are going to eventually get a Nelson tune, get one now. It's better than stock tuning, if your truck does it on his tune, it would def be doing it on stock.

Chris

[badbowtie]

I am not sure they checked the injectors or the fuel filter. The last fuel pressure reading was 44lbs. I have read on this forum that it should be at 58lbs. I want the Nelson tune and was about to order it so I can get away from my Hypertech and get the PCM set for the electric fans. When the Sub began to act up.

[chrisj6]

Fuel pressure should be 55-58, change the fuel filter and see if that doesnt help.

Chris

[RedHeartbeat]

Fuel pressure at idle is totally different than under load. It needs to be checked while driven or on a rolling road dyno to simulate load. The fuel system is really tempermental if the pressure is not correct.

[badbowtie]

<div class='quotetop'>QUOTE(RedHeartbeat &#064; May 6 2006, 03&#58;32 PM) [snapback]52328[/snapback]</div>

Fuel pressure at idle is totally different than under load. It needs to be checked while driven or on a rolling road dyno to simulate load. The fuel system is really tempermental if the pressure is not correct.
[/b]

I think they checked it at idle the first time and it was at 52lbs. I don&#39;t know how they checked it the last time to get 44lbs. They never mentioned about the fuel filter. So maybe thats causing the bad reading and causing the pcm to adjust fuel and cause the bogging down. In reply to one of the other posts, there is no back fire. I feel I am going to get a huge repair bill after all the diagnosis. Thanks keep the ideas going I will relay them to the mechanic. The Sub will sit in his shop until Monday.

[MikeGyver]

It sounds like your catalytic converters are plugged up.

[badbowtie]

<div class='quotetop'>QUOTE(MikeGyver &#064; May 6 2006, 05&#58;12 PM) [snapback]52335[/snapback]</div>

It sounds like your catalytic converters are plugged up.
[/b]

Wouldn&#39;t that cause the O2 sensor near the cats to code. What would the code most likely be if it is the cats

[kwkenuf]

Before you go jumping around randomly changing parts, you need to find out what codes you set. If your last mechanic did not scan it or did scan it but wont share the info... go to an AutoZone or Checker were they will do it for free. Look up the codes and start from there....