200 RPM Idle :(
 

So, yesterday I took my car over to a friends house to show him the progress of bodywork and he lives down the road and on the way back I noticed that somehow my idle very randomly dropped to about 200 rpms. So I thought apex seal went or something crazy. When I got home, check compression on both rotors, and that was ok, then I checked all the spark, and that was ok. So I figured maybe I went over a bump a little too hard on the way home and something in the carb jumped around and finally clogged it after not being "cleaned" after about 10 years. So I took it off and the intake manifold and cleaned it out because there was some weird pink stuff in there and sprayed carb cleaner down every nozzle and small passage way and let it sit over night. I then also changed the fuel filter at the pump to make sure that was good and also checked the fuel regulator gauge in the engine bay and that read 8psi, like normal, and so when I got home I put the carb back together and put everything back on and still the 200 rpm weird idle. So right now I'm going to browse the Hayne's manual to make sure I did not miss any small filters and go through my fuel lines to make sure I didn't miss any. I did drain the fuel tank the other day because there was bad gas that accidently got put in my car so my guess right now is that something is clogged somewhere. When I put the choke on, the engine idles fine at 1000-1200 rpms, like it used to do. So if anyone has any ideas what might be going on that'd be a great help. Thanks.

Is the idle still smooth or the same as before? Use your ears and listen to the idle. Are you sure it's idling that low, or is the tach just off and you assumed the 200 rpm was correct? I've had mine idling at 400 and it doesn't sound much different than 750.

Another thing I noticed is that during revs it seems like there is a ticking thing going on and it goes faster as I rev it higher. I'm not quite sure how to describe it other than that when it idles at 200 rpms, it like ticks the same way when revving it but slower, it comes from the exhaust though, like it's the sound of the car. I don't think the exhaust is clogged because I run headers to resonator to muffler, but I will check the resonator right now.

The idle is smooth, and the tach reads at the lowest bar right before 0, so I'm just taking a wild guess. The idle is extremely low though.

I think a good way to describe how it drives is that it sounds exactly like an ATV, and it will sputter/hesitate/backfire at low rpms, but when full throttle comes around, it still throws me back into my seat and sounds like nothing is wrong. Any ideas?

Check all of your ignition again. The ticking almost sounds like an ignition event. Spark leaks are best found in poor/dark lighting.

Will do. Should both leading and trailing have the same big spark or would the trailing have smaller? The trailing had smaller when I last checked, and that makes sense to me because why would it be as big if the holes for the trailing plugs are so small?

IIRC trailing spark is not as strong on mine, so that's probably fine.

What does the timing light say about spark consistency? Does it look like it's skipping?

Well I checked spark and all is good in that region, but not quite sure about timing. I don't think the timing changed at all during a drive though, but who knows. I've narrowed it down to that something must have happened when I went over a bump on a back road a little too hard and something went wrong then. I got a new brake master cylinder coming today, so I will replace that and if I can get a buddy over I will probably drop the gas tank to check to make sure nothing is clogged in there. Any ideas on what might have gone bad when I went over a bump?

Sounds like its ignition related. Are your sure both leading plugs are firing when its
idling?

The way you describe it, it sounds like its running trailing alone until you
accelerate. The rotary will run on trailing alone just not as well.

Spark should be the same between leading and trailing as both use identical parts. If the size of the hole in the housing had anything to do with it, the trailing spark would be hotter due to the smaller hole, think about it.

Hmmmm, that's true, didn't think about that, but the thing is the car ran fine with the spark the exact same as it is now. When it's "idling" now and i remove the trailing ignition, I can hear the difference, so I know the leading is definitely working the way it should. When driving the car at full throttle, the car sounds like it normally would and accelerates like it should, but not at low rpms/ low throttle. It sputters and bogs until full throttle. I'm currently in the process of dropping the tank, but it seems like when I drained it that the fuel came out like it normally should so I'm debating if I should go any further. I'll work on replacing the brake master cylinder until I hear further from you guys. Thanks.

What do you mean you can hear the difference when you remove trailing? Trailing barely does anything, so removing it shouldn't really have much effect. I know some people run without trailing just fine.

I mean I can hear a very slight difference. Like very slight.

when its dark out, raise the hood and run the engine. look for jumping spark on or around the coils, distributor, plugs, and wires.

Okay, I'll check that tonight then and let you know.

Wiggle your injectors and see if it smooths out.

Just checked and there was no jumping at all. I did replace the cap and rotor and cables very recently, so I'm pretty sure they're all good. And the engine has a Mikuni side draft carb, so no injector problem, but thanks anyway. I'm going to probably end up taking off the carb again tomorrow and respray it down with carb cleaner and see what happens.

My bad I did read that earlier but mind was in diagnostic mode and forgot that important detail.

Make sure your dizzy cap is on straight. They can get off-center and the rotor starts chewing the inside of the cap up. Will make a ticking/buzzing sound if its slight.

I'll check that out later tonight when I get home, but the "ticking" sound is from the exhaust. The tone of the exhaust is like the exact same as a fourwheeler. It's really wierd.

next thing i would check would be the exhaust flow. this will ensure your converter is not plugged. if you run the engine and place a towel over the tips, the towel should move very freely. i can post a pic if you'd like. the ticking could be a loose and swinging split air tube or a loose heat shield on either the underbody or on the conveter (if you have one..for some reason i keep thinking you have a 79..which wouldnt have a converter..)

Yeah, the car is a 79 with a newer engine, either 83 or 82, but my exhaust system is RB headers to a resonator to a muffler, so I don't think it would be caused by the exhaust system being clogged anywhere. I could take off the connector right before the resonator and remove that so I'm running straight pipes just to see if it would make any difference if you think I should do that.

Well this afternoon I took of the intake manifold and carb and tore the carb apart again and did a pretty thorough cleaning and found a thing that was loosened and put it all back together and back in with no success. This is really starting to confuse me. When I pull the choke, the car goes to a normal idle with no problems, but there is an occasional backfire. The problem was caused by going over a bump on a back road a little too hard. Fuel is getting to the carb with no problems at all, I've made sure of this. There is spark on all four plugs, but I'm not sure about the timing. The carb was cleaned out so there shouldn't be anything wrong with that unless I missed something. All apex seals have compression. Any ideas on this problem?

timing should not be affected at all. i know you mentioned a newer cap and rotor..but did you check to make sure the cap didn't get cocked? my tender blue 85 that i sold last year had a similar problem and i had recently installed a new cap and rotor and, who knows how the cap got cocked, but it did, and this is what i found(mind you the engine would still run mostly fine)

http://i636.photobucket.com/albums/u...b/DSC07204.jpg

http://i636.photobucket.com/albums/u...b/DSC07206.jpg