Hey guys,

I'm tired of my car revving to 3000 RPM everytime its cold and I start it, so I want to remove the AWS. Every picture that I've found on here of where it is located, does not match my setup. So, I have attached a picture of mine, hoping you all can help me out. Is 1. (that is circled in the first picture) the AWS?

As well, my tachometer stopped working last fall, and I'd like to get it working again for this summer. I know that the Tach runs off of the trailing coil, and I've checked the connection many times. Again I've attached a picture, could someone please identify where I should check the connection? Is 1. or 2. the trailing coil?

I haven't changed the plugs yet, so I will do that next, if nothing works here.

Thanks in advance,

Dan

 

The trailing coils are number 2 on your photo. Chances are if the tach is not working for some reason the trailing coils aren't fireing.

Why would you remove any of your AWS if you don't want to hold the car at 3000 RPM?? Removing this stuff will make this worse. If the car is stalling out at cold idle then chances are it is too lean. What modifications have been made to the car?

 

The car doesnt stall out when its at idle, I just dont like the excessive noise for the first 3 minutes when I start the car up.

Engines been ported and rebuilt, it's turbo'd, FMIC, etc. Nothing that I know of has been modified on the TB, but the guy who did my work moved away, and was kind of sketchy (after 2 years of being solid).

 

Ahh, ic ic. Well removing the AWS will risk it stalling under cold idle, however, you should be looking at removing the BAC valve, the Air Bypass solinoid, and the air control valve (I think i have all the names right). In one of your pictures you have the thermowax pellet circled. That only raises the idle by a few hundred RPM and should be left on IMO espicially if you are going to remove everything else.

Just as a note, I just finished modifying my Megasquirt so that I can control the BAC valve and make it operate like the stock AWS. I found myself haveing to hold the car at about 3000rpm with my foot on cold mornings. I would leave everything on if it's still working properly.

 

Actually, the circled device in the lefthand photo is the dashpot which keeps the throttle plates from snapping shut. It helps prevent backfiring. The thermowax pellet isn't in view, but it has coolant lines which make it easy to spot.

Anyway, you will need to remove both the BAC and AWS to keep the car from reving up to ~3k on startup. If the thermowax is kept, you'll only be at about 1500rpm on a cold start instead. Besides hard cold starting, removal of the BAC will mean you will have no idle correction when electrical loads are switched on or when the power steering is active.

 

Well right now my CD player doesnt even work, and the power steering was removed also.

Is removing the BAC and AWS wise? Also, is the AWS even in the picture I took?


Oh, and I'm pretty sure now that Number 1. on the second picture is the trailing coil pack... its got T's all over it, and 2. has L's.

 

On your 1986 car it's called by its proper name, not AWS. It is called the Air Bypass Solenoid and located on the left side of the engine towards the rear of the engine.

There's pictures of it in the free online FSM. I suggest downloading it. It has pictures.

 

well... i dont know anything about the AWS, but i do know when i bought my GXL the tac wasnt working and it was because my trailing coil was bad and when i replaced it i had no problem with the tack whatsoever...

 

Right on, I will definately look into that. Did you buy the trailing coil new? Or off of someone on this website?

 

YES!! You are 100% right!! I have no idea where I got the idea that 2 was trailing. For some reason I can't edit my former post to correct the misinformation. If a Mod wants to change that they can.

 

Alright, so I just called the Mazda dealership here in Winnipeg to order a Trailing Coil Pack... they told me there are only 2 available in North America (on their computers at least), and get this. They are $1062.00 EACH. The guy even double checked that, and its no typo.

So, who's got one they want to sell me

Also... are the trailing coil's the same for all years of a Second Gen? My car is an S4 but its got a Jspec S5 in it...

 

They are all the same and yes the trailing coil packs are insanely expensive!!!

I would start by troubleshooting the coil pack. First, make sure it actually isn't fireing the spark plugs. To do this just take the wires off the 2 trailing plugs, get some other plugs and put them in, and ground them to the rotor housing and start the car. If there is spark then the tach is a different problem.

