Two months ago, I have that hesistantion/fuel cut problem at around 6000rpm. I check it out and noticed that the FPR was set at 31 PSI instead of 38 PSI that I got after dyno tuning. So I turned it back up to 38 PSI, the engine run normal again.

However, I noticed that from the Hondata datalog that my injectors are running at OVER 100% duty cycle after 7000rpm, but it was only at around 80% when I dyno tuned the car. And nothing was changed since then.

Last week, the problem came back again, so I thought must be the FPR problem again, but it is not. The fuel pressure still at 38 psi. And I really have no clue what is happening.

Basically what happened is the engine rev up smoothly all the way up to around 6000rpm, and then I hear a "pop pop" sound and the rev won't go up anymore, just like I hit a fuel cut there. But then it doesn't happen all the time.

So anyone know what's wrong? I also kinda wonder why the injector would be at over 100% duty cycle now, but it was at around 80% before without changing anything. Also, there is NO Check Engine Light

My set up is
B18C5 engine with I/H/E and stock internal
B18C fuel rail
AEM FPR
10 yrs old B16A fuel pump
290 cc injectors
stock ignition with NGK wire and RM spark plug

Dynoed at around 180whp

 

10yr old fuel pump ...hmm

 

Is it possible for the fuel to fail only occasionally in high rpm?

 

sounds like when your up at high rpm's you want your injectors to supply enough fuel, but your fuel pump cant provide enough fuel when its up at that rpm range. its fine when its at lower rpm's because it can pump enough. but as we all know, the faster the r's go up. the faster everything needs to happen. go get your self a dsm fuel pump out of a gsx or something and see if that helps.

 

If a fuel pump can't provide enough fuel, will it make the injector to work at a higher duty cycle?

 

if your fuel pump would be failing, then is still would no affect redline. you would lean out on high rpms.
duty cycle of the injectors changing for no reson...mmm
with fuel pressure changes the duty cycle wont change, so..

Its a stab in the dark, but i would check your dizzy.

 

The redline is not affected, it just that I am having problem going past 7000rpm sometime... the engine just got "pop pop pop" at around 6500rpm and wouldn't or having problem go any higher. I let off the gas as soon as it happen, so I don't know what will happen if I keep my foot on the gas.

 

anyone?

 

fuel starvation maybe

 

Is this when you are driving or just sitting still trying to rev the motor.....

You might try a simple test.

If you can rev past 7000 in neutral but can not when it is under load (needs more fuel) like climbing a hill then the car it is likely suffering a fuel starvation problem.

Likely cause of fuel starvation would be fuel pump as already mentioned or dirty fuel filter. You may also have a fuel pressure regulator that is about to pack it in since they should hold the set pressure.

2 cents

 

I just tried to rev it up in neutral, and it still have the hesistation and the "pop pop" sound at around 6000rpm. But if I keep my foot on the gas, the rpm eventually go pass 7000rpm and rev all the way up to 8500rpm after a second or two.

So the engine does the same thing even when it is in neutral, it still hesistate at around 6000rpm for like a second before it continue to rev it up to the redline.

I don't know if it still does the same when it is in gear, because I left off the gas immediately when the "pop pop" sound occurs, so all I know is that the rpm bound around 6000rpm when the "pop pop" sound occurs, but don't know if it can rev past it when it is in gear.

 

yeah it does sound like a fuel problem, like the pump isnt working right, so it cant provide the injectors with enough fuel at the high levels and makes it go into a lean popping kinda. or maybe something happening with hondata or the ecu miss communicating and sending the wrong voltage to the injectors, could change the way they function.




Modified by Little Rascal at 11:18 PM 1/26/2005

 

Just try to rev it up in neutral again. And the hesitation and popping sound only happen at partial throttle. At full throttle, the rev just go all the way up to the redline no problem. It seem like the less throttle I apply, the more the hesitation is there.

However, I didn't get to try it out full throttle in gear yet, since the road is too slippy during the winter.

 

Any idea?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller &raquo;</TD></TR><TR><TD CLASS="quote">

Its a stab in the dark, but i would check your dizzy.</TD></TR></TABLE>

 

There is not clear indication what the problem is IMHO.

"Normally" fuel problems show up under load since that is when you are using the most fuel. In neutral it takes very little fuel to reach the same RPM. No conclusive but I don't think it is fuel.

If it only happens over a narrow range of RPM and then clears I would suspect something ignition related. Plugs, wires, distributor cap, rotor, bad sensor in distributor. Reving slowly may just mean that you spend more time in the problem RPM band and so you notice it more. Reving quickly will likely just cause the motor to pass the trouble spot and the problem may not be as noticeable.

Fuel pumps can't tell how fast the motor is spinning they can either flow the required fuel or not. Clearing up at high RPM is not something a bad pump will normally do.

Sorry to not be of more help.

Dave

 

Is putting the car back on dyno with a wideband O2 to tune it with Hondata again at that rpm range a good idea?