Miss or stumble at WOT after shift.

[Sinisterjw]

So I'm trying to tune my fuel set up but I'm not getting consistent bars on my A/F gauge and I have a bad stumble or miss. Sometimes I only get 8 sometimes 9 or 10, these are consecutive runs. I just switched to a 2.5L set up, the motor is bone stock, ported exhaust manifold, stock garret with 2.5" exhaust housing, 3"exhaust, graingered at 16lbs with some creep, a k&n open element, 52lb injectors with static set at 32psi(lowest it would go) and a cartech rrr with the onset starting at 13lbs of boost, still trying to tune the rate of gain. The fuel pump is working great, the filter is fine, and the pressure at the rail is going up just find under load and holding like it should. The tps is fine, no vacuum leaks, no leaking hoses or bov, temp gauge reads cool. Sometimes I'll get 10 bars, so I'm guessing the 4 wire ntk O2 sensor is working right.(could be wrong there if anyone's had that problem before with spurratic O2 failure) But whenever I get on it in 2nd it runs fine(still have the 8,9, or 10 bar problem) then when I shift at high rpm and floor it, it stumbles or misses for about 2 seconds then kind of cleans up. The A/F gauge doesn't jump to rich or fall to lean when this happens. The plugs read clean with just a touch of carbon on top of the threads and I got no codes. If I accellerate moderately through the rpms it's fine. Anyone have any ideas it'd be greatly appreciated. Thanks.-Jarrod-1988 csx-t

[NAJ]

I am not into performance but since nobody has answered yet.....
16lbs of boost and a stock map sensor and controller?
From what I understand the stock map and controller will only read to 14.5 lbs.

[janus]

yeah well, the stock map is a 2bar map and will therefore only read up to 14.7psi, which is 1bar. it will read from 1 bar vac (or -14.7psi boost if you like ) up to 1 bar boost, for a total of 2bar. if you want to go higher and still involve your ecu you would go with a 3bar, but it will require the ecu is set up and tuned for this. also unless you did the zener-diode or some other kind of fuel cut defender, it would normally cut out above 1 bar boost reading. just some thoughts, hth

[Sinisterjw]

Yes it has a zener diode on it, and it has a grainger, not the stock boost solenoid set up. I think I've found it though. I think the 52lb injectors were dumping so much fuel it was actually coming throught the exhaust in drop form and soaking the O2 sensor not letting it read right. I swapped to 42lb injectors and am still tweaking the cartech RRR, but it's already running way better. Just toying with static pressure, rate of gain, and onset points, but it's very promissing. In case anyone is interested, I'm about to do an install of what seems like a fairly easy junk yard rear sway bar on my csx-t. It'll probably work on others, but I can do a little write up for those of you with shadows and dusters if you're interested. The whole shebang will run me about $25.00. Knowing how to weld helps, but you could probably get by with some creative alternatives.

[janus]

ah well okay, gotcha. let me just ask you this, what exactely are your changes in fuel supply based on? just the narrowband right? i'm not sure about this but this would only give you reliable information for WOT fueling wouldn't it?

[Sinisterjw]

It's just a 10 bar a/f gauge. It's reads at all throttle positions, but it is a tad general. Between that and how the car runs, I adjust accordingly. I used the 2.5's fuel curve difference from the 2.2 and worked from there. So far I've left static at 40psi which keeps the idle good and the throttle quality in vac. good plus it seems to have enough fuel for low boost. Now I just need to find where to set the onset of gain and the amount. I had it set at 6psi at about 2.5 or 3 to 1, now I set it at 9psi at a little over 3-1. Haven't driven it like that yet, but with the old set up it was still stumbling a tad after quick shifts at high rpms. I'm open to suggestions, but the budget is tapped for now, so swithcing to a 3 bar with programmed cals, or installing an egt is a no go for now. Thanks alot guys.