spurvo

Anybody have this before? My car idles just fine, 750 with the lights off, 850 with the lights on, 17 inches vacuum at both speeds. EXCEPT when I have it in 1st gear with the clutch in. The idle will settle to 850 for a moment, then start cycling to almost shutoff, then bounce to 850, then die. If I pop it out of 1st gear as the rpms are falling from 850, they pop right up to 850 and it idles normally. Idles normally in neutral and all other gears. Makes 1st gear creep in the market parking lot a real bitch! This only started recently, and I did search...

So I dug around a bit last night. Here's what I found: My idle speed control solenoid is reading 12.5 ohms at the ECU connector, which is a little bit out of range (manual calls for 10.5 to 12.2 ohms or so), AND my 1st & 2nd switch gives continuity at the wrong positions, namely, the 1st gear position does NOT give continuity like it should, but rather gives continuity in neutral. No continuity for the 1st position sensor in any other gear, only neutral. The 2nd gear position works fine.

The relationship chart in the manual shows the 1st & 2nd switch effecting turbo controls (unlikely active at idle?) and the air pump, but I don't know in what way (typical manual... juuuuust enough info to make you go WHY!!).

So I'm ordering a new 1st & 2nd switch, and will pop that in there when I can. I was wondering a couple things: Does ANYone actually know what this switch really does wrt the ECU? And is that ISC reading too far out of whack?

Thanks for any help, and I WILL post the results of the new switch when it gets in there.

Thanks!!

mad_7tist

resistance readings are temp dependent. if it was hot or cold it may put it just out.

spurvo

Yeah, that actually was my thinking. The engine was still just a bit warm (probably 110F or so), which would raise the resistance. So that's probably ok then.

Just got off the phone with a REALLY busy Ray at Malloy. Have the 1st & 2nd switch on it's way ($27.44 for the switch, a dollar and some for the relevant gasket). So we'll see if this fixes it!

dubulup

1st gear switch...tells AWS not to do it's thing.

I know that's nothing to do with the problem. But how is your AWS? act funny or just cherry?

spurvo

AWS bees a-woikin' fahn ovah heah, boss!

Sorry... I always tap the accel on startup, but have tested the AWs to make sure it's shooting the moon. HATE that rev up...

Plot thickens. I was erroneous in my claims that all other gears are fine. All other gears cause similar condition, that is, you put it in a gear at rest with the clutch in, and the idle dies. IF the lights are on. Or IF the blower is at 3 or 4. Or IF the rear defrost is on. Ooohhhh... E/L sensor, anyone? How do I test that lil' bastid, anyways? Hmmm....

clayne

1st gear switch affects more than AWS.

Anyways, you already diagnosed the problem.

The ISC readings are a symptom, the 1st gear sw is the problem.

FDjunkie

About half way down I wroteup how to test the E/L and the other sensors you're working with.

https://www.rx7club.com/showthread.p...hreadid=303907

dubulup

what page/section?

1QWIK7

iTrader: (33)

i think i have the same problem..today was pretty damn hot, like almost 90 and i just drove the 7 for like 20 min, everything was fine but i guess the outside temp plus the engine temp was too much, it prob killed some sensor and my idle was funky letting off 1st gear.. in neutral, it would be at 1000rpm, but i do my normal driving and it would bog like crazy leaving 1st gear, sounded and felt like i was a beginner 5spd driver, it would bog and jerk..now my water temp at this moment is like 210-215f, i have the fans running at that moment and its 90 degrees outside..i would have to rev like to 2500 for it not to bog..i guess when i do the normal 1500, then let off, the idle was so messed up, it would drop to almost stalling.. it has to be the heat right?

so do you think the extreme total heat just snapped off some sensor to make it this way? cause after startup and during the spring months, (55, 60, 65 degrees etc) the car would act totally normal, only during the hot summer months is this car doing it.. i had the same problem last summer in my talon..

could be the isc?

spurvo

Hey Dubs. I'm looking at page F-196, and it's showing the 1-2 switch (MT) having relations with the Turbo Pre Control, Waste Gate Control, Turbo Control, Charge Control, Charge Releif Control,and Air Pump relay. But it doesn't show the nature of those relations. Interestingly, it DOESN'T show a relationship with the AWS. Most curious....

spurvo

Thiis is the test he's talking about.

