How would I go about doing this? I've been driving around for a while now with no cold idle whatsoever, and it's getting annoying. Basically the idle valve is permanently closed.

Steps I've taken:

1. I am getting no signal whatsoever to the IAC. I get about 2.5 volts on both leads at all times. (to ground)

2. I have gone over my wiring at least 50 times.

3. Obviously I've replaced the transistor like the FAQ says. Only concern is that I used a 688 instead of a 689, which seems to be the more common choice. I've resoldered in 3 different 688's. (the minimum quantity from digikey).

4. I'm worried now that I've resoldered the thing 3 times now that the connections are permanently fucked and there's nothing that can be done now except rebuild the entire ECU.

5. My board is very cleanly done and there are no other problems. I've done every diagnostic test I can think of and the car runs fairly well overall. I really don't want to waste my entire ecu because of this problem.

I'm running fuel and spark on a gslse with a harness from rs autosport (which is fairly idiot proof, and a very nice convenience). The intake and IAC are from an S4 2nd gen. It's NA not turbo

I'd like to get my car dyno tuned but I can't until I get this idle thing sorted out.

I hate making posts like this, but this is basically the only resource I can find where people would be familiar with the specifics of the case and would know the actual IAC and mods that I've done to the MS. I know enough to be dangerous as the saying goes I guess, and this subforum is the best resource in my opinion on the entire RX7Club. I know this isn't a "get my car running, major problems" type of issue but it's been bugging me for long enough that I decided to post it up.

 

So you basically duplicated the same circuit that was on the v2.2 board, with a 1n4001 diode, the ztx688, but you used a 300-500 ohm resistor instead of 1k right?


If not, I'd suspect that your BAC is stuck or bad in some way.

Ken

 

hmmm weird ... this is on a 2.2 board?
where are you grabbing power from for the bac?

 

This is on a v3 board with a MS1 chip, replaced resistor with the diode in place, the 300 ohm resistor and a 688 transistor. Sorry for the misunderstanding. Muythaibxr I've tested the BAC and it's good. But I'm not even getting any signal to it in the first place. I'm pretty sure it's something wrong on my board. But I'm not even sure where to look for problems.

The car itself runs great over all, so it can't be something too terrible.

 

basically you have to duplicate the 2.2 board circuit... a 1n4001 diode, ztx688 or 689 and a 300-500 ohm resistor.

You have to make sure you remove all of the circuit that was previously there too.