Compression down, MPG up? Suspect side seal compromised please advise!
Thread Starter
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
I couldn't even finish the water trick because it wouldn't run while injecting into the front rotor. I didn't even bother checking compression.
talking head
Joined: Apr 2008
Posts: 2,775
Likes: 15
From: Perth, WA, OZ
So I decided to try the stream cleaning trick.....
I used the "one rotor at a time methodology" figuring I would do the rear first, and that would make the front easier once it was un-stuck...no dice.
First thing I noticed was the vac nipple pictured below, when I went to put the line on that nipple. It appeared fine until I rotated it to remove it, then I saw that it was trashed.
I proceeded to hook up the line, rev the engine to 2500 and run 750ml of water through, without incident, it smoked a bit, and steamed consistently but all was well. Until I removed the line and it stalled.
I was able to get it started and rigged the pedal to 2500 and proceeded to hook the line up to the top most nipple on the front side of the uim (which normally goes to my bov). As soon as I stated feeding it water, it began struggling and shortly died. This time refusing to start until I used the fuel cut switch.
Now it won't even idle with everything hooked back up, so I figured I'd come type this up.
Perhaps the rear spark plugs a are covered in carbon and unable to sustain the cleaning of the front rotor?
New theory: perhaps that nipple being broken caused a lean condition that did actual damage to the rear rotor?
I used the "one rotor at a time methodology" figuring I would do the rear first, and that would make the front easier once it was un-stuck...no dice.
First thing I noticed was the vac nipple pictured below, when I went to put the line on that nipple. It appeared fine until I rotated it to remove it, then I saw that it was trashed.
I proceeded to hook up the line, rev the engine to 2500 and run 750ml of water through, without incident, it smoked a bit, and steamed consistently but all was well. Until I removed the line and it stalled.
I was able to get it started and rigged the pedal to 2500 and proceeded to hook the line up to the top most nipple on the front side of the uim (which normally goes to my bov). As soon as I stated feeding it water, it began struggling and shortly died. This time refusing to start until I used the fuel cut switch.
Now it won't even idle with everything hooked back up, so I figured I'd come type this up.
Perhaps the rear spark plugs a are covered in carbon and unable to sustain the cleaning of the front rotor?
New theory: perhaps that nipple being broken caused a lean condition that did actual damage to the rear rotor?
im still under impression that rotor it stalled on has a shitty plug..
install the new plugs again .. see what gives
PS... UIM location will still feed both rotors as goes to common mezzanine .. so expect a stall
Last edited by bumpstart; Jan 2, 2013 at 01:15 AM. Reason: PS
Thread Starter
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
Hmm... well if that's the case, I guess it would stall. What location only feeds the front?
I let her warm up before driving to work today, she idled find in the driveway (16"hg @ 800rpm) but stalled at a stop light about halfway there. I was able to restart without a problem.
I will pull the plugs later today hopefully.
I let her warm up before driving to work today, she idled find in the driveway (16"hg @ 800rpm) but stalled at a stop light about halfway there. I was able to restart without a problem.
I will pull the plugs later today hopefully.
Joined: Mar 2001
Posts: 31,835
Likes: 3,233
From: https://www2.mazda.com/en/100th/
i did the water thing to my Rx8 and i decided to add a little air to the water mix, so i build a little carburetor/wine decanter.
i used a vacuum T, with one end going into the water and the other just saw air. i brought a couple of weber idle jets with me, and this let me "tune" the thing a little. it worked best with the air end open, and a 80 idle jet in the water. if you don't have weber stuff around, an 80 jet = .8mm, and its not super picky anyways.
i did vary it a little, but i could actually do the water thing without a flashing check engine light. although i did go overboard, and the ECU logged 1221 misfires! who knew it could count that high?
i used a vacuum T, with one end going into the water and the other just saw air. i brought a couple of weber idle jets with me, and this let me "tune" the thing a little. it worked best with the air end open, and a 80 idle jet in the water. if you don't have weber stuff around, an 80 jet = .8mm, and its not super picky anyways.
i did vary it a little, but i could actually do the water thing without a flashing check engine light. although i did go overboard, and the ECU logged 1221 misfires! who knew it could count that high?
