FD3Cam

Hey guys,

FINALLY got around to getting my PFC installed and it fixed a ton of my issues! Hells yea! Its on base map with 02 feedback off. Car has emissions removed, JDM carless down pipe, mid pipe, cat back and apexi intakes.

Problem now is that after doing the idle learn, the car is idling around 2000ish rpm when warm. I went in and closed the air bypass screw another quarter turn (it was out about 3/4 turn). So now it sits at 1/2 turn.

turning the screw in that quarter turn seemed to fix it for a minute (back down to 1000ish RPM's), then once I blipped the throttle it went back up to 1500 then eventually crept back up to 2000rpm then held steady.

Should I turn the screw in more or is there something I'm missing?

Thanks!!!

FD3Cam

All at idle:

Water temp 70c
-550mmhg


PIM 1.36V
VTA1: 0.84V
VTA2: 1.63V
VMOP: 1.23V
WTRT: 0.64V
AIRT: 1.27V
FUEL: 3.61V
02S 0.42V

REV LIMIT: 8100
F/C A-E 1000
F/C E/L 1100
F/C A/C 1200
IDLE A-E 770
IDLE E/L 800
IDLE A/C 900

Tem120

iTrader: (5)

did you read the how to for setting your idle??

did you adjust the idle adjustment screw until it was mostly closed with only 1/4 turn open

FD3Cam

Yes I initially did the idle set procedure with the screw out 3/4 turn and it was idling around 2000

Now I closed it all the way to 1/4 turn and its still 1600-1800 when warm

FD3Cam

Do you need to re-do the idle learn when you adjust the set screw?

Tem120

iTrader: (5)

you may have a vacume leak . recheck all your vacume lines ,if nothing is found , disconnect the Idle air control ,and see if that works . if all is well try and redo the idle learning proceedure open up the idle screw a LIIITLE bit , also check to make sure your TPS values are correct , you can adjust the throttle using the throttle screw for the secondary butterflies

you are getting more air into the motor then there should be , try the usual suspects first and if th

FD3Cam

Vacuum is all good I checked the lines not long ago and everything seemed fine.

Ill play with the IAC and re-learn the idle and go from there tomorrow.

alexdimen

iTrader: (13)

Your VTA1 and VTA2 are both high.

Primary or secondary throttle not closing all the way maybe? Disengage the fast idle cam and check that they are closed when on their stops.

On mine I can fiddle with the air bypass screw under the TB within reason and the idle remains solid as the PFC compensates.

FD3Cam

Is that high for idle?

Ill look into the IAC, and the fast idle cam tonight and see if that helps...

Just strange that it idled fine before with the stock ECU

alexdimen

iTrader: (13)

Yep, looks like it.

.1 to .7
.75 to 1.25

FD3Cam

Is that a TPS issue or something with one of the idle set screws thats keeping the butterflies open??

Tem120

iTrader: (5)

check the idle set screws first

FD3Cam

Will do thanks!

Unfortunately I dont have a garage and im at the mercy of the weather so hopefully it gets better so I can get out there and work on the thing

FD3Cam

OK!

I did a bunch of dicking around with the idle screws and for the life of me couldn't get it to idle anywhere below 1800..

I ended up unplugging the IAC and then re-did the idle learn and its idling right at 900 and otherwise runs great. So from what I can tell unplugging the IAC was what needed to happen. Its going to be going into storage in the next few weeks until next spring so ill enjoy it as it is for now and then get it tuned in the spring.

FD3Cam

Now we've got surging idle...

Ive docked around with the idle screws and the only way to kill the surge is to have it idle at like 1500 rpm. Ive checked for leaks and nothing that i can see. It only seems to have an issue idling when its warm (mid-high 80s celcius).

The TPS is a bit out 0.8 and 1.8 at idle, could that cause it? Its a JDM so I don't need to cut the 4 wires and the IAC is disconnected so not sure where to go from here if the TPS docent fix it

FD3Cam

I re set the ECU and it seemed to have fixed it for a while, but once it got warm (83ish) the idle started hunting, then sitting around it got up to 90 or so and the idle smoothed out... ideas?

arghx

iTrader: (3)

Is the throttlebody coolant hose removed, but the fast idle cam still there? That would keep your butterflies open, resulting in high TPS voltages. Please re-read any posts of mine regarding the fast idle system and how it works.

EDIT: here, I'll make it easy for you. Read post #23: https://www.rx7club.com/3rd-generati...6/#post9442162

FD3Cam

Hey arghx,

No the coolant hose is still there as is the fast idle cam.

Ill take a look and see! Ive read through that a few times but maybe I missed something

arghx

iTrader: (3)

Follow the procedure described in that post. Make sure the TPS voltage is changing as you rotate that cam. If it's not changing, your fast idle cam screw is not adjusted correctly.

FD3Cam

Ill give that a try and report back!

