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Hey folks, trying to identify a few things on my FC. Yes, I have used search. Yes, I have read nearly every page in the FSM and I can't find concrete answers to these.
Previous owner has jammed a fuse in this harness, but I can't figure out why or what this actually went to. Diagram says maybe the IAT sensor? Any insight here? Why would there be a fuse stuck in this?
What are these two valves just above the exhaust header? They are disconnected and don't appear to be working.
Can someone confirm if this canister (driver's side) is supposed to go to anything else? The vacuum diagram is a little hard to follow, but it looks like this is supposed to connect to the gas tank, possibly?
Any insight on the above is greatly appreciated, thanks in advance!
#1 is the fuel pump test connector, it shouldn't have a fuse in it, someone has bypassed the fuel pump relay for some reason, pull the fuse and find out why!
#2 are the 6 port actuators
#3 is not a stock part
For the fuel pump test, there's a switch installed in the dash to turn the fuel pump on/off, but I don't think it's bypassing any kind of relay. It's just an in-line switch. Very curious, I pulled the fuse and everything still seems to be working properly. Car runs normally without it there.
For #3, I took a closer look, and it's connected to the oil fill tube, looks like it's just a catch can. Seems an odd place to connect a catch can but... hey whatever I guess.
Very curious that those are 6-port actuators as this motor is supposed to be a 4-port. Seems the seller was not exactly truthful. That is a bummer, as I'm having a lot of issues with this motor.
At least now that I know what they are I can start digging up on how they're supposed to be actually connected. Any advice on where that would be located in the FSM is welcome!
4 port 13B engines will either very old or will be from a TII. The N327 map sensor I see indicates that this car is likely an 88 NA...which has a 6 port NA 13B.
Thanks, that's helpful. The car chassis itself is definitely an '86, I've run the VIN. The previous owner claimed they did a rebuild on the engine, not a swap.
The issue is that I'm having trouble starting the car (it sputters a lot and doesn't start smoothly, but will eventually start, and once started it seems to run fine with no issues) so I'm trying to go through everything mechanically on it. All the threads and info I find jump immediately to "low compression", but there's been enough wonky **** with the motor so far I'd like to eliminate every other possibility before I go down that $2500+ rebuild route.
EDIT: Also, amusingly, that N327 sensor isn't hooked up to jack. I don't even see a connector for it anywhere. How critical is that sensor?
Last edited by Fenrirthviti; 05-29-20 at 07:31 PM.
That map sensor is very critical. The connector is plugged into the bottom of the connector.
The thing I would be most concerned with is the fuse in the test connector for the fuel pump. The car obviously has had fuel pump and or wiring issues in the past and I would correct those before moving on to other areas unless those areas are not readily apparent.
A compression test with a rotary compression tester is essential as you do not want to waste time or money throwing parts at a worn engine. It would be nice to know you are working with a solid engine I would be skeptical of the seller's claimed rebuild skills after seeing the fuse in the fuel pump test connector and the painted 5th and 6th port actuators. Plus it looks like some things were deleted with block off plates...you might be chasing your tail for a bit with that garbage.
I would love to do a compression test, but I don't have access to a tester, and the ones from https://rotarycompressiontester.com/ are on backorder for an unknown amount of time. I have one on order, but I'm trying to handle as much as I can to clean things up in the meantime. I tried the cheap autozone pressure gauge trick but the results were extremely suspect.
It's curious that the motor even runs and drives without a MAP. I can't find a plug that fits it anywhere around the sensor, but it might be tucked underneath the intake.
I'm pretty new to rotaries in general, and the previous owner has pulled a lot of parts off the motor, as part of the emissions delete stuff. BAC valve is partially removed, bunch of hardlines that are not connected to anything, and wiring harness connectors are just floating throughout the engine bay. It's very slow going working through all this and trying to keep things straight on what is actually required or not. I'm doing an OMP delete (the previous owner completely fucked the system, it's not even connected to the throttle, is set up to use some janky external catch-can as the reservoir, and I don't have the patience for it) and will be aggressively premixing. The FSM helps, but it's super tedious to look things up in there since nothing is named what you expect it to be named coming from a lifetime of piston engines. It's further complicated by the information I'm finding is hotly contested between "Yes you should remove this, I have no issues" and "No, you should never remove it!" which makes it hard to know what I actually need to fix or not.
Also, the whole block has been painted, which is something else I never see on rotaries. Luckily, the paint is basically flaking off, and I suspect it was painted while dirty to hide the true condition of the engine. At this point, I'm thinking it might be less time, money, and effort overall to just buy an engine hoist and pull the motor, give it a once over, and then put it back in connecting everything properly. I've attached a bunch of pictures I've taken below, if anything else major jumps out that I should be addressing, I am happy for the advice!
Yeah, I knew that much already. It has a manual cluster at least, but I don't know what other parts of the swap were completed successfully and what corners were cut. It definitely still has the auto diff in it, which isn't a big deal for me as I'm not going to be racing this, and the longer gearing is kind of nice for tooling around town. They claim it was a turbo II trans swapped in, but hard to verify as I don't really know what to look for.
I connected the MAP sensor, and on further testing, the fuel pump now fails to come on with ignition. If I jump the test point on the harness, it will come on and stay on without issue, even when I remove the jump. Reading up, it sounds like there's a bunch of different MAP sensors for turbo/non-turbo, S4/S5, and that they need to match the specific generation of ECU to function properly. Is this accurate? A lot of the old threads link to resources that no longer exist, so it is difficult to fact check.
They claim it was a turbo II trans swapped in, but hard to verify as I don't really know what to look for.
its an NA, case is completely different
Reading up, it sounds like there's a bunch of different MAP sensors for turbo/non-turbo, S4/S5, and that they need to match the specific generation of ECU to function properly. Is this accurate? A lot of the old threads link to resources that no longer exist, so it is difficult to fact check.
Mazda has a designation for a given powertrain/engine. for things like the MAP/AFM etc you can go by the number. N326/N327 is an S4 NA, N318/N319/N332/N333 is the S4 turbo, N350 is an S5 na, N370/N374 is the S5 turbo
functionally the NA sensors are 1 bar, they read from -15psi to 0psi, the turbo sensors are 2 bar, they read -15 to +15psi. the S5 sensors are three pin, 5v power, signal and ground. the S4 sensors are 4 pin, 12v power, 5v power, signal and ground
Thanks, good to know. So sounds like my sensor should be correct for the engine that's in the car. Now I just need to finish going through and checking every single electrical and mechanical connection on the motor...
Thanks, good to know. So sounds like my sensor should be correct for the engine that's in the car. Now I just need to finish going through and checking every single electrical and mechanical connection on the motor...
lol, if it was mine i would basically pull it apart to the bare block and check everything.
Yeah, I already have that manual printed out. I would tear it down if I had the tools or space to do so, but that's unfortunately not really in the cards right now. I'll need to do as much as I can in the meantime to try and mitigate any potential issues, and fix the hackjob of a swap that was done.
05-29-20, 04:29 PM
