Low idle problem
05-30-2014, 11:36 PM
#1
New Member
Thread Starter
Join Date: May 2014
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
Low idle problem
Ok so ever since I got this car I've had an idle problem. it mostly goes really rough and low after driving it hard for about 10 mins and if I turn it off and try to turn it back on after that it won't start until after about 10 mins of trying. Engine shuts off when I come to a stoplight/sign because it's too low to keep it from dieing at a stop I shift it into neutral and rev the car until I move again. I checked my coils and changed my plugs and wires and also cleaned my throttle body. I'm hoping it's not a compression problem but if it is I wanna make sure exactly what it is so I won't get ripped off. Might rebuild the engine myself with a couple other ppl. Anyone know how to run a compression test the right way or where to get it tested for cheap?! Please help I love this car and I really wanna fix it and not sell
05-31-2014, 09:43 AM
#2
Dum Spiro Spero
iTrader: (2)
Join Date: Nov 2008
Location: Outside Philadelphia, PA
Posts: 862
Likes: 0
Received 0 Likes
on
0 Posts
To do a compression test you need a tester…Do you have a tester? Notice that rotary engines do not use the same tester with piston engines. I suggest taking the car to a dealer/rotary specialist and let them do it.
05-31-2014, 11:53 AM
#3
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 240 Likes
on
110 Posts
This link jumps to a post talking all about the compression test, why you need it, and why you need to have it done at a dealer: https://www.rx8club.com/new-member-f...4/#post4533733
The post after that is all about how to interperet the compression scores.
The post after that is all about how to interperet the compression scores.
05-31-2014, 12:02 PM
#4
You can get a general sense of the health of the motor with a regular compression tester. It's not as accurate as a rotary specific test but it'll tell you if you have a bad motor.
Procedure:
Drive the car around the block a few times to get it warmed up, then pull the wheel and pull out the leading plugs on the front and back housing and disconnect the e-shaft sensor. Get a standard compression tester and pull the schrader valve out of the end of the hose and install the hose in the front housing. Have an assistant hold the throttle open and crank the engine over while you watch the compression tester. You should see three distinct bumps as each rotor face goes by; the bumps should be even. Repeat on the rear rotor. If you see two low bumps followed by one higher or just one bump you likely have a bad seal in the motor. If the bumps are even then re-install the schrader valve and repeat the test but note the pressure. Anything under 98 PSI indicates worn seals, and is the bottom end of Mazda's acceptable range. The engine will start and run fairly reliably down to 75 PSI though.
This video shows the procedure on a RX7 with a good front rotor and a bad rear rotor.
Procedure:
Drive the car around the block a few times to get it warmed up, then pull the wheel and pull out the leading plugs on the front and back housing and disconnect the e-shaft sensor. Get a standard compression tester and pull the schrader valve out of the end of the hose and install the hose in the front housing. Have an assistant hold the throttle open and crank the engine over while you watch the compression tester. You should see three distinct bumps as each rotor face goes by; the bumps should be even. Repeat on the rear rotor. If you see two low bumps followed by one higher or just one bump you likely have a bad seal in the motor. If the bumps are even then re-install the schrader valve and repeat the test but note the pressure. Anything under 98 PSI indicates worn seals, and is the bottom end of Mazda's acceptable range. The engine will start and run fairly reliably down to 75 PSI though.
This video shows the procedure on a RX7 with a good front rotor and a bad rear rotor.
06-01-2014, 01:03 PM
#5
New Member
Thread Starter
Join Date: May 2014
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
Ok so ever since I got this car I've had an idle problem. it mostly goes really rough and low after driving it hard for about 10 mins and if I turn it off and try to turn it back on after that it won't start until after about 10 mins of trying. Engine shuts off when I come to a stoplight/sign because it's too low to keep it from dieing at a stop I shift it into neutral and rev the car until I move again. I checked my coils and changed my plugs and wires and also cleaned my throttle body. I'm hoping it's not a compression problem but if it is I wanna make sure exactly what it is so I won't get ripped off. Might rebuild the engine myself with a couple other ppl. Anyone know how to run a compression test the right way or where to get it tested for cheap?! Please help I love this car and I really wanna fix it and not sell
06-01-2014, 01:09 PM
#7
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 240 Likes
on
110 Posts
As low as $90, as high as $250. Typically it's in the $120-$180 range, $150 is really common. If you have a warranty on the engine and the engine fails, and you are covered by the warranty, then the compression test will be free
06-01-2014, 01:37 PM
#8
New Member
Thread Starter
Join Date: May 2014
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
Mines an 04 and the warranty is long gone but I'm almost desperate to find the problem id probably spend nomore than $250 and that's money going to MAYBE find the problem :p
Thread
Thread Starter
Forum
Replies
Last Post
xAgyex
Series I Trouble Shooting
19
11-13-2023 07:51 AM