just cant figure it out?

Hondata installation questions / answers / issues.
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Hybrid_Hatch
Posts: 31
Joined: Sun Oct 06, 2002 1:46 am

just cant figure it out?

Post by Hybrid_Hatch »

OK I have had my hondata s200 fully loaded tunned 3 times (three times) and everytime after I have it tunned no more than 3 days later the car is back to running like crap and it seems like the fuel maps are way outta wack.here is the setup.

99 civic with jumper harness and obd1 p72 ecu (usdm)
B18C1 built
9.0-1 comp
stock cams
550cc injectors
255lph pump
revhard turbo kit

well my tunner is damn good and has alot of 10 second cars on hondata.when I leave his shop Iam very happy and the car runs 110% great but a few days later it acts like its on a far off base map.can anyone point me in the right direction to fix the "after a few day map change"? I even pulled the chip (at29c256) and checked the values to the values of the tune and they match but for some reason it acts up a few days later.
AndyE
Posts: 124
Joined: Fri Aug 23, 2002 2:39 pm
Location: Saint Louis, MO

Post by AndyE »

Sounds like your long term fuel trim (LTFT) is getting out of whack, and pulling all your fuel maps either lean or rich. This is a common problem if your part-throttle (closed loop operation) fuel maps are out of tune.

Check your LTFT with Hondalogger. A well-tuned vehicle that is driven at the same altitude it was tuned should have a relatively low LTFT correction (only a few percent positive or negative).

-Andy
'99 EBP Si
S200 w/everything|12psi JRSC|Heatshield
AEM CAI|Kamikaze headers
Custom (quiet) 2.5" exhaust
Quaife LSD|JUN 9lb flywheel|ACT XTSS clutch
Eibach Pro-Kit/KYB AGX
Full polyurethane bushings/mounts
OZ 16x7 Superleggera + Sumi HTR Z II
Hybrid_Hatch
Posts: 31
Joined: Sun Oct 06, 2002 1:46 am

Post by Hybrid_Hatch »

ok what you say makes alot of sense to me..my car was tunned an hour and a half away from me with a totaly differant air quality and a little bit diff alititude.but can you tell me how to check the long term fuel trim?
AndyE
Posts: 124
Joined: Fri Aug 23, 2002 2:39 pm
Location: Saint Louis, MO

Post by AndyE »

Don't worry too much about the altitude thing, the ECU is *supposed* to correct for changes in atmospheric pressure.

The big potential problems are areas of your part throttle fuel map that are rich/lean *while you're in closed loop*. I wrote a big post on a similar topic a while back, when I was seeing misfiring under boost due to badly tuned part throttle fuel maps. Worth a read if you're new to these issues.

The long term fuel trim is one of the variables that shows up in Hondalogger. I think it's called "Long term fuel adjustment" or something similar. You can graph it and read the value off the graph, or switch to the tabular view in HL to read the exact value.

If you don't have Hondalogger, you'll need to find someone who does (like your tuner).

-Andy
Hybrid_Hatch
Posts: 31
Joined: Sun Oct 06, 2002 1:46 am

Post by Hybrid_Hatch »

you sir have been a big help..I just datalogged it and my o2 long term was at -20 or so..so that explains why it was having issues..I did like you said in that post and reset the ecu and sure enough...car idles great and pulls hard in boost again..and most important..not dieing at stop signs now...

THANK YOU SIR!!!!!!!!!!!!!!
AndyE
Posts: 124
Joined: Fri Aug 23, 2002 2:39 pm
Location: Saint Louis, MO

Post by AndyE »

Glad to help. Now it's time to lean out those part throttle maps, so the ECU will stop yanking fuel to reach stoich under closed loop.

-Andy
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