Gradual death. Low Compression?
 

Hey guys. I'll jump right into it. I apologize as it is a lot to read but i want you guys to have all the details.

So about a month or so ago i was driving my fc. Not pushing it hard or anything just casual driving. I had just filled my tank up with gas and after After about 10 minutes, i noticed some sluggishness on acceleration, almost like my fuel filter was clogging up all of the sudden. when i hit crusing speed everything seemed fine...

About 2 minutes it happened again this time as i was crusing. I could feel the engine starting to die like it was being suffocated. Very gradually the rpms dropped, it seemed pumping the gas helped for a moment, and then the engine stalled.

I tried restarting it, but now it wouldn't start.

So i have absolutely NO idea why it isnt starting. Ive done a few tests (fuel pressure, and compression) My fuel pressure was low, so i replaced the fuel pump. This seemed to help as it came closer to starting but it still wouldnt quite catch.

So i did a compression test. The front rotor is a little low but still ok at 90 psi.
The Rear rotor, said 10psi when i finally got a reading on it.

Heres a video of me compression testing it, i couldnt hold the valve open as i was doing this alone so i just have the over all for the surfaces, but to the ear the front rotor still has 3 strong pulses and the rear sounds fairly good too.

http://www.youtube.com/watch?v=QSfjTNTx-vE



Please ignore my questions in the video as i like to think aloud but!

Do you guys think it is just compression
Or could it be ignition too. The plugs are fouling. haha.

Thank you.

My fuel sock decided it was too clogged up one day and the same thing occured. Change the in tank fuel sock, since it's cheap and see if that solves your issue.

See if the fuel sock is clogged as jjwalker suggested.
10 psi total compression on the rear rotor is really low.
Total compression should be 85 or higher.
The rear rotor could be flooded.


Take out the ignition fuse, pour a little bit oil through the leading spark plug hole with a tube and funnel or something (make sure whatever goes into the hole does not go to far in or the apex seal will hit it) then crank it with a 19mm socket on the alternator pulley (make sure you are going the right way). If you have a clear tube, you can see the oil getting sucked in, and when its in compression, the oil will blow back into the tube. I crank it by hand for 3 full rotation. Then take the tube out. Clean up the spark plug, or get new ones, install it back in, put fuse back in and crank the car and hope that it will start.
Just dont put too much oil into the chamber, I do half an ounce per rotor, a full ounce to me is a lot and will smoke badly for a while at startup.

of course, it its something mechanically wrong with the apex seals, deflooding it will not help, a rebuild will. But to lose the rear rotor all of a sudden is quite strange. if you lost one apex seal, and it broke up, it will be chewed up inside the housing and will cause low compression on all 3 faces of the rotor.

I am having the same problem with my car, almost exact.

The difference is that my car was running before i put on the turbo. I am running the turbo open with the wastegate open.

I start the car, it runs for a couple of minutes, i start the drive, then all the sudden it acts like it is suffocating itself then dies. Wont start back up.


Try doing this:

Unplug the fuel pump relay under the dash (black relay with yellow bottom) and try to start it. If nothing, disconnect the fuel pump harness, keep relay unplugged, take out egi fuse under the hood, and remove all the spark plugs then turn the engine over for about 10 seconds.

This will clear the engine of all fuel.

Clean the plugs very well with brake cleaner and light them on fire, seriously.

Put everything back together and start it. If it runs, let it idle for a while to clear out the engine. If it does not run, start checking your electrical system for bad relays, coils, plugs, injectors, maf meter, tps, main relay, and fuel pump solenoid resistor.

Once you do get it running, do a steam clean. Fill a gallon milk jug cleaned with warm water, run a vacuum line to the bottom of it, attach the vacuum line to where the pressure/boost sensor goes to on the intake, and run then engine (warmed up first) until all the water is gone. Dont go above 3800 rpms.

I'd say the low compression is probably because it is flooded and when you first started cranking it sounded like your battery is low.
I saw you were jumping it at the end of the video so idk.
I third checking the fuel sock but I'd try deflooding it.
Sounds flooded and the backfire sort of points towards that as well.

deflood the thing and buy new plugs

Hey guys thanks for all the responses.
I cant count on all my fingers and toes though how many times ive already tried the deflooding process and to no avail. Because of this though, could it maybe be a stuck injector? and as much as i am de flooding it more and more gas is just pouring in?

