CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Bad gas?

I have a 2002 Mustang, 43,500 miles. I had 1/2 tank of gas and am experiencing extreme hesitation and small back fires on acceleration. The ‘check engine’ light came on. Took it to mechanic, they couldnt find anything, and it eventually stopped doing it. 2 days later its back. I bought a bottle of Heet to remove water from the gas tank since a few people suggested thats what it might be. I was told I need to burn off this tank, then when I fill up again, add the second bottle of Heet. So far I am not seeing any improvement at all. And naturally the engine light is back on.

Is there anything else it could be or something else I should be doing??

It sounds like some of the cars I have seen with a dirty or bad Mass Air Sensor. You could try cleaning it with a little carburator cleaner spray. That is about all I can remember.

well. if you took it to a mechanic and they couldn’t find anything (but the check engine light was on) then you need to go to a different (competent) mechanic.

a check engine light will trigger a code which can be read and then used to help diagnose the problem. now that it has triggered again, go to autozone, or any other reputable parts store. they will read the code for you. (usually for free, since they want you to buy parts from them) get the code, post the code back here.

the code should read (for example)-" PO 1234 " DON’T let them tell you what it says. get the actual numbers and write it down. then post it back here.

just to share; this may be a clogged fuel filter, clogged air filter, engine needing tune up, or several other things. but the code would be able to lead in the correct direction. by any chance has someone been under hood lately doing anything, prior to this hesitation/backfiring episode?

Did the people that suggested you may have water in the gas also suggest you find out why the “check engine” light is on? get the codes read, post back the numbers.

Have you gone by the place you bought the suspicious gas and asked if they had other complaints?

Can you or someone else give the engine area a good visual inspection? do one inspection in the day and do one at night (you are going to be looking for sparks along the spark plug wires),you don’t say what engine I conclude you engine uses typical spark plug wires. Get a spray bottle and fill it with water and spray along the plug wires,this will make the electricity “leak out” easier (night test).

Are you up on maintiance? (I am not talking about oil changes)not a lot of miles but 6 years on ignition parts and filters.

Did the mechanic check codes, record them (write them down) clear them? now they are back you need to compare the old with the new.

As a matter of fact, I had an oil change the week before this began. So yes they were under the hood. They told me the code just reflected that the engine was not running right. I could have told them that!! LOL.
I was planning on going by Auto Zone to have them read the code also. Either tomorrow or Tues. depending on the rain.
Ill post what I can find out.

Thanks

specifically what was done under hood. IMPORTANT. if they goofed up under there it may contribute to the new problem.

get the receipt. what kind of shop did this. cringe. Diffylube??

All I had done was the oil change, and a wheel alignment. They said they also do a check of the belts and normal stuff. I had the work done at Mid Cities Auto, they have done work on my car for over a year, and never had a prob, yet. They are also the ones I took it back to for this new prob.