I have a JDM ITR motor with P73 JDM ECU, Everything is stock except for a 255 Walbro fuel pump,

however, when my clutch is disengauged and when the car is moving, it will idle at around 1,500 to 2,000 rpm, which i dont' think its normal, but when the car comes to a complete stop, it will idle back normal at around 750 to 900 rpm,
So I figure it might be my fuel pump thats making my idle so weird when moving, so I put back a GSR fuel pump in there, and it just did the same thing, but now my idle fuel pressure is at 43psi instead of 55psi with the walbro.

Is it because my walbro that messed up my injectors or FPR or something? or is it that I am missing a vacuum hose here (I just found that it might be missing that today), here is a picture



Before I pay 85 dollars per an hour to have it check out and fix by a shop, can someone help me out and see if I can fix this problem myself?

Thank You

 

i have noticed that every 5spd honda i have ownd has always done this.
as for the vacuum port it is for the evap system you sould cap it off.

 

cap it off as in put a cap on the port? or connect it to the evap system, if so how? But the interesting thing is when I put on a Power FC ECU on it, it will not have the idle problem, the shop said its because the Power FC overwrite something, is it some sensors that the FC overwrite, if so, it might be some sensor problem? any ideas?

 

See the flat head idle set screw next to to the nipple you are speaking of ?
Try lowering your idle via that screw, also look around for more possible vac leaks.

Btw, your ignition timing at the distributor is at 16-18 deg btdc correct ?

 

yes, i think my timing is at 16 deg, but as you said it should be 16-18, what direction should the timing be best, toward 16 degrees, or toward 18 degrees? What rpm should I lower my idle to, what the factory idle set at?

 

Your idle sounds completely normal at a stop.

I wouldn't touch the idle screw or the timing.

However, could be a possible sticky throttle body plate. When you left off the gas, does it ever get stuck?

The top port of the throttle body should be capped off on usdm cars.

 

yes, i am pretty sure my timing is fine because it idles perfectly fine at a stop, However, it does not seem like a sticky TB plate, I will try capping it off and see what happens, what should I use to cap it off?

 

Anyone?

 

go to home depot, they sell plugs that look very professional. It should be in the section with bolts and plugs.

They have various colors, black, green, red, white, etc.

 

I am experiencing this EXACT same issue...please advise if you have diagnosed what the problem is.

Cheers!

 

Hi HGL1668,
can you send me some photo of the fuel manometer to this email?: alex_novi@yahoo.it
thx, Alex

 

what you are describing sounds normal to me and NEVER mess with the idle screw... NEVER

 

it's normal.. leave it alone..

 

normal mine does it too......... always has

 

Your vacuum hose that is missing according to the diagram is coming from the purge valve via charcoal canister which means its rerouting unburned fuel mixture to the intake side of before the the throttle plate so it would not affect engine performance. You might want to connect it back to the canister(better fuel economy) or plug both sides (canister and TB intake).

My analogy for your idle. I believe it is NORMAL. Idle IAW tech manual normally means the car is at park or neutral and car is not moving. I think when car is moving and pistons are cycling more than when car is at stop and therefore pulling more air, most likely from IACV confirmed by the speed sensor which tells the ECU to schedule a little bit more fuel = Hi RPM.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tarikan &raquo;</TD></TR><TR><TD CLASS="quote">...which means its rerouting unburned fuel mixture to the intake side of before the the throttle plate so it would not affect engine performance. You might want to connect it back to the canister(better fuel economy) or plug both sides (canister and TB intake).... </TD></TR></TABLE>

it's not EGR man, so no unburned fuel mixture. the evap purge control soleniod uses vacuum from the intake manifold to purge a vacuum to the gas tank. this pulls gasoline vapors from the tank, runs them through a canister of activated charcoal, which removes hydrocarbons or somethin, and then the engine sucks them through. OBD II uses tank pressure sensors also (thats how they throw that stupid gas cap loose code)

anyways, back to the question, that little vacuum port only has vacuum when the throttle plate is open and the engine is flowin a good amount of air, because it taps outside the throttle plate, basically in the intake tube.

that being open will not cause any noticeable problems. i'd bet you have a faulty Fast Idle Thermo Valve, if your car has one. if not, you may have a bad primary O2 sensor, or even a bad charging system (low voltage makes em run weird, too)

but really, your problem sounds kinda normal, as in not a problem, just a moving idle, which should be approx 800 RPMs above idle when the car is sitting still

 

I had the same issue, but it was because I removed my TB and got something stuck in the O2 senor and ended up removing it to clean it, which caused my senor to go all crazy. I needed up getting my TPS and O2 senor recalibrated and it works fine now. Did you mess around with the TB?