So my 04 Ralliart was getting terrible gas mileage, 150 to a tank and that's mostly highway miles. It was recommended to me to change the mass flow air sensor. So I went to eBay, ordered a new one that eBay said would fit my car. New part comes in, I replace it AND now the car won't stay on for more than a second. Take the new part back out and reinstall the old one and the car fires right up.

Upset I log onto eBay to give the seller hell for selling me a faulty sensor. They apologize obviously, tell me to pitch that one and another is on the way. New part comes in and I experience the same damn thing.

So now I'm baffled, the New part has a number on it of PBT-GF30, and the old part has the code part mr985187.

Can someone please help me? Think I got 2 faulty sensors, or bigger problem on my hands? I'm desperate.

 

stop buying MAF sensors on ebay...get a genuine Mitsubishi electric mass air sensor if you're going to. If your MAF sensor was bad, the car would run like ****. Although a faulty IAT sensor which is in the MAF could result in poor fuel economy during extreme hot or cold weather...my question is: Is your check engine light on? is the air filter clean, when was the last time you changed your spark plugs?


could even be as simple as a faulty fuel level sensor, the tank might not even be empty when the gauge says it is...I'm not saying that's it, but just throwing expensive sensors at a fuel economy problem isn't going to get you anywhere...try datalogging your sensor outputs, see if the IAT signal matches the actual air temperature. Also you'll want to look at your fuel trims.

 

Check engine light has came on intermittently, and when I get it checked the error code says its running lean. I don't think it's faulty fuel level sensor bc I'm still putting in 9-10 gallons of gas each time. Air filter and plugs are new, as they have both been replaced in the last 3 months.

 

what pther codes are you getting...it's unusual you would get a lean code, without being accompanied by another code relating to either a MAF/IAT or O2 sensor...what kind of spark plugs did you use, and what did the old plugs look like, and did you change them because of the fuel economy issue? To me it sounds like a faulty upstream O2 sensor is telling the ECU the system is lean, and then it's adding way too much fuel...have you noticed a loss in power/throttle response, as well? get or borrow a scanner and check your fuel trims.

 

No noticeable loss in power, and I don't know anything about fuel trims.

 

Running lean? What engine mods do you have that you haven't mentioned, and could that be the cause? (e.g. leaky after-market intake plumbing).

So when you "get the engine light checked" I assume it was done by a proper garage? If yes, they will then tell you what needs to be fixed to get the CEL to stay off. What did the mechanic say needs to be done?

 

I just have advanve auto check it, I understand they are not mechanics but they tell me what the codes say. The only engine mod I have is an intake.

 

There are aftermarket intakes that claim to be made for our RA, but in fact their inside diameter at the mass flow sensor is a different diameter than the stock intake pipe. This will cause a code to be thrown.

This has been brought up in our forum before, and it's the cheap ebay brands that are the culprits.

Worth it to check.

 

that would have been nice to know.