Rotary Enthusiast
Joined: Mar 2002
Posts: 818
Likes: 1
From: Phoenix
I wouldn't mess with water.
Mazda developed a de-carbon procedure for the RX8 that works just as well on the RX7's. It involves using a Mazda cleaning product that sits on the rotors for a while, then burns off when you start the car. Your local Mazda dealer probably has it in stock, it's called Zoom Cleaner.
DIY: Mazda Zoom Power Engine Cleaner (Engine Cleaning, Seaform) - RX8Club.com
Mazda developed a de-carbon procedure for the RX8 that works just as well on the RX7's. It involves using a Mazda cleaning product that sits on the rotors for a while, then burns off when you start the car. Your local Mazda dealer probably has it in stock, it's called Zoom Cleaner.
DIY: Mazda Zoom Power Engine Cleaner (Engine Cleaning, Seaform) - RX8Club.com
Thread Starter
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
Little update:
I've been too busy to pull the plugs and get a friend to do a compression test, but I did try reving to 8k+ (in first gear) as soon as I did it began spewing a dark cloud of smoke, somewhere between black(fuel) and blue(oil). The smoke went away as soon as rpm dropped below 8k.
Doing this seems to have had no affect on idle or vacuum.
Next I will pull the plugs, inspect them, and swap plug wires and see what that does.
After that, sea foam or perhaps this Zoom cleaner.
I've been too busy to pull the plugs and get a friend to do a compression test, but I did try reving to 8k+ (in first gear) as soon as I did it began spewing a dark cloud of smoke, somewhere between black(fuel) and blue(oil). The smoke went away as soon as rpm dropped below 8k.
Doing this seems to have had no affect on idle or vacuum.
Next I will pull the plugs, inspect them, and swap plug wires and see what that does.
After that, sea foam or perhaps this Zoom cleaner.
talking head
Joined: Apr 2008
Posts: 2,775
Likes: 15
From: Perth, WA, OZ
I wouldn't mess with water.
Mazda developed a de-carbon procedure for the RX8 that works just as well on the RX7's. It involves using a Mazda cleaning product that sits on the rotors for a while, then burns off when you start the car. Your local Mazda dealer probably has it in stock, it's called Zoom Cleaner.
DIY: Mazda Zoom Power Engine Cleaner (Engine Cleaning, Seaform) - RX8Club.com
Mazda developed a de-carbon procedure for the RX8 that works just as well on the RX7's. It involves using a Mazda cleaning product that sits on the rotors for a while, then burns off when you start the car. Your local Mazda dealer probably has it in stock, it's called Zoom Cleaner.
DIY: Mazda Zoom Power Engine Cleaner (Engine Cleaning, Seaform) - RX8Club.com
.. unofficially they do exactly as i posted
.. yes i had this convo with a mazda tech just last weekend
//// they use water as matter of course on anything playing up with low numbers before trying too much else
when asked for an official decarbon they will use power foam or subaru UCC -and charge for it
Thread Starter
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
Well I finally got a chance to work on the car.
I did the Mazda decarbon procedure except I used sea foam spray instead of the zoom cleaner or Subaru head cleaner since I couldn't find either locally. I got it up to temp and removed the BAC to spray 15 sec worth into each rotor. I let it sit for 2hrs and it cranked right up after. I let it get up to temp and then revved it to 6k 20 times, letting it return to idle each time (surprisingly it stopped right at 7-800 and didn't stall)
Wow! It made a huge difference. I'm now able to drive without stalling at every stop light and it revved a little smoother. This is still running the same plugs that I used for the water treatment a week ago. Also, I didn't have any rtv to re-seal the BAC so there may be a small vac leak contributing to the less than perfect idle I'm now experiencing.
