High Idle And Iacv Interchangability

[rx-line]

Pin 18 won't cause any grief to the ecu, but you need to somehow control the fuel pump and using this pin is the best way.

When the engine stops, your fuel pump must also stop/time out. (You don't want fuel pumping in the event of a crash)

Pin 43 starts the timer for the fuel pump. It also re-sets at every IGN start signal. (I always believed the ecu would not continue without this signal, must have been wrong on that one)

Pin 53 input is vital once you get the car moving. The ECU will operate OK without a speed signal but after a while it gets confused. It see's RPM, TPS, AFM and so on but no speed. It thinks you're sitting still and free revving. You will have inconsistent power delivery without a speed signal input as the ecu will eventually pull timing.

(Many, many smarter blokes than I have been fooled by this one)

Pin 104 is for the fuel pump control module and won't have any effect if left unconnected.

Pin 44 (neutral switch) won't effect your engine as it's a Normally Open switch when in gear. But if you were using HICAS etc then you wouldn't be able to do self checks without this input.

Reverse switch has no input to the ecu.

You need to do thorough testing for vacuum leaks if it still idles so high. These are a tiny engine and only need a small amount of air when idling, so it doesn't take much of a leak to raise the idle.

How many inches Hg does it pull when idling and have you got your IGN timing as correct as you can with these crazy RPM's?

It has a Mines tuned computer lol, So I am wondering if my search for vacuum leaks is futile, I did the propane trick and couldn't find any leaks. I have heard that the AC/Power steering show a drop in signal which used by the IACV. So I am curious as if the IACV is currently unaffected by the AC/PS not being wired or is fully affected. It pulls 20lbs vacuum at idle with 10.9 AFR's, I have no way of checking the timing until i get a series 2 AEM or Nistune.

I fully appreciate your notes on the wiring, something there is little info online for. Which of the two electronic sensors on the transmission is the speed sensor? the one by the shifter or one closer to the engine? there are two wires on the sensor, is it a matter of grounding one and connecting one to the #53 wire? or is there some sort of switch/relay?

RX,

[rx-line]

I found out through the FSM that Pinout #43 is the "START Signal" and changes the ignition timing when cranking engine. (this may be why it has always taken 3 or more starts to start when cold. As well Pin#43 "Increase fuel quantity when starting, Determines injection quantity when ~starter SW is ON.". I am assuming I should at least have this wired to the IGN 12V? yes?

I didn't know the FSM had this much info in it Circ page 318. Still curious as how to wire the Speed sensor.

RX

[jiffo]

You have a 20 gearbox??? it's got a cable drive speedo.

At the speedo head there's a reed switch which generates the speed signal pulse for the ecu.

But speed signal is the fine tuning stuff. Your engine will run fine and "most" of the time never miss not having a speed signal. Certainly not the cause of a high idle.

Neutral switch is closest to the shifter, reverse switch is closest to the bell housing. Both are simple on/off switches.

Pin 43 gets it's signal straight from the start position of the IGN key. It's NOT a constant 12V feed, only an input while the engine is cranking.

Air con and power steer inputs only bump up idle a small amount. With your engine idling at such high rpm they'd have no effect even if they were connected and incorrectly switched. I had presumed they were not connected.

By a rough check of timing I meant are the cams lining up with their respective dots at TDC and is the CAS central in its adjusting slots.

Running out of ideas……..

[rx-line]

You have a 20 gearbox??? it's got a cable drive speedo.

At the speedo head there's a reed switch which generates the speed signal pulse for the ecu.

But speed signal is the fine tuning stuff. Your engine will run fine and "most" of the time never miss not having a speed signal. Certainly not the cause of a high idle.

Neutral switch is closest to the shifter, reverse switch is closest to the bell housing. Both are simple on/off switches.

Pin 43 gets it's signal straight from the start position of the IGN key. It's NOT a constant 12V feed, only an input while the engine is cranking.

Air con and power steer inputs only bump up idle a small amount. With your engine idling at such high rpm they'd have no effect even if they were connected and incorrectly switched. I had presumed they were not connected.

By a rough check of timing I meant are the cams lining up with their respective dots at TDC and is the CAS central in its adjusting slots.

Running out of ideas……..

Hey Jiffo I got you, It could be a vacuum leak that's causing my idle but I assume I should stil have the vehicle speed sensor wired as well as pin #43 etc. Yes it is a rb20 box, so you are saying the dash cluster actually produces the reading for the speed sensor? And I knew what was in order to wire #43 the ignition forward position of 12v, I just didnt explain myself fully I guess lol. I will have to check the TDC at somepoint.

