Thorby

Fuel pump is intermittent or hard shifting to 2nd (OBD Codes 0100, 0732, 0733)? Clean the MAF/MAP sensors first!! Really! Here's how I learned this lesson the long hard way:

Since 3 years ago, my transmission started to fail. When it was cold, it would stay on 1st gear, and rev up to 4000+ revolutions without shifting. I had to take my foot off the accelerator to force it to shift up. Through the years the problem worsened so that it no longer mattered if the transmission was cold or not. Transmission mechanic diagnosis: None. I went to other mechanics (three of them during the years), this time general. Their diagnosis: None.

Now, on to the fuel pump symptom. That one is more recent, since 3 months ago, but I'll explain how it's all related at the end. So, three months ago for no apparent reason my car sputtered in the middle of a drive on the interstate as if the engine was not getting enough fuel. The fuel tank was full to the top. As the weeks passed, this would happen more often and these last few days my car would downright stall in the middle of a drive. It would jerk forward slowly, as if the engine's supply of fuel was intermittent. But here's the catch: Fuel pumps give out immediately, and not during the course of 3 months.

God provides all, even good mechanics (yep, I'm a believer ). Today I took my Maxima to a new mechanic, since the stalling made the car undrivable at this point. He immediately headed to the MAP and MAF sensors and offered to clean them. See, here in Mexico mechanics are not mere parts-replacers. They put serious effort into actually fixing parts before having to replace them, saving us serious dough. 2 hours later, voila! I was most worried about the stalling, since I had gotten used to removing my foot from the accelerator to shift to 2nd. However, the transmission was fixed too!

So I wikipedia it and realize that the MAP and MAF sensors measure the pressure and flow of air going into the engine. They are located right after the air filter, on the tube that directs the air to the manifold. Even though the air filter catches big stuff, tiny dust particles still get through and dirty up these sensors. Also, my intake tube was cracked after the filter for a while and a lot of unfiltered air passed through there until I finally discovered the crack and puttied it shut. So my air sensors were definitely gunky. Turns out these sensors send critical information that determines what fuel mixture the engine will get and when the transmission will shift.

So my mechanics missed or disregarded the trouble codes. Perhaps your mechanic will perfectly understand the trouble code but will still rip you off with a transmission replacement. Or maybe a totally doofus mechanic will replace your fuel pump for $150 dollars in parts, before proceeding to replace a bunch of other things until the symptom finally goes away. Hopefully none of that will happen to you now.

FallenOne

iTrader: (17)

I give this post a Gold star.

Everything Has its Place and Purpose, For Good Reasons.

Honestly, if we all spent more time in our engine bays we'd all have alot less trouble diagnosing simple problems, and even the most complex ones.

TreizeRXH

There should be a "like" button for this. Thanks for sharing the story, def. an insightful read