Hi just a quick question about air pump and bad MPG!

I do have that high pitched sound and I do have the NSK 608VVC3 Bearings to replace in my airpump but haven't gotten around to it with bunch of tests and finals coming up. (My fuse and cat is fine btw)

I have that p0410 code that says airpump will need more time blah blah
but I noticed that my mpg has gone down significantly after that code.

I do make lot of short trips around 5~10 miles in town since I am a college student but I never turn my rx8 off before fully warming up the engine so I don't flood and I do red line is once a day to keep the carbon buildups away from my engine!

I did the search but didn't really see any bad mpg and air pump related posts but I'm wondering if my mpg went from 17 ish city and 23 highway to 13~14 city and 23 highway(high way mpg didn't change for some reason)

so from my deductive reasoning I thought it was airpump that was wasting my gas due to short trips(since air pump does turn on for like 30sec-1min when I start the car cold and lots of short trips mean lots of airpump time.

I just wanted to see what you guys think about it :P I will replace the bearings as soon as finals are over

hopefully it'll fix the bad city mpg problem :P (I know lots of people get 13-14 mpg in city like me but it did all of sudden decline with the CEL p0410)

I'm also gonna do Mazda zoom zoom cleaning over the summer and my ignition system is pretty new(around 3000miles old replaced at the dealership) and they told me that my engine seems to have not much carbon build up! they told me that I was doing a really good job of maintaining my engine!

with gas price above 4 bucks those 3~4 mpg difference really makes a difference to a poor college students!

well Rotary gurus let me know what yall think :D

ps. oh and I don't have any of warm start cold star problems and etc everything seems fine :] except the old suspension :P

103,600Miles(20,600Miles on new engine) 2004 Metallic Grey Rx-8 - AEM CAI, Tanabe Hyper medallion, Axial Flow SS, Clear Corners, red top optima battery and updated starter.

 

ps. ps. I'm not a jack rabbit driver either lol I don't step on my gas except when I'm redlining I keep it around 3k rpm when I shift and sometimes 3.5~4k

 

how did you manage to accurately calculate your mileage

 

oh you know the usual, fill up the tank to full set the trip A to 0 and the next time you fill up the tank I'll divide the mileage by how much gallons it took to fill my gas tank up for ex)
if I drove 200 miles since I last filled up my gas tank and needed 13 gallons to fill up my car then

200/13 = 15.3 ish~

 

well it could be related on a number of accounts. first if the cat isnt coming up to temp OR the sensor is saying the cat isnt coming up to temp then the air pump will run right? so if thats happening then the car will stay in open loop fuel maps longer. the longer it takes for your car to go into closed lopp the lower your mileage will be. if your car is in open loop for your entire driving trip then your using more case then you otherwise would be.

so yes the air pump running and lower mpg can be connected and both be symptoms of separate issue. so first thing is to diagnose WHY the air pump is running more/longer

 

I never said airpump is running longer I just mentioned that

the code was P410 "Air pump will need more time...", or thats how it was written on the dealer's receipt.

I thought that would translate into air pump not running long enough? since it needs more time.

I just looked up p0410 code and found bunch of high pitched airpump noise related problems, which I have, and thought it would go away with the bearing change since my fuse was good.

I guess I'll have to change the bearing and clear the code first to see, just wanted to ask if it's commonly related problem lol. guess not.

 

Sorry, never heard of that issue.

My air pump is on the top shelf in my garage. I disconnected it at the harness connector, it never threw a code. I am not sure if you can get away with that option if you do not have the exhaust fitting blocked off. But, if the valve is normally closed, you probably can.

I would verify that the valve is closed if you seal off the vacuum line (disconnect air pump hose, and vacuum line, start car, see if exhaust comes out the hose), seal off the vacuum line, clear the CEL, then disconnect the pump (at the red connector) and see if things get happier. Unless you are in the arctic part of Texas, it should not matter much. Things might get better, then you can decide if you need to fix the pump.

I agree with above that you could be in some open loop mode, or in the mode where the mixture is held rich to light off the cat.