Disconnect MAP sensor when using AlphaN ?

[Swede]

Hello,
Anybody who can answer if I need to disconnect the MAP sensor when configurate the Accel gen7 system for Alpha-N mode ?

I know this was needed for the old Gen6 system but do not find any instructions for this in the Gen7 system.

Thanks in advance for the answer.

BR Anders Moberg, Club Corvette Sweden

[camcojb]

I do not think it has to be physically un-hooked, as it won't be using it's input in Alpha-N. Guess it wouldn't hurt. Why are you tuning it in that format?


Jody

[Swede]

I am using an individual runner intake manifold (8 x 52 mm throtthle blades)
and the vaccum signal (MAP signal) generated is very bad ( around 9 PSI and rapidly fluctuating). This gives problem in calibrating the acceleration enrichment (transients) during part load and engine goes very lean ( 17-20 AFR) with extrem stumble.

Seems like a small change in throttle opening with this kind of intake manifold gives a BIG change in added airflow which is not able to compensate for with a low MAP signal. (SW function not capable ?)

When using Alpha-N I can program what MAP signal I want to correlate to my trotthle opening and thereby be able to use the whole range of transientcompensation via the TAU table.

Have you maybe another opinion / experience ?

Engine is a Chevy smallblock 383 cui.

/Swede

[camcojb]

Originally Posted by Swede

I am using an individual runner intake manifold (8 x 52 mm throtthle blades)
and the vaccum signal (MAP signal) generated is very bad ( around 9 PSI and rapidly fluctuating). This gives problem in calibrating the acceleration enrichment (transients) during part load and engine goes very lean ( 17-20 AFR) with extrem stumble.

Seems like a small change in throttle opening with this kind of intake manifold gives a BIG change in added airflow which is not able to compensate for with a low MAP signal. (SW function not capable ?)

When using Alpha-N I can program what MAP signal I want to correlate to my trotthle opening and thereby be able to use the whole range of transientcompensation via the TAU table.

Have you maybe another opinion / experience ?

Engine is a Chevy smallblock 383 cui.

/Swede

I ran a Hilborn EFI setup on a 406 with a very large solid roller. It ran great in Speed Density, but I was using a FAST computer. Vacuum was low, but steady. It almost sounds like there's something else going on there such as throttle blade adjustment, vacuum leak, etc. Do you have all the runners tied together to a common plenum for your map sensor? You cannot run a vacuum signal off of just one runner with that setup.

[Swede]

Thanks for your advices.
Yes, all runners are tied up to a common plenum. Do you know if plenum size matters ? Currently I am using a piece of a fuel rail as plenum (vaccum tank).
Maybe need a bigger tank ?

I also suspect that there is something else causing my problem and will look for vaccum leak. The reason I suspect this is that when I disconnect a hose to the plenum (vaccum tank) and thereby create a vaccum leak, no change in idle is seen at all.
Do you know if a leaking intake valve could generate a fluctuating map signal ?
The signal is fluctuating up to appr 3000 rpm where it becomes stable as a rock.

/Swede