Hi. So, I'm getting an L15 and trans (hopefully) shipped to me next week. I'm putting it in my insight which has/is set up with a cable throttle body. My question to the experts is: If I get a JDM TB and JDM ecu, would I be able to ditch the UDSM DBW TB? What problems would I be looking forward to if I attempted such a feat?

2nd question: Has anyone tried to run their engine without the DBW TB connected? Will the engine start/run? If the engine does start, what happens to the engine rpm if you manually move your TB butterfly with your DBW disconnected?

 

Nobody wants to know how easy it would be to convert to cable TB and open up a world of JDM performance mods for their Fits? Post your interest.

I don't have a Fit. The only way I can mess with one is at the dealer. I'm also a novice at engine swaps and tuning. Regardless of all that, I think possible problems with swapping the TB and ECU on a Fit would be gauge cluster misrepresentation. Unless the JDM ECU allowed for unit conversion? Another might be- the USDM Fit uses a Can Bus system (I believe). If the JDM one doesn't, that would cause some issues, right?

 

Well I do know that the JDM gauge cluster doesn't not work 100% on USDM Fits, so I'd imagine the inverse would be true as well. Also, IIRC, the JDM cars also appear to have a different intake manifold, it may just be a question of getting a JDM intake mani and JDM TB and sticking that on top of the USDM L15. It's hard to say though since not many people hear have done extensive engine work to the car. If you can get a hold of Weapon*R, they're currently the only company that I know of who has released a new intake manifold for the USDM Fit and they also have one for JDM Fits. You could inquire to them about any differences between the two and their respective throttle bodies.

 

i want to know this also.
i would prefer the traditional cable throttle to the DBW.

 

What I think youll need is the JDM TB, intake manifold assembly, and the ECU.
Im not sure what problems youll run into. I dont even know if the engine will run with the JDM ECU? It may, Im sure a CEL will pop right away as the emissions are way different out of states then they are here.

Starting the car without the TB plug connected, not sure what will happen. The TB is closed when at idle. It should idle, not very good probably as it sits slightly open when the cars shut off. All you can do is try it.

Anyone interested in do this in a Fit, dont waste your time or money. You wont get anything out of it.

 

I have a bit of info the USDM and JDM TB. The JDM TB has a smaller size TB than the USDM model, I think that will be pointless to change to a smaller TB.

IMO, Switching the DBW to cable is possible. There are 3 wires on the (cable) TPS sensor and with the cable hooked, that should work.

In regards to the JDM cluster, it is not a 100% plug n play. You will need to flip wires to make the cluster to function properly. Some of the lights will not work because the JDM cluster has different circuit board.

 

Thanks to everyone for all the great info! I sent out an email to weapon-r as suggested. Lets hope they can enlighten us about the differences in their intake manifolds.

I'm really curious to know how easy this could be. With the DBW plug disconnected from the TB, will the engine run? Will it go into limp mode? I can deal with a cel if my engine is performing the way it should. It may be as easy as hooking up a cable TB? Who wants to try it? ^_^

ATM, I don't have a Fit gauge cluster. I could get whatever cluster goes with whatever ecu at this point in the game. Then wiring might be made easier. Fit-ment is another issue. I know the S2000 gauge cluster fits in my insight, but I dunno about the Fit's.

At first, I had planned to piggyback ecus like the K20 Fit ppl do w/ KPro. Except, that is proving more difficult to achieve. I haven't emailed Hondadata yet, but I'm guessing the KPro setup is for the Fit and the K20 only and I'm SOL unless I find a way to hook two wiring harnesses together without altering the signals to either ecu. We'll see...

 

I received a reply from Weapon-R and here it is:

"Chris Agloro R&D Dept/Tech:

The difference is in the TB's of each the DBW and cable designs are
different. If you use the Cable style on the USDM you will get a check
engine light, but it should still run."

+100 Points for Chris at Weapon-R for being prompt and courteous (and not wanting the money I offered him) ^_^

So, it's looking to me like you could just buy a JDM cable TB and stick it on the USDM Fit engine. There seems to be no difference in the USDM/JDM intake manifolds.

AJ, do you have a measurement of how much smaller the JDM TB is? Looks like the USDM TB is 50mm?
Source= 2007 Honda Fit Powertrain - Honda - Press Releases - Selected Story

Fit owners: Don't expect your rev hang to go away in swapping TBs. My 02 base RSX had rev hang with a cable TB. I put an Injen CAI on it and rev hang was lessened but not gone. My guess is I/H/E would be a great start in reducing rev hang and gaining HP on your Fits. Money better spent than on a throttle controller IMO.

 

if you sold a kit to switch to cable TB without throwing a CEL... i'd buy it right now!

i think a lighter flywheel would get rid of a little rev hang also.

 

I dont think the JDM throttle body would work with simple bypass wirings on the USDM DBW throttle system. in the first place, the gasket for the throttle body of the DBW system is round while that of the JDM is oval to give way to the intake air control valve ports.

The cooling system hoses for the JDM throttle are parrallel installed from the firewall to the IACV under the throttle while I believe the DBW hoses are mounted in-line with each hose end facing each other above the DBW throttle.

 

Here's a some blurry phone pics of my DBW Fit TB and intake mani.




Pating: can you give more info about the JDM TBs? Links pics etc... It'd be good to have some pics or references for comparison.

 

we have a different mounting pattern for the cable-operated throttle body here in the philippines (which is also the JDM-spec cable-operated throttle body). the intake manifold looks like the picture below. The red line around the mounting surface is the gasket of the throttle body. the connectors are for the IAT sensor and the IACV.





the throttle looks like this from the front:


and the ports for the IACV which is mounted under the throttle body:


and the rear of the TB, noting the port under the round throttle which allows for idling air through the IACV to pass into the intake manifold:

 

here is a pic of the throttle body with the iacv installed under it. note the fittings on the side of the iacv where the coolant hoses attaches to:

 

Awesome. Good info Pating. That TB looks in proportion to mine. May I presume it's from a 1.5 liter engine as well?

 

yes it is from a 1.5L engine, L15A engine.