Rookie84

To describe briefly of the problem I have, the car jerks and stutters when driving at light loads or light throttle input
and while this happens, the AF goes lean at the same time. (15-16)

The car has HKS 280 cams tuned on AEM EMS.
This issue really sticks out when driving down a hill or in traffic with light throttle input.

Upon hours of research, I found domestic V8 owners having this kind of problem with cams. However, I could not find similar cases for an Evo.

As I drive and live in a hilly country with heavy traffic, this would be something I would prefer to be solved.
One problem is that not a single person in this country has extensive knowledge on AEM as no one uses it.
With that in mind, my tuner has pointed to the hardware (cams) of the car for this type of behavior.
With respect to the tuner, my mind cannot be at peace because this might be a simple error because of his lack of experience with this software!

I would like to hear from fellow Evo owners with a similar set-up who might be
having the same problem because I want this out of my head!!!

Is this something that could be tuned out on AEM?
or something that I have to live with if I run 280 cams?

HELP! I want to settle this.

SyZyGy1394

iTrader: (4)

What BOV or DV are you using?

luckybull

iTrader: (7)

mine does the same thing. i have 264's. so your tuner is incorrect.

a lot of it from what i hear has to do with injector sizing. when you double the size of the stock injectors you will run into little issues like this. its annoying as all hell.

try and drive through a neighborhood at 20mph or so in 2nd gear, light throttle.. will buck there also.

bov or DV have nothing to do with this. he is on AEM.

I would love to find a solution as well. my tuner said he can smooth it out a bit, but a lot of low end tq will have to go away.

luckybull

iTrader: (7)

also, subscribed.

andrewzaragoza

iTrader: (6)

if you are on aem and don't have the stock MAF then it is probably an injector scaling issue.

nightwalker

sounds like injector scaling to me. I've been through a similar situation and it was the scaling.

Rookie84

I am using a Tial BOV.

The tuner has tried everything he could but he has never pointed out injector scaling.
Yes the car is running on AEM and with out a MAF.
We have tried to increase fuel until 3000rpms and it has smoothened it out a little bit
but the gas mileage is ridiculous because below 3000 my AF would be around 11-12.

luckybull- yes it is annoying, I have the same issue at 20mph in second gear.

I wish I had a place to take it to that would sort this out...

Rookie84

I had this thread moved here for more technical help.

*edited

I will update when it is solved as I have found some help

luckybull

iTrader: (7)

heck ya! please let me know when you find a solution! driving me nuts!

AEM+twin disc clutch= ****ty to drive daily.

black95tt

iTrader: (13)

According to Dave Buschur and others that have commented on this issue, it's basically inherent to the V1 AEM box. Supposedly a lot of this has been corrected in the Gen 2 AEM. My car isn't too bad, you can drive around it, but it will start bucking pretty good if you let it get away from you.

TheBoz

iTrader: (9)

I had the same problem on my galant. I had to really dial in my tune from 0-5psi, along with messing with the Tip in Throttle stuff. I more or less coppied the stock evo 8 Accel and DTPS stuff.

THe other big thing I did was add a lot of timing to my map in the 0-5psi range. This cleared up all of my issues.

I dont know if this is the exact same issue you are having but it is worth a shot to look at.

Link to my Map:
http://forum.aempower.com/forum/inde....0;attach=6403

Rookie84

Thank you TheBoz. I will check that out!

Hmm, I guess this issue just might be inherent for the V1 box.
I will definitely report back if it can be solved.

TheBoz

iTrader: (9)

Another thing, when my car would start to buck it would run overly rich/lean. If you have days where it is not bad at all and other days where it is really bad, it might be related to you AIT Correction. On maps where the ait correction is set to 0 when it starts to get warm out the car will run overly rich, and on cold days it will run lean.

Also this condition is very hard to log and deal with from the log file. So you more or less have to test different settings until you are happy with the results.

The part of your log you can look at when it is bucking is right when you hit your throttle, look at how the AFR reacts, and that will all be related to you Tip in throttle stuff.

Here is the link to the log files, and full specs of my build, along with a few other pump gas maps.
http://forum.aempower.com/forum/inde...c,26131.0.html

Rookie84

when my car starts to buck, the afr is overly lean (16-18)
I do not think I had it happen when it was overly rich.
It is only prevalent at light throttle and light loads, especially going down a hill.

As for me, I did not really see it reacting to AIT.
However, my fuel does take a while to reach its maximum lean point and it confuses me.
For example....
cold start: 10.8-11.1
coolant temp 64: 11.2-11.4
coolant temp 81: 11.2-11.4
after a warm up drive, coolant temp 83:11.6-11.8
after driving for a while including some WOT runs: 13.4-13.8

What confuses me is that it ultimately reaches 14.2 but it takes a while.
I wish it got to its final setting sooner and I tried to fiddle with some settings.
But I am total newb at tuning period.
And my tuner has never touched an AEM..
I feel that he is pretty good at tuning but he doesn't know English and it is his first time touching this software.

For those who are curious, I attached my map.

Rookie84

BTW, my tuner has already approved about posting the cal file.
I do not want to disrespect him in any way...