Thanks,

[rx-line]

Connecting #43 to my ignition signal has fixed the hard starting problem I had, thanks Jiffo! Flashes right up. I was thinking I could get a emulator for the speed sensor but then I thoguht how would it even get the speed from the rx7 cluster.

Do you think it won't change randomly put me in a safe mode? will I need it for nistune or AEM? or can Is there a setting to turn off the vehicle speed?

Rx,

[jiffo]

I doubt an aftermarket ecu would need the speed signal to the extent that the stock one does.

Someone else could perhaps confirm that info.

It doesn't go into safe mode, hard to explain what it does but power delivery varies from day to day, seat of the pants stuff.

Here's a partial scan from an old Zoom mag. They experienced the same problem and eventually sorted it.

Like I said, tricked much smarter blokes than me as well.

[MagicMikeZ32]

Re idle, are you getting a TPS closed signal (if applicable)? Does your tps have 2 plugs or 1?

[rx-line]

I doubt an aftermarket ecu would need the speed signal to the extent that the stock one does.

Someone else could perhaps confirm that info.

It doesn't go into safe mode, hard to explain what it does but power delivery varies from day to day, seat of the pants stuff.

Here's a partial scan from an old Zoom mag. They experienced the same problem and eventually sorted it.

Like I said, tricked much smarter blokes than me as well.

Wow thanks for that, I have had friends with other cars and the speed sensor has a major role in the tuning and performance of their cars. I am wondering if I can get the sr20 speed sensor? (electronic) and straight wire that to the ecu input? I mean the car runs and drives fine but it does seem like power varies from day to day. I was lucky in the beginning to have the engine's speed analog sensor work with my mazda dash but this ma be coming to an end unfortunately.

[rx-line]

Re idle, are you getting a TPS closed signal (if applicable)? Does your tps have 2 plugs or 1?

It seems like it after I adjusted it, .48v at close, I think what happened was that the adjustment for the throttle plate was a little high it is now slightly sticky all the way closed and where it sits on no throttle. .48v was adjust after. (where it should be?)

It idles at 1100 cold and 1250 warm now. which I am fine with, much better than 2000 lol I would like it a little lower but I'm thinking of replacing the cheap intercooler and building a turbo manifold for my hy35 holset, maybe run it on 8lbs till coils,injectors ecu. Seeing has we still have 4 feet of snow.

Here's a picture of what I've got going on and what I'm dealing with lol

[GTSBoy]

Wow thanks for that, I have had friends with other cars and the speed sensor has a major role in the tuning and performance of their cars. I am wondering if I can get the sr20 speed sensor? (electronic) and straight wire that to the ecu input? I mean the car runs and drives fine but it does seem like power varies from day to day. I was lucky in the beginning to have the engine's speed analog sensor work with my mazda dash but this ma be coming to an end unfortunately.

Search for posts by me using the terms "square wave" for a discussion on what signals come from where, where they go to, and what they look like.

[MagicMikeZ32]

Regardless of the voltage of TPS, you should confirm that the ECU is getting 'closed throttle' signal from TPS.

[rx-line]

Regardless of the voltage of TPS, you should confirm that the ECU is getting 'closed throttle' signal from TPS.

How is this done? I assume by metering one of the wires on one of the two throttle body plugs?

[GTSBoy]

Typically, with an RB20 TPS, if the switch is closed when the throttle is closed, then the merest movement of the throttle towards open should make the injectors double fire. So if you lean over the engine with you ear near the plenum and just twidge the throttle open, and you hear the click-click of the injectors (where you would only have heard the single click at each firing) then it's working.

Otherwise, yes, you can probe the appropriate terminal at the ECU to see the signal. Just get the R32 GTR workshop manual pdf off the net. The RB20 wiring diagrams are in there. Otherwise the ECU pinouts are available via google anyway.

[rx-line]

Typically, with an RB20 TPS, if the switch is closed when the throttle is closed, then the merest movement of the throttle towards open should make the injectors double fire. So if you lean over the engine with you ear near the plenum and just twidge the throttle open, and you hear the click-click of the injectors (where you would only have heard the single click at each firing) then it's working.

Otherwise, yes, you can probe the appropriate terminal at the ECU to see the signal. Just get the R32 GTR workshop manual pdf off the net. The RB20 wiring diagrams are in there. Otherwise the ECU pinouts are available via google anyway.

Right on! So I would probe an injector wire and look for a doubling of voltage? I'll try that if the ear test isn't definitive. I am thinking 1100rpm isn't far off from other mines tuned ecu's?

[rx-line]

Right on! So I would probe an injector wire and look for a doubling of voltage? I'll try that if the ear test isn't definitive. I am thinking 1100rpm isn't far off from other mines tuned ecu's?

I'll check the FSM for throttle closed signal wire.