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Discussion Starter #1
I just installed my fuel system and new VPC chip(for 720's) I have a weird hesitation/bucking down low in the RPM band. It is always below 3700 rpm's and the cars response seems to be alot slower than wiht the stock fuel system and the 550 vpc chip .It is worse when loading the engine wiht a high gear at low speeds( 5th gear at 30 mph then stepping on it). Could this be a VPC problem or maybe too much fuel pressure down low. After the 3700 the car runs fine(really fine :) ). I pulled the plugs and they look brand new. I disconnected my SAFC after talking to Reg Rimer about it being a 2D map and giving the ECU a broken up signal wiht a oscilliscope so that's not the problem. The MAP sensor is in the same place as it was when I had the stock system in and the VPC knobs are set to 12 o'clock. Any ideas?
BTW fuel pressure is set it 36PSI at idle with vacum.

-TY
T-78
 

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Lonestar Dawg said:
Have you tried raising the fuel pressure to see if that helps? At idle with the hose off the regulator, most are running 42-45 psi.
Yeah, definately this is a way to start..my car is around 45psi. Maybe is a bit lean in the low end..try that and see if it helps any.
 

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Discussion Starter #4
I'll try 45psi tonight. My pressure with the hose off is 40psi so maybe thats the problem.

Thanks guys,


-TY
 

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Discussion Starter #5
Looks like I had too low of a fuel pressure. I adjusted to 45PSI hose off and the car rev's so much better. (thanks Lonestar, Jesus). No stumbling and very chrisp throttle response.

Thanks again!!!!!:)


-TY
 

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No problem..glad to help..:)
 

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