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speedjunkie · Postby **speedjunkie** » Mon Oct 04, 2010 9:14

Dave, something important to remember, did you have the engine warmed to operating temp? You'll get higher/more accurate readings.

If you're not seeing any other symptoms of a nearly blown engine, I wouldn't jump too fast to that conclusion. Does it flood at all?

chickenwafer · Postby **chickenwafer** » Mon Oct 04, 2010 9:14

Right now is doesn't have "blown motor" symptoms, it just lacks some power. I never could tell because I thought my FD was quick, until Matt took me for a ride in his

. I never had anything to compare it to really. I has never flooded, and it always starts within a few seconds of cranking.

The engine wasn't fully warm, but pretty warm. I started it up and let it idle for 3 minuets then checked compression. I didn't want it to get too hot so I would burn my arm when I was pulling the plugs LOL.

I'm leaning towards thinking the fitting on the compression tester wasn't tightened in enough and caused air to leak past it. I could only get it hand tight.

Chance · Postby **Chance** » Mon Oct 04, 2010 9:14

what was the compression reading? And which spark plug holes did you do the tester in?

chickenwafer · Postby **chickenwafer** » Mon Oct 04, 2010 9:14

75psi was the average. I used the leading plug hole. Engine was warm but fully.

Chance · Postby **Chance** » Mon Oct 04, 2010 9:14

You need to do it in the trailing spark plug holes and do it with the gas pedal pushed all the way down.

chickenwafer · Postby **chickenwafer** » Tue Oct 05, 2010 9:14

I puled the fuel pump fuse and EGI relay so there was no fuel or spark. Holding the pedal down at that point wouldn't help.

I've always done compression test in the leading hole and never had any issues

Chance · Postby **Chance** » Wed Oct 06, 2010 9:14

suposedly, the right way to do it is with throttle plates open, dont ****ing ask me why I don't get it

chickenwafer · Postby **chickenwafer** » Wed Oct 06, 2010 9:14

The only thing I would guess why is the theory would be with the throttle plates open more air can enter the motor. But that's why there's an idle air bypass. If it provides enough air for the motor to start, then why wouldn't it provide enough for a compression test? The engine is only spinning at like 250rpm anyways.

speedjunkie · Postby **speedjunkie** » Thu Oct 07, 2010 9:14

Weird. Yeah warm is good, exactly for the no-burning reason haha. I still wonder why you got such low readings.

Maybe open the throttle plates anyway, just in case. You never know with these things. Pour some oil down into the engine THEN do the compression test LOL.

iani1.1 · Postby **iani1.1** » Fri Oct 08, 2010 9:14

speedjunkie wrote: Pour some oil down into the engine THEN do the compression test LOL.

you can do that just like a wet compression test. you just gotta squirt a little bit of oil in each face of the rotor.

chickenwafer · Postby **chickenwafer** » Fri Oct 08, 2010 9:14

Ya I've heard of doing that, and with a rotary it's actually a good idea since it does receive oil by the OMP or premix during the combustion cycle, so a "wet" compression test will yield more accurate results. The problem is getting the correct amount on oil in there...too much and you can easily inflate your compression numbers.

iani1.1 · Postby **iani1.1** » Fri Oct 08, 2010 9:14

a teaspoon on each face of the rotor is enough to get more accurate readings. i remember doing it while in tech school.

chickenwafer · Postby **chickenwafer** » Fri Oct 08, 2010 9:14

^They actually taught you about Rotaries???!!!

When I was at UTI they went over rotaries for about 10 minuets. It consisted of "Only Mazda uses these engines, you'll never work on them, they suck".... LOL

speedjunkie · Postby **speedjunkie** » Sat Oct 09, 2010 9:14

^Did you tell them you couldn't believe you were attending a school called Urinary Tract Infection? LOL

When Simon's engine blew a couple years ago, I think he had only 1 apex seal remaining. We dumped transmission fluid down into the engine and push started it, and it would run as long as you kept it above 1500rpm. Man I love rotaries. LOL

iani1.1 · Postby **iani1.1** » Sat Oct 09, 2010 9:14

chickenwafer wrote:^They actually taught you about Rotaries???!!!

When I was at UTI they went over rotaries for about 10 minuets. It consisted of "Only Mazda uses these engines, you'll never work on them, they suck".... LOL

lol i went through the same 10mins of bs. i was just experimenting with a wet compression test on my car. you get a little more accurate reading due to the fact that it simulates oil being injected into the chamber.

i went to lincoln college of technology formerly dadc. kinda of a waste of money and time imo. except for fuel and emissions class and advance electrical. shit was awesome.

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