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What to do with a "weak" engine?

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Old 12-16-2008, 08:12 AM
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What to do with a "weak" engine?

So recently I recorded my gas mileage dropping from 20 mpg combined to about 17mpg combined. I recorded my highway mileage as not being able to hit 20mpg anymore. My power output has diminished to around the 160whp mark with an exhaust, AP, and new coils.

I took my car into the dealer. I bitched and moaned and complained my way into MNAO ordering an engine compression/cleaning under the extended 8 year warranty as a "one time show of goodwill". Yes my car is out of the 5 year powertrain warranty now. The results came back with rotor one between 705-710kpa and rotor two 710-715 kpa of compression adjusted to 250rpms. Mazda rates this as a "8 out of10"... i rate it as **** as the thing is performing craptacularly and not close to a new engine around 850kpa.


So here i am, stuck with a car I've always loved and had plans of adding some pricey mods too - but probably couldn't even beat a stock Mazda 3s in a straightline and gets the gas mileage of a Hummer. I don't think I can justify dropping $2k on wheels on a car thats slower then an econobox. I sure as hell can't justify dropping $6k on a FI kit on an engine thats just about dead.

What do you do with a weak engine? Run the **** out of it until it fails compeltely? Premix which should help the compression but delay the inevitable? Suck it up and live with it? Sell the car while you have documentation the engine is "normal"?


Maybe i'm just in a bad mood. Maybe the world isn't coming to an end. Maybe for some reason I'm just being an emo little baby these last few days.... maybe.... maybe...


oh yea, and I think i might have just got the last start out of my 3 year old battery this morning...
Old 12-16-2008, 08:14 AM
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fix up the body (aero styling) custom wheels, and try getting sponsor for engine upgrades! or just drop a 20b in the bitch,
Old 12-16-2008, 08:26 AM
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r0tor, i feel the same as you (and I bet alot of members do also.) With everything coming out in the next year there are alot of options.

At the moment i like no car payments though, but do have my eye on a couple things. So in the end it depends on what you want long term, same car with upgrades or different car, both will cost you.
Old 12-16-2008, 10:00 AM
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I hate to say it, but I'd dump it while its still running OKAY. Depending on your equity/inequity I would just find a newer 8 and trade it in. Do you still owe money?
Old 12-16-2008, 10:20 AM
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Have every metal part on the engine chromed. Every hotrodder knows, "if it don't go, chrome it!"

-1.3L
Old 12-16-2008, 11:50 AM
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trade it in for a slightly newer rx8. make the salesman believe thats your reason. spend $1000 and get your 40whp back.

if only 40whp was that cheap to get in general.
Old 12-16-2008, 12:04 PM
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Originally Posted by kersh4w
trade it in for a slightly newer rx8. make the salesman believe thats your reason. spend $1000 and get your 40whp back.

if only 40whp was that cheap to get in general.
Its cheaper, nitrous
Old 12-16-2008, 12:11 PM
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trry taking it to the track and reving the crap out of it
Old 12-16-2008, 12:20 PM
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Out of curiosity, what is the likely cause of this kind of loss of compression in an 8? A bad apex seal would be a lot worse wouldn't it? Is it a weakening of the seal between the side of the rotors and the housing?
Old 12-16-2008, 12:38 PM
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Get a motor from a yard, drop it in and rebuild your current motor.

Then, not only will you have your power back, you have an insurance policy and can breathe easy about playing with it.

Of course, you do realize that your compression numbers are actually OK, right?
Old 12-16-2008, 12:54 PM
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OP- are you sure your not losing power from plugs or coils? Are you in high elevation in PA, my 8 can hardly break 80 mph when Im above 5000 feet.
Old 12-16-2008, 01:26 PM
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Originally Posted by MazdaManiac
Of course, you do realize that your compression numbers are actually OK, right?
new high flow cat, new plugs, BHR ignition... if the compression is not the culprit, what is?!?!?
Old 12-16-2008, 01:38 PM
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take a trip to Puerto Rico and find a nice 20B or 26B or RX7 motor laying around(yeah they are everywhere down there) and swap that thing in.......if not just drive it hard and see what happens
Old 12-16-2008, 01:47 PM
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What was your output prior to the swaps? Everything is reconnected correctly (plugs/wires?). What do the graphs look like?
Old 12-16-2008, 02:03 PM
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OP- Over the summer, my car did the same. I honestly though that was it, It had NO POWER at all, litterally I was doing 0-60 in 12-13 seconds. My car was making a knocking noise, the cel was flashing, and I was getting about horrendous gas mileage.

Took to the dealer immediatly demanding a compression test all freaked out, turns out my cat was clogged (loss of power), My ignition wires came loose from age (engine knocking), and I needed new spark plugs ( Misfire code).

After leaving the shop from those repairs, my car felt the same as day #1.
Old 12-16-2008, 03:14 PM
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What kind of high flow CAT...some have failed in as short as 2-3weeks.....might want to check that
Old 12-16-2008, 03:23 PM
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Originally Posted by dannobre
What kind of high flow CAT...some have failed in as short as 2-3weeks.....might want to check that
and that would CAUSE A LOSS OF POWER........


We're geniuses.
Old 12-16-2008, 04:19 PM
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Originally Posted by Renesis07
OP- are you sure your not losing power from plugs or coils? Are you in high elevation in PA, my 8 can hardly break 80 mph when Im above 5000 feet.
im driving out to california on the 27th. i can't wait to see if I can feel a difference there.
Old 12-16-2008, 04:26 PM
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Originally Posted by exsequor
im driving out to california on the 27th. i can't wait to see if I can feel a difference there.
If you dont feel a difference then theres something wrong with your car lol


Literally, going over the mountain by Lake Tahoe on I80, I had to leave my car in 4th to keep going, it didnt have enough power at 80mph in 6th to maintain speed, thats how big of a dif at 8000 feet my car was.
Old 12-16-2008, 04:48 PM
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sold the 8... :(
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i vote get the cat checked
Old 12-16-2008, 04:51 PM
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Originally Posted by 05rex8
i vote get the cat checked
I have to agree.
Old 12-16-2008, 05:17 PM
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Originally Posted by r0tor
oh yea, and I think i might have just got the last start out of my 3 year old battery this morning...

So after I bought a new battery and installed it, I looked at the old one and noticed its not a maintenance-free battery and the electrolyte levels were low.... who the hell puts a maintenance battery on a car anymore?!?!?!?

Old 12-16-2008, 05:19 PM
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oh, and i vote not a cat problem since this is the 3rd one in 2 months its had (1 blown, 1 OEM, and 1 new RP)
Old 12-16-2008, 06:51 PM
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just get a catless midpipe and don't have to worry about any cat problem!!!! haha
Old 12-16-2008, 09:51 PM
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Put in a VTAC 3000, of course.



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