I bought an rx8 which has had a couple of owners previously and has a few mods done to it already. It has two check engine light codes P0126 and P0661 and had no belt on the ac compressor when I got it.

The two codes appear to be the SSV and Low Coolant Temperature. For the SSV I plan to just replace it. For the low coolant temperature, I stuck a thermometer in the coolant overflow on top of the radiator and the temp was still at 155F after 15 minutes of idle in 90 degree weather.

Previous owner put a new aluminum radiator and two very powerful radiator fans in that are constantly on regardless of temp. I'm wondering if the thermostat is stuck open and needs to be replaced, or if the fans and radiator are just that powerful?

For the ac compressor, I checked to see if the clutch and pulley were good and put a belt on since there was none. It all turns properly but has warm air, is the next step to try and recharge it?

Thanks

 

For the A/C does the idle dip when the compressor clutch engages? It either needs a charge or a fix to the compressor clutch or clutch coil. If idle dips at least the clutch is working ad checking the pressure would be next. If it doesn't dip, it's the clutch/coil/fuse. If the pressure and clutch check out, it could be the HVAC control board in the dash. Not uncommon for solder points to break there. You can confirm with a voltmeter in the A/C compressor clutch coil wire if the unit is energizing it when commanded.

Temperature in the overflow is not the same as actual coolant temp, 155 there probably means 170-180 in the core, so that sorta tracks. I'd investigate the thermostat for sure. Perhaps someone took it out while they also hardwired the fans to run full time (bridged the relay in the fuse box?). Clearly they were concerned about heat.

The SSV is pretty common, there are DIY threads for it.

Rx8help.com for other things I would check/replace on any mew to you RX8.

 

Thanks for the reply lots of great info, really appreciate it. Clutch engages on the compressor when I turn the AC on, clutch plate and pulley both spin by hand as well. Pressure reading is normal on the low side. I'll look into the other steps you mentioned.

I opened up the thermostat housing and found NO thermostat lol, looks like one of the previous owners just deleted it. I put one in and flushed the coolant while I was at it.

After flushing coolant I noticed I was getting some blue smoke out of my exhaust which I haven't noticed before (only driven the car a couple times since I bought it though). Could this be from having the front of the car jacked up so high and oil spilling over somewhere? Car starts perfectly whether hot or cold and made the 4 hour drive home from the purchase without a problem, so I want to hope it's not an engine issue.

Other thought on the blue smoke was:
I heard from the previous owner that the car had a tune on it, (guessing reflash?), and in order to get to the thermostat I had to pull the battery and ECU out. Would pulling battery and ECU reset the tune since it completely loses power, or does it just stay no matter what on the hard drive? I'm pretty noob when it comes to ECU stuff.

 

The tune is still on there, it can't be lost by disconnecting power.

Can you determine if the smoke is oil or fuel or coolant? There's no place for oil to spill over. I would check if you have oil in the intake accordeon tube. It should be dry, but if it's not that a clue.
Does the car have a catalytic converter?

 

I'm not sure yet about the smoke, I don't really know how to tell except by the blue color and maybe smell, is there another way to tell? I'll check the intake tube and see if anything is in there.

The car has a cat just from looking under it today, but I'm not sure if it's gutted or not. I'm thinking since the previous owner deleted the thermostat I wouldn't be surprised if the cat is hollow although there's no CEL code for it. I'll pull it tomorrow and take a look to see what the inside looks like.

 

I pulled the cat and it was completely hollowed out, no honeycomb or material at all. Shouldn't that give me a check engine code? Drove it 4 hours home, have idled it a few times, but no codes related to that. At least the cat wasn't plugged up though.

Cat Side

Other side closest to rear of car

 

It would throw a CEL unless the previous owner masked it with tuning software...

Is that actually a hollow cat or a midpipe with a resonator?
Either way... yeah, I guess it's not plugged

 

I'm not sure what the OEM cat looks like, tried to find some pics on Google but it wasn't too helpful, all aftermarket replacement pics.

Here's a pic of it, does this look like the OEM cat?

 

Yep that's original equipment. One other thing to check while you have it apart, is if there aren't pieces of cat downstream in the exhaust pipe. If its been hollowed out because it melted, they might not have realized pieces are lodged downstream, which would cause backpressure and misfires/heat.

Usually loose pieces like that can be heard rattling if you shake the exhaust.

 

I checked the exhaust, no issues luckily.

I went to replace the old SSV and my new SSV didn't come with any hardware (I got it from atkins rotary as a take-off part for a good price). The old bolts don't fit the new SSV, any idea what length/thread of bolt or part number I need so that the bolts fit the new style SSV? Couple pics below:

 

In case anyone finds this in the future, the bolt is M6-1.0 x 40mm. I got one from home depot and it worked perfectly in the new larger top hole. The bottom bolt was re-useable. I also broke a bolt off inside the pulley for the alternator belt and was able to use the same type of bolt M6-1.0 after i cut it down to size.

Car seems to work with no engine codes now, so just chasing down the A/C compressor problems now.

 

I had a bunch of A/C issues mainly due to condenser leak. I stretched its life with a gas refill with sealant on a A/C shop here 2 times (30 USD each) and it lasted like another year. Finally changed the condenser for 100 bucks or sthg and it was freezing cold. Then compressor blew on a hot track day and now I have no A/C
Its still hot but autumn is almost here and 300 USD for the new compressor (its same as Miata btw) its not worth it.