So i'm driving the other day and come to a stoplight when the engine in my '85 gslse starts bouncing between 1500 and 3000rpm, didn't stop until I turned the car off and on. Anybody know why?

 

Do a thread search, this is a common problem with the se and happens to everyone that owns one at one time or another.

 

I'll be nice and answer. You could have a couple things wrong. 1. you could be carbon locked. 2. you could have blown an apex seal. My suggestion would be to pull the plusg and see if the rotors are still creating compression. This might help you diagnose the problem.

 

Well, the above is true, but since its an -SE, you can add about 4 things to that list. You need to check the TPS, AFM, ECU, and there is the possibility that there is other things wrong with the FI system. It could be any number of things. My 88 FI engine in my car does the same thing, but I think its because of an injector. The rear rotor isn't running and I'm getting a LOT of gas out the tailpipe. I'm guessing an injector is leaking, but not too sure and not willing to mess around with it. I'm just converting it to carb.

 

My bet is that z-beater is wrong. Carbon and apex seal problems do not tend to cause surging like that.

Go into the FAQ, there's an awesome sectionthere about GSL-SE idle problems that should help you immensely. It's under the question "Q. My GSL-SE has idle and surging problems, how can I fix it?"

This is what the FAQ is for. Frequently Asked Questions. Start there.

Jon

 

The way you described it there was a problem with the idle at a stop light. In the past for me if I have ever had a problem "all of a sudden" meaning that there was no pre-cursor problem then it had been carbon lock. This has happened to me two times. One while apporaching a stop light, and taking a corner. The latest one which I am still battling. And yes surging did occur on my first carbon lock. Well that is until it flooded.

Good luck!

 

If he had carbon lock, his engine would be locked tighter then ****, and not running.

 

Ding Ding!

We have a winner!

Vipernicus is right, consult the FAQ and your problems will most likely be solved.

 

Most likely some differences here, but I'll throw it out there anyway.

With my '83 maxima I had the exact same issue after washing the engine bay. Tracked it down to water in the connection to the TPS.

So, based on that I'm putting my money on a Throttle Position Sensor issue.....

 

Then why did mine run rough? No TPS adjustment at all. Just a few to clean her out.

 

Run a search on 'SE Surging' and you'll have an entire tutorial on how to fix this. It has to do with a feedback loop that's created when the throttle rods in the TB start sticking inside of the TB itself. This results in a surging idle as the engine attempts to compensate for additional airflow by closing down the BACV, as the BACV closes, it slows the idle again, and the BACV feedback loop begins, opening the throttle by a bit to compensate...

Easy to fix - not related to blown apex seals or an engine that's going to explode. HTH,

 

heres a link where i cut and pasted the entire website text into this site so we don't lose the information...

https://www.rx7club.com/1st-generation-specific-1979-1985-18/gsl-se-idle-faq-link-gone-424918/

good luck! i'm going through the bouncing idle right now too...i'm looking for a vacuum leak though

 

Still a little confused because I have low low low compression on the rear rotor though.

 

Im with LongDuck, your throttle body is sticky. spray some lube on that thing and it should be ok.

 

Hey thanks for the info, i'll get to fixing it when I get back from the F1 race in indy this weekend. Let's go Button!!!

 

I want my $85 back!!! What a f'ing joke!!!

 

.

 

Cleaned the BAC valve and started removing the throttle body by pulling tps connector and coolant line etc but decided against it because I didn't want to have to take everything off, clean it, and put it back when I had to work in the morning and risk it not functioning so I just shot some cleaner onto the throttle plates. At first it held idle just fine but after a few minutes of driving it started cycling around 1500 rpm. Sometimes it drops to normal 800 idle, others about 1000, or cyclying at 1500. When I rev it up above 1500 and let it drop down I can feel it try and catch itself at 1500 but it's like it can't and it drops down to normal idle, really weird. Any suggestions?

I did drive it a bit after only cleaning the BAC valve and it worked like a champ, why oh why couldn't I just leave well enough alone? Sometimes I hate myself.

 

Remove the TB, only, and rotate it 90deg to the left, spray throttle rods where they enter the TB on the inside and outside - wait 5 minutes. Center TB again and rotate 90deg to the right, spray throttle rods where they enter and exit - wait 5 minutes.

Replace TB. Much easier to do than to tell you about it, but that usually fixes sticking throttle rods that cause 'surging'. HTH,

 

That's right, forgot you mentioned they stick earlier, thanks.