Help, my 1991 Toyota Camry LE V6 won't stay running/dies while driving

[91 2VZ]

What's up guys/girls. My name is Chris and I'm new to this forum. I drive a 1991 Toyota Camry V6 as a beater and it's been running fine for me as long as I've driven it. The car has 145K miles. No problems at all except for bad gas mileage where it would average 180-225 a tank. Kinda bad since my other car is a 2000 Honda Civic SI and I'm used to like 325 a tank lol.

Well today as I got out of work and started her up, the engine hesitated at around 300-500 RPM and sounded like it was running on 3 cylinders. I gave it some gas and the engine stalled. I waited a bit and started her up again, it hesitated and I gave it some gas. It cleared up and idle jumped to about 2000 RPM. I also noticed a very STRONG fuel smell coming out the exhaust as well as blue smoke since my valve stem seals are worn.

Well it idled at 2000 RPM for about a minute then dropped to about 500 RPM and died again. I waited a while and tried starting her up again, it did and I quickly threw the car into reverse and drove home before it died again.

On the way home on my street while rounding a hill, the engine died when I was halfway up the hill. I pulled to the side and the engine started and I quickly continued on into my driveway where it stalled again.

At this point, I've tried starting the car numerous times and it will not start. But for some odd reason, the engine starts if I let the car sit for an hour or 2, weird. It also runs smooth if I hold the engine at say 2.5K RPM, no misfires so I assume my ignition coil and distributor cap/rotor is fine.

I did end up pulling the plugs and it reaks of fuel and the tips are wet. So I'm assuming the cylinders get flooded out and cause the engine to stall. I did just change the plugs on the car with NGK copper plugs I believe. I know the 2VZ-FE uses platinum plugs but it's my beater and I didn't want to shell out $50-60 bucks for plugs.

And another thing, I jumped the diagnosis connector under the hood and the ECU is throwing a CEL code 21 for a bad oxygen sensor, assuming I counted the blinks right. The CEL has been on for a while but the car has never had a problem running, just bad gas mileage. But the CEL would turn off for some days then turn back on, but recently, it's been on for the past 3 months.

So my guess is, is it possible that the oxygen sensor has completely turned bad/no longer working and my ecu has no air fuel ratio to read off of? Therefore dumping a bunch of fuel into my cylinders and causing the engine to stall?

Sorry for the long story, any input would be appreciated.

Thanks,

Chris

[white90dx]

Definitely replace that O2 sensor...

It still could be the ignition system, AFM, water temp sensor or possibly something else.

-Charlie

[91 2VZ]

Thanks, I'll try and get the O2 sensor replaced first and go from there. Do you know where it's located? I know it's on the rear exhaust manifold but I can't seem to locate it from the engine bay. Maybe I have to look from underneath?

[typesix]

Also, the O2 sensor doesn't come into play untill after the engine has warmed up to a certain temperature.

[Doctor J]

While dead O2 sensor can cause engine to run slightly rich, it not likely to cause stalling; it will rather run strong with worse fuel economy.
For this particular case, if flooding is evident I would check the fuel pressure regulator and cold start injectors for leaks.
to do so:
remove vacuum hose at the fuel pressure regulator and check for the liquid fuel;
if none present leave the hose disconnected;
unbolt cold start injector from the plenum with fuel line connected, but unplug electrical connector from it.
Using jumper [paper clip] short FP and B+ terminals in the diagnostic box.
Turn ignition on, but do not start the engine.
Look for leaking fuel from regulator's vacuum port or cold start injector nozzle.
Bad coolant temp [ECT] sensor or its connector can cause code 22;

[91 2VZ]

Originally Posted by Doctor J

While dead O2 sensor can cause engine to run slightly rich, it not likely to cause stalling; it will rather run strong with worse fuel economy.
For this particular case, if flooding is evident I would check the fuel pressure regulator and cold start injectors for leaks.
to do so:
remove vacuum hose at the fuel pressure regulator and check for the liquid fuel;
if none present leave the hose disconnected;
unbolt cold start injector from the plenum with fuel line connected, but unplug electrical connector from it.
Using jumper [paper clip] short FP and B+ terminals in the diagnostic box.
Turn ignition on, but do not start the engine.
Look for leaking fuel from regulator's vacuum port or cold start injector nozzle.
Bad coolant temp [ECT] sensor or its connector can cause code 22;

I'll check the fuel regulators and the cold start injector as you mentioned.

I have another question, can regular copper core spark plugs be a problem? Cause I mentioned in my original post that I recently replaced them with copper instead of the recommended platinum plugs. It ran fine prior to this problem with the copper plugs though.

