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Maxing out injectors and new oxygen sensor with no reading.

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alex99gst

20+ Year Contributor
1,339
24
Feb 10, 2003
Nashville, Tennessee
I did a log today on the way home to see what was going on since it's been a while. I figured I was maxing out my injectors/pump running 18 psi on a small 16g and as it turns out, I am. I know it is about time for new pump and injectors now. My main problem is with the oxygen sensor. The car gets much better gas mileage now that I've replaced it and for a while it used to read 0.04, but then when you logged it you could actually see it change. Now that I've logged it, it stayed at 0.06, but doesn't feel like its running rich because it is still pretty quick. I replaced it maybe 3-4k miles ago. It read fine until I seafoamed my car but seafoam claims to be oxygen sensor safe. Do you guys think if I were to get a new pump/afpr/injectors and set the MAFT accordingly that I would be ok? I can't tell what version my MAFT is, but it does have the 4 mode switches and I was wondering if after the new fuel setup if I could set it to rpm mode and then just add fuel up top. Thanks guys.

Alex

Here is the log and then a picture of when the knock reached a peak of 11.
 

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Definately need to upgrade fuel system. I maxed out stock injestors with a small16g and 16psi, with injector duty cycle above 100% at times. I also noticed signs of mas overrun at those boost levels. This was on 3kgt fuel pump with stock fpr.

I went with a mild MAS hack, AFC and a N/T fpr as a solution. Duty cycles are in the high 80's at the same boost levels.

Does the O2 reading show a constant 0.06 at idle or a WOT pull? Sounds like it may need replacing.

I'd suggest a hacked mas/2g mas along with a set of 560's and an AFC instead of a MAF-T.

If your gonna stick with the MAF-T you should be fine with just a set of 560's or even just a bump in fuel pressure and a medium sized pump upgrade.
 
I would rather keep the MAFT for now and possibly go with the newer MAFT 2 or whatever just came out instead of dealing with the hastle of an AFC and wiring up a new MAS. The o2's used to cycle before the MAFT right after I replaced the sensor, but everything runs fine still, I think it just doesn't display the volts right anymore. It might just be time to save for a big new upgrade with fuel stuff and then the new MAFT and a wideband, who knows.
 
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