4AG'T'E Surging on the road and dyno - tune?

[fixeruperer]

from what the car is doing, it should be screaming problems on the dyno ?

when mine was blowing out the spark, it would act like a rev limiter, and if you lift off the throttle a bit, it would pull through it.
a cdi ignition fixed that.

the waste gate looks a fair while away from the manifold, what size spring is in the waste gate ?

a melted cat could do it to.

[mattysshop]

cat has been checked, everything has been pulled apart, and put back together again, they have tried it with just the dump pipe on, same thing.. put that turbo onto an SR20, made just on 300rwhp no problems..

it's got the .5 bar spring in it.. that gate has been replaced with a brand new one exactly the same (Tial 38mm)...

it's not cutting spark, or acting like a rev limiter, it seems to dramatacally slow the acceleration of the car.. as if your opening and closing the throttle... the boost goes from 10-14-10-14 etc

currently it's making 158ish hp @ 15psi solid, but above 6000rpm is where is starts to fluctuate and surge.. when they try and squeeze more timing, fuel, boost in, it happens earlier and worse...

I questioned the dwell and I got ‘dunno there not much to adjust in the ecu. He changed it to the other setting and it went worse’

the tuner says he thinks it's because the plenum is too big....

the worst i've seen with a big plenum is it make the car a bit of a pig to drive off boost and under the curve.. i'm only talking about size, not design...

[midnight_purple_GA70]

its not the vvt coming into it and failing or playing up?

or as chuck suggested a trigger problem?

[mattysshop]

previously the VVT was disabled.. they only got that working the past few days? could be though... will try disabling it.

trigger as in the 20v dizzy? being a mechanicle problem? i have a spare 20v dizzy... we could swap...

[fixeruperer]

dwell in the ecu would be adjusted in milliseconds.
is he reading the timing off the ecu or the dyno ?
the plenum looks nice. ive seen bigger on a 1.6 .
is the tps reading correctly through out the range 0-100%?

does the guy normaly tune the adaptronics ?

tried smaller injectors for shits n giggles ?

[mattysshop]

i have yet to be quoted any timing figures, or where he is reading from..

the guy normally tunes rotors, and circut cars like MX-5's, nissan turbo stuff etc..

i wouldn't think there is anything special about tuning an Adaptronic.. if your a good tuner you can tune anything right?

[fixeruperer]

you would think so, but some tuners will say " wah wah wah i wont tune those". ecu are all different, and some tuners know how some ecu's perform in the tunes and make stuff work.

good tuners are hard to find.

[thechuckster]

Dump the malpassi FPR and get non-rising rate regulator. once you get above 100kpa small changes in VE% will have increasing effects in AFRs.

my experience with a malpassi RRFPR was a pos pita with wildy varying AFRs and line pressures.

[1JZ-Rolla]

The tuner should be able to easily distinguish whether it is a ignition related issue (misfire), boost control issue, or actual compressor surge issue.

When the engine starts "surging", can you audibly hear compressor reversion from the turbo, same like when you would back off the throttle from boost without a sufficiently sized BOV?


I'd be really keen to see an ignition and fuel map for this tune........ but if its true compressor surge/reversion, I think you are gonna struggle to rectify it through the tune alone.


Cheers
Phil

[SHEPPO3930]

try a different turbo, say a T28 off a 200sx to start with. or try a larger rear housing on the GT2871R - there's a 0.86 housing available yeah?

[Duk]

I questioned the dwell and I got ‘dunno there not much to adjust in the ecu. He changed it to the other setting and it went worse’

Tell the tuner to read the Adaptronic manual or perhaps even have a look through the settings, as the dwell timing is easily set in the 'Trigger' tab (should be about 3000/3500 micro seconds for a multi coil set up).
Also, make sure there isn't some weird over boost fuel cut in the 'Power Cut' tab.

The Adaptronic forum is also an excellent resource. Andy from Adaptronic is excellent at getting answers back to members by the end of the day.

[mattysshop]

my mate has spoken to Andy a few times, i'll get him to check that.

went for a drive again to see how the tuner has managed to flatten it out a bit, and now it only comes on about 6k onwards, really noticible in 3rd and 4th (highway pulls)... basically it like drops boost from 15 to 5psi instantly (bov / chatter etc) then slowly spools back to 15psi, then drops again... slowly comes back on... all this is happening over a few seconds if your in 3rd, and it's leaving a massive cloud of fuel out the back..

he has checked plugs, there all a nice light brown colour, he checked up the fuel pump specs as it was just a 'big bosch' one.. and he said it was 165lph @ 72psi.... which i think is crap personally.. and doubt that pump will be enough for the ID1000's at a 20psi tune... but this could be running out of fuel now? not sure you would think that it would be apparant on the dyno...

also he is running the 4G63 coil setup, the ones that look just like the GZE coils.. he added a few extra grounds, as he only had 1 from the chassis to the gearbox, and he said it's a little better, but still doing it... possible coils?? not enough power??

[Bazda]

Im having the exact same issues with my car recently.

Its never done it before in its life until now.
The only thing i've changed is the fuel system, I also ran ethanol through the system so i'm not sure if its damaged the FPR.

My FPR vacuum hose is connected to the ECU as well, possibly there is a leak causing a spike in the line to the ECU somehow.
So I will most likely change it so they run separate lines and also pull the FPR apart to check the diaphragm isnt leaking.

Mine only does it on high loads also - 4th/5th gear.

Fine if you dont ramp the boost up slowly.
We also checked spark and there was plenty of current there, tried different plugs as well.

So for me i'm gona check the fuel system first and see what I find.

Also if you have an IC pipe which leaks or silicone hose expanding under boost it can also do this!

[thechuckster]

would be helpful to see some datalogging, e.g.
- is fuel PWM changing before it looses boost
- is it an erroneous spark cut setting somewhere
- (obligatory AFR behaviour query)
- how is the accel enrichment setup behaving? if it's adding fuel based on some kind of MAP multiplier it could be overfuelling as you accelerate in high MAP regions (would depend on ECU and current accel enrichment method).

running out of fuel (e.g. lean out) on a dyno would be evident you'd think (surge in revs with TPS and PWM at steady state, followed by a miss(es) when it can't combust). You'd also see some minor MAP spiking (with respect to fuel PWM) as the lean-out event occurs.

also, big gap on the plugs might be spark being blown out?

Earthing to engine would also show up on ECU voltage and/or spurious sensor readings?

[1gjet]

I am having similar issues on my 1g after giving it to the tuner in great working order perfectly driveable, i get a car back that is super rich down low, slightly lean up high and pops and farts and carries on low and i cant rev it past past 7800 with out massive popping and cracking, plugs are terribly black and the afr fluctuates abit.