8 is in trouble. Shutting off when I stop
#1
Registered
Thread Starter
iTrader: (1)
Join Date: May 2012
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
8 is in trouble. Shutting off when I stop
Okay everyone. My 8 is giving me problems. I have done a tune up by changing all plugs, wires, air filter, cleaning MAF sensor, cleaning throttle body, changing fuel pump, checked battery level, checked alternator, and starter check. I did a compression test and it was very consistent across the board. (I will post a pick of the compression slip that the tech gave me.) I have tried pretty much everything but to no avail. The car runs fine up start up and idle but when I stop at a light or sign then I run into to problems; the RPM's drop below 1000rpm's and then it shuts off. I have read the forums with the same issue but no one really offers a solution that they found. Please offer some help. I really don't know what to do anymore.
#2
FULLY SEMI AUTOMATIC
iTrader: (9)
did you disconnect the battery? if so your car is re learning fuel maps iirc and should be fine after a few drive cycles. has this been going on long?
#4
Registered
Thread Starter
iTrader: (1)
Join Date: May 2012
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
Yep. I disconnected them when I changed my front suspension (1 week ago) and when I did my abs sensors and fuel pump(yesterday). Could it really be that simple! How long does this take to relearn?
#5
FULLY SEMI AUTOMATIC
iTrader: (9)
mine doesnt always stall at a light but has in the past. a few drive cycles would clear it up pretty quickly. i dont know what your pics are. comp test?
#7
Registered
iTrader: (1)
Should be obvious but you have bad compression, almost hitting 6.0. If you have a warranty get it replaced while you can.
My assumption of the pictures showing the compression test. The picture is of each rotor face compression, so each peak on the picture is a different face.
My assumption of the pictures showing the compression test. The picture is of each rotor face compression, so each peak on the picture is a different face.
#8
FULLY SEMI AUTOMATIC
iTrader: (9)
ive never seen a comp test like that before. where are you from? was it done at a mazda dealer?
#9
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 239 Likes
on
109 Posts
That's an analog compression test, however it is mostly sufficient since you can see the tips of the wave, which is the peak compression point, and every 3rd peak is the same rotor face. If your cranking RPM is ~220rpm or more, your engine is failing. The symptoms agree with that as well, as your idle speed isn't generating enough compression to remain alive. I would guess that when it shuts off, it's hard to get it fired again for a while, until the engine cools off some.
At 250 cranking RPM, the tips of that compression signal wave needs to be crossing above the 7 kg/cm2 line to not be failing.
At 250 cranking RPM, the tips of that compression signal wave needs to be crossing above the 7 kg/cm2 line to not be failing.
#10
Registered
Thread Starter
iTrader: (1)
Join Date: May 2012
Posts: 40
Likes: 0
Received 0 Likes
on
0 Posts
Are you saying that my engine is failing even though the compression test says otherwise. And when it shuts off then it cranks right back up but it will shut off again unless I keep my foot on the gas or sometimes it just dips under a 1000 then sits fine until I drive again but it ultimately shuts off again when I stop
#11
Registered
iTrader: (1)
No no, we're saying your engine is failing BECAUSE of the compression test. Mazda states that for an engine to be classified as not failing, both rotors need to have a compression of 7.0 kg/cm2 or higher at a cranking speed of 250 rpm.
As you can see in your photos and paper you received, the peaks on both rotors is barely above 6.0, unless the cranking speed is below 220 rpm, your engine failed a compression test, doesn't matter that it was consistant.
What octane are you using, and have you cleaned the ESS, checked for pending codes? Could be the simple fact of what RIWWP said, not good enough compression to keep it's alive while idling.
As you can see in your photos and paper you received, the peaks on both rotors is barely above 6.0, unless the cranking speed is below 220 rpm, your engine failed a compression test, doesn't matter that it was consistant.
What octane are you using, and have you cleaned the ESS, checked for pending codes? Could be the simple fact of what RIWWP said, not good enough compression to keep it's alive while idling.
Last edited by blckninja; 06-09-2014 at 10:48 AM.
#12
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 239 Likes
on
109 Posts
blckninja is correct. Assuming that you have a cranking speed of 220rpm or more, your compression test slip shows that your engine is failing. If you don't know your exact cranking RPM, you need to get it, because if you are under 220rpm, then your engine is not failing (just 'weak') and the issue is elsewhere. However, you addressed everywhere else it might be and have a compression test showing failing scores so......
The failing line at 250rpm is 6.9 kg/cm2
The failing line at 250rpm is 6.9 kg/cm2
#13
Moder8
iTrader: (1)
On the dying at idle.
The re-learn is tough. Best way is start over, disconnect battery. 20 brake stomp for good measure, then just start it and let it sit until the idle comes all the way down. At the very end, you may want to turn on the AC to bump the idle a tad. After that, it has learned to idle, and will learn the rest while you drive.
The re-learn is tough. Best way is start over, disconnect battery. 20 brake stomp for good measure, then just start it and let it sit until the idle comes all the way down. At the very end, you may want to turn on the AC to bump the idle a tad. After that, it has learned to idle, and will learn the rest while you drive.
#15
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 239 Likes
on
109 Posts
Low compression means that there is a lot of air and fuel being unconsumed, blowing by into neighboring faces and getting dumped into the exhaust. This is a random mixture of air and fuel (relatively speaking compared to normal), and the front O2 will be swinging around on AFRs, and the ECU will have a lot more trouble figuring out what fuel trims need to be applied, and what it does figure out will probably be wrong.
#19
Mod Edit:
It's rude to jump in on someone else's conversation with something completely off topic. Please read this announcement: https://www.rx8club.com/new-member-f...or%3E%3C-b%3E/
-RIWWP
It's rude to jump in on someone else's conversation with something completely off topic. Please read this announcement: https://www.rx8club.com/new-member-f...or%3E%3C-b%3E/
-RIWWP
Last edited by RIWWP; 06-09-2014 at 01:52 PM.
#20
Registered
That engine does look like it's failing. It's barely above the minimum acceptable 75 PSI and well below the nominal 110-150.
That said, the battery disconnect and learning mode comments are also correct and generally, you perform an ECU reset after disconnecting or connecting a new battery.
I had the same stalling issue with mine after adding coils and a cat until re-setting the ECU, pretty much every battery swap.
That said, the battery disconnect and learning mode comments are also correct and generally, you perform an ECU reset after disconnecting or connecting a new battery.
I had the same stalling issue with mine after adding coils and a cat until re-setting the ECU, pretty much every battery swap.
Thread
Thread Starter
Forum
Replies
Last Post
TeslaMSI
New Member Forum
11
12-10-2015 01:10 AM