3.3 91 Ciera S

[Ian Szgatti]

276,500 kilometers

I am wondering if anybody knows what tempreture the thermostat has to reach before the ECM goes into closed loop mode, recognizing the vehicle to be at operating tempreture.

The reason is... I have a very good fuel pump, fuel filter, spark plugs, new wires, 02 sensor is only 30,000 kms old, clean injectors, good EGR, and generally good throttle responce. If I try to accelerate to fast from a stand still, the car will buck and nothing will happen. Fuel will shoot through the exhaust and burst in the cat. (think about blocked converters during this too??).
The resistance of the primary and secondary terminals is another thing I'd like to know, so I can test them.
To make this interesting, concider that if I accelerate slowly at first and work into the pedal before the cars shifts out of first, the engine will reach a high RMP without missing, and have a lot of power.

I have not done a compression test, so I won't rule out the engine not producing enough cyclinder pressure to sqwak... but I doubt that... it seems under normal driving conditions to operate fantastic. No high oil consumption or coolant loss. I maintain this cars very well.
Could a TPS act sluggish? I know the values are from .45 V to 4.75 V at WOT... It doesn't seem to miss a beat.
Sorry about the very long post, hopefully there are some cars nuts on here who don't mind a challenge... or better yet, somebody who has experianced and solved a similar symptom.

[maxwedge]

If you power brake the engine, load it against the brake ,or pull a hill in o/d does it misfire?

[Ian Szgatti]

The engine would powerbrake, given the throttle advancement was moderate... Going up a hill isn't a problem either unless the grade is such that the transmission needs to kick down, then there is some hesitation before it selects the gear. That particular symptom is most prevailent when the accelerator pedal is left in one position, and ever so slowly increased as the need for power goes up on a grade.. however, if I were to push it quickly to around 75% WOT it will quickly and smoothly select the right gear.
It is the initial snap of the throttle from a stand-still that presents not merely a misfire, but a complete belch from the engine. As I said before, this motor produces plently of pull when driven correctly, and it should still be capable of rapid advance from a stand still.

I am by no-means looking to achieve results for the thrill of speed. I am interested in electronics/mechanics as a career. I am definately a car nut.. and I'm somewhat obsessive about it.. I simply appreciate a well-working machine

[Ian Szgatti]

To add another thought.. I suppose the engine, having 276,500 kms (172,000 miles) could be worn enough to not handle those pressures. As I said, I've not done a compression test, but I do know the oil pressure is very nice.
When I change the oil, I drain the old, and mix a detergent (equal parts) with one liter of fresh oil. I pour that oil into the crankcase. The old oil filter is taken out, sprayed with parts cleaner, and re-installed. Then I run the engine at about 2000 rpm for a minute or so, and then of course drain the engine again, and adding fresh oil and a new oil filter. I do this every 4000 to 6000 kilometers because I don't want any dirt, sludge, or chemical contaminants on my barings!

Another note, my prime suspision is the coolant tempreture. The engine does not reach any more than 170 F. Even in hot weather, I don't think it reached the fully open temp (thermostat full opn temp).
This is why I suspect a flooding condition, in which the rich mixture at idle is what bogs the engine down from snap acceleration... I can see engine wear, but I have always treated this car with respect. I'm shooting for a half million before a rebuild.

[Ian Szgatti]

I am only updating this to put solution to symptom, which is very important for those who seek answers.

The fix to the symptoms I indicated... incorrectly gapped spark plugs. Seems six months ago when I installed them I shouldnt have taken the parts guys' advice on them being pre-gapped. Car pulls nicely off the line now. Didnt discover this sooner until i decided to go with a platmium plug and noted the difference in the gaps.

[maxwedge]

Common issue, a misfire can be tough to pinpoint, it usually will happen under a load in lock up, but will go away when the trans downshifts, good work!

[Matts3100]

I have a 93' Ciera with a 3.3L and it is the same way. I was told its normal for the 3.3L to be like that. I was wondering the same thing too...

[maxwedge]

Start a new thread this is way too old.