Sorry for long note, but wanted to give the FULL story. The car has been in the family since new, been well maintained, and run fine for years. Awhile back I was driving on interstate and it starting to shudder—the whole car…as if the engine was “missing” so badly it could barely run. The acceleration was not so great at this time of course, but it continued to run. And as it happened, large amounts of white smoke came from exhaust. After 10 sec or so, the problem stopped instantly and the car ran completely normal again! Then for the next few miles, this problem started again, then stopped randomly—several times—whether I was idling or just driving. I pulled it over within a 1-2 miles and popped the hood to see if anything was obvious—nothing. It acted as if it would quit, but barely idled. I continued 1 more mile to get it home. By that time, the problem happened 90% of the time—it was becoming less random. And was it would eventually quit instead of idling.

I started it later and the problem became constant—no “normal” running periods, and the white smoke continuous. I left it parked for what became a year, because we had another car (yes, I know this was stupid). Recently I took it to a mechanic.

By this time battery had died so he couldn’t pull any codes from it, and it didn’t start anymore. The mechanic replaced much of the fundamental stuff on the car--all gaskets (head gasket was suspected as possible culprit), plugs, heads checked out ok, 2 valves were stuck—he repaired or replaced them, coolant temp sensor, water pump and timing belt (since he was in there anyway). The list goes on, but the point is it was a significant expense—more than the book value of the car. But I knew if it would be fixed, it would be worthwhile and run at least a few more years.

I got it back 3 weeks ago. It ran great—no problems, for at least a few hundred miles. But it just started to show the EXACT SAME symptoms as before. This time I popped the hood and noticed something dripping from exhaust pipe that is right off the engine block. It dripped every few seconds and leaked through location where one oxygen sensor is mounted. I’m not sure if it was coolant or fuel. It smelled like fuel but I should have verified, and now it has evaporated.

So I’m assuming the REAL problem caused the valve issues (since I left the car unused and with old gas for so long). I pulled diagnostic codes this time. 2 codes came up—1 for coolant temp sensor and 1 for throttle position sensor (TPS). Because the first part had been replaced I checked the TPS per my Haynes manual (removing electrical connector and simple resistance measurement, for different contact pins depending on different set screw ‘gaps’. The resistance between contacts reads properly (infinity/open) at normal position (7.0mm/.28” gap) , but did not read correctly (still infinity) when gap was adjusted (3.5mm/.14” gap). I loosened and rotated TPS. I could get the .5k ohm reading on the smaller gap, but not such that the same TPS position would measure infinity/open with larger gap. Other readings seem ok for this part, however. I plan to change it, but am concerned it won’t fix the problem. Could this be a cause a major flooding of fuel (if that’s what it is)?

For anyone dedicated enough to read this whole saga, I’d love to get any input. Thanks in advance!

 

The engine may have a cold start injector that sprays more fuel into the intake when engine cold. Perhaps the injector is on when it should be off.

Locations would be on the passengers side of the intake manifold.

 

Sounds good. It looks like it does have a "cold start" injector, so I'll check this out first.

Thanks very much!

 

yah seems one!!!please update us that would help some of us here in the future.

 

Latest update. After measuring resistance of throttle position sensor, thinking it might be flaky and ordering another, I think I'm reading I am supposed to apply vacuum to it while measuring. Is that true? I didn't do that. I simply measured, adjusted slightly (not able to get it where I wanted) and tightened it back.

The car is not accelerating so well now (makes sense if I misadjusted the TPS), but the smoke has stopped and the idle issue isn't there--temporarily anyway.

I checked the cold start injector valve--it ohms out fine (2-4 ohms if I remember correctly). There is also a cold start "timer" located beside the coolant temp sensor. I guess it controls cold start injector valve, based on temprature. But it checks out ok also at cold and warm engine temps.

I guess this should be no surprise since it's not exhibiting the same condition now. Maybe it's happening intermittently. And I only drove it a mile or two. I'll try to give it more time tonight, but still open to any info.....thanks for your input, guys.

 

The throttle body has a vacuum operated throttle opener system.

When the engine is off (a no vacuum condition), a spring loaded vacuum operated diaphragm inside a can pushes on the throttle arm via a rod to slightly open the throttle plates.

When the engine is running, vacuum now draws the diaphragm down and with this compresses the spring so that rod is no longer touching the throttle arm.

You need to apply vacuum via a pump to the throttle opener or somehow lower the rod so that it is not forcing the throttle open when the engine is off.

 

I had checked all thing suggested in other responses, with no luck. One time when running poorly, I parked it, popped hood and it stalled just before I could raise hood. But I heard a fast clicking noise (like a relay) that continued for a minute or so--even though car was off. It was the fuel injector at center, front cylinder (not sure which number that is). I ohmed all fuel injectors and they looked normal. That (fuel injector firing after car was off) didn't continue, but I came across a post on another forum with almost identical problem--same cylinder even. That fix was the ECM, so I got one from local salvage yard and it worked!!!

Before that I had gone through all things mentioned by you guys + a few other things--even the ignition switch (not sure why but a mechanic suggested it and it strangely seemed to resolve things for a few days).

Anyway, I meant to follow up and post the fix for any others having similar issues....sorry for delay on that, but thanks VERY MUCH for the support!

 

This type of ECU problem is very rare thus great job in finding the fix! Good job on picking up on the injector clicking noise!

Thanks for posting back!