Problem w/ part throttle misfire. Help!!

s300 and SManager software questions & answers
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jordanelo
Posts: 7
Joined: Sat Dec 08, 2012 11:20 am

Problem w/ part throttle misfire. Help!!

Post by jordanelo »

Okay so i got my car tuned recently and soon after i developed a misfire between 2 and 3k rpm. I can't figure it out. I hold the throttle under 10% and soon after it spikes to 15.5-16.5 afr and starts to misfire and carry on. I notice the ign at about 30 degrees at this point. More throttle and it seems to correct itself.

I didn't want to make any adjustments to ign unless i was sure that was causing it. I was thinking it was more likely fuel. But nothing tells me that. You can see between 4:25 and 4:47 on datalog.

Stock h22a ihe
S300
98 ek hatch
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Spunkster
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Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: Problem w/ part throttle misfire. Help!!

Post by Spunkster »

Have you contacted your tuner about this?
jordanelo
Posts: 7
Joined: Sat Dec 08, 2012 11:20 am

Re: Problem w/ part throttle misfire. Help!!

Post by jordanelo »

No I figured if it was something simple I could fix it it without having to bother him.
Did you see anything unusual in the log?? Plus I was trying to gain an understanding of the program a little better and thought who better to ask then you guys.
Johnny_9
Posts: 312
Joined: Sun Apr 09, 2006 5:12 am

Re: Problem w/ part throttle misfire. Help!!

Post by Johnny_9 »

The ignition timing between load columns is too big - e.g. @2,750rpm - 5 (31.25) and 6 (25.5).
Look at the stock map for the spacing and overall shape. Remember play SAFE and RETARD first, unless you have means to detect knock; if not take it to your tuner.

Analyse/graph the gradient of ignition curve from Decel to Light Cruise to WOT at each rpm band, from 2,000 rpm to 3,000 rpm - the ramp of ignition timing advance on throttle-off ( Light Cruise loads to Decel loads), starts to increase as revs drop from 3,000 rpm to 2500 rpm. You may need to do this in a spreadsheet, graphing the timing vs MAP at each rpm as visualising it from the s300 2D/3D (rpm vs load) is not that obvious.

As you change your timing, what your fuelling in that area.

If you are a novice, it may be faster/easier for an experienced tuner to fix.
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