"I tested the E/L unit by grounding the TEN connection at the diagnostic connector, and attached a small lamp to the FEN (I think this is right, but don't have my FWM with me right now) and B+ connector. With the ignition key on you can test each E/L input one at a time, plus neutral, clutch, etc. The lamp lights (ECU only supplies 20~30 ma so this has to be a very small lamp, or use your VOM in series) when the ECU responds to each input switch, thereby testing the entire circuit. Check out section F of FWM on Electric Load (E/L) Control System, around F-135 or so I think."

So if I have my DVM connected via the current measuring leads to the B+ (i.e. battery voltage) and the FEN connections on the Diagnostic box, I should read ~ 20-30 ma when turning on any of the relevant control devices for the E/L unit with the ignition on, right?

spurvo

If I'm reading page F-67 correct, it's the MEN connection, not the FEN. Thanks for the tip, I'll check these tonight!

dubulup

sounds right...I don't have the manual in front of me. But if what FDjunkie said is correct, you could measure the amperage.

dubulup

Spurvo - how did the test turn out???

spurvo

Worked late, couldn't get to it! Grrr....

Now the post is moved so it'll NEVER get seen, huh? J/K!

spurvo

OK, here's the skinney so far...

With the engine off, the key turned to the run position, and the TEN connection on the diagnosis box grounded.
I measure no current between the MEN and B+ connections. If I turn on the parking lights, I read 36.3 milliamps between the MEN and B+. Turn the lights off, current stops. Turn on the blower fan to position 1 or 2, no current at the MEN to B+. Blower fan to 3 or 4, and I get 36.0 mA between the MEN and B+. Turn off fan, current stops. Turn on defrost, 36.0 mA results at the MEN to B+. Turn off the defrost, current stops. Turn on fans to low speed (relays 2 and 4 grounded) I get no current at the MEN and B+. Turn fans to medium speed (grounding which ever relay is controlled by the thermoswitch, sorry I don't have my FSM handy) and I get 35.6 mA at the MEN and B+ trerminals. Stops when the fans are turned off.

So the E/L is working correctly, which I suspected as it was modifying the idle at the appropriate times. So I wait for the 1-2 switch, and will probably order a new ISC. Kind of fun to have to rev the engine all the time at rest when driving at night to keep it from dying. Feel like a RACAR!!!one1!

More when I know more...

dubulup

Ouch! 250 bones for that (I heard.)

I think I might be able to find you a used one...(probably not the greatest thing)...but you can use it for a test to see if yours acts different.

pm me...if you want to run the test.

spurvo

Malloy quotes $277.38 for the ISC. Ray said he's been getting a lot of requests for these lately, so he's stocking them. Honestly, I've stopped blanching at anything under $500 or so with this car. Fender for ONLY ~$190? Hah!

Anyway, one thing at a time. 1-2 switch replacement first, then we'll reconsider.

RX7Wishing

i have a ISC ill sell you. 50 bucks plus shipping. works perfect.

dubulup

spurvo - any findings on the 1-2 switch?

I gotta ?uestion about the yellow wire???

it appears to connect to a blue connector and a white connector just inside the firewall, I can't seem to locate this pin outs in the wsm.

any idea what this wire is linked too? has input for?!?

spurvo

Update: (sorry it took so long, I was in Nashville)

So I was a little confused about the operation of the 1-2 switch. I received the new one from Ray at Malloy (only about $30, so it was easy decision) and tested it naturally to see how much better it would be than my old, supposedly bad one. I was WRONG about how it is supposed to operate. In fact, the switch is SUPPOSED to allow continuity across the 1st gear wires (lesee here.. that's the yellow and white wires) in any gear BUT 1st, as well as neutral. Not only do I deduce this from the new switch itself, which exhibits this behavior, but also a closer reading of the manual, which shows there to be battery voltage at pin 2K on the ECU when the car is in 1st (i.e. when the switch has no continuity), and only ~1.0 volt when in any other gear (i.e. when the switch has continuity between the yellow and white wires). Had I read that carefully, I would have seen that the wiring diagram is a little "hazy" here, in that it implies that there would be continuity between the yellow and white only when you are actually in first, rather than the other way around.

