bryanl

2004 6MT 9/03 build 25k miles

Been misfiring after driving for a distance, the car would bog around 7k, and flash a cel. First time they couldn't find the code, so I replaced the plugs, coils, and wires.

Misfire persisted, this time I drove straight to the dealership and had a tech climb in the car with me, made a right out of the dealership and punched it, and it bogged, so I could turn right back in at the next driveway.

I needed inspection done, along with the milky oil and taillight gaskets, so I dropped it off on Friday to have them do all that plus figure out what the hell was wrong with the misfire.

Over the few days, they flashed it and did that zoom cleaner decarb on it. Car runs the best since I've had her, and I plan on taking on a long trip this weekend to make sure that misfire doesn't come back.

The real question of this story is, is he said he wanted to do a compression check to make sure my engine wasn't shot. The results he got back were:
Chamber 1: 121.08
Chamber 2: 128.02

He said the range was 98-120, anything below 98 would mean it has to go. From other threads, I thought the general idea was to get the compression from each side of the rotor face, but the tech didn't seem to know about that. He said he hooked it up to a machine and it did it. I asked for the cranking RPM, but again I was looked at as if I had an extra head, and said 'there was none, the machine did it'.

Can anyone explain the compression results to me? I appreciate it, thanks

Go48

Basically, you should be looking for another tech who understands the rotary engine. See the attached sheets from the shop manual. He has access to this manual and based on what you say, he has never looked at this section.

As you will see from the manual, and as you probably already know, in order to correctly evaluate the engine compression you need the readings for each face of each rotor and the engine cranking speed during the test. The difference between the compression readings for each face of each rotor, and the difference between the rotor one and rotor two readings will tell you the health of your engine. If the tech doesn't know that, he doesn't understand rotary engines. Take it to a rotary tech and have it done correctly. Where are you located?

bryanl

I'm located outside of Harrisburg, Pa. I went to Freysinger Mazda on the Carlisle pike(noted that you're south central, you might know where that is).

I should say, the service manager looked at me funny when I asked crank speed, not the tech. The tech seemed to not grasp the 3 individual chamber readings, though.

Looking at your shop manual, the spec is the same as he said, and the crank speed is the variable that I need to find out.

You have any other suggestions in the area?

Go48

Bryan,

See the PM I sent you.

Larry

TeamRX8

iTrader: (25)

the starter won't crank fast enough to exceed a 121 minimum reading limit, the engine will meet Mazda's specs but without the actual rpm reading you won't be able to assess the true overall condition