Ok the car is a 1989 RX7 N/A all stock 186K miles.
My issue: car starts cold start procedure 3000 rpm for 5-10 sec and drops to 1500. Pretty normal right? Yup.
But after ive drove the car no matter how long when I put it in park rpm shoots to 1500 whereas it idles at 750 in drive. I had the intake manifold off so I'm assuming that caused the issue. Does this sound like a thermowax valve to u guys? Stuck maybe? If air got in the coolant system would it cause the thermowax to act a fool?
Thanks for any input guys.

1badvert

 

Sounds to me like the throttle linkage is getting bound up somewhere. Try operating the throttle with the engine off to see if it is always returning to where it should. Sometimes the secondary throttles can get stuck.

 

Would the nut on the secondary throttle cable getting moved to the wrong place cause this?
Because the throttle always goes back where it should
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There are 2 cables. One is for the pedal, the other is for the cruise control. If there is not enough slack on either, then sure it's possible.

 

My cruise control doesn't work anyway. I'll take it off and see

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This is an auto?

 

Yes its an automatic.

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The idle should be a little higher in park then when in gear but 1500 appears a bit high.

 

It wasn't cruise control. It literally goes from 1300 to 1800 RPM for as long as it can. Never stops. Hmmmmpsh hmmmmmpsh hmmmpsh. I haven't touched any of the idle screws, all vacuum lines have been checked. No vacuum leak because it idles perfectly in drive. Doesnt this sound like a stuck thermowax? How can I tell if it is the thermowax? Better yet can I just remove it?

1badvert

 

W/the engine idling press upwards on the throttle linkage at the front of the car and see if the idle speed drops or not.

 

The long one that has the TPS on it? If so it does yes

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so its idles up then drops then idles up again? sounds kinda like you are trying to initiate a drag race?

if thats the case its guaranteed to be a vacuum leak.

the shooting up to 1500 rpm is probably because your thermowax valve is stuck causing it to stay in fast idle. if you look in the manual theres a section on how to adjust it if its high or low. try adjusting it when hot and see if the idle drops. if it does, your coolant passageways are probably blocked. i had that happen.

the other thing it might be is just a poorly adjusted idle stop screw. that just hold the throttle plate open a little to idle. check out FC3Spro.com under the TPS adjustment section. at the very bottom theres a little picture of how to locate and adjust the idle stop screw.

 

It is just staying in fast idle all the time. No vacuum leaks.

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And the car was in park while you did this?

 

Yes.

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If the car is idling normally w/the car in drive and you place the car in park the idle jumps to at least 1500 rpm. Correct? And if so, then if you place the car back to drive does the rpm drop to a normal level? And if so, then does the idle speed go back to over 1500 rpm if the car was once again placed in park? Meaning does the car basically idle properly when in drive, but idles overly high when in park like clockwork or are there times when the engine idles perfectly when in park.

 

That is exactly what the car is doing. Spot on

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A little update. Still doing the same thing but if I unplug the TPS the idle drops to 1200 and sits there and the HOLD light flashes and the CEL comes on. From everything I've heard the fast idle cam is stuck. And I don't have the first clue on how to test the TPS. I do have a multimeter
I also blew out the thermowax with an air compressor. It was not clogged

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The TPS has a Green/Red wire. Should measure close to 1 volt w/key to on and the engine as hot as it can possibly get (not letting the engine completely warm up will lead to a incorrect voltage reading). Use the TPS adjustment screw to dial in the proper voltage. Screw is about an inch long encased in a spring.

And try what was suggested in post #10. Linkage is linkage as there is no short or long to it.

 

What do I set the multimeter to and where do I ground it? I already did the thing in post 10 and it didn't drop the idle it just evened it out

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DC voltage. Meter ground goes to the battery negative terminal.

 

On DCV it says 1000, 200, 20, 2000m and 200m. Which one? Sorry I am retarded at this stuff. And you test on the TPS connector right?

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20 should do. Remember, engine as hot as it can possibly get, which usually means a 20 minute drive. Idling the car for a few minutes is not sufficient.

 

Thank you for all the help

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