Running Too Lean On Afr's

[S3RK]

Just installed a AFR display today and it was reading 13.5:1

Is this a normal ratio? My fuel economy has been pretty poor as well

EDIT: Shit, Must I add I'm running a R33 GTS '93 RB25DE

Only mods is a K&N high flow panel filter & the muffler replaced with a cannon.

Thanks guys.

Edited October 17, 2011 by S3RK

[iseekool]

That ratio is perfectly normal.

[Super Drager]

13.5:1 is actually fairly good for an NA, my cousins NA was tuned to 13.5:1 with an SAFC

[zebra]

at full throttle or cruise?

cruise/low load should be 14.7:1 or leaner

[MBS206]

If it's only the gauge connected to the factory sensor, then ignore the gauge. It's designed for a wideband sensor, not a narrow band sensor, all that they can read is "Lean, Stoich, Rich" they don't return an AFR.

[S3RK]

It's one that actually displays numbers, but I'm having a few issues with it so it's not actually displaying the correct ratio -_-

So what should idle, cruise and full throttle be, just good ratios that won't hurt the car?

[zebra]

bit more to it than just some numbers

[MBS206]

It's one that actually displays numbers, but I'm having a few issues with it so it's not actually displaying the correct ratio -_-

So what should idle, cruise and full throttle be, just good ratios that won't hurt the car?

Is the only thing that you purchased, the gauge? Does it have a new sensor, or does it wire into the old sensor?

If its using the standard sensor, you remove it from the car, and throw it in the bin. It will be as useful in the bin, as it is in your car then.

[zebra]

yes, please tell us exactly what you bought

[mad082]

as above, how do you have it hooked up? if it's simply running off the stock o2 sensor then ignore it as it won't tell you squat, except for at light load when it may tell you whether your o2 sensor is working properly or not.

[S3RK]

^All of the above, it was given to me, the jaycar one that you build yourself. It's hooked up to the ecu wire.

I hooked up my ecu cable today and ran a error test, apparently my knock sensor has an error for the last 25 starts (I believe ECU holds up to 50?)

and roughly 25 starts ago I had to take my car to the mechanic, he is a dodgy mechanic but I was forced to take it there. After he replaced my clutch there was a red light for the exhaust I believe on the dash, so I asked him wtf is this shit and he raises the car back up, pulls this cable out of the cat converter (I think) and rips the inner wire completely out and puts the cable back in, then tells me it's fixed.

I believe that's the secondary o2 sensor? Does it affect the car in any way?

Where abouts is the knock sensor located? and can I replace it?

Thanks in advanced

[PM-R33]

That was the temp sensor for the cat. It comes on when exhaust temps are way to hight (ie a blocked cat). Has nothing to do with O2. It simply just brings the light up on the dash.

It sounds like you have just put a AFR gauge onto a stock narrow band sensor. Meaning it is absolutely pointless.

[89CAL]

Yeah sounds like its reading off the stock sensor. If you want to check your AFR's I'd suggest taking it to a tuner and spending $100 putting it on a dyno and getting them to tell you how it is. If its just a stock ECU this would be your best option, but it shouldnt be running lean.

If aftermarket ECU then I suggest getting a good quality wideband kit.

BTW 13.5:1 sounds rich if anything for an NA, probably about right on stock ECU

[S3RK]

Yeah I don't think the readings were accurate at all, so I wouldn't say it's 13.5:1

Will the temp sensor affect my car at all?

[PM-R33]

Nope.

However the fact the light on the dash came on could be an indication of a collapsed cat.

[mad082]

Nope.

However the fact the light on the dash came on could be an indication of a collapsed cat.

in 99% of cases though it is caused by the sensor being dodgy. mine used to come on the moment i started the car, so unless someone had stolen my car and parked it a few seconds before i walked out the door to go to work i was pretty sure it was a dodgy sensor, LOL

[MBS206]

^All of the above, it was given to me, the jaycar one that you build yourself. It's hooked up to the ecu wire.

I hooked up my ecu cable today and ran a error test, apparently my knock sensor has an error for the last 25 starts (I believe ECU holds up to 50?)

and roughly 25 starts ago I had to take my car to the mechanic, he is a dodgy mechanic but I was forced to take it there. After he replaced my clutch there was a red light for the exhaust I believe on the dash, so I asked him wtf is this shit and he raises the car back up, pulls this cable out of the cat converter (I think) and rips the inner wire completely out and puts the cable back in, then tells me it's fixed.

I believe that's the secondary o2 sensor? Does it affect the car in any way?

Where abouts is the knock sensor located? and can I replace it?

Thanks in advanced

If it's not had a replacement sensor placed in the dump pipe, do yourself a favour, remove the AFR gauge, and forget you ever started this thread.

[central coast person]

+1

And the cat sensor is uselesss on 99% of highflow cats because there is no point to install it so maybe invest in a highflow cat and forget that the mechanic ripped it out? Exhaust shops tuck the sensor under the heatshild when fitting the cats so they are simply installed for someone to say "hey my cars got a warning like, better take it to the mechanic".