OK, so I rebuilt the engine, right? 6 months now, too... Used all new internal seals... RA Apex seals, everything else came new from either Atkins (overhaul kit C) or seperate from Mazdatrix. Followed the Turrentine video to the "T" during all stages of the build, and basically where I stand is here...

I can't start it.

That's a very vague thing to say, I know. I made sure the injectors were opening and closing by spinning the CAS, I made sure the spark was there, and I can hear the fuel pump running. There is pressure in the fuel lines, as well. I tested compression on both rotors, cold of course since it won't start, and got 30/30/30 on the front and 40/40/40 on the rear. I'm assuming that these are alright numbers for rotors and housings that each have ~100K miles on them. All the hardware was spec'ed before starting the rebuild, and everything was copacetic.

I haven't tried push starting yet, as there isn't a good area anywhere around here to do it and I really dont have another car to push it... but I know that my friend's 7 will start without a push with only 85 when cold. Makes no sense to me, since most of the explanation that i've seen here for the needed pushstart is "low initial compression"

So, I know I got air, that's not a problem. I know I got spark... not a problem either. I'm pretty sure I got fuel, as the injectors can be heard and during the compression test I could smell the gas coming from the open plug holes... and even though I have absolutely no understanding of how to do the timing (did read that guy's post about it, still made no sense.) I hear that it would still run, albeit crapily, as long as the timing was at least in the ballpark of where it should be... I heard it when I did it wrong, and it sounded nasty. Sounds just like every other 7 i've heard where it is now.

Also, the engine has turned over before. We pumped some ATF into it, and sprayed carb cleaner in. About 3 times we got it to run for about 2-3 secs before it died off. I'm guessing the ATF finished it's burning.

So, there are the details. I'm pretty much lost as to what the problem is... I'm gonna try and pushstart it as soon as I can find something to push it up to speed (10-15 mph right?) Unless the timing is off enough to make it run way too rich or way too lean, i'm stumped. Please help this poor n00b out.

 

u are not building enough compression. on the pass. side shock tower in the front there is a little black rectangle box thing. they call it a boost sensor. there is a vac line hooked up to the bottom of it. disconnect that and put some oil in it then blow it down the tube. reconnect that vac line.(the oil is to help seal the distance between the apex seal and the housing, thus creating compression) also disconnect the fuel injector resistor solenoid. its also on the pass side under the air box. its yellow and big. then shoot some starting fluid down the intake. have an assistant crank the car until it starts then plug the resistor solenoid back in while its running. it might also help to hold the throttle wide open until it starts.

make sure you dont have any major vac leaks.

-masin

 

OK, went and did that to the best of my ability... Turns out i'm out or starter fluid, and autozone is closed now. Also, I couldn't find the resistor you talked about... leading me to believe it may be missing... I left some stuff out of the first post that might have helped, i realize now. The EGR was removed, as well as the airbox. The emissions spider (excepting the EGR) has also been redone, as far as vac lines are concerned. It has a cone filter adapter on the maf, though. I checked all the vaccuum lines, and they all seem good. Everywhere there isn't one is capped. Only thing I noticed though was that the vac line from the boost sensor was really loose. I'm thinking it may be a leak, being so loose that I didn't really have to pull to get it off. I'll get some vac hose tomorrow and re-run that line, as well as pick up some starter fluid and try it.

Thanks for the reply.

EDIT: The maf was unplugged from the harness and removed from the vehicle so that access was easy to the TB for spraying starter fluid... Was told it shouldn't matter. However, i'm not exactly sure about that. If the ECU reads the default signal (that happens when the maf is gone, right?) isnt the a/f ratio gonna be messed up?

 

i don't want to sound like an idiot but do you use a block off plate when you removed the egr valve ... if not you could be losing compression from there . im sure you blocked it off though ... just throwing it out there .

 

dont put that **** down your MAP sensor vac line, your just looking for trouble there.

 

Those numbers are too low to start on it's own...usually even on a dry used housing rebuild I'll see 75-80psi before initial startup.

Sometimes, depending on the condition of the housings, more of a trick is necessary for startup.

1) remove lower plugs...trailings are of no real concern most of the time.

2) remove egi fuse.

3) crank engine with throttle open to expel whatever is inside the chambers.

4) inject motor oil into chambers via lower plugholes...several squirts/ounces each may be necessary. You can also use open intake runners or nipples, so long as both front and rear chambers get fed.

