Low compression on all faces?

dave5678 · 06-16-2010, 06:54 AM

Hey guys. Car has been sitting in the garage for a couple months because I've been searching and reading non stop. Anyways my compression tester has yet to arrive so I did the poor man's again and my rear rotor has 3 pulses that are very weak. Diagnosis? Personally I have no idea... I've been trying everything figured I would ask before I sell this for pennies. It starts easily and idles until it starts warming up then it seems to go super rich and then the backfiring starts and it dies. One of the other weird things is I can pull the fuel pump relay and it will not die. I checked to see if it was wired differently but no luck there. Any help is greatly appreciated, Thank you!

dregg100 · 08-23-2010, 03:21 PM

poor mans test? you mean listen to the pulses? that doesnt mean jack. get a real compression tester and report back with results.

hades · 08-23-2010, 05:45 PM

1. listen to above
2. do it with a good charged battery
3. where do you live so we can tell you which shop to take it to?

rx4ur7 · 10-13-2010, 11:43 AM

Poor mans test is fine when you have heard hundreds if not thousands of these. Any of us that have done so many of these can tell within a few points of what the tester is going to say.

At least you know if you have a major issue if they are not equal and match for both rotors. Seemingly low on all faces can be slow cranking, make sure battery and connections are good and it is cranking over 200rpm.

But for the DIYer and you do not want to spend the money for the mazda type tester the standard tester with schrader valve removed will give you a good idea.

Yes of course the rotary tester is the best. I do not know about the aftermarket tester and if it gives you the chart for different cranking speeds, Mazda does so that if the battery is weak you still get a proper reading.
From my experience if the pulses are equal on both rotors but the rear sounds weaker and you have high mileage, rear seal springs are probably tired. And it is time to start packing away piles of green paper.

Have you pulled any codes?
How many miles?

06-16-2010, 06:54 AM	#1
dave5678 The Newbie Join Date: Dec 2009 Posts: 18 Rep Power: 0	Low compression on all faces? Hey guys. Car has been sitting in the garage for a couple months because I've been searching and reading non stop. Anyways my compression tester has yet to arrive so I did the poor man's again and my rear rotor has 3 pulses that are very weak. Diagnosis? Personally I have no idea... I've been trying everything figured I would ask before I sell this for pennies. It starts easily and idles until it starts warming up then it seems to go super rich and then the backfiring starts and it dies. One of the other weird things is I can pull the fuel pump relay and it will not die. I checked to see if it was wired differently but no luck there. Any help is greatly appreciated, Thank you! __________________ 1992 Mazda RX-7 Type-R(2+2) FD3S 1992 BMW 525i Wagon - For the daily Autobahn grind

08-23-2010, 03:21 PM	#2
dregg100 Rotary Fanatic Join Date: Feb 2008 Posts: 432 Rep Power: 18	poor mans test? you mean listen to the pulses? that doesnt mean jack. get a real compression tester and report back with results. __________________ '93 SSM Touring-S475... '87 Tii-LS1/T56

08-23-2010, 05:45 PM	#3
hades Rotary Fanatic Join Date: Mar 2008 Location: Freedom Land Posts: 316 Rep Power: 18	1. listen to above 2. do it with a good charged battery 3. where do you live so we can tell you which shop to take it to? __________________ This is going to tear

10-13-2010, 11:43 AM	#4
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson Posts: 231 Rep Power: 17	Poor mans test is fine when you have heard hundreds if not thousands of these. Any of us that have done so many of these can tell within a few points of what the tester is going to say. At least you know if you have a major issue if they are not equal and match for both rotors. Seemingly low on all faces can be slow cranking, make sure battery and connections are good and it is cranking over 200rpm. But for the DIYer and you do not want to spend the money for the mazda type tester the standard tester with schrader valve removed will give you a good idea. Yes of course the rotary tester is the best. I do not know about the aftermarket tester and if it gives you the chart for different cranking speeds, Mazda does so that if the battery is weak you still get a proper reading. From my experience if the pulses are equal on both rotors but the rear sounds weaker and you have high mileage, rear seal springs are probably tired. And it is time to start packing away piles of green paper. Have you pulled any codes? How many miles? Last edited by rx4ur7; 10-13-2010 at 11:48 AM.