ray green

iTrader: (14)

Help, what's wrong with my 12A?

It's in a 1984 GSL, stock except exhaust has been running great on the 110 mile daily commute for the last few years. Then on Wednesday it started to fade while traveling the interstate into work, not bad but annoying at high speeds. Same problem on the Thursday commute, it seemed like fuel starvation so when I got home I replaced the fuel filter and checked the pump output, but both looked fine. No change Friday morning, still the high speed fading, but then on the way home it got worse, I had to rev it at stops to keep it from stalling.

Saturday morning I knew I had a problem, the cold engine hardly ran. I have a 2GDFI installed, so I switched back to the stock ignition to eliminate an ignition problem, still no change. A close look at the ignitors and dizzy cap and rotor showed these were all fine - the plugs are NGKs that were installed about three weeks ago and they look fine. And the timing light showed leading and trailing ignition firing normally.

Still thinking it must be fuel delivery, I pulled the top half of the carb, checked the float valves and level and used the air compressor to clean things up, but there weren't any obvious problems in the recently rebuilt carb (1 year old). Also fuel is jetting into both primaries and secondaries when the accelerator pedal is depressed.

So it's sinking in that it might be the engine. I soaked it with Sea Foam, spun it a few times, added more Sea Foam and let it set overnight. On Sunday I blew out the Sea Foam, added fresh plugs and got it running again. Still no change.

Here are videos of the situation. Here's how it was running Tuesday:

http://youtube.com/watch?v=n3Va3xwWzVQ

Here it is now:

http://s259.photobucket.com/albums/h...=engmov004.flv

Could it be that I have a bad apex seal? I don't have a compression tester but with the plugs pulled both rotors whooshed and blew air like nothing was wrong. Both trailing holes made strong and equal compression when I plugged off the hole with my thumb, while the leading holes seemed to be sucking as much as they were blowing. Is this normal? Just listening to the compression with the plugs out there really doesn't seem to be anything unusual.

The timing didn't change of course but could something else affect timing to make it run like this? I checked for vacuum leaks but everything seems tight and fine.

Do I have a bad apex seal? Is there a way to tell without the official Mazda compression test?

Thanks
Ray

Anex 570

Well I would double check you're fuel output under load, which is kinda hard to do. About the only suggestion I can think of first is if you have a spare fuel pump. Second is you can use a regular compression tester, just have to take out the valve in the end of it and watch the gauge. It'll change a little being warm or cold, so prolly best to do it warm. No telling really if its an apex seal until you get a good compression test. 2 bad compressions and 1 good means a apex seal, 2 good ones means one face has bad side seals.

ray green

iTrader: (14)

Thanks for the suggestion on the home made compression tester, RX-7 buddy Crit has one of these he offered so I will take him up on that.

I wish it were just a fuel problem and I have a spare pump I thought about installing but all the signs are that won't help. While the problem started out on the highway at high speed, it now is happening while sitting in the drive at idling speeds when fuel delivery demands are minimal.

Also I pulled the gas feed to the carb and ran the pump and it filled up my 1 quart receiving bottle with no trouble. As I mentioned above, all the jets are squirting plenty of fuel and gas reaches half way up the view windows on the sides of the carb, so it looks like it is getting plenty of fuel.

Still I neglected to check those two little barrel screens that sit in the fuel horn or whatever it's called right where the gas first enters the carb so in the interests of eliminating everything I will check those out once this cold front moves on by.

But it sounds like the backyard compression test is what I need, thanks for the suggestion. If that shows the compression is good (which it sure sounds like with the plugs removed) then I'll go hunting again.

Any other insights or suggestions appreciated!

Thanks
Ray

Kentetsu

Any weird popping noises while you are on the throttle? Before my apex seal finally went, it would pop when engaging the secondaries. If you have good speakers, or a nice headset, then you can actually hear it in my most recent "Muskegon" autocross video. Not sure if this will help you.

When I get home from work, I'll check out your videos. But in the mean time, it might be worthwhile to visually inspect your jets just to make sure you haven't picked up some debris. Just pull out the two bolts below the window, loosen the jets, then extract them with a wooden toothpick. That way, you don't need to pull the top off the carb again...

dbragg

iTrader: (7)

i have a compression tester here at my apartment if you want to do a test.

if its bad, then theres good news. youll finally get to break into a 12a.

ray green

iTrader: (14)

You're right Donny, I'd love to crack a 12A.

But just in case, I'll borrow the compression tester, thanks!

Where you going to be tomorrow?

