hondata stage 2 / p28

Hondata installation questions / answers / issues.
pills_PMD
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hondata stage 2 / p28

Post by pills_PMD »

i chipped my 94 usdm p28 ecu with hondata stage 2 w/ datalogging.
the car has issues with idling, and i've tried everything i could think of.
the ignition timing is set to 16* the TPS is at the stock setting on an ITR throttle body which is at .47 volts

i've got a jdm b16 sir II in the car. which is a 94 del sol that came originally with a d16z6.

what happens:

the car will start and idle high, which i know is normal, then before the car is completely warmed up the car will drop to around 600 rpm and sputter and surge slightly from 600-800 rpm. after the car is warmed up to normal operating temperature... it will idle around 1200 rpm when i stop at a light... then occasionaly surge from 800-1200 rpm.

then other times it will idle steady around 1000 rpm.
the target idle was set at 850 rpm.
i've heard that this is a common problem with b16 engines using chipped p28 ECU's.

anyone have a cure? anyone hear of this??
thanks

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Post by Hondata »

I think that it's tuning. I suggest:

1. Adjust the TPS so that you get 0.45-0.50V when the throttle is closed. (you;ve done this but this is a general reply).

2. Make a flat area in the ignition table from 0-1000 rpm and 0-550 mbar with 16-22 degress ignition advance (find out which setting gives the best idle quality).

3. Put a lambda meter on the car, change the ECU to open loop, and check that the air/fuel ratio is 14.5:1 - 15.0:1 at idle. You can set the mixture slight rich below 500 rpm which stops the car stalling if the idle speed drops low for some reason.

4. If necessary adjust the idle valve duty cycle control in ROM Editor. If the engine revs tend to hang over 800 rpm and slowly come down to idle speed then reduce the duty cycle. If the idle keeps dipping down too low then increase the duty cycle.

5. If the engine revs up by itself, then cuts out at 1500 rpm and drops back to 700 rpm, then revs up by itself again... reduce the amount of air which bypasses the throttle body as the idle speed is too high and the fuel overrun cutoff is operating.

Hope this helps.
Hondata

pills_PMD
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Post by pills_PMD »

only problem is i dont have stage 4 :(

i'll have to get my guy to try all this for me.. thanks alot

ronin
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Post by ronin »

i had a problem with idle surging that was solved by re-adjusting my cams and cleaning the screen on my iacv.
Long live the silver box!

Sonny
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Post by Sonny »

Using Hondalogger, what does your 'Target Idle' say? (Use option F2)

Sonny
2000 Civic Si (SOLD) :(
1987 CRX Si Turbo (work in progress...) ;)

TorinF
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Post by TorinF »

sonny,
ever see a case where the target idle actually changes in hondalogger?????

that is what I am seeing! what causes that? i have it set in the rom to 750. i haven't seen it ever budge before in hondalogger like it is in my car now.

pills_PMD
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Post by pills_PMD »

my target idle is 850 rpm

pills_PMD
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Post by pills_PMD »

sorry to ressurect this one guys but here is what is new:

i put on an ITR throttle body to go with my ITR intake manifold... no i have no fast idle when i start the car, once it finally warms up I have alot of surging going on and occasionally it will drop to near 650 rpm ...

I need some help!

pills_PMD
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Post by pills_PMD »

we tried what you said and it didn't work. any other ideas?? this is not an uncommon problem... it seems everyone in the greater detroit michigan area has this problem when using a p28 equipped with hondata to run a jdm b16. i head tom payn has a cure for this, but he's not letting the secret out... i'm about ready to go over there and just pay to alter my map below 1500 rpm because i want to keep everything we've written above that.

hybridsol
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Post by hybridsol »

pills_PMD wrote:we tried what you said and it didn't work.
Almost every time the surging you are talking about is due to too much air from the min air bypass. If the surging is below 1000 RPM then it can be related to tuning. Are you SURE ther is no leak anywhere? Even a small leak can cause the 1500 rpm bounce. Did you try the IAC adjustment? (disconnect the IAC valve and trun the screw until the car barely idles, then re-connect the IAC valve) this usually works.

Sean
2002 AP1

pills_PMD
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Post by pills_PMD »

turn which screw?? the idle screw on the TB??

thanks for your replys.

Tommy
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Post by Tommy »

turn the screw in ur head boy :P
blown d16

hybridsol
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Post by hybridsol »

pills_PMD wrote:turn which screw?? the idle screw on the TB??
Uh, yes. There is only one screw to turn, it closes the bypass air around the IAC valve. Turn it in (clockwise) to decrease the airflow. You should be able to get the car to BARELY idle at like 400 rpm with the IAC unplugged. This is the correct setting for the screw. After that, play with the IAC duty if needed, but you shouldn't have to unless the head is ported or you are using 12:1 pistons or something crazy.

Sean
2002 AP1

pills_PMD
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Post by pills_PMD »

there is also some strange screw located on the IAC itself, except mine is completely rusted and won't turn...

JT
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Hondata has a fix for the P28 idle issue

Post by JT »

Hondata recently released a ROM fix for the idle issue with the P28. If you know of any stage 4 users, ask that person to make a new ROM for you, as the notification was sent out to all stage 4 users.

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