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Speed density extreme lean condition when starting off from a stop (9653 V7 SD rom)

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Old Jun 8, 2010, 08:14 PM
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Stock accel maps, but notice what I am referring to-

https://www.evolutionm.net/forums/ec...injectors.html

Post 2 specifically.
Old Jun 9, 2010, 03:05 PM
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Interesting, mine is set in the area you're mentioning at 101.8 Map correlating to 91.0 load. I'll bump this area up and see what the reaction is, thanks for the insight.
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Old Jun 11, 2010, 11:24 AM
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Curious as to your findings so far. I was bored at lunch today so I was re-reading many old threads on similar subjects...even found the one where you were talking about this earlier and discussing the ***Warmup Enrichment vs Load and RPM table.

Btw, have you adjusted the two maf comp warmup tables and the warmup enrichment tables from the stock values?

Also, have you tried adjust the async and sync fpw tables at all? It seems like some people have had success with these tables, and if your issue follows what 03white saw, it appears that the sync fpw may be the issue.

Of course, when this exactly happens is important. If it's only when warmup up or even after completely warmed up, for example.

Also, out of curiosity, have you adjusted your IPW cranking/running (whatever they are named now) for your bigger injectors? I think all of the subject tables are in mrfred's advanced fuel control thread. That is just a great thread...has to be one of the best of all time ... I'm curious as to how you are getting on with this. If you're still having issues, I would like to suggest some things to try (if you haven't already).
Old Jun 11, 2010, 08:53 PM
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Originally Posted by l2r99gst
Curious as to your findings so far. I was bored at lunch today so I was re-reading many old threads on similar subjects...even found the one where you were talking about this earlier and discussing the ***Warmup Enrichment vs Load and RPM table.

Btw, have you adjusted the two maf comp warmup tables and the warmup enrichment tables from the stock values?

Also, have you tried adjust the async and sync fpw tables at all? It seems like some people have had success with these tables, and if your issue follows what 03white saw, it appears that the sync fpw may be the issue.

Of course, when this exactly happens is important. If it's only when warmup up or even after completely warmed up, for example.

Also, out of curiosity, have you adjusted your IPW cranking/running (whatever they are named now) for your bigger injectors? I think all of the subject tables are in mrfred's advanced fuel control thread. That is just a great thread...has to be one of the best of all time ... I'm curious as to how you are getting on with this. If you're still having issues, I would like to suggest some things to try (if you haven't already).
I haven't really gotten time to make the VE table changes that were suggested (have a bad vibration issue that's taking priority at the moment), although oddly enough when I changed my external wastegate springs to a stiffer setup the issue lessened a bit and the leanest I've seen it go lately is around 16afr. I had tried adjusting both the async and sync fpw tables, but neither gave me the results I was looking for in the trouble area. It would usually richen the mixture before and after the normal lean spot, but never where the problem occurred. Never once did I touch the maf comp warm-up tables, I never saw an issue with them really, and when the car is cold it runs about 1-1.5 points richer until it comes up to temp. After it warms up is when it leans out, and the FPW is always 2.5ms in the problem area on every log I have that captures this event. Nothing I do to any table seems to change that 2.5ms value either, so I wonder if it's a by-product of stutter fix #2 in effect, as I don't remember there being a lean spot before I ran any of the stutter fixes.
Old Jun 11, 2010, 09:52 PM
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If you are only logging 1-Byte pulse width, you will not see a lot of change in IPW when this is going on.

Figure injector dead time is ~0.7ms so your actual pulse width is around 1.8ms. 1-Byte resolution is 0.256ms so figure 0.256ms of variance on a 1.8ms actual IPW means your AFR can vary about 15% under these conditions yet the log will not show any change in IPW at all.

15% lean is 16.9:1 AFRs, as you can see, you can get an AFR that causes poor drive ability yet it might not show up at all when logging only 1-byte IPW.
Old Jun 12, 2010, 10:13 PM
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Hmm, yeah that makes a lot of sense, I'll have to look into logging a 2 byte IPW and see what comes up. I'm sure the dead time on my FIC 1050's doesn't help much either, but I have to admit the more I play with the latencies the more they run just as smooth as stock.
Old Jul 4, 2010, 08:24 PM
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I forgot to update this from my previous posts...

Mr. Bradley is correct on the correction around the 100Load range, I adjusted my sensor VE up about 5% and it completely cleared out ANY lean issues I was having with the initial stop and start in first gear and improved the drivability and tip-in greatly throughout the rest of the range. I would count this thread as problem solved.

Thanks everyone for your input!
Old Jul 4, 2010, 11:06 PM
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Did it solve the actual IPW changes or is the car just rich enough on average that it hides the IPW cut out?
Old Jul 6, 2010, 09:24 AM
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Problem only 1st gear?

Does AFR spike rich shortly after the lean problem?

Something to consider is quality of fuel vapor with modified EFI, the WB will only report accurate AFR if fuel is accually being burned.

Last edited by C6C6CH3vo; Jul 6, 2010 at 09:26 AM.
Old Aug 25, 2015, 07:06 PM
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old topic but I felt the need to necrobump. I was having this EXACT problem. Ihave been playing with the Sensor VE settings a bit. I got the lean condition to go away, only for it to run rich in the later gears. Then it was running rich in the later gears and lean in 1st gear, LOL. Anyway I think I ALMOST have it gone. It was a bit lean in 1st and a bit rich in 2nd. I made one more small adjustment and I'm about to test on my way to the gym.
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