MinkHeel

I've been having issues with my 2006 RX8 for a few weeks. Basically, when it gets hot it started surging under even minor acceleration -- felt like the computer was cutting the throttle. Replaced coils, plugs, wires. Replaced coolant and changed oil. [All of these needed doing anyway]. Not fixed. Took it to dealership for a compression test, it failed and they installed a new engine last Friday/Monday/Tuesday. When the mechanic test drove it on Tuesday, the weird surging was still there when it got hot. Various consultations with Mazda ensued. Checked "ground" issues, sensors and other stuff. No fix. The latest educated guess is that the PCM is bad. So, they are installing a new PCM on Friday. Dealership (Montgomery Mazda in Charlotte, NC -- which is great) told me today the PCM has an 8-year/80,000 mile warranty [my car has about 79,550 miles, so WHEW!]. This is the first I have ever heard/read of a longer than 60,000 mile warranty on the PCM. I searched here and googled to see if I missed it, but got nothing.

Anyone else had PCM failure issues?

[Also, the dealership told me you have to have 2 keys to program the new PCM, I only have 1 key, so I have to buy a new one. Not a big deal but curious about that too if anyone can enlighten me.]

Eager to get my baby back -- hopefully with a new bounce in her step.

Bladecutter

What rpm range does the surging happen in?
I would bet that its something else, like the SSV valve, or a faulty fuel injector.

I bet its still there after the PCM change.

Also, dd you reset the ESS profile (stomp brake pedal 20x), and clean your MAF?

BC.

RIWWP

iTrader: (2)

"when hot" could easily be a fuel pump issue as well.

I was unaware of any coverage for the PCM beyond bumper to bumper, however it's possible that it's linked to emissions and covered there? Federal Emissions warranty is the only one I'm aware of that is 8yr 80,000 miles.


Yes, they aren't just blowing smoke at you about the key thing. Fortunately, with the PCM going in under warranty, they won't be able to rape you in the wallet like usual for re-coding keys. Usually they charge something like $150 a key, and $200 to reprogram. You can code a 3rd key yourself at home if you have 2, but dropping to 1 key leaves you at the dealer's mercy unless you can find a locksmith with the PCM equipment. If a locksmith has the equipment, they usually drastically undercut dealer prices.

MinkHeel

Well it wasn't the PCM. Replaced and still acting up. The surging/throttle issue happens at all RPMs from 2000 to 8000 and everywhere in between (though it usually happens on the lower end -- 2500-3000 if it is going to do it). Interestingly, it has never done it when the car is not in gear (MT). Once it was surging and I pulled over, took it out of gear and reved the engine up to 8000 and held it there and it did fine. Then put it in gear and happened again immediately. Clutch or transmission problem?

Dealership has checked the sensors as well (as least they say they have).

RIWWP

iTrader: (2)

Do you mind going back and fully describing everything that is happening when this is occuring?

How long has the engine been running, how long driving, ambient temperatures, what kind of throttle load are you using, what gears, etc... Plus, what exactly is it doing. Describe it in a sentence or a paragraph rather than a single word like "surging".

Be specific and clear. Don't leave room for misinterpretation or misunderstanding.

nycgps

iTrader: (1)

Pcm is part of emission control system so its always covered under the emission warranty.

Well, u should ask them to check the fuel pump

MinkHeel

When I starting thinking about how to describe it more specifically, one of the things I was going to say was "it sort of feels the same as when you are about to run out of gas" -- the throttle response just stops and if you try to give it more gas it "surges" (a slight burst then back down, then back up and back down, etc.). So, accelerating and suddenly it is like your foot slipped off the gas a sudden loss of throttle and the transmission pulling the engine back.

The dealer discovered the problem -- the "sock" in my fuel pump was clogged by some unknown substance. The tech described it as being like metal filings almost that had hardened into a near cement like consistency. So when things got hot it was like I was out of gas as the fuel pump could not suck gas through this blockage. Apparently the head RX8 troubleshooter for Mazda was involved and said he had seen this issue on other cars but never on an RX8 before. Lucky me.

I use Idemitsu Premix (4 oz per tank) and wonder if that could possible have caused this -- but I can't imagine that it did.

Glad to have my RX8 back -- now to break in the new engine.

nycgps

iTrader: (1)

u get those "gunk" with or without premix.

Gasoline might look "clean" to our eyes, but it's actually Full of junk. That small sock down there is just like the air filter we use in our AC, we don't see dust usually right? but it's all around us and it gets trapped on the filter.

RIWWP

iTrader: (2)

The good news is that your filter trapped it, rather than your engine.

MinkHeel

True dat.