emrayray

I am new to rotary engines. My car is idling high and I am stumped. The throttle sensor, bac system and atmospheric pressure all test good. I can not find any vacuum leaks. When I bought this I had to buy a few wrecking yard parts, one being the mass air sensor. could that cause the issue? If anyone has any ideas I would be forever in your debt. Thanks for your time.

RotaryRocket88

iTrader: (7)

NA or turbo?

If NA, you'll have an idle adjustment screw on the top of the TB. If you jump the initial set coupler (green, 2-wire plug near the leading coil), you can raise/lower the idle speed to a certain extent.

An overly tight throttle cable can also force the engine to idle high, so check that there is a bit of slack here.

A third option is the thermowax cam is not disengaging once the engine warms up, which would cause it to idle high all the time (around 1500 RPM). The thermowax is on the back side of the TB, and it has a little piston that moves a cam, which adjust the throttle plates.

A fourth option is the throttle stop has been played with. This would most likely appear as a normal 1500 RPM cold idle, which then only drops slightly once warm. The throttle stop determines the final throttle position as long as the thermowax cam disengages.

emrayray

I am sorry, it is non-turbo. when it is cold it runs at 1500 rpm but once it warms up it is about 2100 rpm. I idle screw on top of the throttle body is turned all the way and the stop screw on the throttle cam is backed off where it is not touching. Also there is slack in the throttle cable to it is not too tight. How do I adjust the idle by jumping the plug?

RotaryRocket88

iTrader: (7)

Idle speed increases when warm?! That shouldn't be possible. Unplug the BAC, and see what happens. You could also unplug the AWS solenoid, which is the gold colored solenoid near the oil filter. It has an air line going into the side of the plenum, but it's only supposed to be active for the first ~17 seconds after startup.

emrayray

When I unplug the BAC when it is warm the idle drops a a little, maybe a few hundred RPM. I will try unplugging the aws and se what it does. Thanks and I will post in a little bit to let you know it if helped.

emrayray

I did not help. It idles at 1600 on start up the creeps to 1800 then once it warms up and the bac kicks in ti jumps to 2100. How much adjustment can I get jumping the plug and doing whatever it is that I need to do to adjust it?

satch

iTrader: (1)

With the car idling, press upwards on the throttle linkage at the front of the throttle body and see if the idle lowers. Also, does the car have cruise control as if it does that cable could cause for a higher than normal idle speed.

emrayray

The cruise control cable is not hooked up and when I push up on the throttle it does not change.

satch

iTrader: (1)

W/the BAC unplugged what is the lowest the idle will drop to?

emrayray

1900 rpm is the lowest warmed up with the BAC unplugged.

emrayray

I am such a noob, it is a 87 not a 88. Sorry. And it is a GXL if that makes a difference.

satch

iTrader: (1)

You might want to take a wire w/battery voltage and touch it to one of the BAC terminals that are part of the BAC and not the harness itself and then apply a ground wire to the other BAC terminal being careful not to touch both wires to the same terminal and do this briefly as hold the voltage wire to a terminal and touch the ground to the other terminal long enough to make the BAC click. Do this a series of times as your BAC might be stuck open somewhat and your goal is to unfreeze a possibly stuck open BAC solenoid.

emrayray

The car did come with a spare one in one of the boxes. Maybe I should just swap them. The extra one did test good with my meter.

satch

iTrader: (1)

If a BAC ohms out according to spec doesn't mean it can't be stuck. And which throttle stop screw are you referring to. Is it the one behind the throttle body closer to the driver's side?

emrayray

I just checked the BAC and when I put a vacuum to the air intake side it is not leaking. and the idle screw I was talking about is the one on the forward side of the throttle body. The dashpot on the back side of the throttle is backed off so it is not touching. Am I missing an adjustment screw? The car was parked for 7 yrs. I cleaned the fuel tank and put a new fuel pump/sock in and new filters also. It came with a box of spare parts when they bought it.[My nephew] But they said it ran fine. I am guessing that since he was 18 and it was his first car that he did not know that it was idling high. Since it came with a spare BAC and other misc parts I am assuming that who they bought if from was having the same issue and gave up and sold it.

satch

iTrader: (1)

That screw should be tightened fully and the lever that should rest upon it is for the "secondary throttle plates" so if it is fully screwed down and the lever is not touching it that would cause the secondary plate to open up some and thus a higher idle would ensue.

And this would explain why the RPM increases as the car warms up as the secondary plates are to be held closed while the engine is cold as governed by the double throttle diaphragm and as the engine warmes up the diaphragm allows the secondary plates to open more which would increase the rpm.

emrayray

The screw I am talking about threads through the throttle body, not the screw on the arm with a spring on it.

satch

iTrader: (1)

Well that would be pretty much the center of the throttle body and not the front of it but it's not important.

Are you sure the timing of the CAS is correct. You can open up the top of the CAS to take a peek and it should look like the pic in the link provided.

Post #3. https://www.rx7club.com/2nd-generation-specific-1986-1992-17/new-13b-first-start-loud-boom-timing-question-978911/

emrayray

Thank you , I will look tomorrow and see.

emrayray

The CAS looks right. Could a leaking egr valve cause this?

satch

iTrader: (1)

If you spray some carburetor cleaner around the EGR and other places as well while idling and if there is a vacuum leak the idle will steady out some. And take off the intake duct to the throttle body and look at how much the primary throttle plate is open as it should be all but closed to where the opening is a fingernail thickness at best. And even though the cable to the cruise control is not hooked up make sure what it would be connected to is in the proper position.

emrayray

I was wondering of the egr was stuck open if it would cause this. And yes the throttle plate is closed all the way. I was told that a bad Mass sensor could cause this. I did put a wrecking yard one in. I can run down and get another one for $45 at upull it. I think I might do that to rule that out. I sprayed starter fluid all around the intake, egr valve, and all the vacuum hoses without any idle change.

satch

iTrader: (1)

If you jumper the fuel check connector and disconnect the AFM you should be able to start the car. You'll then be able to tell by the idle speed if it was caused by the AFM.

emrayray

I replaced the air flow meter and it runs the same. It seems to run ok other than the high idle. I drive good..

satch

iTrader: (1)

When it comes to the screw on the front of the throttle body that relates to the secondary plates is the screw tightened all the way down and is the lever firmly touching it. And about what length is this screw?