Nisaja

Hey guys, I just purchased my first FD. It's an amazing car but I got a few questions. Firstly I must add that I'm not new to rotaries. I've owned 4 RX8s and I currently own 3. But I know nothing about boosted rotaries. I'm trying to figure out if these are common issues and have known fixes. Thanks in advance!



Engine



It feels like the turbos don't activate at times. When accelerating in first or second around 2000rpm, sometimes it's not that fast, but sometimes it gets wicked fast. However on both occasions the power dies down after 4500 rpm. I'm guessing the second turbo doesn't work properly?



The car doesn't have a BOV, but it makes a "peww" noise when I let go of the gas. It has HKS filters for the turbos though.



Sometimes its really slow to rev past 6000rpm, even in neutral. It feels like it's hit a wall. Like a smooth rev limit?



There's a small leak at the AST filler cap. I've read that you can eliminate it completely. I have no access to RX7 specific parts. Can it be done using generic parts?



I'm getting a fuel smell around the left rear wheel arch. Can't seem to find any leaks. Any known fuel lines down there are prone to leak?



Interior



The seatbelt light is always blinking, and in tune with that, the little light on the door's keyhole, and the steering column key hole light blinks. The power windows go in tune with that light too. Think of it as being wired to a turn signal. The windows roll down when the light is on, and stops when it's not. It basically rolls down intermittently.



The odometer backlight always stays on.



The speedometer doesn't work, but seems to work like a boost gauge? It moves up when the boost builds up.



The rear of the car makes two noises. A creaking noise (like when you open a door) and scratching noise.



Thanks a lot. Just trying to figure out if these are known issues. Any help will be greatly appreciated.

SpinningDorito

iTrader: (2)

Stock ECU? If so, jumper the diagnostic port and see if you get any engine error codes. Sounds like a problem with the turbo control system. Look for vacuum leaks or missing vacuum lines. Could also be a bad solenoid which I think should throw a code

If its on the stock system, it should have a BOV somewhere. Ignoring that, there is an almost identical "CRV" that could also make this noise depending on how things are routed.
Less likely, but it could also be a boost/intake leak when the secondary turbo tried to kick on which might explain your first problem.

There are aftermarket ASTs for the RX7. I would try a new AST cap first, if that doesn't helpt I would use one of those, or lookup how to delete the AST all together. As I mentioned in your last thread you should really think about pressure testing the coolant system to make sure its a bad AST/cap.

Not sure about the RHD models, but on US 7s yeah there are fuel lines near there. All of them. I wouldn't really advise continuing to operate the vehicle until you track that problem down.

On the other issues, sounds like your gauge cluster may not be working right. Its not uncommon, and generally required replacing some capacitors or other board components.

Seatbelt light could be a bad/unplugged sensor, or an issue with your CPU 2 unit. Hard to say until you troubleshoot it more.

As far as the blinking I am not sure. The first thing you need to do is go through all the wiring and see if its OEM or if someone has done custom stuff somewhere.

Rear of the car sounds like bad bushings, but possibly other things. Take a look at the suspension under the car and see what kind of shape it is in.


I would pick one item and work it through instead of going after all of them. It sounds like you have a long road of troubleshooting ahead of you to get everything fixed up.

I'd personally start with the fuel leak, the boost transition issues, and testing your coolant system so you can make the appropriate repair (hopefully just a bad AST or bad cap)

Edit:
And no matter what issue you are fixing/investigating I would always check the condition of any wires/rubber hoses/lines/fuel lines that are in the area you are looking at. Most likely they could all use replacing with new rubber/silicone. You'll be able to tell very easily if they are old/cooked/brittle.

Maxwedge

iTrader: (1)

Since you are using the internet to talk to us, you have the same access to RX7 specific parts as the rest of us here . The internet . Mazdatrix, Atkins, Ebay, this forum's classifieds, etc etc.. Also, Mazda still sells many parts new for your car.

Nisaja

Thank you so much and hello again! I bought the car. Looked too pretty.

I'm assuming this car doesn't have an OBD2 port? There are no CELs on the dash. I just remembered that after coming home from a drive, after about 20 mins, putting the key in and turning it to the "on position", I saw a light on the dash that said "HEAT". Is it the cat? It went away after I started the car.

That's cool that it has a stock blowoff. The car has an HKS intake for the turbos. It only makes the pssshhh sound when I lift off the throttle. I'll try to get some pics. Problem is live in a small tropical island in Asia and there are no rotary specific workshops here.

The speedometer tries to go up with the boost lol. It's like a small boost gauge.

Nisaja

Thanks man. Problem we have an import ban because of Corona that's why I asked about using generic parts.

SpinningDorito

iTrader: (2)

I don't think the JDM models have the same check engine light the US models do, but you should still have the black diagnostic box in the engine bay (should be near the fuse boxes) that you can use to check for codes. On a really quick search, this seems like the procedure you may need to follow https://www.rx7club.com/3rd-generati.../#post11543127

If you have a LHD model with the heat light instead of the CEL that would be interesting, so I am assuming you have a RHD Rx7.

Well I am not saying your car has the valve, I am just saying that the stock sequential turbo system should have both a BOV and a CRV. Having the HKS intake shouldn't change that fact as far as I know.

Nisaja

Sorry for the delay. Spent the past two days just cleaning car and doing some cosmetic work. It's a JDM model. I looked the VIN up. Says 1993. The engine has been changed though, according to the previous owner. He got down an engine from a crashed 7 in Japan.

I drove the car a bit yesterday. Turns out if it doesn't boost, letting go of the accelerator and flooring it again does the trick. Say I'm in second gear, when I floor it, sometimes it's wicked fast, other times it's like my RX8. If i let go of the gas and floor it again it goes wicked fast again. But no matter what, it slows down after 4500rpm. Sometimes it doesn't rev past 6000rpm.

SpinningDorito

iTrader: (2)

There's not much more I can say other than what I have. It's definitely not driving right and you'll have to narrow it down.

I posted a link that should help you check for any engine error codes, which might help narrow it down. There's not really any shortcuts on the vacuum lines. If you remove the upper intake manifold and the lines are brittle and old you really should just replace them all. It is a long job, but it is doable.

You should also check for any kind of custom wiring, turbo timer, boost controller, etc that could potentially be malfunctioning.

I would not ignore the fuel smell. Check all the fuel lines in the engine bay and replace with new. The fuel pulse dampener is also common failure point that results in a fuel smell/leak and it can catch your car on fire. There is also the connector between the primary and secondary fuel rail that was recalled and replaced with a more secure connection from Mazda. If you still have the old style you should try to source the newer one.

Easiest way to access the FPD is to pull the rats nest which you'd need to do to replace all the vacuum lines anyways.

I also really wouldn't advise beating on the car anymore until you fix some of these issues. It's hitting some sort of cutoff and you need to address that. Just the turbo system having issues would not limit your RPMs, so you may have a problem with the fuel pump, fuel filter, injectors, etc.

Nisaja

Thanks a lot. It has an HKS turbo timer. I hate it honestly. I might just take it off.

Fuel pulse dampener. Got it! Will look it up. I was just reading about the infamous rats nest.

The fuel pump was replaced by the previous owner. When I went to see this car a few months ago, it seemed like it was running on one rotor. It was fine after he replaced the fuel pump. I'll look into it. Still reading and learning haha.

SpinningDorito

iTrader: (2)

I would remove the timer.

I would check on the pump. There is no guarantee they installed the correct fuel pump.

Nisaja

Yep true. Thanks a lot. I'll update this thread once I look into them.