Rpm drop before catching idle speed. surging low load, speed

s300 and SManager software questions & answers
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Itritr
Posts: 3
Joined: Sun Apr 17, 2011 5:05 am

Rpm drop before catching idle speed. surging low load, speed

Post by Itritr »

12:1 compression ratio
Skunk2 Pro2 Cams
310 cc injectors
8lb flywheel
stage 1 clutch
P06 chipped to p28
B18c5 in integra

I have two questions, I hope you can help me with.
My idle is set to 900, after reving the engine the RPM goes down to 700 before eventually going back up to idle speed. If possible i would like to avoid this quick dip in RPM as my oil pressure goes low.

Second question, while at low speeds and low loads (1000 - 2500 RPM). the car drives as if I was applying the accelerator pedal on and off. Rpm goes up and down and it gest worse and worse, meaning with just holding the acc pedal steady, the rpm will raise and drop for 200 rpm, then 400, etc etc feels like a jerking up and down, until i either give more gas or change gears, seems to happen in 1st and 2nd.

Please help!!!
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Quade
Posts: 40
Joined: Sat Jan 24, 2004 7:44 am

Post by Quade »

What is your target Air/Fuel ratio in the idle range? I believe you may need to set the target mixture richer. When you release the accelerator after revving there isn't enough fuel to maintain the target rpm so it falls below. It only recover because the IACV kicks in and opens up to bump the rpm back up to the target idle rpm. You may also need to set the target mixture richer in the areas above idle rpm range; say up to about 2000pm in the low load areas (21-17inches for example). This should reduce the rate at which the rpm falls from 2000rpm towards idle and help with the recovery. It may also help with the jerking in 1st & 2nd gear. Data-logging is your friend. Hope you understand me. Let me know.

Itritr
Posts: 3
Joined: Sun Apr 17, 2011 5:05 am

Re: Rpm drop before catching idle speed. surging low load, s

Post by Itritr »

Hi, thanks for your reply. I am attaching a datalog of the "surging" please let me know what you think or how to fix it.
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Johnny_9
Posts: 312
Joined: Sun Apr 09, 2006 5:12 am

Re: Rpm drop before catching idle speed. surging low load, s

Post by Johnny_9 »

u need to post the tune as well.

Johnny_9
Posts: 312
Joined: Sun Apr 09, 2006 5:12 am

Re:

Post by Johnny_9 »

Quade wrote:What is your target Air/Fuel ratio in the idle range? I believe you may need to set the target mixture richer. When you release the accelerator after revving there isn't enough fuel to maintain the target rpm so it falls below. It only recover because the IACV kicks in and opens up to bump the rpm back up to the target idle rpm. You may also need to set the target mixture richer in the areas above idle rpm range; say up to about 2000pm in the low load areas (21-17inches for example). This should reduce the rate at which the rpm falls from 2000rpm towards idle and help with the recovery. It may also help with the jerking in 1st & 2nd gear. Data-logging is your friend. Hope you understand me. Let me know.

need to set the mixture richer in the areas above idle rpm range; say up to about 2000pm in the low load areas (21-17inches for example)...right on dude. Also racing cams need a richer mixture due to low speed exhaust reversion

Also advance the ignition - reversion makes it burn slower.......

your fuel and ign need to 100% right in the idle and off-idle areas, if u are using race cams. somehow in my experience hondata is very sensitive (too bad tunes by newbies) in this area
u may need to richen those cells by +30% and add 5 degrees timing

log yr STRIM/LTRIM

Download the latest version and adjust the overrun recovery rpm

good luck - c a tuner if u want to play safe. mistakes can be expensive

Quade
Posts: 40
Joined: Sat Jan 24, 2004 7:44 am

Re: Rpm drop before catching idle speed. surging low load, s

Post by Quade »

Hey Dude.

Under Ignition Compensation in the Parameters section adjust the following values:

Set all "Throttle Tip in Retard" values to zero.
Set all your "TPS Adjustment" values to zero.
Set all your "Gear Adjustment" values to zero.
Set all your "Retard duration values to zero"

Go for a test drive and let me know.

No need to adjust these values to achieve normal drivability. Looking at the values you have in there I would think you don't understand/appreciate what these values are used for. I know we all start out not knowing, however, I would recommend you find someone who can sit with you and explain the basics at least. Failing that it would take a quite a bit of typing to explain. Reading the contents in help would also be useful.

Itritr
Posts: 3
Joined: Sun Apr 17, 2011 5:05 am

Re: Rpm drop before catching idle speed. surging low load, s

Post by Itritr »

Thank you all for the help, i have not had the time give all those solutions a try, hopefully this weekend.
I will let you know

x6h0ztx
Posts: 32
Joined: Sun Oct 03, 2010 2:38 pm
Location: las vegas

Re: Rpm drop before catching idle speed. surging low load, s

Post by x6h0ztx »

Quade wrote:Hey Dude.

Under Ignition Compensation in the Parameters section adjust the following values:

Set all "Throttle Tip in Retard" values to zero.
Set all your "TPS Adjustment" values to zero.
Set all your "Gear Adjustment" values to zero.
Set all your "Retard duration values to zero"

Go for a test drive and let me know.

No need to adjust these values to achieve normal drivability. Looking at the values you have in there I would think you don't understand/appreciate what these values are used for. I know we all start out not knowing, however, I would recommend you find someone who can sit with you and explain the basics at least. Failing that it would take a quite a bit of typing to explain. Reading the contents in help would also be useful.

What dose Ignition Compensation settings mean and do ?
if i set all the ignition settings that u posted above, am i supposed to feel a difference ?

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