Coolant Seals
 

Had a previous problem with idle hunting. Unplugged the air control valve and it idled normal for about 5 minutes. Was also in process of flushing coolant and car started to idle hunt. I let it run for about 10 minutes hoping to burp the system but started to see the constant little bubbles. From my understanding this is a sign of a blown coolant seal. Car has no white smoke coming out of the exhaust only the constant bubbles and strange idle. I shut the car off when it got about to 82c. Any ideas? Coolant also looked darker.


https://cimg9.ibsrv.net/gimg/www.rx7...3d3143d5d7.jpg

Doesn’t appear to be coolant seal related. I think what you’re seeing is just turbulence from the water pump. The loping idle is probably a separate issue.
The IAC will get dirty over time but is easy to remove and clean up with carb cleaner. Not sure it will cure the idle issue but can’t hurt.

thanks for the positive feedback. I will clean the IAC. After the funnel emptied back into the rad there was some residue left in funnel. Looked like a thin film of dirt.

https://cimg9.ibsrv.net/gimg/www.rx7...6df665cb29.png


When you changed coolant did you drain the block? There is a separate drain for that which is sometimes overlooked. If you didn’t it may just be some gunk from old coolant that was stranded in the engine.

Re: the loping idle my first suspect is usually a vacuum leak.

Seeing some dirt in the funnel is normal. There ends up being crap in the cooling system over time.

Dale

I drained the coolant from the block as well. I pulled the UIM today and cleaned out the IAC. Problem still persists. If I do start the car with the IAC unplugged it seems to run normal for 3-5 minutes. After that it goes back to loping. I swapped out a bunch of vacuum lines today but no luck. I also tried to adjust the cruise and throttle cable with no luck as well. I’m headed out of town again tomorrow so will have some time to do some research before I get back after it.

I tried to burp the system again today and it didn’t look as bad so I feel better not thinking I may had blown a seal. That and I still have zero smoke out of the exhaust.

Sounds like you have a vacuum leak somewhere. If you are running the stock sequential turbo set up like I am I would start by checking each of your vacuum lines, your check valves, that your pressure/vacuum tanks are not leaking and especially the line to the map sensor. If that doesn't work you might need to start checking each of the solenoids individually. When I went through the entire rats nest I could not believe how well my car ran and how well the twin turbos worked afterwards. I realized this is how it was supposed to run normally, but as these cars age there is a lot of little things that can begin to fail. This is why so many people simplify the vacuum system or go single turbo. Personally, I like the sequential set-up and will probably upgrade the the BNR twins soon.

So for what is worth... When I had trouble with my idle, I was getting internment idle hunting, high idle (like 2800 - 3300 rpm) and then other times it would just work and idle normally. Long story short, the throttle cable was just a smidge too tight. I only discovered this after cleaning the IAC, checking voltages, checking for vacuum leaks, replacing gaskets. Anyways, don't forget to just reach over and verify that the throttle cable isn't sticking.

If it’s not a vacuum leak from a hose or connection consider checking gaskets...TB or at the UIM/LIM.

I was fiddling around with the throttle cable adjustment but either had idle surging or extremely high idle, no in between. UIM gasket was recently changed and I flipped it twice since I was still getting the same outcome. I am in need of a retune so I'm sure the shop will find out that the problem was something small that I have overlooked. :pat: Thanks for all the suggestions. Whenever I get the car back I will post the solution.

Update on the bouncing idle. I left the country for an extended amount of time and dropped the car off with Banzai. Surging idle found to be caused by the idle speed control. Since the AC was removed from the car the ISC was disabled. Wanted to post in case someone runs into the same issue.