1coolmazda

iTrader: (7)

Hello,
I have a 1985 GSL-SE with the 13b I just finished working on and now I am driving it. But when the car is just standing still in neutral and not in gear the idle is fine but as soon as you put it in gear and keep the clutch in the idle goes up and down. Its alright when you drive it and when you let the clutch out, just when you are sitting still with the clutch in and have it in gear the idle goes up and down.

thanks

mazdaverx713b

iTrader: (91)

first thing for that issue is to check for vacuum leaks and adjust the throttle position sensor. i'm sure there is a writeup on it here on the forum. you'll need to make a special tester light for for the procedeure. i made one and can post a pic if need be. where in OH are you located?

Rx-7Doctor

iTrader: (13)

What repairs did you just do?

1coolmazda

iTrader: (7)

I bought the car for 200 hundred dollars all it needed was a fuel pump but I put a used gas tank that was super clean in side and out and replaced the belts and did brakes on the car. Its only got 103,000 miles on the factory rotary engine. Yes can you post a picture of the tester light. Columbus, Ohio

mazdaverx713b

iTrader: (91)

i'll post the pics this morning. really simple to make. i'll see if i can find a writeup on testing the tps..

1coolmazda

iTrader: (7)

Hello,
On my 1985 GSL-SE RX7 with the 13b. The car only has 104000 miles on the rotary engine. When you start the car it goes to 4000 rpm then when you kick it down it starts to surge real bad. So I looked on here and I checked the vent solenoid valve and the vacuum solenoid valve and both are good. I checked the bac valve and cleaned it. Now I took the throttle body apart and cleaned it out. I will put it back on tomorrow. I also replaced the TPS with a good one and I adjusted it. That still did not work. And I looked for vac leaks and I can`t find any at all. What else could mess with the idle its fine when you drive it down the road. Its when its idling is when it will not run right.

Thanks

LongDuck

Search on "SE Idle Surge" - you'll find thousands of threads on it.

I'll be a Super Forum Member and go you one further; keep reading.

The SE's have an aluminum throttle body. They also have steel rods that connect the throttle linkages to the butterfly valves in the throttle body. When you run steel rods through aluminum housings, you get something called 'spalling' of the metals. This is micro-corrosion which results in microscopit grit developing where the two dissimilar metals touch. This grit increases the friction of the parts moving against one another. Re-read that last paragraph, and then prepare yourself to take in the Truth.

(ready?)

Okay, so the EFI SE's are complicated beasts, right? If you put 104k miles on that car, you probably already know this, but the fact that you're asking the above question is a testament that you have not fully mastered the -SE. Your SE Fu is weak.

The Throttle Body, with excess friction on those throttle rods, combined with tight tolerances on cold start causes the throttle rods to lag slightly to intake air volume coming into the engine. As the engine RPM increases due to more air coming in, the Bypass Air Control Valve tries to shut down excess incoming airflow, along with the Secondary Throttle Butterfly valves closing to try and 'choke' the engine. As the RPM begins to drop, the throttle rods stick, the BACV allows more air in, and the Secondary Throttle tries to open the Butteerfly valves to unchoke the engine - the RPM goes up. As the RPM goes up, the BACV cuts off bypass air to drop the RPM, and the Secondary Throttle Butterfly valves close, dropping the RPM. As the RPM begins to drop, the throttle rods stick, the BACV allows more air in, and the Secondary Throttle tries to open the Butteerfly valves to unchoke the engine - the RPM goes up. As the RPM goes up, the BACV cuts off bypass air to drop the RPM, and the Secondary Throttle Butterfly valves close, dropping the RPM.

This is called 'surging'. Ahhhh-soooo... I can hear you from across the internet; the sound of one hand clapping.

Fix it by removing the Throttle Body, turning it 90 degrees so the throttle rods face up and down, and oil it with some kind of lubricant - a light oil, not something heavy. Hell, maybe silicone oil if you have any around. I use 3-in-1, but never use WD40... never. Let it soak in for 5 minutes, and then turn the Throttle Body 90 degrees the other way (so you can let the oil run down the rods on the other side), and do the same.

Reinstall. Start the car. Gasp in wonder and amazement.

You're welcome.

1coolmazda

iTrader: (7)

Well I put my throttle body back on and it still was surging so with the car running I unplugged the vent solenoid valve and the vacuum solenoid valve and it cleared right out. But when I checked them to see if they work, I took them off the car and applied voltage to them and the valve would open then shut with no voltage applied. I don`t know if they are bad. But I have been driving the car with them unplugged and the runs great no problems.

74RX4

iTrader: (10)

Vent should be open when 12v is connected. Vacuum should be closed when 12v is connected. 85 FSM chapter 4B, page 52.

These links might help also.

http://fm.no-ip.com/gslseidle.html
http://www.jimrothe.com/mazda/84_tra...ual/index.html

1coolmazda

iTrader: (7)

Last night I left them on the car and did the voltage check you can hear the valve open and close. But like it said on the vent solenoid valve with no power on it I could not blow air through it. but what is weird with voltage on it I heard the valve open but I could not get air to go through the line I know there is a canister that is under the intake manifold that has a line that goes to the vent solenoid valve I think there is something wrong with that canister.