Thanks

FD3Cam

arghx,

I did as the post suggested. Checked TPS when cold and moved the idle cam (it changed). Let the car get up to temp (85) and moved the cam, and it didn't affect the TPS at all. So it is not affecting warm idle.

However, i just let the car sit and get to temp (didn't drive it) and it did not hunt whatsoever. It seems to only do it sporadically after I actually drive the car a while. I have the AAS open about 1/3 turn, and if I use the idle screw (front of the TB) to lower the idle it runs quite rough (shaky). I have to keep the idle around 1400 for it to be smooth.

My TPS with the fast idle cam fully disengaged (fully warm) is at VTA1: 0.81 and VTA2: 1.57. So they are a little out, could this be my issue? Why would the idle surge be intermittent like it is? Just sitting there there letting it warm up the car won't do it, but if i drive it (say after 5-10KM) it seems to surge at idle....

Not sure where to go now.... if its not the TPS I'm at a loss

FD3Cam

Don't know if its related but I went to open the PIM (NORMAL) settings screen and the car died without me changing anything. Don't know if thats a thing or not just seemed odd...

arghx

iTrader: (3)

With your TPS voltages that high, it means either the TPS needs adjustment, the TPS is bad, or the throttle adjusting screw is not at its factory settings. I think when you say the front screw you are talking about the throttle adjusting screw. That physically moves the resting point of the primary throttle blade.

A lot of times the throttle is sticking or surging when the engine is warm and you slow down and come to a stop, like in a neighborhood. That's where this post https://www.rx7club.com/3rd-generati...2/#post9674944 comes into play: it is for adjusting the decel behavior, both mechanically on the throttlebody (with the dashpot) and with the ISC duty cycle and ignition timing controlled by the "F/C" settings.

However, if you say the engine won't idle steady at near stock rpms, something might be up.

Here is what I would do. You absolutely need to verify you have no vacuum leaks. You will need to pressurize your intake system using a tester like www.boostpro.net/prodtester.htm . It's just a PVC cap with an air compressor fitting. Since you have twins, you need to cap off one inlet and feed air into the other. Verify no vacuum/boost leaks that way.

Then I would turn Idle IG control off, which will fix the timing at -5L -20T, just like in the service manual procedure. Turn the throttle adjusting screw so that VTA2 = 1.0 volts (VTA 1 will be less than 1). It should be able to drop down to about 700. You may need to open the air adjusting screw a little bit.

Stock ports should idle mostly smooth 700-800rpm with no accessory load and idle IG control off (timing fixed), with airpump not running but AFR at least as rich as 13.0:1 . All I'm suggesting you do is basically recreate the factory idle set procedure. If it won't idle under those conditions, you've got something going on (vacuum leak etc).

FD3Cam

OK great thanks arghx!

Even if I back out the throttle adjusting screw all the way, the TPS will still not read within spec (for VTA2 at least), so I suspect maybe the TPS needs adjusting?

I have the IAC unplugged and IG control OFF right now, should it be back on?

I will certainly try the tester as well, only problem is im in canada and am anticipating putting the car into storage in a week or so... I was just hoping to have it running well before putting it away.

Ill start with adjusting the TPS as you suggested, then mess with checking for vacuum leaks. It may be a topic to revisit come spring unfortunately as Im running out of time. Only bummer was the car didnt have these issues before the PFC..

but either way ill start with the TPS and go from there! Ill order the pressure testing unit and see what happens, otherwise ill order my datalogit and AFR gauge so i can better tell whats happening exactly.

arghx

iTrader: (3)

I can't figure out exactly how you are doing this, but here is the principle to keep in mind: when I close my primary throttle plate, TPS voltage goes down. VTA2=narrow range TPS, meant for low loads. If you keep turning the screw and the throttle plates are closing but the idle isn't going down, you've got air leaking.

Remember, air comes from:

1) throttle plate opening angle (screw on the front of the TB + fast idle system)
2) air through the idle speed control valve
3) air through the bypass passage (screw under the TB)

did you remove the emissions before installing the PFC? The stock ECU doesn't like to run without an air pump.

Here's the priority:

1) can't be vacuum leaks or it will never run right. No sense in running if you're on the wrong road.
2) with no airpump and no cat, AFR has to be about 13.0:1 or richer when you drop the idle down. Higher idle will tolerate leaner mixture. If too lean it will surge or stall due to misfire.
3) throttle plates have to be cracked open a bit and TPS should be in spec
4) air adjusting screw should be cracked open, less than 1 turn
5) spark can't be totally messed up. on an FD you don't have to worry about the crank angle sensor being installed wrong so it's hard to have your spark out so much that it kills idle

The thing is, you are flying blind without a datalogit and wideband, and I see you recognize that. Ask a pilot what happens when he flies at night in clouds with no instrumentation.

I understand man, I've lived in warm climates and cold climates and the clock is basically ticking in the cold climates.