Start up flare control-mafless

[hymey]

Hi guys,

When going mafless I have troubles with start up flare control. This is B5133. If I don't take out enough timing, the revs flare to over 1500rpm. If I bump up the settings higher than standard, it only flares to 1200rpm but then pulls aggressively towards idle speed, the engine sounds like it dies for a second then idles smooth. I have also played with upper and lower idle/timing correction. I was just wondering what's the trick to get them to start well(just like when maf is connected).

Does the table refer to actual rpms. Or rpms over desired idle speed. ie. 0 deg or 0+550.

Cheers

Joel

[hymey]

Just some feedback from this. I had to decrease cranking airflow B1832 and slightly increase values in B0138. In doing this I could make figures in B5133 less aggressive.

Joel

[ringram]

Interesting, the HSV LS2 doesnt flare at all. Mind you I have reduced desired idle speed and airflow.

[hymey]

I have mine idling slightly higher with idle air flow increased slightly. Cranking idle air flow adjustment has given me the best results. Have you experimented here ringram.

[The Alchemist]

Glad to hear its working out for you :)
Mike

[ringram]

Im trying to get mine down to 700 rpm ;) No joy yet.

[hymey]

What are your settings like on B5128, B5129, B5130, B5131 Ringram,

I thought I had my start up issues sorted. In a busy service station in Brisbane my car refused to start.

It would cough then die. After I reflash it it starts perfect everytime. I dont even have to change any settings. It will be OK then for a while. It doesnt flash codes. I have turned off light off cat protection also altered cranking idle airflow, Cranking enrichment, over and under idle speed correction, start up flare control,cold start timing, cranking timing. I have altered the VVE table. Once the MAF is plugged in it starts fine.

Yet if I tune a mafless LS1 it starts and runs first kick very nicely, without the need to change to much. The e38 is a very different bit of gear and timing alterations play a big part in how it idles. I found mine likes + or - 3 degrees correction than ramping up to + or - 7 degrees. Any more its two aggressive, any less it hunts or hangs.

As for starting it has me stuffed so I think the MAF tune is going back in until I can think of something else.

It seems to be a timing issue but even turning of flare control and working entirely on idle overspeed correction it still persists to be troublesome.

[ntae]

Joel as you have found out the only way to be on top of the E38 ecm ,is to own & drive one every day , there are lots of tuners in OZ that only see a E38 when a customer wants a tune & spend a day or two flogging it on a dyno run after run

You got my attention with (it starts up fine after a reflash) , i found the same thing after i went a smaller cam ,i think there must be some sort of ecm learning going on ,it turned out to be spark being pulled, i could see it with the scaner, B5132 i set this to 7 across the table and leaned out the cranking fuel as well . i found being able to turn off idle spark with DVT a help as well with the idle set up

Good luck

Geoff

[Delco]

Hi guys,

When going mafless I have troubles with start up flare control. This is B5133. If I don't take out enough timing, the revs flare to over 1500rpm. If I bump up the settings higher than standard, it only flares to 1200rpm but then pulls aggressively towards idle speed, the engine sounds like it dies for a second then idles smooth. I have also played with upper and lower idle/timing correction. I was just wondering what's the trick to get them to start well(just like when maf is connected).

Does the table refer to actual rpms. Or rpms over desired idle speed. ie. 0 deg or 0+550.

Cheers

Joel

If you get your airflow and fueling right they start up perfect and settle immediately on the desired idle speed with no under or over flair , big cams are a delight compared to the early stuff.

[hymey]

95% of the time It starts and settles perfectly. It is only 5 % of the time it happens.And if it dies I just reset the computer or reflash it and boom away it goes, so in our case there is something goin on. I have found LS1s not to have this same problem. As ntae suggests it is a timing problem. There is timing being pulled somewhere. This is only a thought. I havent watched it on my scan tool.

Ideally(and I havent tried this yet) we should be able to turn off any spark correction and flare control and have a perfect start up. If idle airflow and fueling are correct it should settle without those parameters in place like a dirty old carb:redface:

[swingtan]

Hymey, it almost sounds like idle relearn is having some effect. The reset / re-flash is clearing out the learnt data allowing for a start. as a matter of interest, when it doesn't start is there a pattern? Like it's only after a 5 min stop or something like that. B0138 is an interesting table for this type of issue. In my stock tune, there is some very weird settings compared to latter models.

[Delco]

95% of the time It starts and settles perfectly. It is only 5 % of the time it happens.And if it dies I just reset the computer or reflash it and boom away it goes, so in our case there is something goin on. I have found LS1s not to have this same problem. As ntae suggests it is a timing problem. There is timing being pulled somewhere. This is only a thought. I havent watched it on my scan tool.

Ideally(and I havent tried this yet) we should be able to turn off any spark correction and flare control and have a perfect start up. If idle airflow and fueling are correct it should settle without those parameters in place like a dirty old carb:redface:

Sounds like airflow is out and its using timing to correct the idle speed or you are using too much idle timing.

the fact its better after a reflash indicates it is learning so you desired is different to your actual airflow.

[hymey]

Hymey, it almost sounds like idle relearn is having some effect. The reset / re-flash is clearing out the learnt data allowing for a start. as a matter of interest, when it doesn't start is there a pattern? Like it's only after a 5 min stop or something like that. B0138 is an interesting table for this type of issue. In my stock tune, there is some very weird settings compared to latter models.

Hey Simon and Dan,

Yeah, When its cold or warming up its fine, If I have been driving for half an hour then stop, Its likely to not start then and after a reflash boom away she goes.

After I reflash it it maybe OK for another 30 minutes or so then it does it again, Normally when its hot. Not so much from driving around town or to work and back but longer city driving, stop start driving.

I have adjusted fueling in b0138 that makes a difference also cranking idle airflow, they make the biggest difference.
It seems to like more idle air flow then stock, if I run less it idles worse. If I run more it improves, It is better with 600-650.

Timing is only 13 degrees, once the engine is running it idles very smooth and I dont require much spark correction.

I will connect the scan tool next time it does it.

BTW had a big week of tuning, need to have a break on it for a week or so. Didnt sleep for the last 48 hours, My OCD and bipolar mind went into a bit of a spin yesterday, reversed into another car out the front, come inside passed out had a panic attack then slept for 14 hours. Off work for a week and I think my Mrs would kill me if I were on here atm.

Thanks for your help

Joel