[Doctor J]

If they are gapped properly, in short run there should be no such symptoms you are describing.
However the specified plugs should be used to avoid long term problems.
There is a possibility that something got knocked off from its place, the vacuum line broke, the intake hose between Air flow meter and throttle body got cracked , etc., so this should be checked out also, including distributor cap and rotor.

[Justin727]

I gotta say possibly vacuum leak. When you took off the intake manifold plenum did you replace the plenum gasket when you replaced the plugs? Its always a good idea to replace that everytime the plenum comes off..

I also suggest the intake boot and or possibly lines like Dr.J said.

[91 2VZ]

So I checked the fuel pressure regulator and no fuel came out the vacuum tube going to the intake plenum so the diaphragm inside the regulator is ok I guess. I also took a look at the air filter. It was dirty as hell so I got a new one. No help with the engine running conditions after the new filter was installed.

Didn't get to the cold start injectors since it started raining.

Originally Posted by Justin727

I gotta say possibly vacuum leak. When you took off the intake manifold plenum did you replace the plenum gasket when you replaced the plugs? Its always a good idea to replace that everytime the plenum comes off..

I also suggest the intake boot and or possibly lines like Dr.J said.

Well I actually changed the plugs without removing the intake plenum. I stuck my arm back there and somehow I reached the spark plug holes/wires etc. I used multiple extensions to remove the back 3 plugs. It was a pain and my arm go pretty scratched up but I got it done in like 20-30 mins. Fronts took me like really quick lol.

Also, after starting the engine with the new air filter. It sounded as if the engine was running on 3 cylinders again right on start up. As I gave it more gas, idle smoothed out and then I let go of the gas pedal. RPMs climbed to about 2K and stayed there for a while. It then dropped to about 700 RPM and then would want to cut off every couple of minutes. The engine did warm up a little bit. Temp needle was just 1 cm or 2 from cold.

[Justin727]

you'll be suprised how much more quickly it is to catch the plugs without the plenum on. Not much to it.

i also tackled valve cover gaskets, pcv valve, grommet, tube seals, valve cover grommets. Completed that along with cap and rotor in under an hour taking my time.

That being said you did check the cap and rotor? Actually take the cap off to see if there is any oil accumulated in the cap??

[91 2VZ]

I haven't checked the cap and rotor but there is grime all over the distributor body. I'm getting a new cap/rotor this weekend and I'll see what happens then.

[Mike Gerber]

Check the engine coolant temperature sensor. It may be out of range and constantly tell the ECU that the car is cold. This could cause an excessively rich mixture, especially when the engine is warm. It could explain the stumbling, the gas smell in the exhaust you mentioned, the wet plugs and also the poor fuel economy. To check it you will need a digital volt/ohmeter and the specs from any manual. Just a hunch here.

Mike

[91 2VZ]

Originally Posted by Mike Gerber

Check the engine coolant temperature sensor. It may be out of range and constantly tell the ECU that the car is cold. This could cause an excessively rich mixture, especially when the engine is warm. It could explain the stumbling, the gas smell in the exhaust you mentioned, the wet plugs and also the poor fuel economy. To check it you will need a digital volt/ohmeter and the specs from any manual. Just a hunch here.

Mike

I don't have a volt/ohm meter on hand. I will look into this. But if the engine coolant temp sensor was out of wack, wouldn't it throw a CEL for it? Right now, the only code I'm getting when jumping the diagnosis port is a code 21 for the oxygen sensor. Nothing else.

So I pulled the cap and rotor and here are some pics of what I found. Oil was all over the cap and contact points. Rotor seemed corroded with caked on carbon. These seem to look like the original cap and rotor from Toyota.

Distributor, that's oil/oil stains on the bottom of the housing.


Cap, oil all over. Bottom contacts were the worst.


Bottom contacts.


Upper contacts.


Rotor, was corroded and had black carbon on it.



I'm gonna be getting the correct Denso platinum spark plugs tomorrow along with a new cap and rotor. I hope this fixes my problem. If not, I'm going to replace the oxygen sensor since the ECU is throwing a code for it.

[typesix]

But if the engine coolant temp sensor was out of wack, wouldn't it throw a CEL for it?

No, if the coolant temp sensor is out of range, it will not activate the CEL, therefore the need for the multimeter.

[Mike Gerber]

typesix is correct. I once talked to a former Toyota tech about the same thing. He said it would only throw a code (on OBD1 systems) if there was no signal at all or a dead short in the ECT sensor. You need to borrow a digital volt/ohmeter and check it out. Does Autozone loan one out in their tool loaning program?

Mike