whats happening here? ae86 3sge tuning

[Fantapants]

so dealio is, i have the 3sge beams in my 86 running.

Its on blacktop quads running and adaptronic with a tune from an identical speced motor.

It starts up fine, and idles well, but when i try to throttle it up it gets all emo.


http://www.youtube.com/watch?v=z60u5YyMacg


When it has a LITTLE tiny bit of throttle, it revs up fine, then stumbles back down like its hunting. Give it a bit more and it gets all shitty and starts to stall. Hold the throttle at the rev up tiny bit place, and it just revs up and down from about 1000 to 2000.

Im not really sure whats going on, but need to get it going shiny people

any help appreciated.

[assassin10000]

Is the TPS bad?

Andrew

[Fantapants]

yeah i was thinking that.... but i cant get the laptop to fire up to plug in and check the ecu for the signal..

[assassin10000]

Blacktop 20V Tps pinout & setup. Make sure the 'VTA' pin has resistance at all times when you rotate the rotor.



Silvertop is exactly the same pinout and can be used as a replacement.

Andrew

[jondee86]

Could be two things happening... one sounds like fuel cut and resume (big surging), and the other
is choking on throttle. Probably you will need to calibrate the TPS values (max and min) in the ECU,
and you will need your lappy plugged in to do that.

Cheers... jondee86

[Fantapants]

recalibrated the tps through the ecu. under light throttle it pics up really well and goes through the rev range to 8000.

still farts and carries on under sharp throttle openings, but keep it shallow and smooth, it seems to have cleaned up the problem.

however im thinking under load, ie on the road or at the dyno, the problem will be exacerbated ??

[thechuckster]

how/where is the FPR vacuum reference connected to the intake?

same query applies for the MAp signal for the ECU

and your sure you haven't tinkered with any accel enrichment?

[Fantapants]

removed the fpr vac attachement. without it the fpr holds rock steady 40psi. With it attached it was all over the place, i think thats more for boosted engines with rising rate function?

the signal for the map sensor comes from the standard vac tube on the blacktop throttle on throttle 4. when its unplugged from the hose, everything runs the best, but not awesome, but maybe the signal is shit cos it only one port?

[aussierider]

For a the best vacuum signal you will have to connect all four throttle bodies, I think the other way around it would be to tune tps only,

[Fantapants]

well yeah idles MUCH better when the vac sensor is not attached to anything.....

will plug 3 of the throttles into a vac chamber and get a read of that, see if that has any improvement...

suggestions have been made for injectors being shitty and needing clean.... but i would have though at idle they would show issues just as much as under load?

[beerhead]

You also might need to balance the throttles. If each cylinder has different flow at idle it'll stumble a little and make the map sensor fluctuate which part of the map your in at low revs. I'm going through similar teething problems with my gen2 3SGE with ITBS atm.

Hey would I be able to get a copy of your map/? Might be a closer match than my 20V ITB map I'm playing with atm.

[thechuckster]

i'd focus on cleaning up the MAP signal. You could also consider inserting a small mig welding nozzle in the vacuum line going from your vac chamber to the ECU.