First off I have a 2001 stock ecu. Stock 7 lbs of boost with just the FMU for fuel control.
I am also using a Blox map block.


Well I have a new issue. I have still not resolved my lean issue but that is another story at the moment I think. Or maybe, if I am lucky, connected.
Recently my car has been skipping and hesitating when heavy on the throttle. Not just in vtec either. Has been happening around 4k rpm's. Tonight when driving the idle for a little bit got stuck around 11 afr and then stuttered real bad and caused the car to jolt back and forth until I got on the clutch again.
When it is stuttering or hesitating I also hear popping from the exhaust.

Anyone know the likely culprit for this?

Another thing, my Walbro seems to be making a different noise now. Can't remember what it used to sound like but think it was more of a hum. Now it is making a strange pulsating sound.

 

Well, I guess if you consider them being connected good news than your in luck. On the other hand you need to resolve this in a timely maner or you'll likely have failure. Because your running too lean your heads heating up and causing detonation which is that stutering and poping exhaust you were talking about. S2k's have been known to run lean on thease kits. I wouldn't drive it untill you at least rich it out some. I'm not real sure about 1st gen 2k's but i'm sure someone else on here knows how to dial in your fuel problem.

 

Well when the popping is happening I checked afr's and were in mid to 12's so not lean then. Runs really lean wot in vtec though.

 

Any one else have any ideas?

 

A little more details, and explaining it a little more clearly would help. You're saying that at idle the a/f ratio was sitting around 11:1, and caused stuttering? Perhaps a bad FMU/bad injector(s)? That would be my first guess. I always think it's a good idea to pull the plugs and checking them individually. That way you get an idea if one cylinder is running much leaner/richer than the others/etc.

I do recall reading about people having problems with the MAP sensors for s2k's (haven't had a problem w/ mine yet). Perhaps that could be the culprit.

 

These symptoms sound similar to what a stock ECU does when it sees boost. 4k rpm and heavy throttle is right around when the MAP starts to really see boost in a centrifugal supercharger setup.

I think you need to review the wiring to your FMU (I'm assuming that's the equivalent of the Comptech EMS and not just referring the rising rate fuel pressure regulator). I suspect you have either a bad connection or maybe confused the wires on the harness that go to the stock ECU.

Good luck!

 

Good idea on the bad injector...

As far as the MAP, I experienced some minor stumbling at partial throttle at around the same RPM when my Comptech kit was stock. I believe this is pretty normal. OP, you can try disconnecting and reconnecting the MAP sensor to see if the stumble clears up if it's at partial throttle. That seemed to help with mine...for some reason.

What the OP is describing is at heavy throttle and I never had this issue at heavy throttle. Hmm...

 

Well it is really weird since nothing has changed.
The fmu is the rising rate fuel pressure regulator.
I am using the Blox MAP block piece instead of the comptech esm. I removed that a while ago and has worked perfectly normal on the Blox MAP block.
WOT in vtec it goes lean. Even full throttle around 4k especially when the car has not been driven for a long time(3 bars on temp gauge) but will go lean into 13's then.
WOT in vtec will go very lean.
1st, 2nd and 3rd gears seems like it will go really lean. wot in 4th seems like it doesn't go as lean.
1st gear feels like it doesn't really get boost for some reason. Feels really sluggish and doesn't go as lean as 2nd or 3rd gear it seems.
I have been struggling with this setup for months now about going lean but the hesitation is a new issue I have not had before at all since february.

About the fuel pump. Does anyone else get a whooshing pulsating noise from it? I think it used to just make a humming noise but now makes a weird pulsating noise when on.

I am still needing to check the fuel pressure at wot to see if that is messed up.

Things I have changed to check out the running lean issues.


injectors, fuel rail, fuel pump(both Walbro 255's) MAP sensor, 3 FMU's, Comptech ESM, Vortech MAP clamp, Vortech timing control box, re checked all wiring, checked plugs, compression test, fuel pressure at idle revving which was normal haven't been able to check wot yet as gauge was mounted to rail.

 

Stupid question but, have you turned up the pressure on the FMU?

 

So the car runs perfectly fine off boost (except for the occasional hesitation?), just on boost it runs very lean?

It sounds like the only sure bet at this point to rule out the fuel pump/FMU is to install a fuel pressure gauge, and monitor it while driving. If your fuel pump is making strange noises, that sounds like the likely culprit, but the only way to be sure is to monitor the fuel pressure. If the fuel pressure isn't rising as it should w/ boost, you'll know the culprit is either the FMU or pump at least. Good luck.