5) replace plugs with known working/unfouled ones. Stock plugs foul easily in the presence of oil and fuel, so use another set that came out of a running engine shortly ago...or a new set.

6) replace egi fuse.

7) hook up a jumper car or battery charger set to "engine start" to give the starter/battery/ignition that extra umph.

8) With throttle open, crank the car. Expect it to start roughly, be prepared to feather the throttle and keep it going if it wants to bog out and die. Get it stabilized and hold your rpms at 4k for a few seconds, if it seems to clear up then drop it to 3k or even 2500.

Have someone checking for leaks during this time, and also have them prepared to raise your idle adjust screw on the throttlebody to hold your 2k-2500rpm idle so you can get out of the car...do NOT expect the car to settle down and idle on it's own yet. Expect much smoke from the tailpipe, under the car as the external exhaust parts burn off contaminants, and the enginebay, as those parts burn off stuff. Only shut the engine off if absolutely necessary.

Let it run at 2000+rpm for several minutes while you observe gauges, check for leaks, etc. IF everything seems normal and the smoke dissipates after 10 minutes, drop the rpms down slowly until it acts like it wants to spit and sputter, bump it back up 100 or so, and lock it down. Repeat until you get it around 1200-1500, which is where I leave mine for a few hundred/thousand miles.

 

my car will never idle with the MAF off, or the TID not connected snugly (TII tho)



this is kinda OT,

but i was curious, if it takes this much effort for us to get a rebuild to start and run and break in...

when our cars were sold off the lot brand new 0mileage... how do they run/idle/drive etc without any of this effort?

does mazda run the engines on engine dyno's or something till it breaks in? (so our 0mile car actually has several 100/1000 miles on the engine) or they have some "special" techniques?

 

There's quite a difference between a new housing, new iron, new seal engine, and a used housing, used iron, new seal engine. Not so much after all is said and done, and breakin is complete, but on initial startup, it's easy to tell the difference. You simply have better sealing and compression immediately.

 

isnt 30-30-30 good, while holding the needle down ?? I get 45-45-45 and about 120 overall compression.. I guess it depends on the guage. I keep seeing people posting 120-120-120 or #'s like that, Cant you only get those #'s from a mazda tester?

So you tried to start the car with the afm off?

 

yeah 30's 40's and 50's are pretty much normal with a regular piston motor compression tester with the schraider valve removed now with the valve installed and the motor making about 3-4 revolutions you definatly wanna see 120+....if not the compression is not within spec.

 

a) put the MAF back on, the car may try to start with it off but it won't stay running or run worth a **** with it off.

b) do a search for "fuel cut switch"

 

I tried this. Didn't work. Made sure the combustion chambers were empty of everything, then replaced the old plugs with new ones. Added oil into the chambers and tried to start. Same old thing happened that did before, no start. Took the plugs out for a visual and they were covered with oil... as expected. They're out and drying now, but the main point is that the car still didn't start. Maybe I did something wrong, i don't know... for the time being, anyone else have any ideas?

 

exactly my point.

 

You must have another problem then...no spark or no fuel delivery. I know you said you had spark, Im just going over possibilities. It's not all that complex of an issue really.

You're going to have quite a challenge getting it fired up with compression being that weak.

 

Well spark looked good, i think my injectors aren't flowing right. I smell the gas, but I don't think it's getting the right amount of fuel. Me and a couple guys attempted to push-start the car, and it sorta worked. It was actually running, but it didn't run for long. I'm looking into getting my current injectors cleaned, balanced, and flow-tested on the chance that it would be the problem.

As for the low compression, is there any other way to fix that other than ripping the engine back apart and starting from scratch? It's not too much work getting it out and apart, nor even back together... but if the compression numbers are as bad as you guys make them look (e.g. 120+) and my thinking is correct, i probably need new housings, rotors, or both.

 

I got the same exact prob. I bet I have restabe the CAS 150 times and wore the threads off a new set of plugs.

 

Compression will come up quite a bit when (if) you get it started and run it up into the rpm's for an hour or 2 to seat those seals. Until then, oil/atf and a strong battery charger/jump/rollstart is the only way to increase compression. I would not take it apart.

