Cobb calls it "FIBET..."

nsfw · **Joined:** Thu Nov 23, 2006 2:23 am **Posts:** 2565

FIBET = Fuel injector boost error trim. Interestingly, Cobb says this table should be filled with zeroes if you get FMIC, to avoid going rich upon boost increase. That sounds a lot like a problem I've been having, so I'd like to try experimenting with this table... but I don't see such a table in my ROM.

Am I overlooking something, or is it not part of RomRaider's definitions yet?

Thanks!

merchgod · **Joined:** Thu Mar 30, 2006 2:38 am **Posts:** 5336

This has been discussed before by one of the guys that tunes with OS and Cobb (littleblueGT? or airboy?). That is the tip-in enrichment comp boost error map in RomRaider. Not the best name that they gave it in Cobb's software and I believe, for whatever reason, they used no conversion (raw values) for that table, so 0 is equivalent to -100% in RomRaider.

mickeyd2005 · **Joined:** Wed Oct 25, 2006 4:32 am **Posts:** 3040

NSFW wrote:

FIBET = Fuel injector boost error trim. Interestingly, Cobb says this table should be filled with zeroes if you get FMIC, to avoid going rich upon boost increase. That sounds a lot like a problem I've been having, so I'd like to try experimenting with this table... but I don't see such a table in my ROM.

Am I overlooking something, or is it not part of RomRaider's definitions yet?

Thanks!

I have read their description several times. I am about 90% sure that Cobb's definition and usage is incorrect.

wrxsti-l · **Posted:** Wed Apr 08, 2009 5:38 am

merchgod wrote:

they used no conversion (raw values) for that table, so 0 is equivalent to -100% in RomRaider.

If Cobb suggest setting 0 to all cells when you fit a FMIC, should we perhaps be setting all cells to -100 if we have a FMIC?

nsfw · **Joined:** Thu Nov 23, 2006 2:23 am **Posts:** 2565

That doesn't make sense to me though - as I understand tip-in, the problem (very brief lean AFRs upen sudden throttle openings) should get worse with a FMIC, and therefore demand more tip-in, not less.

merchgod · **Joined:** Thu Mar 30, 2006 2:38 am **Posts:** 5336

Setting that table to a raw value of 0, if that is what Cobb suggests, would disable tip-in enrichment alltogether.

Airboy · **Posted:** Wed Apr 08, 2009 5:49 pm

NSFW wrote:

That doesn't make sense to me though - as I understand tip-in, the problem (very brief lean AFRs upen sudden throttle openings) should get worse with a FMIC, and therefore demand more tip-in, not less.

I think the idea behind changing that table is to deal with the rich dip in AFR on spool-up. I don't think it would help much since the issue is mostly due to time delay in MAF reading and when the air actually get to the cylinders.

WolfPlayer · **Joined:** Mon May 01, 2006 6:15 pm **Posts:** 126

merchgod wrote:

Setting that table to a raw value of 0, if that is what Cobb suggests, would disable tip-in enrichment alltogether.

This is absolutely 100% true. I talked to Christian about it and confirmed that when you set this table to 0 (or -100% in RomRaider), Tip-In is completely disabled. Additionally, doing this has 0, Zero, Nill, no affect on the FMIC rich spike. The problem is that the FMIC rich spike is not an immediate thing. The rich spike can happen seconds after stabbing the throttle to 100%. Stab the throttle to 100% at 2000rpms. By the time you hit full boost, tip-in enrichment based off of a change in throttle is long over.

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jagstyle · **Posted:** Tue Nov 24, 2009 7:10 am

so what are you guys doing with this table?

nsfw · **Joined:** Thu Nov 23, 2006 2:23 am **Posts:** 2565

I forgot.

I think I left it stock.

jagstyle · **Posted:** Tue Nov 24, 2009 11:57 pm

Cobb says:

Cobb Help File wrote:

Fuel Injector Boost Error Trim

Table description – a single row defined by increasing boost error and associated Tip-in fuel trim values.

Tuning tips – This table defines a richened fuel mixture during Tip-in when boost is above target. It helps
keep fuel mixtures appropriately rich when boost increases rapidly during tip-in. When using stock
injectors these values should remain unchanged. When larger injectors are utilized these values should be
reduced proportionally. For example, if the stock injectors are 500 cc and 1000 cc injectors are used then the boost error should be multiplied by (500/1000)*boost error injector trim. In this example boost error
injector trim will decrease by 50%.

anyone do this for larger injectors?

samtron42 · **Joined:** Mon Feb 16, 2009 5:57 am **Posts:** 22

i have used the idea -100% in romraider, it does assist in throttle stab issues due to rich spike,though it still has a rich spike it does ride better in the slight on off throtte blips expecially during heel toe and down shift.s not much enprovement to go crazy over but cobb does it and so will i LOL it does make some improvement with modded injectors so i kept it..... tunes are car specific try it and if it doesnt suit your needs then go back.. take your time and tune in progression it will be then that you start seeing your slight details come through to your benefit

MFB · **Posted:** Wed Jul 21, 2010 1:43 am

Based on the definition description of this table, here's a simple spreadsheet to help you guys rescale this table to your bigger injectors. Since Im using bigger injectors, it does make sense that I should be using less fuel compared to smaller injectors on boost error. Computation used raw ecu value (same as cobb) and converted back.

Attachment:

Rescale Stock throttle Tip in Comp on Boost Error Table for Bigger Injectors.xls

mrf582 · **Posted:** Tue Oct 26, 2010 1:00 pm

samtron42 wrote:

i have used the idea -100% in romraider, it does assist in throttle stab issues due to rich spike,though it still has a rich spike it does ride better in the slight on off throtte blips expecially during heel toe and down shift.s not much enprovement to go crazy over but cobb does it and so will i LOL it does make some improvement with modded injectors so i kept it..... tunes are car specific try it and if it doesnt suit your needs then go back.. take your time and tune in progression it will be then that you start seeing your slight details come through to your benefit

Does your car stumble during tip-in now? Theoretically, your car should not run any tip-in enrichment with those values at -100%. How does the car react to varying rates of tip-in? 0 to 10%, 0 to 25%, 0 to 50% etc.

MFB · **Posted:** Sat Mar 31, 2012 12:16 am

Does this table get activated on postive target boost error on 100% accerator pedal? If you follow interpolation then full tip in is active for 100%? Im hunting down what adder table makes final fueling base richer compared to OL fuel table during a wot run. I see it active between 2000 rpm to around 3800 rpm. During this time to peak boost, positive boost error is present and richer final fueling base compared to OL fuel table. Ive compensated for this by leaning out OL fuel table but rather find the real cause. Wideband confirms the same as well.

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Cobb calls it "FIBET..."

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