Whisper

I have rough idle when warming up. That's expected. Then, when it's warmed up to normal operational temperature, it goes to 800 and is fairly smooth. Drives smooth, too. However revving and letting go of gas causes a significant dip before it goes back to being stable at 800, which I guess is also common. I had minor surging issues when it's running a bit warmer, at about the center on the temp gauge when sitting in traffic (my normal is maybe 3/10th with the electric fan on), but if I kept the cooling reasonable, it would be fine.

Now, the odd stuff that confuses me:

When I throttle ever so slightly, maybe to a 1000 or so and then hold it there, the rpm is just too rough. It plummets then recovers then plummets then recovers. It's a cycle, and it shakes the whole car. Gets worse as the engine gets warmer and warmer. If I just let it idle on its own though, it's steady at 800. This is major headache, because anything that requires driving super slow, such as backing out of a parking space, is nearly impossible without the car literally shaking all over and feeling like it's going to stall or come apart.

Also the following started happening today after I swapped the air funnel and cleaned the throttle plates a bit (didn't change anything else). All idling is same as before, but as the temperature climbs, the RPM starts to climb too, and starts to surge and bounce. First real slight, then more and more, as it warms up and gauge reads just left of the middle. Then it simply goes nuts. Surging up to 2100 and bouncing back down to 1100. These revs don't sound too good, either. Like its missing or something. However turning the car off and letting it cool for a few minutes and turning it back on makes the throttle steady again, until it warms up more...and then we're back to surging.

I'm guessing BAC is to be checked (though disconnecting it doesn't seem to do much when it's surging), and possibly need to take off my TB and clean it from the inside. But I don't understand why it only happens at higher temperatures... Could the issue be with the O2 sensor? Hotter exhaust causing bad reading or something? Suggestions?

justint5387

iTrader: (1)

Did you change the fuel filter lately?

Whisper

No. I don't know when it was changed. I only got the car a few months ago.

RXnos1200

iTrader: (24)

also check your adjustment for the tps..............

Whisper

Yeah, I'll look into that, although it seems that if my TPS was off there'd be other problems...

Pulled the throttle body and cleaned the plates from behind a bit. It actually didn't look too bad.

Now I have BAC valve off. It moves smoothly, but is there a spring inside? I don't know what's the right amount of force that's needed to push the plunger in. I'm gonna assume it's fine. Would probably clean it still. What cleaner to use for this?

RXnos1200

iTrader: (24)

[QUOTE=Whisper;8753718]Yeah, I'll look into that, although it seems that if my TPS was off there'd be other problems...


not really. but when you give it gas it can buck and stumble or not respond at all. hold the idle to around 1500 and the idle may go up and down. If it does then I'd check the tps adjustment. good luck

Rx-7Doctor

iTrader: (13)

As found in this forum-

https://www.rx7club.com/1st-generation-specific-1979-1985-18/1st-gen-rx-7-faq-page-237777/

Q. My GSL-SE has idle and surging problems, how can I fix it?
A. This can be tricky but David Lane has created a page with lot's of excellent hints
on Solving GSL-SE Idle Problems Also LongDuck has added some excellent
suggestions in this GSL-SE Rough Idling Problem. Here are some other informative
threads: ...surging SE's and GSL-SE going nuts at IDLE!! and wacked idle and odd
acceleration at part-throttle Also be sure to check out the Mitchell Manual (1984 RX-7
full manual, pg 240-241) Technical Service Bulletin

Whisper

Thanks. Yeah, I've been reading that today. Definitely good info.

But here's another thing: I was taking a closer look at the throttle rod and noticed that my dash pot doesn't even touch throttle lever. Is that normal? From what I understand the little plastic plunger is supposed to smooth out the return to idle, but on mine it can't possibly do that. Maybe that's why my RPM plummets before it recovers to idle - it drops too quickly and BAC can't keep up, since dash pot doesn't slow it down. I just unscrewed the dash pot further out, to the maximum distance, and it still barely reaches the lever. Could it be that my throttle rod has been messed with and everything is rotated? How far is the plastic plunger supposed to come out? Maybe my dash pot is bad.

Should I adjust my throttle rod so it's rotated more counter-clockwise towards the dash pot? Of course that would close my throttle plate, which I'll have to readjust. I don't really know all the intricacies of the system and what should and shouldn't be touched.

Whisper

Ok, update.

Lubed BAC valve so it works smooth. Also checked both solenoid valves, no problem there. Set the thermo piston and fast cam to spec. Checked for vacuum leaks, couldn't find any. Moved the dash pot out of the way, so it doesn't block the throttle from returning all the way. Adjusted the RPM to where it should be. Set the TPS.

Start the car, let it warm up, idles smooth at around 850. Rev it a few times, it goes back to around 900. Take it for a test drive, and it's all sorts of inconsistent. Sometimes it feels like the motor is struggling to idle, even though it's idling at 900 - 1000 RPM. Sometimes it starts to surge a bit (not as drastic as it was before, though) from maybe 900 to 1200. And sometimes it doesn't even go down to idle - stays at 1200. One time it even climbed to 2000 and sat there until I revved it and then it dropped down to a 1000 and started to surge up and down. And yet sometimes it idles smooth at 900.

I thought maybe sticky throttle plate or sticky throttle rod, but everything seems to move smoothly.

Also another thing. If it's surging, and I push in the clutch, it goes up and stays at 1200 smooth, and if I let go of the clutch it drops down and starts to surge again...

I'm confused.

rx-7ames

iTrader: (1)

That is so weird because I just got a GSL-SE today and it is doing the same thing. Surges between 1000 and 700. I push in the clutch and it idles smoothly at 700. I don't get it.

thunkrd

iTrader: (1)

this happened to me after i cleaned my tb. iirc i also did a tps adjustment, and played with the other adjustments.

slow5oh

call me crazy, but several of your symptoms sound like intake manifold air leaks. my car had ALOT of idle issues but ran great at the higher rpms. lower intake manifold gasket was leaking. I changed the LIM gasket, UIM gasket, and removed all the emissions **** i could get my hands on. car couldnt run better if i put a brand new motor in it now.

rx-7ames

iTrader: (1)

would spraying the uim and lim gaskets with something like carb cleaner show a leak? I know I should probably check for any vacuum leaks in general too.

widz

iTrader: (1)

the idle could have something to do with the clutch because my idle went to crap after my clutch went out....im gonna try replacing my release cylinder and see if it helps my idling...is it hard to change the release cylinder or is it pretty much bolt on and off?

Whisper

Wow, that was a serious bump.

But yeah, I sorted it out a while ago...and I'm not even sure how. I guess I cleaned the vacuum lines that connect to vent and vac solenoids, and somehow after that the issue just disappeared.

slow5oh

i would think so, but apparently not always. I was able to find one vacuum line that had slipped off the uim by spraying with carb cleaner, but the main leak that was causing it never did show up. in fact, the reason i changed the gaskets was because i removed the uim and lim to install a header on the car, and decided to change the gaskets while i had everything apart. turns out that fixed the problem, lol fixed by mistake.

rx-7ames

iTrader: (1)

Oops, i feel dumb. Didn't even realize i bumped the thread that much. I just found it doing searches. Sometimes I have so many tabs going from searching old threads and reading new threads I forget to look at the last posted date. Well, I have seen worse though. At least is wasn't several years old.