Yet another power loss issue...

Jasper_the_2nd · 08-30-2010, 01:02 PM

I've been dealing with this for a while and figured I'd post on here and see if anyone can suggest anything that might speed up the process.

Noticed some lack of power last summer on long drives. Cruise would fluctuate on hills after being on the highway for an hour or so. The dealer hooked it up, but it didn't show anything.
Then a coil went bad (second from the firewall, if I remember right). Car ran like crap, had to wait for the dealership to get their diagnostic computer fixed (even though I was sure it was a coil, wire or plug), never threw a CEL. New coil, new wires, new plugs. Seemed fine but I didn't take any really long drives before parking it for the winter.
This year, first long drive, power issues started again. After half an hour or so (depending on the weather) the engine gets really sluggish, cruise would drop from (for example) 120 kph down to 105-110 on a hill, then climb to 130+, once the engine finally started making power, before coming back down.
Took them two drives to get it to do anything. They picked up a few misfires on coil #3, so I replaced all the remaining coils and put in a new set of plugs. No effect on the issue, although the car does seem a little perkier when it is running normal.
Took the mechanic for another drive, over a hour this time, with the computer hooked up the whole time. He could see the car having issues (the cruise actually gave up at one point, which I'd never seen) and he could even hear the difference from the exhaust (it gets "burbbilly" when it's having it's issue. But still no CEL.
From reading on here I got them to drop the cat and take a look but it seems fine.
They had a theory that it might be the MAF or fuel pump but I can't see how either of them could be temperature related.
Noticed, and pointed out to them, that on a hot day I could take it for a 15 minute drive through town (with no issue) then park it for half an hour, and it would have the issue when I started it back up. That's why I think it might be temperature related.
Had them run a compression test last week. Results (which they said passed) were:
Front rotor: 95 at 225 rpm
Rear rotor: 85 at 225 rpm.

My concern is the rear rotor. When I normalized the 85 for 250 rpm, it is at or below what I read was the min (96.4?) depending on the elevation I entered.

So, any thoughts?

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Jon316G · 08-30-2010, 05:24 PM

Quote:

Originally Posted by Jasper_the_2nd

Front rotor: 95 at 225 rpm
Rear rotor: 85 at 225 rpm.

We need the results for all three rotor facings.
A rotary compression tester will give you them.

Jasper_the_2nd · 08-30-2010, 06:48 PM

I'll see if I can get the numbers for each face from the dealership tomorrow. They only gave me the numbers I posted above.

Spirograph · 08-31-2010, 12:46 AM

Does the rotary compression check process foul plugs? I'm at 50k and about to do a seafoam or mazda foaming cleaner followed by a coil and plug swap. I've never checked the compression and figure I should before I move states. If I do a compression check and it fails then I'll have to replace the plugs/coils and pay for another compression check, but if I do the plug/coil swap first will it foul my new plugs?

Jon316G · 08-31-2010, 03:51 AM

Spirograph- None of the ignition components has anything to do with the compression test.
In fact, you "disable" the ignition system by disconnecting the eccentric shaft positioning sensor.
Also, to perform the compression test, you remove the leading plugs from each rotor to install the transducer.
So feel free to install new coils, wires, and plugs... it won't make a bit of difference when it comes to the compression test.

Spirograph · 08-31-2010, 04:13 AM

Thank you.

JAMinRX8 · 08-31-2010, 08:54 AM

i thought as long as the compression test was above 80, you were fine.

Jon316G · 08-31-2010, 09:01 AM

Quote:

Originally Posted by JAMinRX8

i thought as long as the compression test was above 80, you were fine.

Mazda's minimum spec is 98.6psi (at 250rpm)
Sure... your car can be a little lower and still run.
Besides the compression of each rotor facing, there is also tolerances for the difference between the chambers and rotors.
This is why we need all three rotor facings for each rotor along with rpm.

Jasper_the_2nd · 09-10-2010, 03:07 PM

Ok, much frustration later...

Went back to the dealership to get the numbers per face.
They don't have a rotary compression tester, but Mazda Canada says the numbers are fine....
So they think it is the fuel pump.

In the mean time I called the dealership 40 minutes from here. Asked at least 4 times over 2 phone calls if they had a rotary compression tester. They definitely did. (anyone see where this is going?) So I took time off work and drove over this afternoon (the car driving like crap most of the way (having to gear down to 4th to stay at highway speed on a hill so that Kai wouldn't pull away....)).
Big surprise, no rotary compression tester there either. The guy on the phone must have "asked the wrong tech."

So just put out a request on the local car forums to see if anyone in Nova Scotia has a proper tester....