I did the Mazda decarbon procedure except I used sea foam spray instead of the zoom cleaner or Subaru head cleaner since I couldn't find either locally. I got it up to temp and removed the BAC to spray 15 sec worth into each rotor. I let it sit for 2hrs and it cranked right up after. I let it get up to temp and then revved it to 6k 20 times, letting it return to idle each time (surprisingly it stopped right at 7-800 and didn't stall)
Wow! It made a huge difference. I'm now able to drive without stalling at every stop light and it revved a little smoother. This is still running the same plugs that I used for the water treatment a week ago. Also, I didn't have any rtv to re-seal the BAC so there may be a small vac leak contributing to the less than perfect idle I'm now experiencing.
Well I finally got a chance to work on the car.
I did the Mazda decarbon procedure except I used sea foam spray instead of the zoom cleaner or Subaru head cleaner since I couldn't find either locally. I got it up to temp and removed the BAC to spray 15 sec worth into each rotor. I let it sit for 2hrs and it cranked right up after. I let it get up to temp and then revved it to 6k 20 times, letting it return to idle each time (surprisingly it stopped right at 7-800 and didn't stall)
Wow! It made a huge difference. I'm now able to drive without stalling at every stop light and it revved a little smoother. This is still running the same plugs that I used for the water treatment a week ago. Also, I didn't have any rtv to re-seal the BAC so there may be a small vac leak contributing to the less than perfect idle I'm now experiencing.
I did the Mazda decarbon procedure except I used sea foam spray instead of the zoom cleaner or Subaru head cleaner since I couldn't find either locally. I got it up to temp and removed the BAC to spray 15 sec worth into each rotor. I let it sit for 2hrs and it cranked right up after. I let it get up to temp and then revved it to 6k 20 times, letting it return to idle each time (surprisingly it stopped right at 7-800 and didn't stall)
Wow! It made a huge difference. I'm now able to drive without stalling at every stop light and it revved a little smoother. This is still running the same plugs that I used for the water treatment a week ago. Also, I didn't have any rtv to re-seal the BAC so there may be a small vac leak contributing to the less than perfect idle I'm now experiencing.
Thread Starter
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
I prefix and I have a working omp, and sea foam is petroleum based. Pretty much covered there. I also put a half can of sea foam in the gas tank before I started.
Now if only I could find a friend to do a compression test....
Now if only I could find a friend to do a compression test....
Thread Starter
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
Do it.
I just did a comp test, and the front is still even 90's. However the rear is up more than 10 psi, between 70-80 (previously 60) . Only problem is I can't tell if the pulses are even, it sounds like it might be 2 low and 1 high but it could be the opposite.
Checked plugs too, darker than before, so it seems to be running a little richer. Although the afr doesn't indicate as much.
I just did a comp test, and the front is still even 90's. However the rear is up more than 10 psi, between 70-80 (previously 60) . Only problem is I can't tell if the pulses are even, it sounds like it might be 2 low and 1 high but it could be the opposite.
Checked plugs too, darker than before, so it seems to be running a little richer. Although the afr doesn't indicate as much.
Lives on the Forum
Joined: Oct 2004
Posts: 5,150
Likes: 167
From: Japanabama
All I know is that engine problems do not increase mileage.
A 3 MPG difference is a minor fluctuation. Not an indication of anything. Following a truck or a difference in temperature or air pressure could have made the difference. For all I know, one weigh might be slightly more uphill or downhill than the other.
Are you measuring compression with a real rotary compression tester or are you just eyeballing it on a standard piston engine compression gauge?
If the engine pulls as hard as it used to I wouldn't worry about it.
A 3 MPG difference is a minor fluctuation. Not an indication of anything. Following a truck or a difference in temperature or air pressure could have made the difference. For all I know, one weigh might be slightly more uphill or downhill than the other.
Are you measuring compression with a real rotary compression tester or are you just eyeballing it on a standard piston engine compression gauge?
If the engine pulls as hard as it used to I wouldn't worry about it.
