Automatic stalls, then struggles to go up gear, revs bouncing - would low/bad fuel explain this?

Question

I had a hair-raising incident yesterday. My engine (automatic transmission) cut out while driving at around 30mph on a main road, just like a manual stalling. It restarted on the first attempt as soon as I'd realised what was happening, after putting it into parking gear etc.

After this, it drove but struggled to shift itself above second gear and struggled to accelerate. If I accelerated a normal amount, the revs would lurch and bounce up and down alarmingly without the car gaining speed like it was stuck bouncing between gears. I put it into "2" and drove slowly, and it seemed better, but even then the revs occasionally went up or down for a moment with no obvious reason.

I was down to about 20% fuel, and this is a country where fuel quality can be low (sometimes literally watered down). I crawled along to a petrol station and refueled - after refueling, it was a little slow to accelerate at first especially going up hill, but after about 15 minutes on the road seemed pretty normal.

After letting everything cool down, I checked transmission fluid levels*, and they were normal. No problems at all shifting between positions on the PRND2L stick, either - reverse reversed, park parked, drive drove, 2 and L behaved as expected.

Could what happened be explained by low / bad fuel or should I do other checks as well?

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*_{oops, I should have checked transmission fluid while the engine was idling, not after letting it cool down (according to the Haynes manual for this car and model). Actually, my transmission fluid was low - topped up now.}

Answer 1

What you have described are classical symptoms of what happens when a bad batch of fuel finds its way inside an engine - sputtering/coughing/misfiring during low-load operation.

If the issue recurs with fuel that is known to be good, another possibility is that the fuel supply system is unable to deliver the required amount of fuel, causing the engine to misfire. Things to check in such a situation would include:

• a clogged fuel filter
• a malfunctioning fuel pressure regulator
• a weak fuel pump

Symptoms of fuel starvation usually manifest themselves under high-load situations, so sudden acceleration, going uphill and high speed travel will all be cases in which the engine could misfire in case of inadequate fuel supply.