I've been researching some *quirks* with my FD, one of them being this "hunting idle"--when in 1st or Reverse gear, the RPMs fluctuate between 1100-1400 RPMs when idle. I've seen some suggestions on replacing the LIM, adjusting the throttle, etc.

This morning, I took it to a Tuning shop, and we pulled the rubber intercooler hose (leading into the IC) to find that there is a coat of oil along the hose walls. He diagnosed my idling problems as a result of faulty turbo oil seals, and a rebuild/new set of turbos is in order. What do you guys think of this? I thought I'd get some opinions before I spend money on a rebuild or new set of turbos.

Thanks in advance.

 

I dont think leaky turbo oil seals are going to make your idle hunt. It is unlikely any of that oil will make it into your engine at idle so you have 2 seperate problems.

What engine management do you have? Have you adjusted your air bleed on the throttle body? Have you checked for vacuum leaks?

 

So the oil in the IC hose is in itself a separate problem and I will need my turbos rebuilt--is that correct?

In regards to your other questions--I have the stock ECU, have not adjusted air bleed on throttle body, and I don't know how to check for vacuum leaks. I've been searching under terms like "check vacuum hoses," and I haven't come across any sort of how-to on how to properly check them. Suggestions?

 

It's most likely not a problem at all. A coating of oil in the IC tubes is normal. There are usually a few symtoms of turbos failing:

* lower than normal boost (with all turbo control components functioning properly)
* car smokes
* oil pooling in the IC without driving the car really hard (like on a road course)

I would suggest you leave the turbos alone right now and start here:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/fixed-my-idle-problems-backfiring-bucking-more-170731/

 

Mahjik, thanks for the response regarding the turbos and for posting the link. I'll check it out. Much appreciated!

 

I agree w/ Mahjik. I, too, have a thin coating of oil in the IC pipes...it's pretty normal unless you start to see the symptoms that Mahjik listed.

Good luck.

 

I'm afraid you've experienced how regular "tuning" shops are hopelessly ignorant of RX-7s. It's almost amusing. Good thing you didn't spend much money on them.

Dave

 

check your clutch switch, there are 2 one for the starter one for the trans. also chek your tps. what does it idle at when hot in neutral? may need a minimum air adjustment under the throttle body

 

for leaks, look for broken vacuum hoses.

 

I'm going to say TPS adjustment on this one. The stock ECU will compensate for an air/vacuum leak and will not cause the idle to fluctuate.

 

I've followed the TPS adjustment instructions and I've set my voltages to 1.00 and 5.00 for the 2nd wire, and .48 and 4.32 for the bottom wire. This helped some with the unsteady RPM--it fluctuates within a smaller range (200 RPM as opposed to 300-400 RPM before the adjustment). Specifically, the idle now fluctuates between approximately 1000-1200 RPM when in gear.

The above results were taken from just a small drive around the neighborhood; I'll be able to better gauge the results when I drive it on extended runs this weekend.



I've also lost a 7mm socket within the recesses of the engine bay in the process.

 

It's also a good idea to clean the ISC - a sticking ISC will cause all kinds of idle wackiness, including surging idle. VERY common problem on pretty much any car. I fixed a surging idle on a Volvo once by cleaning it's idle control valve.

That tuning shop should be shot for that diagnosis, BTW. But, that's the trend - people look at big, complicated things instead of focusing on the simple things that every good mechanic should know. You gotta learn the fundamentals.

Dale

 

Thanks for the info, Dale. I'll take a look at the condition of my ISC tonight. Do you recommend any specific type of cleaning agent?

 

I followed everyone's advice above with my hunting idle issue and even though it cleaned some things up, it was still not steady. Then I switched to a PowerFC and all my idle issues were resolved...

For you I would say that since it is when you are in gear it would be a clutch switch issue. Because you cannot be in gear and idling without the clutch engaged...

 

I used brake/carb cleaner when I cleaned my ISC...and then lubed it with some aeresol lubricant I have around..