rx-line

Those are my thoughts skyrine, Thinking I'll post them up on ebay unless a member wants one Timing is the unknown for me, my wideband shows it running rich in boost around 10's with 30psi fuel pressure. keeping the throttle in spot reads 16's with it though. RX

Okay, Thanks man. Explains a lot! I've ran that mines ecu for a while and seems to work fairly good, I like the stock with the lower rev limit but I may switch back. Are they as bad as everyone says they are? I have three ecu's; a mines tuned, stock and a chipped one for 555cc injectors and z32 maf which i do not have. Thinking of nistune but cant shell the cash now. Can you tell me anything from my Afr's above? Seems they should not be that lean cruising or rich as i back off the throttle. Rx,

TP cut as in Throttle position??? Will the speed sensor not wired have the ecu reading different signals? or just one? As I stated the mines ecu had never gave me this problem. And as far as I know they heighten the rev limit and delete speed cut, anything else? That's why I think it is speedo related. I have no power steering, no clutch fan, no ac, rb25 turbo, fmic, ffp. fuel pump, 3" exhaust, etc. Pulls hard and was beating an overboosted tuned mr2 last night until boost cut at around 14psi.

Hey folks, got the rb20 back in my rx-7 and sourced a stock ecu to replace my mines tuned ecu. Seems to pull as hard, runs about 15-16 afr's running down the road and quickly changes to 10-11 when throttle is opened. If you back off it richens down to 8's and goes to the 14.5-16 again. Which I can live with, car pulls very hard. and creeps around 14 psi high in the rev range. However the car feels like it is completely shutting off at about 6000RPM in 3rd gear and has done this consistently since i have swaped the ecu. I do not have the transmission wiring wired as I never got the lower harness. As well my rx7 dash is run by the speedo drive and does output a signal to the ecu. I am thinking it is one of three things. AFM air flow cut knock sensor speed sensor. Anyone know of a bypass or way to check these? if not I will have to put the mines ecu back in for drag weekend. Rx,

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

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?

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

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

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.

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,

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,

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

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,

The neutral switch and reverse switch are not wire as well.

It holds 20lbs vacuum at ilde, so a vacuum leak would cause it to run less? I got it to run about 1100rpm cold by doing the unplug set to 850rpm and plug back in (IACV) method. I alos adjusted the throttle plate all the way down adn set the tps again. I would say the no AC/Power steering (Or wiring for it) may be causing the high idle, and to compensate the idle screw is in far and causing it to die after revs. Odd that it revs to 1250rpm after being up to temperature. Correct me if I am wrong here. I have another question for you folks about wiring. I did not receive the lower harness (starter,neutral switch, speed sensor etc.) with the engine/trans and am curious as to the repercussions of not having these wires going anywhere. Wire# 18- (Fuel Pump relay) - I use the fuel pump harness for the mazda 43 - (Ignition Start Signal) 53 - (vehicle speed sensor) 104 - (Fuel Pump Volt Control) I assume one of these is causing it to run 10.8 afr's on idle even with reduced fuel pressure, My guess it would be the Vehicle speed sensor. I am unsure what color or even which pick up on the transmission is the speed sensor as both have green wires coming form em and the pinout says it should be yellow/green... not green/yellow.... RX,

Yes I have an innovate wideband running separately from the computer. The old O2 sensor was shorting out, may have caused the problem? Anyhow the new o2 fixed the problem oddly enough. RX

Solve this problem and I'll send you 20$ on paypal lol

So I have my air regulator hose (Cold Start) plugged off, I adjusted my throttle body to just above close (sticky zone) and the tps sensor to .47 volts. the car runs at about 1500rpm with the idle screw almost all the way in ( 1 and 1/2 turns out). I turned my fuel pressure down to about 30psi with the vacuum line on and has an AFR of 11.8 warmed up @ 1500rpm no load. I check the Bov and it doesn't open at all during revs or off revs so no leaks there. However the car wants to stall out after any revs above 2000rpm. I do not have AC or Power Steering, I will check for vacuum leaks with propane another time but I am doubtful. How can I get my revs lower without the quitting after revs? is the IACV to blame? RX,

The Plenum, is a front facing Mailbox style plenum that was built in-house. It is just the top half of the receiver which is bolted to the original bottom receiver with gasket paper between them. I can't imagine it leaking. RX

"It's only cracked open the smallest amount to stop any chance of jamming due to temp changes". That was always my thought behind it, and how I set it up when we built the intake. Sometimes when troubleshooting you wonder what goes through the little Japanese engineers minds when they designed these cars. Why is my idle so high then? with the idle screw all the way in, with the old setup it would still run at like 2k rpm. I have ran it without the "coldstart" and it still has a high idle. I'm guessing a vacuumm leak, but I've been over everything and have not seen any signs of a leak. RX,

True, I had put a "check" valve in from a honda, It could leak IDK, it's from 1983. No lines are currently going to it. RX

Also will connecting the brake booster (currently line is plugged) make it idle higher or lower? RX

I ran the car for about 30 mins in -10 it never hit 180 degrees but the rad was hot, I changed the orientation of the vacuum lines in the below noted diagram. It idled at about 800rpm with the IACV idle screw adjusted about half way. It would die off reving like always, So then I figured I would adjust the throttle body adjustment screw for the throttle. Now I'm thinking the cold start is bad (I opened it up a while ago) since it never kicked down into low rpm. I think if I adjust the TB screw so the throttle is open a fair bit and adjust the IACV down with a new cold start I should see about 2k on cold and 1k rpm warm? Correct me if I'm wrong. Also I take it the cold start closes off when warm? Thanks for all the help man!

I've cleaned both valves, I am going to have to look for vaccuum leaks. I would like to know first if I have the lines correct. Here is an image I drew up on paint so you may get an idea lol. I am unsure if the vacuum going to the cold start from the piping should actually go to the otherside of the cold start. Thanks, RX

Hey guys, I have an rb20det with intake, intercooler etc. She has a high idle, TPS seems to work properly. I am wondering if the RB20's come factory with "restrictors" before the Idle air control valve and cold start. She idles around 2500 cold. and 1800 cold there abouts. I am wondering if the Black/Aluminum "cold start" is interchangeable with the 92 Nissan Sentra unit, as well what are my options for the IACV? RX,