In my search to fix my idling i came across a bunch of threads with usefull info but it doesnt particularly apply to HBP/BP motors.

For example: Calibrating the TPS. i recalibrated mine thinking the voltage was off, shortly after i did it, realized my numbers were incorrect because i have to have the throttle plates open slightly to allow more air flow so the car wont stall. thus it threw off my vta and vta2#'s

Id like to try and start an archive of info/tips that are HBP/BP specific.

So one of the biggest issues with the HBP is the high idle. currently mine idles at 2000rpm. i would like to get it down as my old engine idled around 1400, so i know its possible. For those with hbp motors, what is your idle and best method to tweak your idle?

Currently i have...
the air adjustment completely closed
idle adjustement screw ~2 turns in
throttle plates slightly open

Im thinking of backing out my idle adjustment screw some more and opening up my throttle plates more... would that be a smart trade off? i would think that would lower the idle rpms no?

 

lol ^

I have no clue Bubbles.

 

wel I had the same problem, gave it more fuel and played with the idle adjustment screw helped alot.

than just kept playing with the ems s2r , it likes FUEL went from 1900rpm idle to a 1280rpm idle and makes the brap brap sound much better now.

also play with the timing but i would not recommend it if your a novice, also more fuel means more sparkplugs.

mine even had a/c idle at 1420rpm

afr went from 15.8 at idle to 12.4 @idle half bridge btw

 

i might be reading that wrong, but having the throttle open more = higher idle, yes?

you'd probably have to retune the fuel, and maybe the timing but i don't see why you can't close the throttle plates more, or put them to stock.

my P port is actually similar, the ENGINE is happy to idle @700rpm, but the CARB doesn't really like it

 

From my experience, they will definitely idle around 1000rpm or lower. Close the throttle plates enough and it will get there. Just don't expect much vacuum--it's like a heavily cammed V8. If the vacuum gets low enough it will be difficult for the power brakes to even work.

 

Combined with less timing, it should idle lower and mainly smoother. IIRC Peejay idled his HBP on bridgeported secondaries. And I think its logical. It will recirculate exhaust gases no matter what, but its better to pull intake air earlier from bridgeports than making vacuum, sucking even more EGR, and then performing intake on primaries.

 

I'm actually idling at about 1400. I'm actually using the idle solenoid and it's working well though I've recently (relatively) started with an idle hunt issue but it settles down if I bog the motor down.

I'm nowhere near my car but will be early next month. We'll see what this thread does and I'll give you my settings then.

 

I am running a HBP, not really by choice, that is what was in my car when I bought it (I did re-build it so maybe I am a little responsible ;^) ). Some day I'll change but for now I have got it running fairly well.

Rock solid idle at 980 to 1020 rpm. Settles down nicely when I pull up to a stop sign. Haven't experienced any surging for quite a while now.

Running a PowerFC and am running an idle air controller. With the IAC I started at approximately 2 turns open (idle air screw) on the throttle plates and slowly (over a matter of a few days) kept opening them up. The idea was to lower the IAC duty cycle.

Best advice I can give - if you really want to learn and get a good idle, do a search and read every post by arghx...

 

Thanks!

i keep hearing this timing thing. im getting scared cuz i have no idea how to tune. might have to start..... (spare motor here i come.....)

if i close the throttle plates, what do i do to compensate? cuz it will def stall out if i just close the plates.. is timing the only way?

+1 on the timing again.. really need to learn this..

so jealous. please update with your info when you can

wow thats freaking cool. did u mess with the timing like everyone else said or is the IAC the big secret?

all my emissions are deleted and i cut the wiring so thats not going back........ er ever lol

 

get some video of this thing

 

I think that when you run an IAC you cannot run manual idle control. You have to allow the PFC to set idle air amounts and idle timing. At idle it constantly varies air and timing to try and hold the idle speeds you have requested.

This explains it a lot better than I can...

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/how-make-your-untuned-pfc-basemap-safer-idle-better-no-datalogit-needed-841706/

look at #27

 

If its idling too high, then you need to close the throttle plates or the air adjustment screw under the throttle body. You don't need to worry about timing if your using the ISC as it will take care of that for you. The only thing you need to worry about is fuel delivery. If your afraid to tune, you should let a tuner fix your car as they would solve the problem in a few minutes.

thewird

 

The engine's demand for air at Idle is no more than a stock engine; in fact due to the porting the actual air flow is probably less, hence the higher manifold pressure. The higher manifold pressure is telling the ECM "I need fuel" when in reality it doesn't.

It sounds like the throttle body has been tweeked so much it's probably near impossible to calibrate so I would start from scratch and set it up per the FSM. and put a couple of extra turns out on the air bleed under the plates. There should be no need to set the throttle plates anything but the factory positions. Make sure to hold the cold idle cam away when setting up the TB. The IAC will compensate for the RPM set point in the ECM. When at stable idle note the IAC position and if too far outside of the 50% median open or close the idle bleed to bring it back.