BTW, the 120psi is bullshit...that's the number you see from a fully broken in, new or excellent used housing rebuild. 85 is the lowest acceptable limit for a running engine (old original) but that doesnt really apply to rebuilds since they will be constantly IMPROVING, not slowly getting WEAKER like an old original will be. But yes, your numbers seem quite low.

Rotors have no real effect on static compression numbers unless the seal slots are worn out. Seals and rotorhousings form compression.

 

Well i'm really feelin' like a n00b right now... I had an asistant helping with the car, of course... he was the one who hooked most of the stuff up while I was at work or in class. I took a look at his handiwork, and noticed that he had the fuel lines reversed. The main line was going to the FPR, and the return to the Banjo that replaced my dead PD.

The car started and purred the second it was cranked. Ran for a good while too. Course, now it won't idle. Thus, I'm now presented with my next hurdle. Also, it seems that the car overheats easily. Every time I start it, it runs for abouit 10-12 mins and the coolant buzzer sounds. At that point the throttle comes up and I have to fill the radiator back up.

Any ideas, guys?

 

Wanted to edit above post, but can't... even though it says I can

We got the car to idle at about 1250-1300 stable, and when not idling the rpms can drop to about 900 before it shakes like its gonna die. Drove it around the block a bit, seems solid enough. Just a couple more problems to work out. The clutch needs to be bled, and it seems as though the coolant system might be over-pressurizing. Additionally, it no longer drinks the coolant, the level stayed even good, until a line on the back of the UIM blew off and sprayed hot water all over me (curse having the sunroof open)

All in all, it's been a pretty successful day. Thanks for all the help guys.

 

Bumping up the idle is a trick I use to get rebuilds to drive easier.
Congrads!

It sounds like you got a coolant leak somewhere.
Check to make sure nothing is dripping under the car!
How long did the water pump sit around?
The damn seal on the water pump tends to fail if it sat out of the engine for a long time (more than a couple week?).


-Ted

 

Your problem is that the engine is flooding because of the low compression. You wasting time and money getting the fuel injectors cleaned.

You need a method of killing the fuel pump when you are trying to start the engine. If you have to, remove the connector from the fuel pump to do that. Do not substitute that method with pulling EGI fuses and that nonsense. Either make a fuel cut switch or pull the pumps plug.

You have at least one other person helping you, so do this: PUll the plug off the fuel pump.

Remove the lower plugs and spin the engine for ten to fifteen seconds to clear the engine. Put the plugs back in.

Buy a can of starter fluid. Have your helper spray fluid into the air intake for mo more than two to three seconds at most. Spray into the intake before the filter.

With a fully charged battery, start the engine. The starter fluid should have been enough to get it to run for a moment. Do this procedure once again but this time your assistant should be ready to reconnect the fuel pump plug the INSTANT the motor starts running.

It isn't going to idle on it's own. You'll need to manipulate the gas pedal to keep it going.

Before doing the above, since your engine has been going through a bad period lately, you might want to get common engine oil into the rotors prior to pulling the two lower plugs and spinning the engine for several seconds with the fuel pump disconnected. I figure this engine is without any lubricant around the seals by now and you have to get some lubricant in there first.

Trust me, you have too much fuel and it's flooded.

 

The water pump sat around on my porch for about 7 monts... climate controlled, but 7 months none the less. We replaced the water seals, and there weren't any leaks we could see... though wouldn't the pressure in the system be low if it had a leak and not high? I was thinking the lines probably weren't sealing correctly. Maybe I should go replace all the coolant lines I can, so that they all seal well?

Oh, and the car starts right up, no flooding. If there's a hint of it though, I will install the cutoff switch like everyone is recommending. Thanks for the suggestion though.

 

Well, if it had a leak on the internal seals, then the pressure would high.. and overheating occurs..

 

I have a similar problems with very low compression after a rebuild on all 6 chambers. Car runs fine after I push start it but there is no way it will start cranking. I have about 2-3 hours of total run time on it and 40 miles and the compression hasn't changed (25 to 30). After cranking plugs are covered with oil and some fuel. When she runs fuel vapor is coming up the oil fller neck. Can I expect some improvement or should I start ripping the block apart again.

Thanks
CW

 

If it's that bad there is either a problem with your test procedure, or more likely a problem with the engine. I normally see 70-90psi before any run time, and 85-105psi after a few hours/miles. Then it builds somewhat more slowly over the next few hundred miles to 115-125psi.