I have been delving into the literature here for a few months now. Great community! I hope I can stick around and contribute but I may be screwed out of my X here pretty soon... Maybe someone can help.

Bought my 1st 04 AT RX-8 at auction. Super cheap ($6500), great condition, but wasn't able to pre-check the compression. Turns out, it was bad, and needed a new engine. Dropped 2k on a nice 20k mile 05 engine, and the guy who sold the car to me put it in for free. Dropped it off with a smile and rode my bike to work the next day.

It is now six weeks later and I am still riding my bike.

The mechanic (he is not a mazda or a rotary guy) can NOT figure out what is wrong with new engine. It starts instantly, boosts to about 1500 rpms, chokes to 500, back to 12, and then dies. I dropped by to test drive it and to get it rolling I had to start it in neutral, punch the RPMs to 3k, and drop it into gear while accelerating. On the freeway it rides smooth, but there's a delay between hitting the gas and it actually accelerating. Anytime it drops below 2k rpms it simply dies. There's a lot of popping in the exaust when it's sitting there, attempting to idle, and it's tossing an intermittent misfire and random misfire code.

With the help of this community I have been attempting to guide him toward possible solutions, but nothing seems to solve it. Here's a list of everything he's performed to diagnose it:

• Replaced Plugs and all 4 coils (not the wires as they appeared to be new)

• Replaced the maf sensor

• Swapped the injectors from the other engine

• Swapped the throttle position sensor assembly

• Dissconected the catalytic converter and ran the car to see if it was plugged

• Checked the fuel pressure (60 psi) and flow

• Put a new o2 sensor in it

• Cleared the NVRAM with the brake pedal,

• Checked for vaccum leaks

• Took it to Mazda and they said change maf, plugs, coils and wires.

The only thing I can think of is one of the wires is actually bad, he missed a vaccum leak, the TPS is installed wrong or something, or the fuel computer is heavily addicted to a crack.

The cost of parts and labor is slowly rolling up and he is at a loss, ready to just dump it back on me. Each attempt at solving it seems to take him a week. If all else fails, I guess there's always the lull of a slow slip into an antifreeze-induced coma...

 

find a mechanic who knows rotary engines. you're in for 10k already

 

how many miles on the car? these engins have an extened warranty 8 yrs/100000 miles

 

You know for sure the new engine is good?

Check the wiring harness for grounds that are loose or unconnected, or pinched wires. Sounds like a vaccum leak/maf sensor not functioning or a fuel issue but since you've already checked those, I'm not sure.

 

This might sound dumb, But is the replacement engine a 4 port from an 05 AT? If it's the 6 port from a manual car, you're going to have all kinds of problems. I'm not sure if it would start at all though.

 

Yeah, I've been looking for a good rotary mechanic in Utah who hasn't been defiled by dealership bureaucracy.
The car just rolled over 60,000 miles, but it's a rebuilt title so I believe that voids the warranty...
Compression on the new engine seems waaaay better, and it was cleaned before the shop shipped it, so I'm assuming they got any carbon out. Maybe a seafoam or two would help though. I'll have him check for the harness issues bose, thanks.
The engine was a 4 port from an AT for sure.
By the way, thanks all for confirming how amazing this place is

 

Where are you at in Utah? I'm towards the south east end of the Salt Lake valley.

 

Have an air compressor, or access to one? If so, here's an easy way to test for vacuum leaks. Used it on my car effectively: http://www.turbobricks.com/forums/sh...d.php?t=204269

I didn't use those instructions, but they're pretty similar. I used a rubber coupler (3" to 2") that fits over the throttle body, and then a PVC capping that fit into the 2" section. Drilled a hole in it big enough for a valve stem to fit through, applied hose clase, and applied compressor. No seal gunk required. Showed me exactly where I was leaking. Note; on our cars if you do this method, there is a line going from the intake manifold to the tube just before the throttle body that will leak. This is normal, just plug it with your finger and everything will be shiny.

 

I'm up in Ogden bose, but I work in Farmington.
That's a great test Scotty, I'll give it a shot. Thanks!

 

i dont think the title effects the engine warranty ... i could be mistaken thou

 

wait a minute doesnt the 05 at also have the 6 port or is that just 06 and newer??

 

Ok, so I'm replacing the wires on the off chance that one of them's bad, and then I'll seafoam it as per https://www.rx8club.com/showthread.p...hlight=seafoam

If that fails, I'm taking it to Mazda and bending over. :P

 

Your throttle body is bad, replace throttle body.

I had same EXACT issue 2 years ago. Whenever I pushed the clutch in, it would go straight down to 0, no hesistation. Sounds the same except with an auto trans.

 

BTW where are you located? find a local member to meet with and swap throttle bodies to see if it fixes the issue. When I had the same issue, a member drove from Indiana and put his throttle body on my rx8 and it worked.

Post in your states thread for help. Hopefully a veteran member lives near you that can give assistance

 

hey snow where are you from? lmk i can probably help you out with a throttle body if you want to try it

 

Actually, if it is the throttle body I've got an extra one sitting in my garage that I know is good I could sell you.

 

Awesome thanks guys. I live in ogden, utah. Let me inspect my throttle body and I'll get back to you. Just put new wires on and it actually helped the idle quite a bit. It still has a real rough idle and jumpy acceleration, but not as awful as before.
Seafoaming soon, I'll keep you posted.

 

I swapped the TPS assembly from my old engine, which includes the throttle body. The swap made no difference, so either both are bad or it's something else.

 

Really stupid question, but are you sure it doesnt have bad gas? How does it drive? Is it just an idle issue?

 

Yeah I only use premium. If I can get it onto the freeway there's a definite lag between hitting the gas and feeling it accelerate, and its pretty rough when it does.

 

is it rough DURING acceleration? Once it gets rolling, is it smooth?

 

Yeah It's pretty smooth rpm-wise other than the time lag, although the smoothness is probably just the kinetic energy of the engine spinning and overpowering the problem. For example, if I'm just coasting at 70mph the rpms are smooth. I want to speed up, hit the gas, nothing for about 1-2 seconds, and then the rpms jump.

 

this may sound stupid, but i heard a similar story and the guy said his rotars were not aligned properly when he bnought a used engine, its like someone tried playing with it and misaligned the rotors.. i was not sure that was possible, but who knows.

 

another stupid question...... There's a thing called a VFAD, its the intake flap connected to a tube thats under your front bumper, is that connected properly? If not the flap will stay closed not allowing air until your other intake ports open.

Let me look up a picture so I can show you what Im talking about....Give me 5 minutes here

 

Tell your mechanic to try removing this part, and cap the vac line that leads to it, have a hunch this may solve your problem....... Worth a shot at this point anyways right