Art20c

Cold reads 3.41 Kohms on each contact. Now I will warm-up engine and mesure hot resistance. Will post readings later.

Art20c

Hot, when temp gage on 1 mark, both contacts read 347 ohm. Engine was running OK, then after a while, idle started fluctuate; hit gas - sounds like dirty gasoline, when trying to raise RPM. With WOT, engine runs on almost 0 rpm for several seconds, then stalls. Removed air filter housing, disconnected 6 pin plug from MAF, idles steady on 500 rpm, then in 10-15 sec dies out. If trying to open throttle with MAF disconnected, stalls immediately. Connected everything back, disconnected ground from battery, put it back, start the car, runs ok. Turn ignition off, then start again, same problem.

Art20c

disconnected O2 sensor, disconnected ground from battery, connected ground, stared the engine, there is no difference when o2 is connected.

Ted928

It very well may be the MAF (If it is not the MAF, then it will be soon). When my MAF went bad, the car could run for a few minutes and got really bad as it warmed-up.
Anyone near Brooklyn willing to give some help???
If not - PM me your address and I'll let you try mine.

Art20c

Started engine this morning, ran abolutely normal. Let it idle for 5-6 min, then turned it off. Started right back again, and it was back to its routine, idle jumps up and down, slow opening throttle results on uneven RPM at about 1200-1300, etc.

Art20c

OK, here is summary: got MAF from Ted928, swap them, same thing. Checked TII resistance at LH and EZK connectors-OK. Checked throttle sensor an LH and EZK connectors- OK. Checked O2 (as described at http://members.rennlist.com/fabric/WSM_24-219.JPG ), and this is what I found: at the beginning, engine runs fine, voltage from O2 is about 0.4 V (fluctuates a little), then when getting warmer, voltage is going down to 50 mV and down to minus 1mV - engine starts running bad, idle up and down, hesitates when trying to open throttle, finally stalls. In other words engine is doing as described at the beginning of this post. What I think is if O2 sends very low voltage signal to computer, it thinks that there is not enough gas and dumps more gas in, hence rough running. BAD O2 SENSOR?

John Speake

The link you provide doesn't work for me, so I can't confirm the measurement method that is described there.

But what you describe does certainly indicate an O2 sensor or wiring fault.

Art20c

http://members.rennlist.com/fabric/WSM_24-219.JPG

John Speake

OK, yes, graph is correct. Yours isn't..... looks like sensor is bad.....

Last week fuel sold by three supermarkets here was contaminated with silicones. Killed several thousand O2 sensors.......

But they always do have a limited service life...

Art20c

could bad O2 cause such symptoms that I have?

John Speake

It is possible. To confirm this is the problem, try the following -

1) Disconnect battery ground strap near tool tray.
2) Disconnect O2 sensor at 3 pin plug.
3) Reconnect battery.
4) Start the car and see how it runs.

This precedure forces the LH ECU to revert to a default mode where it recognises that there is no O2 signal, and it then reverts to a fixed mid range setting.

Let us know what you find.

Art20c

I did the procedure above. When cold, was running OK, then when reached normal temp, started doing the same thing, idle fluctuates, no power, opening throttle results in engine stall, only one way to keep going is to constantly pump the gas pedal, sound like very late ignition, you know, like when you ran out of gas, and you step on gas and it goes BOOOO... in exhaust. There are few pops from exhaust when pumping gas pedal, exhaust very hot. Bad LH or EZK?

Ted928

Another possible reason for running rich is the pressure reg and pressure dampers. If there is a tear in the vacuum diagram, gas will be sucked into the vacuum lines. Verify that they hold vacuum. Also, test for proper fuel pressure with a pressure gage on your fuel rail.

Art20c

I will check that, but why its running ok when cold?

John Speake

Sounds like a very weak mixture ?

Did you try both O2 disconnect and MAF swap at the same time ?

Maybe a LH problem...