Hi guys,

I'll try to describe as much as possible.

Car was running great before I started those projects. (2weeks ago)
- Remove all emission. as per Rotary Resurrection website.
- Install open pod filter
- Install cheap Bosch O2 sensor, I suspect previous is dead, trouble code reads either O2 or Crank sensor, i'm not sure, it blinks, on, off, on, off intermittently, not always.
- Mod OMP to run with 2stroke oil, tank not installed yet.
- And halfway through e-fan mod.

It started fine, as soon as it's going down to idle, it sputter and stall.

I bump the throttle line up, i keep it at 2K rpm, it runs, but sputters and jerks, backfire when revved to 3-4Krpm and release and throttle. backfires when accelerating.

No trouble code. and I found out that the TPS was out of adjustment,
adjusted that, it stayed... engine sounds better, idle at 1K rpm.

but still sputters...

I'm suspecting air flow sensor, I placed it upside down for a whole night...
anyone suspect that too?

anyway to test a airflow sensor?

Thanks,

Car
- 86' S4
- NA, 5speed
- only mods is cheap no cat exhaust system.

 

And I also swapped the injectors from my parts car,

I'm not sure on the condition....

 

I bet it's the injectors. If they're all old and crusty, they could be stuck open, making the engine run pig rich which would explain the backfiring and lack of power. You can have them flow-tested at a fuel injection shop, and they'll be able to clean them if they're clogged/stuck. If you can't find a place locally, I'd recommend sending them out to Witch Hunter Performance

Having the AFM upside down overnight won't hurt it, I had one sitting in a box in my garage for like 2 months, I installed it in my car recently and it works fine.

 

Did you replace your Oil injectors with some Block off bolts?(bolts with a cruch washer)?..
Won't they suck air instead of OIL if they are still on the Engine?.that would make the engine run like ****,as it is Sucking air.(like a vacuum leak).

 

Thanks for the link, will definitely look at it. I'm thinking of that too, since exhaust fumes stink....

No i have kept all oil injectors in place, i just modded my OMP with a nipple and block off the engine oil intake.

 

I agree that just leaving the AFM upside down overnight shouldn't cause it harm, however the method to test the AFM is well documented in the FSM.
Witch Hunter does great work on injectors.
Sounds like you've got a vacuum leak.

 

I dont think i got a vacuum leak to the atmosphere...I can't hear any vacuum leak.
I'm now pretty sure it's the injector, i took it off a car which has not been running for years...thats pretty silly of me. And i'm sure my current injectors is leaking too.
Filling up the form to send for service. Will remove intake manifold tomorrow, should be out in time for tuesday.

Thanks guys. Will update if it does not work

 

Certainly clean the injectors. Before you put them back in, check the impedance. Mazda changed the impedance of the injectors in, I think, the middle of 87. Cars later than that have a different impedance injector and no injector resistor. I don't know what year is your parts car, but if it is not an 86 you may have a problem with a mismatch between the impedances.

If I understand your post correctly, you have a trouble code (5?) even after replacing your O2 sensor? That would indicate that the ECU is not seeing the new sensor. If this is true, pull up the carpets on the right side, remove the cover plate and check the O2 sensor voltage at the back side of the connector at the ECU. It should be between 0 and 1 volts, and more than .45 if the car is running rich.

If the voltage is not there, pull the connectors off of the O2 circuit at both ends and check it for an open or ground. If the wiring is bad between the ECU and the sensor, there is no way for the ECU to see it.

While you are in there you can check the voltages of all the other sensors, including the Air Flow Meter, at the ECU. Compare voltages against the values in CH 4 of the FSM. If one is out of range, it may lead you to a bad component.

Once your injectors are back in, you can check for proper ECU operation by connecting a 12v led between the center two pins on the check connector. The lamp should be on for idle and acceleration, off (lean) for decelleration, and flashing on and off for steady rpm (not idle).

 

Thanks for the info.
I have check my injectors and my parts car injector is both LI, 2-3ohms, parts car is 87'.

I dont quite get the last phrase, regarding connecting to center two pins.
Which connector are you referring to?
I have my LED's plugged into the driver side(behind battery) to check for trouble code.
- both lamps come on when switched to ignition, and goes of after a while.
- no trouble code yesterday.

I have removed the injectors from the car, will be shipped Witch Hunter tomorrow.

