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I just started having a performance issue that I am getting worried about. Last week while driving on the freeway, I stepped on the gas and when I hit about 4,000 RPM the engine started running rough and sounding strange like my timing was off or was having detonation problems. I do have a cold air intake from JLT and a SCT tune from Evolution Performance. Living in California I am running 91 octaine fuel. I called Fred at Evolution to ask what he thought was going on and he thought I may have bought a bad tank of gas. So I ran the tank down to nearly empty, added a octaine booster and filled it up at my local Chevron. Unfortunatly the problem has not gone away. In fact, it even runs rough at low RPM's now and performance is noticably off. Does anyone have a suggestion on how I should address this problem before I take it into the shop ? If I do take it in, I will most likely put the stock tune in and airbox on.
 

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I just started having a performance issue that I am getting worried about. Last week while driving on the freeway, I stepped on the gas and when I hit about 4,000 RPM the engine started running rough and sounding strange like my timing was off or was having detonation problems. I do have a cold air intake from JLT and a SCT tune from Evolution Performance. Living in California I am running 91 octaine fuel. I called Fred at Evolution to ask what he thought was going on and he thought I may have bought a bad tank of gas. So I ran the tank down to nearly empty, added a octaine booster and filled it up at my local Chevron. Unfortunatly the problem has not gone away. In fact, it even runs rough at low RPM's now and performance is noticably off. Does anyone have a suggestion on how I should address this problem before I take it into the shop ? If I do take it in, I will most likely put the stock tune in and airbox on.


Yes, I would put it back to stock before you take it back in for service.1st I would check and recheck all your lines and your MAF to make sure everything is connected properly.Then I would put your stock intake and tune back in and see how it runs.If it runs good put the after market intake on and reload your tune.
 

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I'd reflash it to stock and put the stock airbox back on first. If you are still having problems, at least you've ruled out the CAI and tune as the problem.

Have you checked for any vacuum leaks? Fouled plugs? Maybe you did have some bad gas and it clogged an injector? :confused:
 

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Another thing you could try would be a product called Sea Foam this stuff is great for bad gas clogged injectors etc.
 

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Additionally, make sure you installed the MAF sensor in the proper direction (arrow towards the SC). Yes, reflash to stock and drive. Rule out the aftermarket. Is there no 93 octane in Ca.?
Guys you are responding to a six month old post.:confused: After all it is not second gear.:rolleyes:
 

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Sea Foam is also a great candy reminescint of a butterfinger candybar.
 
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