Thread Starter
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
All I know is that engine problems do not increase mileage.
A 3 MPG difference is a minor fluctuation. Not an indication of anything. Following a truck or a difference in temperature or air pressure could have made the difference. For all I know, one weigh might be slightly more uphill or downhill than the other.
Are you measuring compression with a real rotary compression tester or are you just eyeballing it on a standard piston engine compression gauge?
If the engine pulls as hard as it used to I wouldn't worry about it.
A 3 MPG difference is a minor fluctuation. Not an indication of anything. Following a truck or a difference in temperature or air pressure could have made the difference. For all I know, one weigh might be slightly more uphill or downhill than the other.
Are you measuring compression with a real rotary compression tester or are you just eyeballing it on a standard piston engine compression gauge?
If the engine pulls as hard as it used to I wouldn't worry about it.
All that is out the window now, since compression is down and idle isn't solid. Yes, I did use a piston compression tester, the numbers aren't so much important (I used this same tester when I bought the car and the original engine tested (90-90-90) (87-87-87). That engine lasted 5 years).
It is weird though, because it drives just fine and half the time idle is fine, but some times it hunts and most of the time it thinks about stalling when I come to a stop. Like when I first stop, idle drops down to below 5-600 and vac is around 10, but within asecond it so it's back up to 750+ and 17-18"hg. nd I don't really feel comfortable making "pulls" considering what happened last time.
Thread Starter
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
After looking at the video I made numerous times, it seems there is one strong pulse (77ish) followed by two week pulses (40ish). So I guess that means the apex seal is stuck or cracked, or chipped.
Although, if it were cracked/chipped I doubt sea foam treatment would bring compression up from 60-30-30. So I will grab the strongest injector cleaner I can find, fill up, and take a trip down to Orlando. When I get back I'll do the cleaning again and do another comp test.
Although, if it were cracked/chipped I doubt sea foam treatment would bring compression up from 60-30-30. So I will grab the strongest injector cleaner I can find, fill up, and take a trip down to Orlando. When I get back I'll do the cleaning again and do another comp test.
Thread Starter
Joined: May 2006
Posts: 3,881
Likes: 3
From: Jacksonville, Tampa & Tallahassee
Didn't end up driving to Orlando, so I'm just now finishing the tank. I'll try to do the cleaning again this weekend and see what happens.
The symptoms are strange though. It never stalls when cold, and runs/pulls fine. But after it warms up when I come to a stop it stalls half the time. Interestingly, it mostly does this when in neutral, if I leave it in gear and depress the clutch it's usually fine. And it always starts up afterwards.
The symptoms are strange though. It never stalls when cold, and runs/pulls fine. But after it warms up when I come to a stop it stalls half the time. Interestingly, it mostly does this when in neutral, if I leave it in gear and depress the clutch it's usually fine. And it always starts up afterwards.
Senior Member
Joined: Aug 2010
Posts: 415
Likes: 8
From: Treasure coast
Dang, sure have some bizzare symptoms!! You and I know ECU don't care if you're in neutral or not. Or does it?
You have Goopy apex right? Me hear they are not easily broken. Surely you haven't attempted to boost it past 15 psi?
Recently, I had one week pulse prior to dis-assembly. Didn't see anything wrong when apart. Don't even think a side seal was stuck. A total mystery. I had a situation once engine got warm engine would become erratic and die. Turned out to be the ECU's main ground on the block underneath the TB was not bolted down tight.
Me you would have a hard time sleeping at night. I'd be pulling it out and taking it apart.
You have Goopy apex right? Me hear they are not easily broken. Surely you haven't attempted to boost it past 15 psi?
Recently, I had one week pulse prior to dis-assembly. Didn't see anything wrong when apart. Don't even think a side seal was stuck. A total mystery. I had a situation once engine got warm engine would become erratic and die. Turned out to be the ECU's main ground on the block underneath the TB was not bolted down tight.
Me you would have a hard time sleeping at night. I'd be pulling it out and taking it apart.