Jaime Enriquez

From recent experience, a blown apex seal sounds much worse than that. I won't idle at all either....sounds like a lawnmower.

Post a vid like the first one....engine shot would help us to hear more.

Jeezus

iTrader: (4)

when my old engine had a broken apex, it would barely start. After flooding it numerous times it finally cranked over, but needed gas to keep running.


I hate to hear if it is a broken apex, that car ran great when I see it

Box_Man

Actually, my engine sounded EXACTLY like this when it blew, but it wasn't a broken apex seal. I was having oil consumption problems and large amounts of smoke on deceleration, and eventually it wouldn't run on both rotors. I assumed that the front rotor had a bad oil seal, because it would foul plugs quickly. When I took the engine out, the front exhaust port was oily black (rear was normal tan). When I disassembled the engine, the front rotor housing had chatter marks and really bad step wear on the irons. the apex seals were not broken, but the oil control rings looked kind of bad (but not broken).

boyee

iTrader: (3)

well check my thread out https://www.rx7club.com/1st-generation-specific-1979-1985-18/my-rx7-sick-%3D%5B-579862/ it has some vid sound clips there. maybe its a vacuum leak since you can rev your car fine but doesnt idle

FirebirdSlayer666

iTrader: (3)

Just on the off shot, have you checked the trailing ignition out put? Check if the coil is firing. Judging by the ease of you being able to start it, I doubt it is a blown apex seal. When mine went, it was very difficult to start hot and it took a bit to start it cold. I also had to crank the idle up to keep it running

Kentetsu

Can't view the second video, down for maintenance. I'll check again tomorrow. When my apex went, the car would idle but it looked like it was shaking itself apart...

mazdaverx713b

iTrader: (91)

Ray, dumb question, but do you have a catylitic converter on the car? i fear the worst my friend. a compression test will tell you a lot. post back the results

Glazedham42

iTrader: (4)

Ray,

This may or may not help, but try removing a spark plug on the front rotor. Pull off ALL of your plug wires too. Crank it over several times and listen to all three apex seals puffing through the spark plug hole. You should be able to hear nice puffs on all three of the apex seals. Usually if you have a bad seal you can hear the difference just by cranking it over. You will hear two weak puffs, and then a strong one if you have a bad seal. Repeat the same procedure for the rear rotor. This is a good free test that may or may not tell you more info. It's like the poor man's compression check.

Good luck!
Jamie

bliffle

What do you know about the history of this car? How many miles when you bought it? What did the sump oil and coolant look like when you got it? Did it have a coolant leak? How many miles have you put on it? Have you been using MMO or 2-cycle premix? Do you warm it up in the morning? Do you observe the redline?

Jeezus

iTrader: (4)

Hey Ray, if it comes down to it I still have a spare 12a here I have not torn into. I kept it around in case of emergencies. I guess this looks to be the beginning of one (hopefully not). Let me know if you need it, I can run down there sometime and we can just exhange yours for mine. I saved the one without the front cover oil leak.

Kentetsu

This is why I love this community! This is what its all about. Last fall, when I was in need of a motor, Perfect_circle drove a couple hundred miles to deliver one to me and helped me install it along with a few other friends. Love that warm fuzzy feeling!

ray green

iTrader: (14)

Yep for sure, the last four posts have been nothing but good news and generosity. I'm up to my ears in broken down cars, my wife's jeep just went on the fritz again (thought I had that one fixed) and I'm trying to figure out if I can fix the white one or whether I need to put it in the hospital and get the silver one ready for the road - it all rests on that compression test.

Jamie your idea sounds like its the poor man's answer (and I am one of those) so I will try that first - I wish I had thought of that trick!

Also Crit has a ghetto compression tester that he will loan me, hopefully if Jamie's methods doesn't work I can pick that up tomorrow and put it to use to see if it really is a compression problem.

Dave no cats on the White One, just a bonez pipe hooked up to the stock manifold and back to the stock cat back system - a poor man's racing beat set up.

Stu thanks, I might take you up on that. Would you and your Carolina boys want to do the rebuild, maybe put a mild street port in it? (Stock is fun, but life is short).

Bliffle, I got the white one about three years ago with 83,000 miles on it. It needed some minor brake and exhaust work and I swapped in a tranny that didn't growl in high gear, but after those minor repairs I got 60,000 trouble free miles doing the daily commute, almost all out on the highway doing the speed limit and a few other speeds. Everything about the car is in top shape, I maintain my GSLs well, but I think I did make a couple mistakes that together may have contributed to wrecking an apex seal, if that's what's happening.

