So I got my car running the other day and it was running ok becides some exhaust leaks and other little stuff here and there and felt safe to drive around for the night. Well, it ran good at 8psi for most of the night and then for some reason it just started running lean, really lean. So I headed back and limped it home. Then around half way home, the car went from full lean, to full rich. Weird. Now for some reason the car wont go past 1200 RPM's even at full throtle. It idels at normal RPS but vaccume is really high, around 10. I thought mybe I fouled the spark plugs so I replaced them along with the wires. Still nothing. The only thing I can think of is maybe my injectors said **** you I'm not working anymore or mybe my 02 sensor ate ****. If anybody has any input that would be sweet. Oh, specs on the car: 90 with a 14b turbo, megan dp and manifold, custom fmic, greddy RS bov, walbro 255 fuel pump, vortec fmu, e-manage, ect. I have some 305cc that I'm gonna put in and see if that helps, probitily not though.

 

what unit is your 10 vacuum? psi?

 

I had a similar problem - running sounding like one of the cylinders is not even in the car any more, idle rough but ok, lean and rich all over the place. On mine it was a badly leaking injector seal that did it.

Try letting the car idle and pull each plug wire one by one and see if you can hear a difference in the engine. If you dont, thats the cylinder that is giving greif.

Report back!

DB

 

sounds like someone has a major vacuum leak. or lack of fuel

 

i vote for vacuum

 

Let us know how the Megan Racing stuff works for you. I may go that route as a prelim. turbo setup.

 

I need to come over and see your new car. I didn't get to see the old one before it got wrecked. The blue one in your avatar is gone, right?

I think this weekend is clutch install... finally. Only now I'm not so afraid of it. I hope my new motor mounts get here before then, I'd love to do them simult.

 

Where could I have a vaccum leak that would cause that big of a problem?

 

Sounds like what happens when the MAF gets disconnected on my car (nissan 240sx), the car goes into safe mode ie won't let you rev over certain amount and runs super rich. Check your MAF and make sure it's still working/plugged in.

 

Actually, this happens when the full pump is not getting power. The VAF meter just happens to supply power to the fuel pump but only when the meter is open. This can be jumpered...

Now here is the cute part... even without the pump running the car can generate enough vac to keep it idling and running but not allow it to rev up. Yes, I scratched my head for hours trying to figure this out. The fuel pump would prime giving it enough juice to get the motor started then it would pull this ****.

So I vote for no power to the fuel pump... could be a variety of sources... bad relay, bad fuse, diconnected VAF, bad pump, or bad wiring.

Mark

 

Thanks for the help so far. I checked around all the vaccum lines I could find and everything looked good. I swaped out the MAF with a spare one I had and that didnt help. I really dont think its the fuel pump cause I can hear it when the car is turned on. I swaped out the old injectors with some 305cc and the car started for a few seconds and then it just died. Now it wont start anymore. I'm really starting to get pissed.

 

checked your timing.?

 

Make sure the wire from your Emanage TPS is not connected to the on/off TPS of your car. Cut the wire and start again if it is.

 

Which wire is that?

 

If you have the Emanage Auxilliary TPS input as seen in the first post on this thread connected to the cars' TPS(on/off switch on a '90) it will not run.

https://www.miataturbo.net/forums/showthread.php?t=581

If you are running an "Autotune" this line on the Emanage should be connected ONLY to the green line on the Autotune.

 

No thats not it. I had the emanage in the car for several months before I turbo'd it. You got me excited though. Then I though about it and was like damm, thats not it.

 

what about your brake booster line i just replaced mine as it was leaking couplers, worn clamps, pcv stuck open. vacuum leaks dont have to be big to cause problems they just have to be there.

 

The autotune doesn't activate unless under boost. So there could be a problem with your wiring even though it ran ok before the turbo. It will affect fueling in two ways. Sending the ECU fake O2 signal to make it run richer and will read the O2 signal and apply the EMB additional injection fuel map.

I wouldn't rule it out just because it was running well NA.

 

I dont have autotune.

 

That's precisely my point... You'll hear it when you first turn the car on and once it's started the ECU will shut it off, because there is a CAS signal but no VAF signal to command it on. Leave the car idle and then check the FP... You might be surprised. Put a fuel pressure gauge on the rail and you'll see if I am right or wrong real quick. If the pressure stays steady while idling, then I am wrong, but if it drops off... then I'm right.

Mark