Startup prob, +85% Fuel trim required !!??

jordancivic · Post by **jordancivic** » Thu Aug 02, 2007 4:05 am

Hi guys,
Im a little confused about something, i have a b16a2 with Precision 680cc injectors. I have made a startup calibration and let it warm up fully. Problem im getting is that i require a 85% overall fuel trim to run correctly. So im doing something wrong.

Calibration and datalog attached, as youll see i lifted the revs at a standstill and fueling looks even upto around 3k.

Just why 85% trim? its like the injectors are 440s or something!

jordancivic · Post by **jordancivic** » Thu Aug 02, 2007 4:30 am

BTW fuel pressure is fine and im using a resistor box. Idles fine and sounds fine with +85%. But obviously once i start tuning im going to run out of injector duty. Walbro 255lph installed. Engine and most ancills have been replaced for this build so no previous running history. Thanks

planetspeed · Post by **planetspeed** » Thu Aug 02, 2007 5:24 am

Have you changed the current injector size to 680cc in the Parameters/fuel trim?

jordancivic · Post by **jordancivic** » Thu Aug 02, 2007 5:39 am

Yes, it would be flooded with fuel otherwise. Im having to add 85%

jordancivic · Post by **jordancivic** » Thu Aug 02, 2007 7:21 am

As soon as i touch the throttle to lift the revs it goes very rich and then leans out to 15:1 as the revs settle.

I have just changed the FPR for a spare which made it around 1AF point richer. Overall trim now 70%. I did notice that there seemed to be no fuel when i pulled off the return line, usually there is a little spray of fuel?? I havent removed the new one.

Could this be a prob with fuel supply? Pressure is steady at 40psi while running. Is there an essential component of the fuel supply line from the filter to rail that may cause flow problems? can i assume that everything is fine from the filter back as this is where i am getting correct pressure.

Im out of ideas now lol

Post by **Spunkster** » Thu Aug 02, 2007 9:41 am

could be a problem with the banjo bolt fitting at the filter or to the fuel rail....some are not compatible from one vehicle to another especially with engine swaps. If this is the case it will still have fuel pressure, but not have good flow to the injectors or return.

jordancivic · Post by **jordancivic** » Thu Aug 02, 2007 9:55 am

I have just finished checking the washers and i was missing one on the fuel rail. Its a serated type washer and i didnt have a spare so i replaced with a normal washer of the same size. Same problem.

Could this simply be the missing serated washer? i cant see how, u? It runs at 15:1 upto 3krpm at standstill.

Post by **Spunkster** » Thu Aug 02, 2007 11:51 am

I don't hav ethe specifics of the differences, but if you contact a shop familiar with engine swaps, they will probably know exactly what to check for.

jordancivic · Post by **jordancivic** » Thu Aug 02, 2007 11:52 am

I have now placed the ordinary washer next to the fuel rail and the serated washer between the nut and line.

I really cant see how another serated nut next to the fuel rail will make any difference. The serated washer is on the fuel rail intake side. Does anyone know of any other differences between models like hose size or a different sized nut on the rail?

I havent missed something stupid on the calibration?

Getting desparate now.

jordancivic · Post by **jordancivic** » Thu Aug 02, 2007 2:20 pm

Ive been researching for hours now, only once was it mentioned that honda use different diameter pipes/banjo internals for different models.

I will take mine to the breakers tomorrow and see if i can find one with larger diameter.

Spunkster, i understand now what u meant, cheers. Ill report back.

jordancivic · Post by **jordancivic** » Fri Aug 03, 2007 11:54 am

Right i got a new pipe and the banjos at both ends now how the internal groove, same problem.

What the hell is going on here!!!!

The treaded connection on the fuel rail only has a fuel inlet at the end, i would have thought it would have a hole through the side like the filter bolt. How does enough fuel get through basicallt the threads??

I have pics of everything if anyone can compare for me.

jordancivic · Post by **jordancivic** » Sat Aug 04, 2007 2:02 am

UPDATE

This only seems to be a problem at idle. If i set the fuel adjustment to 0 and add 70% fuel to the first few columns everything appears ok, fueling normal everywhere else. I havent driven it much until i find out what going on here.

HONDATA PLEASE HELP, car has been off road for 2 years, my birthday tomorrow and im desparate to get it running. LOL

jordancivic · Post by **jordancivic** » Sat Aug 04, 2007 2:24 am

Someone else seems to have the same issue :

http://www.hondata.net/forum/viewtopic.php?t=5995

HELP

Post by **Spunkster** » Mon Aug 06, 2007 9:42 am

It may just be the characteristics of the injectors you are using. This is why we only recoommend the RC injectors. Since these are probably peak and hold injectors as well that is making the problem even worse for you.

jordancivic · Post by **jordancivic** » Mon Aug 06, 2007 10:13 am

Ill leave the overall comp at 0, adjust for idle and see how it looks. Ill post the calib and datalog if i have any luck.

Yes they are peak and hold. Thanks

UPDATE, everything seems fine, must just have been the injectors. Thanks for the help