I posted a few days ago about my slow TII and most people said to do a compression check. I took my car into my Auto Mechanics class today and did a compression test and I got three even pulses from both rotors. 28 PSI EACH! Am I doing this wrong or what? You are supposed to hold the pressure releif valve when testing right? I tried doing it without holding it and the pressure just built up to like 80 PSI. Help me out, I'm taking it back in tomorrow to re-test. That motor shouldn't even be running with 28 PSI.


Also I noticed the spark plugs were a little loose when I was removing them. As I drove home I noticed a HUGE power increase. How much would loose spark plugs slow me down?

EDIT: Also how do you check gap clearance on these Rotary Sparkplugs?

 

well some testers with a realase valve dont work right like that, you need a tester that has a shrader valve in it( one like a tire),and you remove that valve.so the presure replaes back intot the engine....
but if it built up to 80 then thats the highest compression out of all 3 faces on that rotor. which is pretty low...

rotary plugs from NGK BUREQ9 BUREQ7 ( i think thats the number?) are designed to be gapped corectly. looking at them i dont see how you could gap theres nothing to bend anyways haha....

 

if your spark plugs are loose, you're losing compression through the plug hole...that's why you felt a difference in power after you tightened the plugs. you restored that compression. when you recheck compression tomorrow, make sure the plugs that you don't take out are tight.

 

was the car at wide open throttle?

 

when i did the comp check? no, should it have been?

 

^^ i hope he was not running it at WOT while doing a compression test.... WTF

 

I doubt you would get 28psi then 80psi on cumulative.

Something was wrong.

I'd day you'll see around 70-75 psi pulses when done right.

Here is what we've done to my car.
Run it to warm/avg running temp.
Shut off and let sit for like 10 mintues so you don't burn yourself.
remove top trailing spark plug.
remove ingition fuses
someone puts the pedal to the floor(WOT) then cranks
person holding the pressure guage holds in the release valve and watches pulses.

 

how big of a difference would the WOT thing make?

 

Are you supposed to be at WOT? I've never heard that before.
Also, the plugs are BUR9EQ/BUR7EQ

 

The plugs dont need to be gapped right?

 

the vent on your gauge, does it vent outside, or does it bent back into the spark plug hole.. if it vents outside then it wont build up pressure to proper readings.

lol i allways get where hte letters number goes in the plug name haha..

 

damn, i dont think our shop has one that vents back into the housing...is that a rotary specific thing?

 

well see with the valve open to the ousside when compressed air goes in, it just shoots right out the open vent hole ( reason your only seeing 28 psi)

where as if it vents back inside, the pressure inside the housing maintains ( builds to around 80, judjing by your case) then it drops when the rotor moves past and the next compression cycle begins.... so u would see pulses,, of 80...80..80 or something like that...

ive found a few old skool comp gauges my dad has have the valve in he bottom. like i was talking about.

so pretty much with this guage u have, u can only test the highest compression out of the 3 faces, but sometimes a damaged seal can give you high comp in 1 face and two low ones in the other, but yours wouldnt see the low ones....

 

wait are you using a piston compression tester or a rotary compression tester, i think u get different result, i think this was mention in an old posting.

 

****...any other way to test?

 

well, does the car run ok? if the car runs fine, and your just curious how much compresson its making max, use hte tester with the valve closed,crank it over for a few seconds, and report the number u get on each rotor.

that will give yout he highest of the 3 face, and if u allready tested with the valve closed and got 80psi on 1 rotor as the highest, then thats pretty low,meaning this motor either has high milage or pretty worn out...

 

well if he was running the car with loose spark plugs for a while i would give it a week of driving with them tourqed to proper spec and check the compression again, it could have lowered compression running it improperly

 

im almost sure that what it was...whats the torque specs for rotary spark plugs?

 

I think its a 1/4 turn past finger tight, or something like that. Be careful not to get it too tight or you will cross-thread the holes. And no, you dont have to gap them.
Also, I just used a standard 10 buck piston engine compression tester from o'rielly's. I just held in the button, and it went to 90 or so on each face on the front, 5 or so on the rear (seals corbon locked in place)