Fuel Trim 30%?

[Chappy]

So earlier this week I installed a Hondata s300 chipped ECU in my car and some 440cc injectors.

I loaded up the base JR supercharger map and I go to start it up and it was pretty much dying and idle, I plugged the computer back in and saw that it was adding 35-40% fuel trim in closed loop so naturally I was like F&!# and I added some fuel trim...well I kept adding until I had a good idle (0-3% fuel trim in closed loop) and I logged it going around 5% trim in open loop which is alright. The only problem is it is running well at 30% overall fuel trim, which correct me if I'm wrong, seems a little ridiculous.

So I am thinking I must have either a vacuum leak, fuel leak, or something like that. I have a 255 fuel pump that is less than a year old so I cant imagine it is bad. But like seriously, it runs well at 30% trim doesnt smell rich at all (I don't have a wideband...I'm getting one next week)

Just wanted to post this up here to see if anyone has any input. I have checked almost ever vacuum line in the engine bay and they check out so fuel leak maybe? I just replaced the gas cap. So its not there either.
Anyways, hope somebody has some input on this haha.
Thanks.

PS.
Mods: I wasnt exactly sure where to post this b/c its about programming the ECU, but has to do with fuel and engine stuff..so sorry if you dont like it posted here.

 

[jdmjim]

yeah, it sounds like its compensating for a vacum leak. whats your o2 read? i wonder if it is bad?

 

[acclude]

Are you sure you specified the right size injectors?

 

[Chappy]

yeah, it sounds like its compensating for a vacum leak. whats your o2 read? i wonder if it is bad?

My o2 is only reading from like .68 to .78ish when I drive. I did see it spike up to 1.2ish when I started the car once but I don't know why it is only reading down to .68 so I guess that could be bad?

The ECU has been set up for 440 injectors so thats not the issue.

I am going to put on a friends FPR this afternoon and see if that helps...I don't smell fuel anywhere after I drive it fairly hard so I don't think its a straight up leak in the fuel system. I have checked every vacuum line going to the manifold and I cant find any leaks.
I have tried completely disconnecting the PCV and EVAP system from the manifold and plugging up the nipple on the manifold and that didnt help any.

What else would affect the fuel pressure?

 

[jdmjim]

i bet fuel pressure is you demise, what is it? usually its all related to the fpr

 

[Chappy]

i bet fuel pressure is you demise, what is it? usually its all related to the fpr

Yeah, thats pretty much what I am thinking. I dont have a fuel pressure gauge so I am not sure what it is, which is too bad because that would tell me for sure.
Hopefully the new fpr will do the trick.

 

[jdmjim]

sounds good man :thumbs up

 

[Chappy]

well...I put 2 new fuel pressure regulators in and neither of them made a difference. So here is where I am.
-New FPR
-New Gas Cap
-New injectors
-New fuel filter
-less than 1 year old 255 fuel pump
-no vacuum leaks
-not improperly connected pcv or evap
-ECU is set up to run 440cc and knows stock is 240
-runs amazingly at 30-35% fuel trim, and wont even idle at 0%
-stock fuel rail but that should be enough for 440's I think

Maybe it could be a clog or leak in the fuel system? I dont smell fuel so its kind of a long shot but this really has me baffled. Am I missing anything?

 

[jdmjim]

you really need to do a fuel pressure test, at least rule that out

 

[Chappy]

you really need to do a fuel pressure test, at least rule that out

Yeah. I am going to get my friend to bring me his fuel pressure gauge.
What else could it be if it wasn't a fuel pressure problem? Maybe I am just dumb but at this point I kind of feel like it must be a fuel pressure problem.

 

[jdmjim]

i wish i knew more about the tuning end of it, unless its some kind of program error

 

[Chappy]

Haha. Jim if it wasnt for you on CI I am pretty sure I would just be talking to myself. Thanks for giving me your input.
I just went ahead and bought a fuel pressure gauge so until that gets here looks like I am just not going to worry about it. Now its time to do all the other things I want to get done! Great...haha

 

[Chappy]

Alright, I have an update.
With 0% fuel trim the fuel pressure at idle is 43psi which is the correct fuel pressure to my knowledge.
But at 43psi the car will not hardly idle and dies if you give the throttle a stab.
The car finally starts to idle well once I up the fuel trim to around 30-35% and the fuel pressure is steady around 50psi (which to my knowledge is a little high for idle)

I am pretty much stumped at this point. Maybe its the o2 sensor?
Any have any ideas?

 

[suspendedHatch]

I know a bit about tuning but you are talking in relative terms. Do you have a wideband O2 sensor? What are your actual air fuel ratios?

How is your fuel pressure changing? It should only change with vacuum unless you have some wild electronic fpr that I haven't heard of. It must be changing because of the change in vacuum when the RPM changes.

 

[Chappy]

I know a bit about tuning but you are talking in relative terms. Do you have a wideband O2 sensor? What are your actual air fuel ratios?

How is your fuel pressure changing? It should only change with vacuum unless you have some wild electronic fpr that I haven't heard of. It must be changing because of the change in vacuum when the RPM changes.

I just bought a wideband o2 and I should get to install it if not this weekend next week sometime.
Once I know the exact a/f ratios across the band I'm hoping to be able to figure this out.

I will let you know what I see once I get some time to put the sensor and everything in.

Thanks,