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Throttle problem after DPFI to MPFI swap

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Old 01-09-2009, 02:08 PM   #1
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Default Throttle problem after DPFI to MPFI swap

So after I swapped my D16A6 into my Civic CX, I noticed that between shifts it would take approx. 2 to 3 seconds for the revs to drop. I've cleaned the throttle body, EACV and I replaced the throttle cable with a brand new SI one. Now here's the thing, this problem only happens when the engine is warm. With no load the problem is still there. The throttle opens and closes no problem. I've checked the pedal assembly, checked for vacuum leaks and the throttle cable adjustment. No problems! The FITV isn't plugged in, would that cause the problem? Any help would be great

thanks

edit: the setup if it helps
- D16A6 with 200, xxx km's into a Civic CX hatch using the fourthgenhatch.net DPFI to MPFI tutorial
- 4-2-1 headers
- crush bent exhaust
- I replaced the fuel filter, timing belt and water pump when I did the swap, plus the cam, crank and rear main seal
- All the connections are soldered and heat shrinked

The car runs great and has good power (I was driving with the D15B2 for more than a year!) but the only problem is a grind going into 5th gear (GM synchromesh fixed it.. for now) and the slow rev dropping between gears.



Yes, the wiring looks like ****, I'm leaving it exposed till I get all the bugs worked out just in case I need to hack up the wiring again!

Last edited by nicholasmak; 01-18-2009 at 09:24 PM.
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Old 01-09-2009, 04:08 PM   #2
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Default Re: Throttle problem after DPFI to MPFI swap

i would make sure that the dashpot on the throttle body isnt adjusted too far. the purpose of it is to slow down the rpm drop when shifting, it works off a vacuum source from the manifold. theres a tab on it that almost or maybe even touches the throttle valve. try disconnecting it and plugging off the manifold vacuum source and see if it goes away
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Old 01-09-2009, 08:51 PM   #3
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Default Re: Throttle problem after DPFI to MPFI swap

You may have a slight vaccum leak somewhere, it happened to me.
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Old 01-09-2009, 09:33 PM   #4
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Default Re: Throttle problem after DPFI to MPFI swap

Ok cool, I'll check the dash pot and recheck for vacuum leaks. I'll post my results!
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Old 01-18-2009, 02:42 PM   #5
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Default Re: Throttle problem after DPFI to MPFI swap

So today I finally got around to working on my car (school full time etc etc), I checked for vacuum leaks 4 times (twice when cold, twice when hot) and still nothing. I took off what I believe is the FITV (it was unhooked from when I did the swap) and I have no idea if this could be the problem. The car idles high when cold, but I guess its doing it with the EACV? I'm not too sure how this stuff works. I also disconnected the dashpot and cappped off both ends (the dashpot and manifold vacuum nipple) and the problem is still there! I'm stumped guys!

Is this the FITV?



I opened it up to see if could be adjusted like the ones I saw when I did a search on FITV's, this one just has a spring and a block off sorta cap on one end and a rod (seems to be electronically controlled) to push it open on the other.
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Old 01-18-2009, 06:42 PM   #6
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Default Re: Throttle problem after DPFI to MPFI swap

Ok I just unhooked the purge solenoid cut-off valve vacuum line and capped the manifold and the problem is still there (running out of things to try!). Would a malfunctioning EACV/IACV or whatever cause this? I cleaned it with throttle body cleaner and the motor ran fine when it was still in my CRX. Any way to eliminate it as a possibility? Unplug it when the engine is warm?
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Old 01-18-2009, 06:57 PM   #7
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Default Re: Throttle problem after DPFI to MPFI swap

try loosening the throttle cabe adjuster.. if its too tight then when u let off the gas, the butterfly deal isnt gona close like it should.. itl keep it open slightly
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Old 01-18-2009, 07:14 PM   #8
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Default Re: Throttle problem after DPFI to MPFI swap

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Originally Posted by DOHCED8 View Post
try loosening the throttle cable adjuster.. if it's too tight then when you let off the gas, the throttle plate isnt going to close like it should. it may keep it open slightly
also maybe once it warms up some part of the tb assembly is getting jambed? does the throttle plate close any faster between when its hot or cold?

