notveryhappyjack

iTrader: (4)

my friends 12a will not hold an idle, everytime the clutch goes in the engine dies. When under acceleration the car shakes / bucks hard as the rpms increse, I haven't heard any weird noises but I have a feeling its the engine.

I have never blown up a engine let alone a rotary what should I look to identifiy if the engine is blown ?

diabolical1

iTrader: (3)

hard to start

poor/rough idle

little-to-no power

smoke

less than 6 good "pssh"-sounds when turning by hand

these are general and most common symptoms.

Rx-7Doctor

iTrader: (13)

And the good news is that it might be just a bad leading ignitor or a huge vacuum leak.

diabolical1

iTrader: (3)

ooops! yeah.. i guess i should have mentioned alternatives, too.

well, to add to what Doc said, timing being off, bad ignition, bad carbie can all manifest in what you describe.

when did the car start acting like that? was it sitting for a while (over a 2 years)? a little recent history might help pinpoint the problem.

notveryhappyjack

iTrader: (4)

i went and changed the spark plugs with some better condition ones and when I went to start the engine it was very difficult, I got it started on about the 5th try and drove it around the block, when the gas pedel is pushed it seems to shake alot (especially around 2-4k rpms) I put it into nutral and reved it to 4k and it was still shaking, then I floored the pedel to 6k and at higher rpm's the engine was not shaking/bucking around at all but rather really smooth.

I'm scratching my head on this one but I think the fuel filter is the next place I will look for a fix since the problem seems to me to be fuel related, maybe clogged fuel filter could be the culpret ?

anyone else have an idea whats is going on here ?

Rx-7Doctor

iTrader: (13)

Did all these symptons occur after the plug install?

notveryhappyjack

iTrader: (4)

recent history

I found this car at my local mazda dealership where I used to work, it was owned by my old boss who is the current mazda service writer. My friend was looking for a car and I showed this one to him and we drove it around and he liked it enough to buy it. The car prolly sat a few months (2-4) before we bought it, it has 190-ish thousand miles on it and was a two owner car before my friend owned it making him the third owner, the first owner who was a older gentelman took good care of the car and kept a big binder of maintence records which were thrown in the trash by the mazda service writer shortly after he bought it It leaks about 1/3 a quart of oil a week right now.

this problem is very recent, my buddie called me today and told me the car just started acting up, he said he was backing out of his parking spot at work and the car stalled on him, when he went to restart it became very hard to start and to keep running, he nursed it home and called me immediatly after....

notveryhappyjack

iTrader: (4)

no doc, problems were going on before I touched it and kept happening after I changed the plugs. the plugs really didn't change much

notveryhappyjack

iTrader: (4)

what makes me wonder is the fact that the engine seems silky smooth at 5-7k rpms with plenty of throttle responce and down low it barly stays running with shity throttle responce.

GregFD3S

notveryhappyjack

iTrader: (4)

thats what I was thinking the second he called me, what tools do I need to do a compression check at home ? since the car doesn't stay running to drive it anywheer.

diabolical1

iTrader: (3)

sit your friend down and have him tell you everything he touched on the car. make sure he's never pulled the distributor for any reasons. makes sure all ignition components are functioning and at least decent.

start checking for vacuum leaks. there is a spot right off the secondary runner for rotor 2 that i've had issues with in the past and it's hard to detect.

GregFD3S

Compression checker (rotary, or you can use piston if you know how), spark plug socket, socket wrench.

First things first... take off your leading spark plugs on both of your rotor housings. Pull off your EGI relay to cut off fuel and ignition.

The least you should have is about 80 PSI on all faces.

876portturbo

iTrader: (4)

The blown motors I have been around are extremly hard to start, usually needing full throttle to fire, and dont pull at all. I'm sure each case is different, but the two I messed with had both dropped rear apex seals, and it was obvious what the problem was. Also when you pull the plugs, your looking for consistent psst,psst,psst. Just my two cents

notveryhappyjack

iTrader: (4)

I didn't check anything when i pulled the plugs, I just swaped them with some new-er ones as I didn't have brand new plugs.

I'm a little confuesed on the compresssion checking, do i take one spark plug out at a time and plug in the checker then crank it over ? do i take all 4 plugs out ? what if the car stars up ? sorry if this is kinda a newb question but this has never come up on my own car since I have owned it so I haven't had to learn how to test compression.

happy-nead

Have you checked for fuel?

fluffysheap

To keep the car from starting up (or trying to ignite the mixture that you are blowing out the plug holes) you should remove all the plug wires.

If you are just checking "blown" or "not blown" you don't really need any equipment at all as long as you have at least one working ear. Just crank it with the throttle held open, one plug on each rotor out and all the plug wires disconnected. A good rotor face goes "CHUFF!" as it goes by. A bad one goes "pff." Since it's very rare to blow all six faces at once (especially on a non turbo car) you cannot really mix this up. Plus if you want something to compare to, listen to what your car does on the same test. Sometimes it takes a little while (10 seconds) for the full compression to develop.

I'm thinking ignition myself, probably leading ignitor.

Hades12

I put my thumb over the hole,

You will feel 3 pulses if you feel one with two kind of pulls then the seals are gone.



Check for good spark on all 4 plug wires, A burned cap/ rotor button can have the simptons you are seeing.

A fuel filter will have the oposite simptons, run ok down low but stumble up top.

rotariesrule

a good motor sounds like this when cranking with the spark plugs out: chug , chug, chug, chug, chug, chug , chug, chug, chug, chug

a bad motor goes: chug, chug, nothing, chug, chug, nothing, chug, chug, nothing.

a really bad motor goes: @#$%7, #$%^#, $#@%^$#

shmacklepap

iTrader: (15)

What if it goes chug, chug, shhhhhhhh, chug, chug, shhhhhh

chuga chuga wooooo woooooo!!! I think I'm screwed......

aa35199

iTrader: (1)

my 7 had a very similar problem with the exact same symptoms, only difference was my cats glowed cherry red while this was happening. Try dumping alot of carb cleaner down the carb while its running, then when its warm turn the motor off and spray some more in and let it sit. I went through a whole can, but it fixed my barely running engine like magic. A very wise man that worked at advance auto parts once told me, try the cheap stuff first when trouble shooting.

notveryhappyjack

iTrader: (4)

will some show me where the leading ignitor is located ?
i think that is the problem

notveryhappyjack

iTrader: (4)

I think I found them, can someone verify the ignitors are located on the front of the distrubtor ? there are two of them and they have a mitsu emblem on them part # j109 ?

josh...just josh

if the old j109 is bad is the only symptom no spark? or could it be weak spark too?

Nicholas P.

iTrader: (1)

The two coke can looking objects that have spark plugs going to the distrubtor cap are called coils. the ignitor is inside the distrubtor. I think the leading coil is on the front from the drivers view and the trailing coil is on the rear.