That's true but running with your MAF sensor dis-connected is not the same as running with a defective one.

 

I got the new MAF tube installed today. I put stainless steal mesh screens before and after the MAF. I also installed new spark plugs. The car is running better now. It idles most of the time within +/-.3 of stoich and it is not hunting for the proper AFR anymore. The airflow numbers are much more consistant, too.

I didn't reset the fuel trims but I think I need to reflash it and start from scratch with the tune. Without resetting the trims my LTFT was +19 on the AP and my STFT was right around 0. Most of the time it was +2 to +5.

I took it for a short drive and it is very smooth under light acceleration and at cruise with the AFR right about stoich. When decelerating or pushing in on the clutch to come to a stop the RPMs drop to about 1200 then gradually fall to around 800. However, every once in a while the AFR will go to 13.5 and the car will stumble and sometimes die. I hope MazdaManiac can tune that out and I might have him increase my idle speed a little.

Anyway, it is running better with the recent changes and hopefully the few issues can be tuned the rest of the way out at the Chicago dyno day.

 

Get rid of the screen after the MAF.

 

Why? Christian seemed to think the turbo was causing the problems not the MAF tube itself? Can you explain it to me? I have no problem doing that. Its easy. But I would like to understand what is going on?

 

Well, how far from the turbo is the MAF now?

 

I only moved it about 2 inches further away and the tube is about 2 inches longer. I will take a pic and upload it.

 

good to hear your sorting it out.

new pic's please

 

New pics.

 

If you want a screen after the MAF, put it right in front of the turbo, not at the end of the MAF tube.

 

I will remove it and see how it runs. That should determine if it is needed or not, right?

 

looks cramped in there. the recirculating air from the BOV can't be helping the situation either so close to the MAF.

I'm glad you woke me up to this problem. I think I'll end up with the same situation with my set-up.

 

Yeah its cramped. In order to remove that screen I have to take off 5 t-bolt clamps, 3 couplers, and 2 pieces of pipe. Its a lot easier then the Greddy kit to work on the turbo tho.

 

+1....

 

I removed the screen behind the MAF tube and the idle is fluctuating again. The STFT goes from -25 to -10 and the AFR from 15.7 to 13.5. The airflow readings are 5-6g/s most of the time but sometimes they will go up to 8-9.

 

Did you try moving it to the inlet of the turbo instead of the outlet of the MAF tube?

 

Thats the next test. I just wanted to make this change then see what the results were.

 

This is like a freaking game of clue.... LOL

Is was..... MAF screen on the turbo inlet with the 1/4" honeycomb.

No wait! It is MAF 2" further from the inlet; 2 screens and a new housing.

No!!!! It was Colonel Mustard in the library with the pipe wrench.

HEHE; good job Tdiddy; I think you are real close to an AP friendly solution. Consistency is key. Good luck on phase 72 of the MAF housing.

 

It was tdiddy in the garage with a MAF tube.

Hopefully a screen at the compressor inlet will do the trick. If it doesn't, should I try a screen at the compressor inlet and a screen at the outlet of the MAF tube? Or is that overkill?

 

If you have the parts; quite frankly I would try every combo I can until I idle (warm) at about 5 g/sec and I am no longer hunting. Then phase 2 would be to compare your wideband and fuel info with your MAF g/sec info and see if it make sense (in and out of boost).

If you don't have all those screens laying around; I would say that 2 screens behind the MAF would probably be overkill; unless your air reversion and turbulence is really really bad.

 

I got plenty of screen material. If it improves with one screen at the turbo inlet then I will try another at the MAF tube outlet and see how it runs.

 

hmmm - wonder how your turbo will like eating mesh .......

 

I don't think it would like it at all. Its just a test at this point. If it works and fixes my problems then I will look for a more permanent solution.

 

what is the diameter of the holes in your screen? it might not be smoothing out the flow enough...

normally...all you need is smooth flow going across the wire...so before the wire and and as close to it as possible is the key...

 

This is what I am using. http://www.pegasusautoracing.com/pro...p?Product=3640

 

If its good enough for the Grand Prix guys, its good enough for us.