Following the logic, the switch provides continuity between the red and blue wires when the switch is fully pushed in, that is, when you engage second gear. From the ECU test procedure, there should be ~1.0 volt at pin 2L when in second gear (i.e. when there is continuity between the red and blue wires), and battery voltage when in any other gear or neutral (i.e. no continuity).

So my 1-2 swicth is not the problem.

More: I tested the ISC resistance on dead cold engine. 11.6 ohms, right in the middle of spec. Might be ok, then. BTW, the way I'm testing this is to connect the voltmeter on resistance setting between the blue with green stripe wire, pin 4Q, on the top connector for the ECU, and the black with white stripe, pin 1B, on the bottom connector for the ECU. This bridges the common ECU connection for solenoids (#16 in the round circle on page B1a of the wiring sheet) and the appropriate pin for the ISC control. Quite the contortion act to get down in there with a light, the book, and the ohmeter!

I tested the AWS solenoid as well (it's right there), and it read 12.6 ohms (brown with yellow stripe, pin 4P, top connector, opposite side from the above ISC wire). Out of spec by around 10%. Hmmmm... so I went and disconnected it at the solenoid to see if this was the problem. Nope, I still get a dying idle with an electrical load when I put the car into gear. Sigh... kind of nice that the rpms don't shoot for the moon in the morning, though. Seems like the driveability is a little better too? Hmmmm some more!

So I'm back to square one. Maybe air pump circuit related? The relationship chart shows the 1-2 switch effecting the air pump somehow (but how exactly, is of COURSE not revealed), but then am I sure it's 1-2 related, and not neutral switch related (dies when taken out of neutral)? I must admit I've not tried checking the idle speed with the TEN connection grounded to see if it's correct, so that's the next easy thing to check (like maybe the ISC is able to control idle, but only barely, and the E/L shoves it out of its range of adjustability? Hmmmm....).

I can't believe you've read this far!

Dubs, which yellow wire where, exactly? blue and whire connectors inside the firewall are ECU connections, yes? Although with the fan recall wiring update, I think there's an extra chunk of harness involved that's not in the wsm, which may be your confusion... if it's the same yellow wire listed above, then there's your answer! 1-2 switch...

mad_7tist

have you tried adjusting the air bleed socket?

spurvo

Yeah, I did that. idle went up a little, down a little as I move the socket in and out with the screwdriver. Just like it's supposed to, right? And grounding the TEN connector with the engine running makes the idle go up just a bit, to say 800 rpm (lights and loads off). Anyway, not sure what the problem is STILL! It's perfectly driveable, except in the dark you gotta play with the throttle more. Sigh...

dubulup

I had too

Thanks bud, you did answer my question. I haven't had the chance to test yet...

I'm wiring an E6X (haltech) and the "how to" for tranny harness, just says cut these wires out of these connectors.

I've got the (tranny) harness fabbed, but I wanted to know what I was cutting and why. The Yellow wire from the 1-2 switch is cut and is the only one that isn't connected to anything.

spurvo

Cool! Minor update: Now the idle wants to live above 1000 rpm unless I wilggle the shifter a bit. Went under there and tested the neutral switch. Most inconsistent thing I've run across! Put it in neutral, the switch has continuity. Put it in gear, the switch loses continuity. Put it back in neutral, the switch remains discontinuous (neat word, huh?), I wiggle the connections I'm using to test, then there is continuity. Oh. Sticky switch?

Ordering new neutral switch after I write. Further, the 1-2 switch is not all peachy as well, in that it behaves correctly in 1st and neutral, but putting it in 2nd only gives a blip of continuity, not continuous. So that needs replacing like I thought. Too damn bad the switches are at the TOP of the damn tranny. I forsee a difficult weekend ahead... more when I know it!