Stumling on acceleration

[coleman]

Before today, my car was behaving horrible all the time. Now it's just when it is under load.

When I give the throttle a blip at idle, it hesitates for a moment before it revs up. On the road, the engine runs great until I try to give it a decent amount of load. I can accelerate fine, at higher engine RPM and low engine load. If I am at lower RPM and I push the pedal down more than maybe 25% throttle I feel a vibration proportional to the engine's RPM.

So I think I still have a misfire. One day my car starting doing this, and it started getting worse and worse. My spark plugs were totally fouled when I replaced them today, they were just a little ashy last week.

The entire ignition system has been tested and is known to be good so I know that the fouling of the plugs is a secondary problem cause by whatever the real issue is.

After it started doing this, I suspected a fouled injector and I sent them out to be cleaned. Same symptoms before and after cleaning.

So I suspect maybe the VAF is giving false readings to the ECM, and it is running PIG RICH. When it does this vibrating/shaking I see some bluish smoke coming from the exhaust. When it's not doing so, no smoke!

Any advice?

[Tazman2]

Bluish? Thats oil burning... maybe you have some real bad blowby or something?!

[Onehalfasia]

It might be a sensor...like the coolant or temp sensor, cant remember what its called, but mine was bad, and my car would stutter, and run rich, and was really f'ed up. After I replace it everything was fine, it plugs into the block...someone might know what its call? It was a temp something. Or thermo?

[coleman]

Good point, the coolant temperature sensor might be broken (seems common on these cars) which could cause an excessively rich idle at higher than normal engine RPM. That could be causing the fouled plugs and the stumbling also. I have two Proteges, I'll swap out the sensor with a known good unit and see what happens.