trying to help a friend find out what might be wrong with his car.

Car: Mazda Mp3, 5 speed

problem: when he steps on the gas, he feels lack of power(sluggish). after a second or 2 the car gets power and drives. idles low and stalls sometimes.

problem just happened after he got gas. hes thinking maybe accidently added 87 instead of 91 gas. can the difference in gas cause this kind of problem? or from your experience what else could cause the sluggish feeling when you step on the gas. and low idle? dirty maf?

Thanks guys!

 

engine oil overfill?

clogged engine air filter?

dirty throttle body (or a sticking throttle body?)

spark plug misfire?

wrong engine oil? (might account for the different idling rpm)


different fuel can make a difference in performance although I don't know if it's measurable by feel (it's definitely measurable via dyno)

 

Ask him if he gassed up during, or right after, the tanker truck was filling the station's underground tanks, or if he remembers? (I've cautioned you guys several times about that). That is a sure-fire way to get water, dirt, and sludge stirred up from the bottom of the tanks (particularly if they are old or not sealed well), through the pumps, and into your own gas tank. The station is supposed to have filters to keep this from happening, but they don't always work. Once that junk gets in your tank, it settles to the bottom, but if you then let your own tank get low, it gets picked up by the fuel pump and pumped through the fuel lines to the fuel filter and injectors, plugging them up, and cutting down on or blocking the flow of fuel to the engine. This will cause exactly the type of drivability problems you describe. To prevent this from happening, always wait 5-10 minutes after the tanker truck finishes and disconnects the hoses.....THEN you can gas up. And keep your own tank at least a quarter to a third full...no less.

If he has been using El Cheapo brand fuel without the good detergent packages that the better name-brands give, like Chevron, Shell, BP, etc....he could also have the injectors and valves plugged up with carbon...another major source of drivability problems.

My advice? Have him use ONLY good gas brands for a while (Chevron and Shell have the best detergent packages) and see if that helps. If not, then try a dump-in-the-tank fuel-system cleaner like BG-44K (BG-44K is one of the best available....it is usually not sold in regular auto parts stores; only repair shops). If that doesn't help, then the fuel filter, fuel tank, and lines will have to be looked at for a major cleaning job.

 

thanks for the extra info.
i didnt get a chance to ask him if there was a oil tanker.
my friend added some octane booster and it drivers fine. most likely the fuel.

 

might have been water in the gas ?

 

I once filled up when I was down in Mexico for Spring Break, my Honda Accord ran like crap, the engine severly reduced the ignition timing just to keep the car from pinging so it could be driven, but it was way down on power. After a tank of US premium fuel it was fine again.

 

sounds like its just some bad gas. only time will tell,