Stock airbox fail

[Wurf]

So ever since I've owned this car, I notice that between shifts when romping on it a bit, specifically 1-2, and 2-3 then 3-4 which is mostly in town before I let off, this car hesitates right after I let out the clutch and I hear a backfire pop. It's highly muffled but I hear it. I've posted this before, and other members have said its the traction control in the DSC.

It's not. Running a PG SRI, the car does NOT do this. As a matter of fact it runs a lot BETTER with an SRI than the stock airbox save for a bit more jerky behavior at lower speeds in first gear because of the increase response.

I put the stock airbox on the car for oil changes and then switch back to the SRI. Last week I threw a CEL and didn't bother to have the code pulled because I needed a change. Put the stock airbox on the car, reset the ECU in the process, got the oil changed and now I'm driving with the stock airbox again. SAME behavior - car hesitates between shifts and I hear pop from the rear.

Could it be the stock MAF is signaling more air to the ECU than what's really entering the motor creating a rich condition that's causing the backfire? Or could it simply be the stock tune is so pig rich that once the factory parts are back on the car, this is the result? Whatever the reason, I'm ready to swap back. Not sure about the CEL as I didn't pull it and it hasn't come back but if it returns, I'm going to have it read at Autozone. I don't have a DH. Maybe that would be a wise investment.

Car runs fine other than this hesitation and idles a little better but is significantly slower, less responsive, and not as much fun to drive compared with running the SRI.

 

[CWPspeed3]

ive switched between the stock box and sri a couple times as well and i know exactly what your talking about. the stock air box sucks

 

[MSMS3]

Stock air box is restrictive as hell. Car and Driver dynoed before and after change to a Mazdaspeed CAI and picked up over 20 whp!

So, it is logical to conclude that the stock air box does not send the same mass air flow reading from the MAF sensor to the ECU due to the lower oxygen flow compared to SRI or CAI.

I think the ECU's fuel trim adjustments when changing back and forth take some time, perhaps as much as 50-100 miles of varied driving to make the change. No wonder it will stumble for a while when cutting air flow after the ECU has adjusted for more.

Maybe something else is going on too, like a dirty air filter on the stock box, but I tend to think it is the fuel trim adjustments by the ECU taking some time.

Any aftermarket SRI or CAI will flow much more air than the stock air box. It takes a pretty big increase in flow to produce a 20 whp gain. But that gain is absolutely true.

 

[Wurf]

Yeah well I thought I would live with the stock airbox for a month or so and I can't stand it. The SRI is back on the car again and it's SO much better. I just can't believe the stock setup is so lame. The stock airbox is good for one thing though, and that's winter driving because no point in having all the extra power when snow tires are on the car and roads are wet, salty, or snow covered.

 

[coololddude]

The stock airbox is supposed to SUCK!!

 

[CWPspeed3]

The stock airbox is supposed to SUCK!!

exactly, that way you get the $300+install MSCAI from the dealer! which is what i would have done if it wasnt on stop sale at that time.

 

[Wurf]

Stealership is the wrong place to go to install an intake. At least around here in Michigan anyway. Never tell them you have one, never let them service your car with one installed, and never bring it up. Install it yourself or have a friend help you and if you ever need to take it to the dealer, reinstall the bad, stock air box assembly in the interim. From what I've read here, Mazda will almost certainly not honor the warranty in the worse case scenario of zoom zoom boom unless they believe the car was completely stock and if you leave them any "outs", they will take them and deny your claim.

On my car the only evidence they might find are marks on the bolt head of the accordion hose where it connects to the TIP, marks on the clamp for the PCV, marks on the nut for the battery ground, and any reset of the ECU as a result. I'm not sure that's a saving grace for me or not in the event of zoom zoom boom, but I'm sticking with just an SRI and maybe a FMIC some day until the warranty expires to avoid that. I simply don't want to risk it.