In regards to your picture above. thats not your fitv (fast idle thermal valve). the a6 doesn't even have one. it is a fast idle control solenoid valve and is used to increase the air flow rate for fast idling at extremely low ambient temperatures (when coolant temp is below -14 degree fahrenheit or -10 celsius) and when engine speed is below 1,800 rpms.
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Old 01-18-2009, 07:15 PM   #9
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Default Re: Throttle problem after DPFI to MPFI swap

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try loosening the throttle cabe adjuster.. if its too tight then when u let off the gas, the butterfly deal isnt gona close like it should.. itl keep it open slightly
Not doubting you or anything, but would a poorly adjusted throttle cable cause a problem only when the engine has warmed up? I'll give that a try after school though

thanks!
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Old 01-18-2009, 07:18 PM   #10
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Default Re: Throttle problem after DPFI to MPFI swap

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Not doubting you or anything, but would a poorly adjusted throttle cable cause a problem only when the engine has warmed up? I'll give that a try after school though

thanks!
doubt it. if anything the cable is going to be more rigid when its cold and cause such a problem to act up then, not once its all warmed up.

also, the ficsv is not needed unless you actually see temps that low. and its not going to cause a problem if you remove it. just make sure you plug up the hole in the intake manifold if you leave it off.

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Old 01-18-2009, 07:30 PM   #11
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Default Re: Throttle problem after DPFI to MPFI swap

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Originally Posted by D16SiHatch View Post
also maybe once it warms up some part of the tb assembly is getting jambed? does the throttle plate close any faster between when its hot or cold?

In regards to your picture above. thats not your fitv (fast idle thermal valve). the a6 doesn't even have one. it is a fast idle control solenoid valve and is used to increase the air flow rate for fast idling at extremely low ambient temperatures (when coolant temp is below -14 degree fahrenheit or -10 celsius) and when engine speed is below 1,800 rpms.
I don't believe anything in the throttle area is jamming, it opens and closes fine when warm too. I originally thought it was the throttle cable because the DPFI is super long and I had to put a ton of bends in it to make it work with the A6. I guess the problem was there when I drove the car home after I did the swap too. I think I could make the plunger thing inside that fast idle solenoid stay permanently shut just in case its opening up between shifts, just so i can be 100% it's not doing anything. Any way to check the EACV? Other than that, I really have no idea where to go from here
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Old 01-19-2009, 02:11 PM   #12
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Default Re: Throttle problem after DPFI to MPFI swap

Ok I just got home from school, I cleaned the throttle body before I drove home and the problem is STILL there. I think the problem is something I must have missed while checking the throttle assembly or probably EACV related. Any thoughts?! I've checked the throttle area over many times so far and I've elimated a bunch of possible problems..
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Old 01-20-2009, 06:29 PM   #13
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Default Re: Throttle problem after DPFI to MPFI swap

bump!
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Old 02-07-2009, 06:15 PM   #14
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Default Re: Throttle problem after DPFI to MPFI swap

ok I finally got around to working on my car yesterday, I covered the EACV/IACV hole with tape and the problem is gone! But would the fault be in the valve or something electrical? The wires for the valve were extended for the swap. Any way to test it? I want to narrow it down before I start replacing parts!
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Old 02-07-2009, 06:27 PM   #15
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Default Re: Throttle problem after DPFI to MPFI swap

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ok I finally got around to working on my car yesterday, I covered the EACV/IACV hole with tape and the problem is gone! But would the fault be in the valve or something electrical? The wires for the valve were extended for the swap. Any way to test it? I want to narrow it down before I start replacing parts!
so at this point the only problem is that it is slow to come down to idle?

to test the iacv, ground the blk/yel wire and hook up +12v to the blu/yel wire. colors may be different since you've extended the wires and such, but i would imagine you should be able to determine which one is ground lol.
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Old 02-07-2009, 06:37 PM   #16
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Default Re: Throttle problem after DPFI to MPFI swap

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so at this point the only problem is that it is slow to come down to idle?

to test the iacv, ground the blk/yel wire and hook up +12v to the blu/yel wire. colors may be different since you've extended the wires and such, but i would imagine you should be able to determine which one is ground lol.
yeah that's the only problem right now. So I'd be sending power to the IACV and I guess it should open up/close? I think I could also check for resistance between the ECU pin for the IAC and the connector, maybe I did a bad soldering job hahah
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Old 06-11-2009, 08:50 PM   #17
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Default Re: Throttle problem after DPFI to MPFI swap

UPDATE: I fixed the problem! Turns out the ECU was acting up. I've been trying to figure this out for like 6 months. My boss had a PG7 out of his old Integra laying around, so I swapped it in and it drives like a dream. Feels like it has a bit more power too, possibly because the PG7 maps are different. Thanks to everyone who's helped me out!
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