I whas out today to tune AE with my WB.
I seems that I got a lean spike when I apply throttle fast. I played only with "Accel Delta TPS mult VS Delta TPS".
No matter how much I increased the values the trend is the same.
If I apply throttle fast I get a quick lean spike, then it goes rich.
So this leads me to a theory.
Could it be that the WB is faster then the ECM?
Also when I go ABOW a certain amount in the tabel "Accel Delta TPS mult VS Delta TPS", the lean spike acctualy gets bigger? And this leads me even more to the theory that the ECM is to "slow" for the WB.

As you can see on the screenshot the lean spike is just a fraction of a second before the AE makes the A/F rich.
Thanks

Its a 730 ecm 8D code..

/devil..

 

It's kind of true that a wideband is faster than the ECM. But a better way to think about it, is that engine airflow and fuel flow dynamics are faster than the ECU's logic for determining what the fuel requirement is, and it's ability to get the fuel to the cylinder in time to burn.
key points:
a) Lots of fuel sticks to the ports.
b) Air flow changes faster than MAP.
c) TPS is the only anticipation, but since it's sampled for fast changes only .015 seconds, the fast air flow can sneak its way into some cylinders before the ECU calculates a fuel change request.
d) most people don't drive in this worst case scenario.
e) a little lean spike like that won't be on the emissions test
f) a little lean spike like that won't be felt by the average user, and possibly not felt at all

 

So in other words. If the driveability is good and you got no tip-in knock. Dont worrie about it ?
Its good to know, so I dont get crazy trying to tune it away hehe

Thanks

 

Can you log the wideband in TTS? or use tunerpro, it would be good the see all data in the same scan.

/N

 

I havent done the mod yet so I can log WB in the ALDL stream.
But I can log both TPS/RPM/MAP with the Z1 software. What info do you whant m8?

thanks

 

You know I was going to post the same thing but I am seeing a lean spike in the lower MAP regions. When I open the throttle I am lean from 0-50kPa then it goes rich. I was looking at my tables and could only find the multiplier based on MAP. So far I have not logged a new run to see if this helped.

 

Yup. expect that lean spike in WB logs. It may be more prevalent in TBI'd vehicles. it was often said(maybe just me) you foot can provide air faster than gas. add to it a drop in manifold vacuum(high map) and it further erodes atomized fuel in plenum.

Grumpy once said a larger injector may be beneficial as it can introduce fuel faster? maybe consider that or crank up the FP and retune the VE. Thats easy. Having a larger TBI unit does not help either. I was successful in learning of the AE-RPM multipler first this spring. for reasons UNK it was not spoken of much here or I was asleep or is only needed with a bigger cam. With countless changes to ATTPS or AEMAP with every combination i could imagine nothing worked. engine breakup at 2400-2800 rpms. fall flat on its face. The AE RPM multiplier worked !!!
I dumped in (literally) 55% more AE right at 2400 rpms and it carried the motor to 2800 nicely. It was all about lack of enrichment right at 2400 and no where else. go figure !

 

I got this spike at all MAP areas. Its more if I mash the throttle from 3000 to 3500 then from IDLE to 1500rpm. And only when I apply throttel superfast.
Its really no probleme, I just whanted to verify this with you guys so I dont try to cure something that cant be cured with the 730 ecm.
I am a strong beliver in what Ronny says ...you foot can provide air faster than gas..
Ronny, you talked about AE-RPM multipler. Can you explain more about that? Thanks guys for helping.

Regards

 

Another few things to note:

1) factory air filters and ducting are restrictive, and won't allow toooo much of this lean spike.
2) factory TBs are small, and the TPS rate of change vs Airflow rate of change is smaller
3) factory manifolds are usually run hotter, including the TB. This reduces AE requirements.

As long as it's not backfiring out the intake, it's probably not worth fighting.

 

I am not the one to explain AE as it has kicked my butt for too long. But the AE RPM multiplier fixed my nasty bog at 2400-2800 rpms. the way i see it AE TPS adds fuel based upon a quicker movement of tps that would trigger a need for AE. AE MAP i will presume is same with a rapid change in MAP or maybe after the tps is witnessed it looks at change of MAP and adds some fuel based upon resulting MAP. not sure on that. i did a lot of experimenting with TPS vs MAP values and currently have AE biased heavily toward TPS. seems to work for me. now on the RPM%. it appears that allows one to add more in a specific RPM range. for instance i would and did roll on gas getting on xway from standing stop to 60 mph. with a manual trans i would go through gears and all was well till the tach hit 2500 rpms then engine broke up and car would not accellerate at all. in fact i would be caught in no mans land if traffic was zipping along. embasrassing to i might add. if i avoided AE car would run through gears 0-80 mph nicely. so RPM% allowed me to add more AE right at 2400 and 2800. i think stock bin had zero there for multiplier. now it has additional 30% at 2000 60% at 2400 and 35% at 2800 and like 10% at 3200. maybe my cam was the culprit(224/230 @ .05) as it seems to wake up at 2500 rpms ?

 

Ronny, I think you may have only crutched the problem.
AE only lasts for the time the throttle or MAP is CHANGING + less than half a second. At full throttle, nothing is changing except RPM.
If it's breaking up at 2500 with steady throttle and load (but high load), it's your VE's fault. Possibly also your PE could have a huge mistake in it as well if it's only at large throttle.
The way to test is to get into high gear, and get to 24-2500 RPM, and hold it at high load without allowing the RPMs to go up (foot brake it). Check VE first (if you have a wideband) or look at integrator in closed loop.

Not saying you're wrong, just saying it doesn't sound right from your description, and trying to help.

 

Quote: AE only lasts for the time the throttle or MAP is CHANGING + less than half a second. At full throttle, nothing is changing except RPM.

This is no where near full throttle. this is a steady increase in throttle of TPS that is only sufficient to engage AE. i will say 5%TPS to 35% TPS. in fact if i went to a faster accelleration and blew past 2500 rpms into PE(set at 40% TPS) then the break up would be very short term and the PE would allow the 0-70 to occur with no big issues. the WU display shows the AE event and that is when-where the engine used to break up.

i have done about 20 Learns(EBL) this spring and the VE tables are spot on. that area of 2400-3000 rpms and higher map are easy to log. in fact they are rich 124 or so rather than lean. i have ran higher rpms/map as well to get some hits in areas i dont normally see. i think for reasons i dont fully understand my engine needs AE right there?

i am running 22.5 lbs FP with 80 lbs. my AETPS tables are graduated for TPS 122-1098 in increments of 61. my map is 0-30 Kpa at 61 and 40-80 at 122(i know that is weak).

now my WB is toast again so a new sensor is going in next week in a differennt location. i bet i see AE A/F at 11.0/1. looking forward to graphing AE as i bet it looks swell.

Edit: no problem with any constructive criticism. it is welcome and encouraged.

 

Here's my AE stuff-
I've pulled a bunch from what I 'thought' I needed, now that I have the WB. The WB showed 11.0-11.3 AFR when AE kicks in in lower RPM, so I pulled some and now it hits about 13. probably still need to pull more. No lean popping, truck still accelerates. I'm going to try to get AE AFR of 13.5. GMPP TBI vortec manifold runs hot! Those PW's are right around stock EBL