Hi S2kers,

I am having issues with my car of late and I really need some help from all of you to chime in on your thoughts and areas I should focus on to solve it, I will also cover what I have done and checked to date.

Car details;
•2003 AP1 s2000
•Running HKS FCON IS piggy back ECU and tuned
•Fuel Pressure Regulator was installed previously to the engine (ill let you know why below)
•Innovate AF gauge installed
•Full piping from manifold to exhaust has been changed
•Everything else remains stock when it comes to fuelling etc

The issues;
1.When starting up the car again, after the car has already warmed up, my car will crank and start but will die out and can't hold the idle rev and the next start will require me to hold the ignition button longer in order for the car to fire up – it will usually fire up again on the 2nd try however its a slow fire-up and sounds very much like a scoobie firing up with a low grunty sound.

2.Went to the track, took a hard right turn, downshift to second gear prior to the turn, pressed on the accelerator, no response from the engine, car doesn’t seem to accelerate, after about 3-4 seconds whilst my foot on the accelerator the power will suddenly come back and there is a jerk forward from the sudden power coming back in (no engine check-light or code and car performs as usual)

3.During long drives cruising around 4k rpm, car would suddenly loose power at the engine, my is foot on accelerator at this time, nothing is happening then all of a sudden after a few seconds the engine power comes back and car accelerates again.

4.Sometimes when driving as I downshift to a higher gear, press the accelerator, again no power from the engine for a few seconds, then power comes back in and car jerks forward.

I am not able to recreate the scenarios above as and when I want, it seems to just happen on and off and at random periods, of course i try to capture when it happens at what revs etc but its very sudden incident with no error codes or any pending codes showing up for that metter.

So what did i do recently to the car prior to it acting up?
•First thing is that i changed my fuel pump from a Walbro 255 back to the OEM Fuel pump, wiring and all was checked and double checked to ensure it is wired properly.
•I re-tuned the car to ensure AF ratios were at safe levels. Not going for HP more for consistent torque and HP.

That’s all that was done to the car thus far, previously I never had this issue prior to the change of the fuel pump.

What have I checked thus far;
•Checked all sensors and cleaned them out, MAP, Air temp, TDC
•Checked fuel pump wiring and voltage – all in good order
•Checked spark plugs and changed them
•Checked idle valve, changed to a new set altogether
•The piggy back ECU doesn’t seem to suggest any issues at the time of being tuned

What I suspect;
•Seems to be a fuelling issue somewhere?
•Could the Fuel Pressure Regulator be causing this?
•When the issue happens and I pump the accelerator I can hear the car sucking in air but no power from the engine.
•AF gauge seems to show a high reading when the issue happens, similar to when you let go of the gas or decelerating
•Dodgy coil pack, but i recently changed all my coil packs

Any inputs would be much appreciated.

Thanks.

 

Hi, any inputs from anyone?

MAP sensor a big suspect in this?

 

Have you checked valve clearance?

 

It sounds like a fuel realted issue to me. Which fuel pressure regualtor are you using and can you go to stock? Why are you running an aftermarket FPR anyways, seems unnecessary with your set up

 

agreed, MBH.


sounds like it's starving for fuel.

 

Hi,

Slowcrash_101 - no I have no checked my valve clearance yet, just curious how this would impact and cause the issues i'm experiencing

MBHs2k and jagg - I think at the time when installing the Walbro fuel pump set up the mechanic went ahead and installed the FPR as well, i also questioned why i needed this. The brand is a local brand.

I want to go back to stock the issue is im not sure what goes where and how to undo this. Is there any guide on this that i can refer to? ideally id like to take it out.

 

Was the car working fine, before the mods? You still have the old OEM parts?

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Well if your valves are overly tight they can cause misfires, and worse lead to burned valves that can't hold compression.