First, about three months ago, I stopped adding my 8 oz of MMO to every tank full of gas, as I had been in all my commuter GSLs for the last seven years. Hundreds of thousands of miles and never even the slightest problem with any of the 12As I've been driving - I really believed they were bullet proof. I'm going back to the MMO from now on.

Second the car was running so well I was beginning to drive like Stu, all the time. I was even stopped one predawn morning a few weeks ago in Gwinnett on my way into work. I was read the riot act (yes everything he said was true and then some) and then was let off with a warning and a comment about my "little car" and "getting killed". I think our police officers like 1st gen RX-7s.

So put 2 + 2 together (not enough lube and hot rodding) and you get a wrecked seal - it ain't rocket science.

So now I've got to fix the jeep and we have a major freeze coming tonight, which means I now have to move the dozens of house plants I just put outside last week back in the house - all before the sun goes down. If I get that done I'll do Jamie's poor man's compression test. If that doesn't work I'll try Crit's ghetto compression tester. Then I will report back.

If it really is a bad apex seal we can archive the video so people can listen first hand to the bad news.

Thanks y'all!

Ray

Glazedham42

iTrader: (4)

We're all pulling for ya Ray!

ray green

iTrader: (14)

Thanks Jamie, we're still waiting for the fat lady to sing on this one, I haven't given up yet.

Hey Boyee, my engine sounds just like yours in this clip:

http://youtube.com/watch?v=v3JifX9jhr0

You say that was just an ACV problem? It's probably wishful thinking, but maybe I don't have a bad seal after all?

It's getting good spark to all four plugs (shown with the timing light) so I don't think it's ignition. Also I've swapped out all the ignition components one at a time without affect (more wishful thinking).

But maybe those jets Ken is talking about? No ACV on this one but maybe it's something else screwing up the fuel flow?

I'll do the compression tomorrow with Crit's modified unit (no offense Boyee, but your paper towel compression tester is too ghetto even for me).

Who knows, maybe the White One isn't dead after all?

warwickben

iTrader: (1)

i feel for you man, this winter i put so much work in to my car(80sa).rb header, (respeed coil overs, rear adjustable perches, front sway bar)gilmer drive breaks ect. friday i got to the point i could stake it off the jack stands and start the car. i needed a jump and dint want to wait for my new battery as soon as i put the jumpers on i blew a fuse able link. thought it was cause i got jumped by a f250 power stroke twin battery's by the way. replaced all my fuses and battery Saturday. as soon as i put the ground on popped the main fuse again. i started freaking out think i fried my car.my buddy who went to uti works nights came by monday during the day. i came home and he had wires every where. he loves this car as much as me. he didnt even notice i installed the gilmer pulleys. i asked him if he checked the alt wiring cause its the only thing i unwired my self. he looked and was like **** cant be that easy he checked it and that was the problem. i went to the doc's and when i came home he re wrapped all my wires and washed my car. turns out i forgot to use a nylon washer between the signal cleaner thing and the wire that goes from the alt to the battery.

i dont know if its just me but when things go wroung with my rx7 i assume the worst and it turns out to be some thing stupid easy to fix, i hope this is the case for you. by the way my car has 60,000 on motor and 300,000 on the body so i mit ebe more up tight then others.

ray green

iTrader: (14)

I'm with you warbicken, I'm hoping it's some stupid thing.

I'm thinking Sea Foam might be the answer. Here's what I did before the sun went down:

bliffle

I don't think you damaged the engine when you discontinued MMO unless your OMP is also kaput.

74RX4

iTrader: (10)

Check the bottom of the hose that goes from the #2 anti-afterburn valve to the intake manifold. Sometimes heat from the exhaust melts the hose. The resulting hole causes a rather large vacuum leak.

ray green

iTrader: (14)

Tim I wish it were true, but you know the condition of things under my hood - everything is pristine and I know and love my Rat's nest, there are no vacuum issues, unfortunately. I've had problems with that afterburner hose before, even when it went bad it didn't make the car run this bad.

As far as the Sea Foam smoke goes, yes that's what happens. In fact I had to wait a few minutes to take the pictures until the smoke wasn't completely obscuring the car. I've been soaking it overnight in about half a can of Sea Foam, delivered directly through the carb. If it's a stuck or dirty seal maybe this will help.

I going to get Crit's homemade compression tester this afternoon, that should tell us what's going on.

Thanks for the help and feedback guys! (and yes Stu I'd want that street port to be compatible with the stock Nikki, I'm too old to learn how to tune another carb).