No doubt the ECM is supplying too much fuel at idle so the map needs to be leaned out in the pressure ranges at idle. This will get that crisp idle back.

 

i think people are misunderstanding. i do NOT have an IAC. it has been deleted long ago...

 

That's fine, your problem is still the same. Close the plates and remove fuel.

thewird

 

I don't have an ISC on mine idles fine @ 1200. I do have it raised a day so it still idles fine when cold..

 

raised a day?
do i still have to mess with timing?

 

No, you pretty much never need to touch the stock timing in the vacuum part of the map. The computer controls the idle timing if you have everything setup right with throttle and tps.

thewird

 

Assuming you are using a Power FC:

1) If "Idle IG Control" is ON and idle speeds are NOT set to 0 (which can only be done in a Datalogit), the PFC will constantly adjust the timing in an effort to get the idle speed close to the target speed. What this means is, if you raise the idle speeds, the average ignition timing will increase although it will still fluctuate.

If water temps are less than ~60C the ignition timing will come from the IGL and IGT maps. This is important if you have deleted the fast idle system. Advancing the timing in these maps will help reduce the chance of stalling when the engine is cold.

2) If "Idle IG Control" is OFF but idle speeds are NOT set to 0, ignition timing will be fixed at -5L -20T without A/C or electrical/fan load. -5L -20T correspond to the FSM spec for checking ignition timing. I don't remember off the top of my head whether the ignition timing will come from the IGL and IGT maps if water temps are less than ~60C .

3) If "Idle IG Control" is OFF and idle speeds are set to 0 (requires Datalogit), the PFC will always use the timing from the IGL and IGT maps. This is commonly referred to as manual idle control.

From what I have seen, cranking ignition timing is always controlled by the IGL and IGT maps. This is important because sometimes it is helpful to advance cranking timing in order to get the engine to start faster.

Advancing the ignition timing can somewhat compensate for less idle airflow. You can close the throttle plates (or air bypass screw) and advance the timing, or you can open the throttle plates and retard the timing. You just have to play around with it. There are also some tricks with the timing to help smooth out idle during warmup. We have discussed this kind of stuff in the Power FC tuning group.

 

You only need a datalogit if you want to set the idle speeds to 0 (to turn off idle control completely). Otherwise you can do everything on the commander. arghx, ignition timing below 60*C is from the ignition map.

I used to like all the manual idle control stuff because it gave more control. But in reality the computer does a much better job of it under all conditions IF its setup correctly. If you don't have an ISC, you can play around with the throttle plates to get your preferred timing. By closing them, the computer will try to compensate by raising the timing, if you open them, the computer will try to compensate by retarding the timing. The stock base vacuum timing is advanced enough in the idle area already so no tinkering needs to be done (at least on 9:1 rotors). You really just have to play with it, however your TPS NEEDS to be in spec with the throttle plates at all times for the ECU idle timing to run correctly.

thewird

 

well because i need more air to idle, my tps volt readings are higher. but without any of the adjustments, everything is in spec except VTA2. i cant get it past 3.6 at the open position...

should i be calibrating it according to my settings while i idle or all the settings backed out?

 

With the car off and the thermowax disabled (assuming you still have it), unscrew the throttle screw completely so its not touching the throttle. Screw it down until it touches and then turn it another full turn. Set your TPS voltages to FSM spec now somewhere in the middle to high. Now completely close the screw under the throttle body and then open it 3 turns.

Set all 3 PFC idle settings to 1,200 (you can play with this later) and the 3 F/C's to 1,600 (again you can play with this later).

See what it does. Only make adjustments with water temps 80+. If its rich or lean, don't bother making adjustments until afr's are proper cause that can affect the idle. Often you'll have to make fuel changes after making the adjustments as well. It's really a balancing act until its butter.

thewird

 

Also, again, the porting will cause the system to operate in the higher pressure ranges of the fuel map (instead of the P03-P06 you may be in the P05 to P08) which will cause a rich idle and difficult to stablize. Either remove fuel or realign the map's pressure ranges via datalogit. Most importantly, as thewird says make sure the TPS is in spec and the throttle blades are per the FSM. For initial setup use the air bleed screw. Also for the initial setup F/B needs to be off or the Fuel Correction Map recalculated to show 1.00 in all cells (probably both is best to start with).

"well because i need more air to idle" - Not true; unless you have a larger displacement engine more air is not required. The only thing you have to compensate for is the removal of the IAS which at idle the bleed screw can do.

 

I have no ISC and my idle control is off - zeroed out via the datalogit.

Only idle control I use is the adjustment screw.

It doesn't like to run cold but after a bit, car is happily brapping along at 1600-1800 RPM (where I like it anyway).

Problem now is I just added AC. It will immediately kill the engine in short order when it is running. I have to raise the idle without AC to 2400-ish to even hope to keep the car running when the compressor kicks in. No good.

Is attempting to allow the PFC to control idle going to help? This will only allow the PFC to make timing changes since I have no ISC?

 

Yes, the PFC would add more timing when you push that A/C button.

thewird