Cliffs at bottom of post...


Ok here is the deal...

02 S2000
Comptech supercharger stock boost with supporting parts I.E. FPR, 255lph pump

Ok here is what is going on. The other day my car was acting a little funny. 2 hard pulls and was running great. Went for a 3rd pull and vtec was not pronounced and wideband was reading leaner than normal. Now I have a VAFC installed just to smooth the A/F out just a bit. I do not mess with it ever.

So I took the car to my local tuner who then dyno'd the car and made a few adjustments. Car made 317 whp and tuner said it was very very slightly lean up top. but again VTEC was not pronounced (was not noticeable) To be honest with you, I don't really care if it is noticeable or not, however it has been in the past, so i know something is not right.

I get the car back to my house and decided to check the wiring on the VAFC and low and behold there was a connection problem on the extension harness. found 2 loose connections and fixed them. Proceeded to test drive and found that vtec was now pronounced and "poppy" again, however the car was super lean up top. Decided that, that was not safe so I richened it up all the way across the board after vtec engagement. Drove the car agian and still lean between 6k and 8k rpms, (i didn't pull past 8K) I then richened it to max all the way across the board from 6k-9k, agian took for a drive and found that although much richer than before, wideband never read lower than 12.8.

Is it possible that the fuel pump is slowly dying on me? It is a walbro 255. Does this make sense. I mean really the car should have no problems with it being lean if I'm using stock pulley and High flow pump right?

thanks for reading all of this.


CLIFFS: Car runs lean after vtec engagement even with VAFC richened to max, wondering if Fuel pump is problem.

 

Im curious, why are you running a VAFC with FI?
You need a FULL EMS for your setup, such as a AEM EMS or at very least a respectable fuel computer like the Greddy e-Manage, etc.

VAFC is better suited for NA applications with minor bolt-on mods (Not aggresive cams or ITBs, etc).

My S2K is not FI so please feel free to correct me here but I dont think Stock ECU + VAFC should be run with FI.

 

well with the base kit that comptech sells (what i have installed in my car) There is not fuel management required. It has an FMU (rising rate fuel pressure regulator) and a high pressure fuel pump. The base kit ran a little rich for my application because I used a WALBRO 255 instead of the Comptech pump (previous owner did not include pump) when i first installed it. I was able to get a very nice air/fuel mixture with the VAFC. Basically the only thing you can do with a vafc is pull fuel and set vtec engagement point. I have placed my order for AEM ems. However with the set up I have now, this is fully capable of good numbers and running safely. (as long as your injectors and fuel pump is good. LOL

I've pretty much narrowed it down to fuel pump.