berkel

iTrader: (5)

Hey all,

The other day we had a thread about part throttle. I noted that my car seemed to pull better at partial throttle, and I even noticed that it would feel like it suddenly bogged if I went from partial throttle to WOT in the higher RPM ranges. I attributed this to the much richer WOT map. I avoid partial throttle at higher rpm since I don't want PTHB and extreme lean conditions.

Anyway, I was merging on the hwy today and I think I was WOT in 4th gear revving from 4500 rpm to a little before redline. Right around 6krpm I felt a bog or sudden loss in accel. Not drastic, but I did feel it SOTP. I'm fairly sure I was WOT the whole time, so different from the previous experience where I went from the leaner partial throttle to WOT.

I have an MBC and it reads just under 20 psi on my DEFI mech gauge teed at the FPR.

Could this bog just have been the transition to the extreme rich portion of the map? I only really feel this in 4th and maybe 3rd gear. 5th would be too fast for most traffic, and 1 and 2 are so quick you don't notice. I worry that it's pulling timing, but I don't think my boost is that high, unless my gauge is way off. It reads ~ 1 psi higher than the stock config, but doesn't taper nearly as much at high rpm so I think the gauge is fairly close.

I'm not running out of fuel? It's not that abrupt so I don't think so. Anyway, I hope it's just from being so rich, and my SAFCII will fix it. I should datalog or something to see what my timing is doing. Maybe I can run the stock map with SAFCII and check the knock sensor reading. Is the knock sensor fairly accurate?

Sorry for the novel.

Thoughts?

FB

bigd

Sure sounds like the standard Evo VIII timing pull. You can REALLY feel it, it takes a dive around 5500 and climbs back up. I forget how many degrees exactly, but it feels like a big lump in the acceleration.

My cure was to get an XEDE. It's a world of difference. Smooth pull all the way to redline. Most people who have gotten the Works reflash have said the same thing. I would imagine they perform similar smoothing of the timing maps. I chose the XEDE because of programmability and the fact that a remap requires sending the unit back for changes (returning to stock, retuning, etc.).

The latest XEDE controls timing, A/F and boost. It really makes it a different car.

rarson

Only reason XEDE controls timing is to cover up the hackjob that it does on the MAF signal. It does nothing in the way of controlling fuel that an AFC doesn't do.

I highly doubt you'd be able to feel the car richen up switching to a WOT map like that. Most likely the bog you're feeling is going from really high timing at high rpm (part-throttle) to suddenly WOT which the ecu sees and has to pull a lot of timing in order to get on the lower timing map.

If it were fuel cut, you'd be wondering what you broke.

berkel

iTrader: (5)

Thanks for the reply.

You think it's just stock timing? I was just worried that I have too much boost or something and I was running out of fuel or pulling timing because of knock. I just didn't think my boost was too high. I forgot to mention I'm running 94 octane Sunoco.

My original plan was for an XEDE, but due to budget limitations (baby on the way ), I have an MBC and SAFCII on the way for now. Unfortunately I won't have timing control, which I know can be a big help, but hopefully leaning out the pig rich top-end will help quite a bit.

I will try to monitor when I install the SAFCII before changing the map and see if it's sensing knock.

Thanks,

FB

rarson

You don't really need that timing control. Dave isn't using any. The only real reason you would want it is to raise timing if you can get away with it, but the AFC will accomplish this for you. Be aware that by leaning the AFC out, you are reducing the MAF signal which in turn will move the ecu to a lower fuel and timing map. This is the same thing the XEDE does, but the XEDE allows you to fix the timing adjustment for a "safer" tune. In reality, all you really need to do is find a balance between fuel and timing that doesn't allow excessive knock. This is what you'd be shooting for anyway if you had complete control over everything in the first place.

connor4200

did you find your problem just happend to me in my evo 9 mr
got walbro 255 and cams clutch but it doesnt seem like the engine is having a hard time with rpms not a clutch slip either