Also, by fuel sock do you guys mean the filter thats on the bottom of the pump? or is it something else?

Wowzers, that is a WEAK crank. When all else fails, push start!

Tried push starting. Still wouldnt start.

if the rear rotor is putting out 10 psi, theres something wrong with it.
If you put in oil and did a compression test and its still low, then you are going to have to take the engine apart and rebuild it. Compression shouldnt be that low, all 3 apex seals are broken or something.

Get someone to crank the engine while you hold the bleeder down on the front rotor. 90 psi peak just shows the highest, but you may have low compression on 1-2 faces. In my experience, starting an engine with 1 blown rotor is usually possible, but it can be difficult.

take out all 4 spark plugs and get a small mirror so you can see in the holes. turn the engine until you can see all 3 apex seals on both rotors. get back to us with the results. you will be able to tell if there is a jacked up seal or not.

Okay, we are still ignoring the FUEL SOCK.

Spend $10 and change it out before purchasing a motor!

Check the fuel sock, if that dont work....pull it with something put it in 3rd go about 45mph and slip the clutch out.

i have a brand new fuel sock. i replaced it after this all started, as well as a brand new fuel pump.

@Just Startn

I had my dad line up behind me in his truck and push me. it still didn't fully catch. And that was trying twice. Once with me popping the clutch and, once with it left out and him just pushing.

@Blackrotary I will try this with my next step once it warms up in the next few days.
Next step is

1. pull all plugs, Check it with a mirror like you said.
2. if all looks good, then try deflooding again, clean my plugs/purchase new ones and, add some atf into the trailing plug holes.
Hopefully it'll start after that.

Ill let you guys know how it goes in the next few days.

so i tried the de flooding since it finally got nice enough to warrant me being outside and still no luck. After i deflooded it and put the egi fuse and my plugs back in i tried to start it and heard a loud bang after cranking a little. Not sure if this was a backfire or something in the engine blowing apart :s. I am getting it towed to Rx7 specialties for a rebuild/port.

Hey guys so im going to resurrect this thread real quick with a new question, related but not.

Since my current engine is shot, and im looking at rebuild kits and the like.
I saw Racing beat is selling a rebuild kit for 1500ish
But Mazdatrix is selling complete engines for $2500

So right now im leaning to just getting an engine from Mazdatrix if they have one in stock, I know theyre reputable. But my question is, are their engines as good as their parts? does anyone know?

I presume you're quoting a price for the Mazdatrix "A" Level rebuild? Any other level is insanely expensive due to new parts. Even at the "A" level, they replace all rotor seals, including side seals, oil control rings, etc., not all of which is necessary, depending on the condition of your existing seals. The "rotor kit" seal package they sell is over $1300, which is almost the price of a basic rebuild.
Nothing wrong with that approach, but it comes at a cost.

For engine builds, you do have some cheaper options, especially if you can ship your engine and its housings are in decent shape. There are several threads on this topic. Here is just one: https://www.rx7club.com/west-rx-7-forum-193/northern-california-rotary-shop-thread-693971/

There are also some options for relatively inexpensive shipping. Once you decide on a builder, he should be able to help you with that.....

You can't determine the extent of the rebuild until you take apart the engine and inspect the parts for wear. Most of the "dead" engines I've seen have unrepairable housing wear.

this is exactly why im leaning towards just buying the entire engine as stated above

yes i am talking about an "A level" The nice thing about theirs is that if they already have a core engine there they just use that. Which it wouldnt matter much if i need to ship mine there first anyways. The biggest factor is that i live in canada. I was quoted 3200 at my closest shop up here, and that was for a basic rebuild, no rotors or housings included.

The most cost-effective options are:

-Learn how to rebuild the engine yourself

-Buy another car

not necessarily... i was planning on rebuilding myself, i made that clear earlier. But thats still a potential 2000 dollar process if i have to buy new rotors on top of my seal kit.

You will never need to buy new rotors. There are so many used N/A rotors in great shape people basically give them away. The housings on the other hand will cost you $0-$300 each depending on what's available in your area.