8 cylinder front engine iconic vehicle
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By Crumpler
#133789
Hey gentlemen, sub thread for the vems tuning.
Basic VE mapping done.
Road testing yesterday and shifting AFR's are pretty squirrelly (Greg, substitute any obtrusive marsupial here).

Ok, so I didn't address AE yet.
I had a couple of shifts with mid-load RPM's that caused a fuel starvation and the car shut off on the interstate :popcorn:

So looking at log, there is no tip in seen, just lean. My question is relative to the raise in enrichment and the answer is probably more trial and error, but Vems has an Acceleration Enrichment gauge. Currently the highest number I've seen is 0.1.
What number is more appropriate? Or what guidelines for AFR/Lambda at that initial throttle poke?

There's also an issue, which overlaps, of letting clutch out on manual tranny and rpms going up on the back end of a shift.
Vems has a separate category for throttle v. acceleration enrichment but same concept as above in relative terms,

Dave
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By grepin
#133908
I haven't really had the same issues. Mine is an auto however. I did have it over fueling when off the accelerator and it was fixed in this area. Base Setup -> Rev Limit/Overrun/safety and set Overrun fuel cut. Maybe this could be an area you could explore.
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By worf
#133926
One of the functions of the OE vacuum-controlled fuel pressure regulator and pressure dampers is to provide transient enrichment to manage knock sensitivity in conjunction with fast changes into high load operation. Or, IOWs, to help prevent tip-in detonation. At high-load - no or little manifold vacuum - this system just adds more fuel due to higher pressure. Which is sorta Ok, but not ideal.

Why? ‘cause computers in ‘80s slow. By the time the LH figures out that the throttle has been opened almost to WOT it’s too late.

VEMs not slow. I would assume 10,000 times faster. At least. And 32-bit? Not 8. Basically 40,000 times as powerful.

I have to assume that it is able - if properly configured - to handle all of this stuff by itself with no need for the manifold-vacuum-dependent fuel pressure of the OE system. On the other hand, any ‘smarts’ for that could by zeroed-out thus reverting to the OE system,

Is it possible that you are getting either constructive or destructive interference from the two transient-condition fueling systems?
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By hans14914
#133990
While its not directly applicable (being a different platform), the EMU Black Training document is really a great primmer for any modern standalone. There are lots of resources out there, but this is a great read for anyone, and currently freely available on the ECUmasterUSA site:

https://drive.google.com/file/d/1-_NAly ... 2CXCW/view

I dont recall it having any detailed specifics one AE, but it does cover a lot of theory, and fundamentals for building a base config from scratch.
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By worf
#134007
hans14914 wrote: Mon Feb 14, 2022 2:08 pm There are lots of resources out there, but this is a great read for anyone, and currently freely available on the ECUmasterUSA site:
Nice. D/L'd.
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By Crumpler
#134092
Thank you guys for following thread.

Greg I will look at that too, thank you.

Dave, that’s a good point as usual. Hopefully VEMS can outwit the 80’s hardware.

Hans. I appreciate it, that link helps me with more then one area. VEMS just doesn’t have the same resources for support unfortunately.

I dug into the logs again yesterday and it became apparent that there are some VE cells not optimized yet And some of the events fall into those cells(both lean and rich), so more work there.

It is also apparent that the AE was nil in the original configuration. The forced induction probably makes the issue more relevant.
I increased AE and got a shoulder artifact on the lean bumps. It was explained to me that there should be enough AE present to move richer then the target and then normalize into target lambda.
With doubling AE yesterday it still only reads 0.7, so work to do there too.

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