GSL-SE idle seems rough
 

My first post to this forum was long and detailed...and got no responses. Since then I have learned a ton and answered most of my own questions thanks to the great resources here. So a big thank you to everybody.

My one question remaining is this: My car runs and idles fine. I have replaced plugs, wires, rotor and cap. Still the idle (and non-idle when it is slow enough to tell) seems to be missing or something at times. Not in a pattern or rhythm that I can tell. To me, it reminds me of an old muscle car idling. Here is a '69 Charger https://www.youtube.com/watch?v=xFsDguI2sxM

My car isn't so pronounced, but the engine block does rock a bit. Nothing violent, just gentle but not smooth.

This is my first rotary car, but seems off to me. Any ideas? What I have considered are:

1. Seals. Seems that bad seals would be rhythmic
2. Ignition.Coils seem just fine. Distributor and igniters have not been touched. Is this a likely area? Igniters seem to cost way too much these days. Like over $300 in places, so I hope this isn't the issue.
3. Injectors. I have not pulled or checked the injectors.

Advice on what to look at next would be appreciated. Also, importantly, of the potential causes, would any damage the engine if driven this way?

Thanks!

Is it idling low or is it just missing? Have you checked for vacuum leaks and have you cleaned the throttle body? Have you adjusted the idle screw on the top of the throttle body at all? Have you adjusted the TPS recently?

The engine is missing, not idling low. I have found no vacuum leaks. I have tested and replaced vacuum lines just to be sure. TB has been cleaned as far as possible without removing it. Have not touched the injectors. The TPS is adjusted per the FSM and also checks out electrically.

Some new information is that I took it out to get gas and it bucks like a bronco, looses power, just drives terrible under load. This is quite new, so am going to check compression to see if I have issues beyond the fuel system. Also found the aux actuators are non-functioning with the plungers in the closed position. There is an audible leak when pressure is applied the the back pressure tube that connects to the exhaust.

I am on the right track to check compression/seals next?

A compression test is always a good idea but in this case, I doubt that you've lost compression. It sounds like a fuel delivery issue to me. Have you tested the mass airflow meter per the FSM? Its really just a resistance check. I would check that and check your grounds. The EGI system is sensitive to having good clean grounds. There are two black wires with ring terminals that serve as the injector grounds. They bolt to the emissions rack I believe. I'd have to look at my car to be sure. You'll want to find those and make sure that they're clean and secure.

What brand of plugs did you install? NGK BR8EQ-14's? If not, replace the plugs with them. Was the car sitting for some time before you started driving it?

Maybe I should check the fuel pump/filter. Didn't think of that obvious step.

I will check the grounds. I did replace with NGK BR8EQ-14's, so that is good.

The AFM is another story. I found it with water in it and rusted, when I removed the black plastic cover. I cleaned it out with PB Blaster, but I guess maybe it is not reading right, although it mechanically seems ok. The AFM looks expensive to replace. I will do a resistance check on it like you suggest and see where its at. In another place I learned I probably should test it while tapping on it with the back of a screwdriver as well, to simulate actual driving.

Yes, the car had sat a number of years with occasional starting before I got it.

I have a spare maf if you end up needing one. I'd change the fuel filter just as a precaution but I'd lean more towards the maf especially since you found it in such bad shape. But definitely test it and see where the resistance lies. I don't see a need to tap on it while testing it. If you need the specs let me know and I'll post the test procedure and specs from the FSM.

Great, thanks! I will test. I have the FSM with the pinouts. Can I test straight resistance or do I need to energize and test voltage? Thanks for your help.

Ok. I tested the AFM and got bad results.

1. The fuel switch is supposed to be infinity but is 365k. This is enough to turn the pump off, so probably not an issue.

2. The temp sensor is ok.

3. The resistances when the gate is closed are all within ranges.

4. When the gate is moved, resistance is supposed to smoothly transition up to a max of about 1k. What I am consistently seeing is a "curve" that goes up, shoots to infinity, returns to a reasonable range, and then begins to actually descend before finally increasing until the end of travel. All resistance values past the very early part of the curve are above 1k Ohms--so above the expected max. The overall effect, I suppose would be the ECU thinking the AFM was at WOT most of the time, while the TPS says otherwise. Since the early part of the curve seems normal, idle must not be affected.

I couldn't find the injector grounding wires. Do I need to remove the intake? If they are wrapped with other wires that may explain why I didn't find them.

I have ordered a fuel filter and may take you up on the extra part you have. Message me the details.

My gut is this isn't everything, but it feels like I am narrowing the field.

You'd be surprised at what a bad MAF would cause an ecu to do, lol. I'll get into my SE parts and spec out the extra MAF's that I have to be sure 'they're good. I think they all are because I was having an issue with my car and I remember testing them and trying a different one as a just in case kind of a thing. Odd thing was that it was breaking up because of a bad coil...which passed the resistance check. I replaced both coils and the engine has been running great since.

The ground wires should have a black coating and have a ring terminal on that bolts to the emissions rack. I'll look at my car tonight after work and post a pic of the wires. The SE is sensitive to having clean injector grounds and even if they're not the cause of your issue it would still be a good idea to ensure that they're clean and secure. It sounds like you're on the right path.

Just got to check the compression and all three readings for each rotor are equal. Overall, compression is around 120 psi.