Got my car tuned

[mullett]

Got the MR2 tuned a couple of days ago, picked up 8hp with the jaycar AF adjuster alone, but now it's a pig to drive, because it ONLY works on load points, there's no RPM points. So full throttle, it's great, but part throttle, its a real pig, with dead zones etc. Soooo...can you rig up a relay to switch the AFM output from standard at partial throttle, and when you reach full throttle it diverts the output to the AF adjuster? Are relays quick enough for this, and will it create a noticeable splutter? Just wondering if anyone's tried this. If not, I'll try it and see what happens

RM.

[TA-022]

splutter???? dun know.

but relay and reid switch would work fine.

similar things are done by people for limiting boost in certain gears and on accel
pedal to activate NOS only under full load.

[whatthe?]

Dont AFMs report a change in frequency (Hz) to the ecu rather than a voltage change?

Maybe using the TPS is the way to go, ie lo/hi throttle, say under 30% for low (cruise) and 30% + for high?

Edit - forgot not all AFMs are Karmann type, others use voltage changes, still reckon TPS is easier to use tho!

[mullett]

Yeah, it's a decreasing voltage AFM as far as I know. Making the switchover happen wouldn't be hard, but I'm not sure if it would create a problem for the ECU or something.

RM.

[whatthe?]

I just thought TPS because thats how an SAFC switches maps for hi and low throttle. Get the voltage at 30% and bobs your uncle, switch over to the jaycar box above that. You'll never see above 30% TPS for cruising anyway.
Just my 5c

Cant see why switching would cause any problems, the jaycar box is just modifying the signal sent to the ecu, a relay switching it to active should be quick enough for the change in signal not to upset anything, it's only modifying the AFM signal after all, not stopping it

[oldcorollas]

but now it's a pig to drive, because it ONLY works on load points,


So full throttle, it's great, but part throttle, its a real pig,

so... it's only got load point adjustment, ie AFM.... and now at part load it sucks, and full load it is ok??

are you sure they tuned it at all?

surely, if they had tuned for part load also, then part throttle would be ok?

did "they" explain why their "tune" was so shit?

[JustCallMeOrlando]

Umm, who tuned it? It shouldn't be affected at part load, that's the point. If done correctly, it should be a fairly seamless driving experience. Don't bother with a switch or anything, take it back and get them to do it right!

[mullett]

It's bizzare, but basically, if you've got a certain load point at full throttle, that load point can crop up on part throttle elsewhere. Because it doesn't have RPM points, you can't tune certain load points at certain RPM. So if you tune one load point for cruising or whatever, if that load point comes up on a full throttle run, the adjustment is wrong. That was the worst explanation ever, but I'm sure someone can work it out

RM.

[JustCallMeOrlando]

Ultimately though dude, a load point is a load point, and if it's not working right, then they've tuned it wrong, and they need to readjust it.

[mullett]

I'll go and have a chat to him tonight. The way I saw it was the load point which worked well at full throttle was interfering at part throttle because there are no RPM points...

RM.

[JustCallMeOrlando]

Thing is, the load point should still be the load point, regardless of whether it occurred at X or Y rpm. The engine is still ingesting Z amount of air and needs to be fuelled accordingly.

[mullett]

I see what you're saying, but does it work like that? If it's lean at full throttle on one load point, will it be lean on part throttle? EG: if the mix has been richened up for full throttle, and it was already rich at part throttle under the same load point, wouldn't you have a light throttle with waay too much fuel? Not sure, I'm still learning about EFI....

Cheers, RM.

[NeoNasty]

I presume that you used the Jaycar digital fuel adjuster?

If so the unit is designed to work flawlessly with the standard ECU. Ie. If you dont modify the map, it wont adjust the outputting signal. What goes in goes out. Perhaps the car didnt need adjustments at low throttle applications, and they should change that.

From what I have heard, most people have found this unit to be very good. It sounds like a tuning fault to me.

I have built one and was going to put it into the Celica, but with a new purchase I might save it for something else....

EDIT: If you only want it to coem on under heavy load get the "delta throttle timer" and use that to switch the DFA on. BAM.

[JustCallMeOrlando]

I see what you're saying, but does it work like that? If it's lean at full throttle on one load point, will it be lean on part throttle? EG: if the mix has been richened up for full throttle, and it was already rich at part throttle under the same load point, wouldn't you have a light throttle with waay too much fuel? Not sure, I'm still learning about EFI....

T'sall good. My reasoning is, you're unlikely to encounter the same load condition at part throttle than you will at WOT. There will be a big difference with the output of the AFM at 50% throttle and 100% throttle, just due to the amount of air it requires.

[mullett]

Ah, fair enough. WOuld the supercharger affect this? Because the car only feels really bad at low throttle openings when the supercharger switches on. Maybe it pulls enough air thru to disrupt the AFM? No idea. Or maybe he messed with some load points which don't come up on WOT and forgot about them...

RM.