yenkomike

iTrader: (2)

I am having a issue with surging at 2100 rpm this is a lq4 turbo build everything has been changed that I can think of with no success. at 2100 the engine will surge and go lean. I have increased the ve table over twice the fuel to get good afr but the surging will not stop. less rpm like 1800 it is perfect and above 2400 it is perfect. but I cannot get this to stop.

lq4 ,218 jarrett cam,holley hiram ,war 100mm t.b., microsquirt.

I have changed ecu's plugs,coils, ve table and no change. this engine has been ran and driven with this tune and ecu but not with the big intake and t.b. it is like it is getting a fluttering in the intake and I cant fix it. any ideas will be apprecieated.

I have a log I will try to post.

yenkomike

iTrader: (2)

this is a ruff tune but you can see the p.w. duty cycle and rpm go crazy at about 2000 rpm

jasonsnova

If everything else was the same any chance you have a vaccum leak? Seems tweaking the 've table should of fixed it if it was a rich/lean condition

yenkomike

iTrader: (2)

no leak checked it a few times.

ls3fox

i have herd of the big t.b. causing a surge maybe try going with a smaller t. b. and see if it helps

yenkomike

iTrader: (2)

that is my next thing to try. might try a adaptor and a stock t.b.

JoeNova

I'm seeing it go rich, not lean. Both times I see the surge, your PW goes way up and your AFR bottoms out.

yenkomike

iTrader: (2)

it doesn't seem to matter if I lean it out it is worse. the more fuel I add the less it surges. and in that tune I have the fuel over twice it needs to be just to tame the surge. if I smooth the ve table out it surges and reads 17.5 afr . this happens only at about 2100 rpm and about 60 to 50 kpa . everything else is smooth.

JoeNova

Does it do it if you hold steady throttle? It looks like it cleared up while maintaining steady throttle. Possible accel enrichment issue?

yenkomike

iTrader: (2)

if you keep the rpm steady it will keep doing it but in lower gears it is slowly getting faster and when it gets to about 2300 it is smooth again.

jasonsnova

On my car when I 1st started to drive it I also had a surge at 2100-2300ish rpms , I have ls3 Chinese sheet metal intake (like a Holley sniper) and a 102mm tb. It seemed to go away mostly after some driving in learn mode (Holley hp). So I'm wondering if it is related to the large TB??

JoeNova

Open your throttle until it reads 60% TPS and recalibrate that as the maximum value.

Go for another drive. See if it makes a difference.

spray280

iTrader: (5)

I've had a surge problem since making a sheet metal elbow & going to a ported super vic.
Problem area is 1700-2200 3-4% tps. Only way mine quit was adding fuel, setting learn to
0(Holley) & lowering closed loop comp limit to 3. If I go leaner than about 13.5-13.7 surge comes back.
Have thought maybe the 90mm throttle body might be contributing but am too lazy to try a smaller one.

yenkomike

iTrader: (2)

this one will surge at 10.0 gas scale if I take it that rich. but that is the only area.

I might try a stock truck intake and see if that does it. if so it might stay that way.

pdxmotorhead

Long shot,, but,, If your running a MAF, I've had to add tube in front of them to get the air flow smooth, other wise the MAF signal would flutter at certain RPM's sort of a harmonic problem, With a CAI on a BMW I had to put about 1' of tube between the MAF and the filter to make it calm down. (It only had about 10 inches of tube before.. ) Also had problems when it was too close to the throttle body.. Needed a good 8 to 10 inches of distance from the MAF to the Throttle body as well ..

JoeNova

He's not running a MAF.

I still say you rescale the big TB to read wide open at 60% and see if that helps.

stevieturbo

manifold pressure seems to stay even...so is rpm actually changing ?

Do you have any silly closed loop features active ?

Injector pulse widths do not appear to be changing massively....so is your wideband reliable ?
Presumably you're saying this is a real and noticeable problem when driving, and not just that you're seeing things on a log you are not happy with ?

What is ignition timing doing during this ?

Upload a full log.

yenkomike

iTrader: (2)

I will try to upload a full log. the car bucks and misses at that rpm kind of a flutter. I smoothed the timing flat in that area of the table. tps stays solid. and afr rich makes it better but not gone. map seems to girate in a circle when it does it. only does it at 2100 rpm and 60 and 50 kpa of my 16 by 16 table. everything else is good.

tried my ecu and tune from my nova that is great and it does the same thing no change at all. the only thing different is holley hi ram and huge t.b. and tps sencer. everything else has ran good on this tune /engine. thanks .

ly2sn95

To me it does look like an accel enrich problem. may try and set it to 100% in all the areas or set tpsdot high enough to not trigger AE and go try it.
EDIT. The pw goes down initially when it starts fluttering. does the tps sweep smoothly KOEO?

JoeNova

I think its accel enrich too. You can't use accel enrich settings from a stock sized TB on a larger TB.

This is why I said scale the TPS. Open throttle 60% and set it to the max. The larger TB flows as much at 55-60% as the smaller does at 100%, so it will cause your accel enrich to act as if you are using the smaller TB again because airflow/TPS% ratio will be restored.