tuning problems

[92Typhoon1679]

Well ive been chasing this problem for some time with no relief
I replaced ALL Engine sensors
New cap and rotor
New Plugs gaped to .035
New plug wires
took off throttle body just to clean and replace gaskets
replaced Checked and re-checked all vacume lines
Engine is completely stock except ATR headers and A2A intercooler

Problem is when i start the engine it idles terrible rough and surges between 750 rpm up to 1,500 rprm for about 5 min and some time dies
then when i put it in drive some times it dies
after about 5 min it starts running good but not perfect but it hold a idle when in drive

a couple of months ago i kept blowing the ECMB fuse and put a 20 amp in there.

is my fuel pump going out? it still has the stock fuel pump and would that make a difference if i change it to a 255

my fuel presure is about 38 lbs at idle and goes up to about 42 when i rev up the engine
but it goes up and down when the engine is surging.

please help ive tried just about everything this is my work truck and i need it running.

 

[SBNova]

Re: tuning problems

I would guess you need a new pump. Having a new pump in my Ty has made a huge difference in the way mine runs. I would say start there. As for the fluctuation in fuel pressure your having, the ECM does not alter fuel pressure. The only things that can change the pressure are the vacuum line to the regulator- is it leaking? When the engine speed changes, so does the vacuum signal it produces, which could alter the fuel pressure. The only other thing that could change the pressure is a voltage fluctuation. When the engine idle speed changes, so does the voltage output, which may change fuel pump output. Is you alternator good? How many volts do you see at the battery when its running, and when its surging?