If you have no spark, next, with the key in the on position, check that there is approx 12V on the black/yellow wire. If that checks out then you'll need to look at the wireing diagram and check continuity on the other wires that go from the ECU to the coil. The wire diagram can be found in the FAQ.

If you have no spark, 12V on the b/y wire, and the other wires check out then the coil is probably bad. Note, you will have a bit of a challenge since you have an S4/S5 hybrid when it comes to chaseing the wires.

 

I just zip tied the fast idle cam up out of contact on mine since my T-wax was bad and holding my idle speed up all the time.

 

Sounds sweet.... what is that, and how did you do that??

 

That's not what you are trying to do. The fast idle cam only increases idle by a couple hundred RPM. To get the car not to shoot up to 3k you need to disconnect the valves discussed earlier in the thread.

 

He initially asked about the AWS.

The *AWS* rpm is a product of the Air Bypass Solenoid opening for seventeen seconds plus the BAC's output for seventeen seconds. Eliminate the Air Bypass Solenoid and the cold start rpm will go down a bit to something like 2300rpms for seventeen seconds. After that the higher than normal idle speed (750-800 rpm) is controlled by the fast idle cam riding on the water thermowax's piston. A non fucked up throttle assy will control that rpm to approx 1100-1300rpm and gradually drop down to a idle of 750 rpm. That's if the throttle body hasn't been fucked to death already.

The idle mixture is a product of the water thermosensor on the back of the water pump housing plus the afm output. Talking fuel at idle.

As for the Trail coil assy not working (tach), seems to me you'd ring out the wiring b/t it and the ECU first and compare the output/inputs of it with the FSM figures. Plus the Trail assy HAS to be bolted to the chassis with at least one of the three bolts.

 

Perhaps I have a different problem then, because if I start it up (from cold), and dont touch the gas, I can sometimes get it to idle normally, and warm up. As soon as I touch the gas, it shoots up to 3000 RPM, and stays there until the temp. gauge starts to move, and then it slowly drops down to like 900 (ish). This normally takes a couple of minutes.

I attached another photo of the engine, can anyone see what my problem is?

 

You did not say what car/engine you have. Your profile says 86, which means a non turbo. The last picture shows a turbo engine. So the Air Bypass Soenoid is located on top of that engines intake manifold but won't work at all if you didn't extend the original wires from the stock non turbo location on the left of the engine.

Your problem sounds like *somethings* not quite right with the water thermowax assy and the linkage to it.

The green check valve in the picture seems routed wrong and the BAC valve does not look like a series four turbo BAC. Plus the large red hose does not look right. Probably because the BAC isn't the right one.

It might even be related to the intercooling piping and the aftermarket BOV. No way to tell from here.

 

I see, well the guy who put the whole thing together seemed to be a bit of a hack, and he moved away, and I havent been able to contact him in over a year.

Let me know if there are more pictures I can take that will help diagnose this problem.

To my knowledge its an S4 NA Car, with an S5 91 TII Motor.

 

Alright, regarding the Tach, I put in all new spark plugs today, and I wasn't getting any spark from the trailing plugs. I don't have a voltmeter, but I do have a little light tester. So I probed the leading coil (a single female end of what looks to be a bullet connector) and I got the light to light up. I probed the same connector on the trailing, and I got nothing.

I have come to the conclusion that the trailing coil pack is shot. Is this accurate??

Also, the car has been driving fine this whole time without the Tach, is this normal for not having trailing plugs working??? (If this is the case)

 

does the tach work when starting the car and then once you hit 1000 rpms it cuts out?

if so it could be due to slow cranking speed. I am not sure what the magic number the computer looks for but if it's too low it will shut off the trailing coil. totally pointless if you ask me

 

No sir, the tach does not work ever.

Also, should the trailing coils fire all the time? or only at certain times..?

 

well to isolate the trailing coil failure from a tach failure find somebody to help you and pull one of the wires going to the spark plugs from the trailing coil and hold it on there with a gap and have the assistant start the car. If you don't get any spark then double check your wiring connections on the trailing coil and try again. if still nothing your trailing coil is shot. try and find a junkyard car to replace it.