Before people get mad and redirect me. I have red through the forum and tried what has been recommended in the past to no avail.

My current problems that require immediate attention is the deafening backfire when letting off the gas for a few seconds and engine braking or even coasting for that matter. It shakes the entire car and sounds like a shotgun went off right next to you.

Checked the vacuum lines. All seated good and were replaced by previous owner. haven't found an exhaust leak either. The car does have a full Racing Beat exhausted (dual tip if that makes a difference). Previous owner says that it might have a mild street port but the engine was rebuilt before he owned it. The car does have a quite but distinctive rotary loping sound to it. Emissions equipment all seems to be functioning minus the air pump which has a block off plate that's sealed correctly. The car idles smooth at 800rpm once it's warm. Acceleration is good with no hesitation or power loss throughout the rpm range. I'm currently at a loss so any info is appreciated. Even if you may think it's redundant. Photos of the engine bay below in case that helps. Thanks!


-Matt

 

Oooooookay, Matt - I'm gonna give it to you straight because you seem like a 'No BS' kinda guy, so here goes;

1) Your SE has a number of blocked off orifices into places that shouldn't be. The PO seems to like to mark these with red caps for some reason...
2) Your Air Pump isn't needed, as it primarily works to inject cooler air into the exhaust on deceleration - but if you can hook it up, so much the better. The rest of your (limited) rats nest is still there trying to do its job.
3) You're running non-stock Coils, which means they may be leaking and causing all manner of misfired, leading to your shotgun effect. Stock Coils run forever and are designed as sealed units so they can be mounted horizontally; not all are designed this way.
4) The SE has an Air Muffler located underneath the Air Filter Box, and I'll bet yours is missing. It's a plastic tube about 6" long, and I'm guessing the intake port it should be connected to will be easy to find, because it's likely to have some kind of red plastic bottle cap shoved into it. Without it, on deceleration, the car will sound like a UPS truck running around at 9pm trying desperately to find an address.
5) Racing Beat made a lot of exhaust systems, and none of them are known for causing backfiring like you mention.
6) You need to check your timing, because that engine bay looks all kinds of "shade tree mechanic", and they're not known for using a timing light, if you catch my drift...
and,... of course,...
7) You still have a major exhaust leak letting oxygen into the system, you just haven't found it, yet.

BONUS! P.S.- your Fusible Links are about to start an engine fire. Get those wire stunts replaced with actual Fuse Links right away, and points for the bungee cord battery hold-down, too.

 

One other question not related to this issue. Without an air source, like the air pump, your 5th and 6th ports will not open at the ~4k RPM level. This will rob high-end power. The previous owner might have wired these open.

 

The 84/85 SE uses exhaust backpressure off of the Main Catalytic Converter (*or the Resonator, for Racing Beat systems), not the Air Pump. That was incorporated along with an Air Solenoid for the 2nd Gen cars. Actually, that could be where his exhaust leak is located, if the pressure line from the Resonator isn't hooked up.

But, yeah - I'd bet $$$ those 6-ports have red zip ties on the Actuators...

 

Awesome input! I'll be sure to take a further look into all of those things. Not familiar with the air muffler but I'll take a look at the breakdown in the fsm to see what that's all about. Yeah this car has a lot of work to be done to it. I have found countless connectors on the car that are disconnected and seem to have no "partner" if you will. This is my introductory to a rotary car before I rebuild my dad's road race 2nd gen. Is it possible to swap those fuseable links with standard fuses of the came amp rating?

 

Where would these ports be located. Mostly black zip ties were used by P/O so nu luck there 😂

 

If it would help, I can post a picture of my SE engine bay as its all stock and could aid you in some reassembly. I also have the FSM and could post pictures of the vacuum diagram as well.

The 5th and 6th port actuators on the intake manifold at each end. The upper part that says RE-EGI is the dynamic chamber. More into that later. Below the dynamic chamber is the actual intake manifold.

 

Modern fusible links can be used for the old wire based ones.




https://www.oreillyauto.com/detail/c...le+links&pos=1

 

The photo would be helpful. I have the full fsm on my computer actually. I've been reading up on it. I just discovered that not only was timing off. But it appears that spark plug wires for trailing were going to leading and vice versa. No idea why it was running but I'm trying to reset timing IAW the fsm.

 

Awesome. I'll de sure to grab some of those. I confirmed that only 1 of those is actually a fuseable link. Weird how it was just hard wired.

 

I've just finished setting the ignition timing up properly. Took some troubleshooting as the timing was off when I matched the crank angle sensor and the pulley tdc up. I had to manually advance about 2 teeth on the sensor and I was able to get it on the timing pin on the front cover for the leading ignition. For the trailing timing I was able to get it close but not all the way to that pin. It was slightly retarded training timing. Not sure if that will cause me problems in the future.

I would say that the trailing timing is about a half inch off. But that was the closest I could get it.

As of now there hasn't been any massive backfires. Just a few small ones. I'll have to take it on a lengthy drive in the near future to test it out.

 

You said it ran fine before, and someone must have moneyed with that thing extensively to achieve that goal. Good luck, and report back. Something tells me that car is going to have a lot of other issues needing to be sorted out,...

 

Took it to a local rotary shop today. They said that I got the timing really close but they went ahead and made it to spec for me. They also said I only had about 15lbs of vacuum when there should be 20? Not sure how to diagnose that problem. The variable resistor for idle mixture is shot as well. That was unplugged as my understanding is that it defaults to fill rich if it's unplugged. Not entirely sure about that though. I'll have to do some more digging. They didn't say that they found any exhaust leaks however they did say that if I can chase down all the problems relating the the car running rich than that should solve my backfire issue.

I took off the BAC today and inspected it. It was clean as far as I saw. I believe there is supposed to be an adjustment screw that goes into the side but mine just has another "red cap" and when I pull it off it creates a vacuum leak.

Feels like I'm going in circles.

I'm getting pretty close to just pulling all to the accessories off this engine and reinstalling everything one at a time and properly. Just intimidating considering I don't really have a solid reference point or something to directly compare to.

Edit: they also pointed out that there was a jumper on some test connection that had the fuel pump always running. Not sure why that was done but I removed the jumper and the car still runs fine.

They apparently set my tps but that caused some weird low idle issue now that I have to solve.

 

Lots of information here on this forum from me and "GSLSEforme" if you search on our usernames and that item (BACV, TPS, EFI, etc.), and it's all there for the reading.

Glad you got somebody to put their hands on it, as that will tell you a lot more about what it's doing. You're going to have your work cut out for you, as the PO appears to have taken a lot of shortcuts along the way - the kind of shortcuts that typically create problems until they've been corrected.

Welcome aboard and get to reading,