DCrosby

Rebuilt engine with non seq. setup won't make 10, or barely does.

So I have my 1K mi, on the car, and I babied it all the way, but for some reason, when I open it up now, I'm struggling to make 8-10 PSI, and it even stutters and hesitates, but does make 10 PSI... usually right before I run out of RPM's and need to shift...

We had the turbos apart during the rebuild and turbines looked good, the secondary looked almost pristine.
Our next culprit is the fuel system going to the engine.. Filter tank etc.. to see if there's a clogged filter or something, since turbos are making boost, not leaking oil, and the housing had 1 minor crack in it, that was small and didn't even get close to the gasket... so it's doubtful it's the turbo... any ideas ??

I have another gremlin, the Air Pump clutch doesn't turn on, @ Idle anymore... yet if you short out the wires @ the ECU it turns on, which suggests the wiring is fine, we tried 2 ECU's a '93 and '94 and both do the same thing so most likely it's something telling the ecu, that it's not needed possibly a rpm sensor !?

Thanks,
-DC

pshaw118

it stutters and hesitates while you're driving or only at idle? I ask, not because I have any kind of knowledge to help you, but because of my curiosity, and to help others in diagnosing your problems. You can thank me later.

MazdaRx7Racer4Life

yes, you have to be more specific so gurus can diagnose, afterall, you are asking for help on a forum, where nothing but words can be seen or heard, it helps to be as descriptive as possible.

DCrosby

Sorry I though that was clear that it shutters in the 6-10 Psi range, so under boost, where the second turbo is supposed to provide the extra 5 psi... and of course all injectors are wide open...

Mahjik

iTrader: (1)

Hey DC,

For the air pump, you should check the AC fuse located under the hood on the driver's side. The air pump apparently shares that circuit and maybe it got shorted out.

As for your other problem, I would first see if you can check your fuel pressure (and your original message seemed clear to me ).

vchacon

Did the moving idle clear up?

DCrosby

Sort of, it's still a bit rough due to the Airpump not beeing on but other than that it's better....

Yes we checked the AC fuse, and it's okay, plus it wouldn't work if teh AC fuse was blown, and you tried to trigger the clutch from the ecu side of the harness.... would have to go through AC Fuse...

Batmobile

Is the engine vibrating heavily? If so, it may be blown. What is your vacuum reading?

DCrosby

Thanks, Batmobile, but I know what a blown engine is like, plus if you recall I just got it rebuilt.. so no, plu sit's not an idle issue, it's a boost WOT issue... it handles fine below 5 Psi...

DCrosby

After running the car with new fuel filter, and checking fuel pressure, I believe it to be electrical in nature, since intermittently I get a sudden jolt of 10-11 psi, which is very disconcerting.
I believe it now to be a coil issue, any ideas ?? How much are coils and where would you get one !? Are aftermarket coils better !?? I know Ignition amps are desirable above 14 psi, but what about the coils !? Since they're all part of the ignition system ?
BTW new wires and plugs were installed during rebuild.

-DC

Mahjik

iTrader: (1)

Here's a reference for pricing on the coils:

http://www.mazdatrix.com/ign-1.htm

I'm sure Ray at Malloy Mazda can beat those prices to save you a few bucks. You might check the grounding that is on the coil rack before replacing them.

As far as different coils, I've heard Steve Kan recommending the FC coils, but you need an amplifier to use those on the FD.

DCrosby

Cool, thanks, 130 / coil isn't that bad, especially if it's only one coil... I guess I should count my lucky stars it's a coil and not a gas issue (Boom Again )
What about some of the MSD ignition coils and stuff ??
What's better about the FC coils ?? More Voltage Amplification ??

Mahjik

iTrader: (1)

Can't help you there, but here's the thread I was referring to:

https://www.rx7club.com/showthread.p...hreadid=260205

IMO, I would go with the stock coils and maybe the HKS Twin Power if you want an amplifier. You'll have more work with non-stock coils as you'll be forced to relocate them.

DCrosby

Interesting, yeah I'm running out of space to put stuff pretty fast and I guess if the stock coils are good enough for people running 30 PSI, I'm fine with it as well, and I belive my trailing coils are bad, not my leading ones, but I'm not certain... I'll keep everyone posted...
(As a Note, not everything boost related is a map or vaccuum hose issue )

Kento

Can you explain this a little further? Also, I don't have the FSM handy, but isn't there a way to check the coils resistance to see if they're good? I'd do that before suddenly chucking them for new ones (and trying to narrow down possible causes further).

DCrosby

Yes, I would check them before I go run out and buy new ones, I'm just trying to look at a best case / worst case scenaio, also if I'm replacing I'd like to get something better than stock, unless stock is more than sufficient....

And I'll be checking grounds, and coil resistance, before proceeding...

Kento

Need you to explain the "sudden jolt of 10-11 psi" a little further. Is it a pretty nasty "break up" of power, and does it seem to be rpm-related?

DCrosby

Okay, so not on every run, but once in a while, I go WOT, in 1'st Shift @ 5K get 8psi, then in second WOT, boost builds @ 3K I stay WOT, and as I approach 4-6k every so often I get a pretty sudden boost of power and it hits 11psi, then when @ 10-11 psi, while still building toward 7K power will drop and come back in a jery kind of fassion and that's usually when I get scared and let off.. in fear of breaking my motor...
The jerkyness is kind of like a missfire or what I experienced during my blown apex seal, but then it just sluffed off and wouldn't return... this comes back and goes after 5k @ WOT once I make 10 Psi, which is only 20% of the time... most of the time I can only get 8psi...
And yes they're non sequential.

dubulup

I don't see an ECU in your sig.....

*edit* I don't mean to be captain obvious here.

Kento

When you say "jerky kind of fashion" (I imagine that's what you meant) and "fear of breaking my motor", you're talking about a power interruption that's more like fuel cut than a misfire? If so, I'd say it's more a fuel control issue than electrical (at least with regards to the coils, etc.).

Fumanchu

He's running AEM