Car running lean at high rpm

[RedlineGX]

Hi guys, recently installed an air/fuel gauge and had my suspicions confirmed. I have a converted manual '97 GX and the car is running lean after 5000 rpm or so, right down to 2 bars red.

Car has on ApexiN1 exhaust, decat, custom cai, FP Regulator, plat plugs, magnecor leads, GPX injectors, Evo8 Fuel pump.

FPR seems fine, its a rising rate set at about 44psi. Changed Fuel filter, the pump is new. Changed injectors to GPX injectors after I noticed the problem cause my mate had some spares. Also changed the 02 sensor, engine coolant temp sensor, Stepper, Coil packs, and I'm getting no codes from the ECU.

I've got a 65mm TB and intake and the RPW extractrs & downpipe coming along with an emanage but was wondering if this sounds like a mapping problem or a fuel delivery issue sicne i think the TB & downpipe will make the problem worse.

Car pulls great and runs rich right up to 5000 rpm and then falls off a bit and gradually drops to 2 bar lean at 7000 rpm.

Any thoughts would be appreciated. I'm not too concerned if its a mapping issue because I;m getting the car tuned on a wide band sensor when the emanage comes.

[RedlineGX]

Anyone else got in an air/fuel gauge that can tell me how theres compares at high rpm. Just wondering if the FTO in general has the tendency to lean out at high rpm.

[spetz]

Normally they start running richer before MIVEC kicks in (5500 rpm) to be on the safe side.

It's quite odd, but I guess since the car is going on the dyno the tuner should be able to tell you exactly the problem?


By the way, how does the car go? Nice list of mods

[RedlineGX]

Goes great up until 5000 rpm or so. Get a lot of wheelspin when launching from 2000rpm or over with 45 series 17z but feels like it falls off in the high rpm. Hopefully the extractors and tuning should sort that

[Chiangstar]

Goes great up until 5000 rpm or so. Get a lot of wheelspin when launching from 2000rpm or over with 45 series 17z but feels like it falls off in the high rpm. Hopefully the extractors and tuning should sort that

thats odd... usually its the other way around with fto's... less power in the lower rpm and more power in the upper rpm

i'd be worried about running lean at high rpm... thats what exploded engines are made of

simon

[RichardH]

Hi guys, recently installed an air/fuel gauge and had my suspicions confirmed. I have a converted manual '97 GX and the car is running lean after 5000 rpm or so, right down to 2 bars red.
...
Any thoughts would be appreciated. I'm not too concerned if its a mapping issue because I;m getting the car tuned on a wide band sensor when the emanage comes.

Don't jump to conclusions until you get it checked on a dyno with a top quality AFR sensor thingy.

Mine sticks to 13:1 AFR at wide open throttle, right up to 7500rpm. No tuning really necessary - it's ideal, basically. Loads of info on this here...

http://www.ftowa.com/html/workshop/workshopart11.html

So get thee to a dyno. 15 minutes plus $60 or so and you'll know exactly what the story is.

- Rich

[RedlineGX]

Ok thanks guys. Yeah I'm not 100% confident that the gauges is accurate since these things have a tendency to be a little off but still seems strange it would lean out after showing a rich condition. Anway I got my emanage now. Between two minds wethter to wait for the extractors & TB or put it in now.

[p13nox]

sorry to go off topic, but I'd be interested to know what your rolling road figures are with all your mods. I have a GX and am slowly doing most of the mods you have listed.

So far I haven't actually gained any power, although it does feel quicker out on the road.

[RedlineGX]

Ok back again.
To answer your question p13nox, biggest problem is that we dont have an easily accesible RR to use down here. I'm using a v.good auto electrician/mechanic who's got a ton of software and other ingenious stuff to tune cars. Top guy! But not sure if he can give me actual HP figures? Will see. However the car is a lot faster than when I first got it. Also bare in mind the only real 'performance' mods are the exhaust and intake ones. Everything else adds a little but not really a hugely measurable gain, altho I'm interested to see what the emanage does. Btw how long have you had your car?

Ok second thing. Took my car out tonight after hooking up a gauge extension that amy mate could read while I drove. Fuel delivery is fine and pressure stays at 60psi at what where it is with vaccuum off. So i dont think its a delivery problem so got my fingers crossed that the gauge is just wrong.
Only other concern would be wether or not there is a blockage somewere after the FPR altho unlikely. Anyone know wether or not this woudl effect the reading of the FPR or would it have to be a problem before it?

[RedlineGX]

Ok got car on a wide band sensor and its running great....rich through the whole range so dont trust them bloody gauges unless you get the sensor kit for it.