 

OK, the impedances match, that eliminates one possibility.

If you have checked codes at the check connector, to the left of the battery, you know that it is a six pin connector. As you look into the connector with the locking pin on top, there are two rows of three pins.

The codes show up on the first pin of row 1 and the first pin of row 2. The second pin in row 1 is +12v.

If you look at the second pin in row 2, it is called the 'green lamp' pin. The factory code checker has a green led that connects to this circuit. It is a pull-to-ground circuit just like the two code check pins. But it pulls to ground when the ECU senses a rich mixture on the O2 sensor, and back up to high impedance when it senses a lean mixture.

An led connected between the second pin of row one and the second pin of row 2 will then light up when the mixture is rich, and go dark when it is lean.

You can use one of the leds you wired up to check the codes; if it works in those positions it will work in this one.

The led should light up as follows:
idle: on (rich)
accelerating: on (rich)
decelerating: off (lean)
steady rpm (not idle): flashing on -off about 8x in 10 seconds

If the ECU is seeing its sensors normally, after warm up it will go into closed loop mode (actively modifying the mixture to get close to perfect air fuel ratio); that is indicated by the lamp flashing on and off.

If it will not flash at a steady rpm, something is wrong, and the ECU is not getting the signals it needs to go into closed loop, or the ECU is busted, or you hooked up the lamp backwards...

If the car is idling normally, it should be in open loop mode (not flashing) but with the lamp on, showing a rich mixture. IF the lamp is off at idle, the car is running too lean at idle, and this may be related to your problem.

 

okay, quick update,

I got my injectors back last week, fitted everything back,
start it up, runs great, idle fine, starts around 2,000rpm, pull it down to 1,000.

i left it alone for a week, while I install my power steering, without the batter hooked up.

Tried to start it yesterday, same symptom, rough idle,
I gotta keep my foot on the gas to keep it running, once it heats up,
it sound better, I have to unscrew the idle adjuster to the max, to keep it at 1K rpm.
and it's still very choppy...

Will test the O2 green lamp later.

 

hi there,..

i've check using the green lamp,

it wont go into closed-loop mode.

I'm getting 0.65v at Green/yellow wire from ECU
second from left. (O2 sensor)

is that normal?

this is really annoying, it runs, fairly rich, and it idle at 600rpm, wont stay running when cold.

 

See jpg.

The yellow, yellow/red and yellow/black all pulse a gnd signal to make the LED/Green lamp on Mazda tester, go on/off.

Were you driving the car when checking this out? Or were you in the driveway with the clutch depressed and transmision in gear? when doing this?

 

O2 voltage of 0.65 volts is either 'normal' rich or 'too' rich. Hard to tell with a narrowband oxygen sensor because the voltage vs. AFR curve goes flat in the rich range (i.e. .65 could be just a little rich, or a lot, no way to tell reliably.)

What it does tell you is that the mixture is not too lean, which eliminates some possibilities.

Have you set the idle mixture per the FSM procedure?
When was the last time the injectors were cleaned?
That it will not go into closed loop is a concern... but make sure you tested it either IAW the FSM procedure, or while driving at a steady speed. Even a normally operating system will not go into closed loop sitting in the driveway unless you fool the ECU into thinking you are driving by disconnecting the neutral switch and the TPS according to the FSM procedure, and then running it at 1500-2000 rpm. I find its easier to put a long lead on the green lamp tester and go driving.

If it will not go into closed loop at 2000 rpm on the road, it is likely one of three things: the ECU is not seeing a valid O2 sensor (but you seem to have that); the ECU is not getting the temperature signal that tells it the car is warmed up (necessary for closed loop); or the ECU is faulty.

Whatever is keeping it out of closed loop may or may not be related to your idle problem. The car normally runs in open loop at idle and under acceleration; in theory a bad O2 sensor or inability to go into closed loop should not affect the idle... however I found otherwise on my car. it may be that running in open loop all the time fouls the plugs, and then it runs poorly at idle. My idle cleaned up nicely within a short time (hrs, not days) after fixing the open loop problem.

I would identify and correct whatever is keeping it out of closed loop, and then reset the ECU (disconnect neg bat cable for 5 sec). Then try again. If the problem doesn't go away, then you can look elswhere, having eliminated that possibility. Do not assume that there is a single problem.