I know this has been discussed elsewhere, but haven't found much concrete info in my searches...

Idle: +3.9 to +4.5
Cruising: +8.5 to +12.5
WOT: +17.5 to +18.5
Vacuum at idle: -17.4

[Cobb SRI/TIP, Synapse- no tune.]

Is this normal because of the increased air intake?
Dirty MAF? (using stock Cobb filter)
Suggestions?

Uh...wot should be 0...that positive is bad. Did you disconnect the battery before the install? Try reseting the ecu by doing so and see what happens.

tbot wrote:Uh...wot should be 0...that positive is bad. Did you disconnect the battery before the install? Try reseting the ecu by doing so and see what happens.

Greeaaat... Yeah I was seeing this about a month ago. Disconnected the battery, and these results are after 300-500 some odd miles.

I've never seen my LTFT's peg 0.0 at WOT, btw:mellow:

Wouldn't LTFT like that indicate unmetered air? Have you checked for leaks in your system?

Honestly I would get a tune. I had lots of problems with the stock tune once I started modding. Running the hypertech now and my LTFTs range from -6 at idle to -2.5 part throttle and 0.0 at WOT. I have never seen positive trims on this tune.

dsm_luck22 wrote:Wouldn't LTFT like that indicate unmetered air? Have you checked for leaks in your system?

Honestly I would get a tune. I had lots of problems with the stock tune once I started modding. Running the hypertech now and my LTFTs range from -6 at idle to -2.5 part throttle and 0.0 at WOT. I have never seen positive trims on this tune.

I've pretty much just done a visual inspection for loose hoses and such. Is the vacuum at idle normal? I think that's about what its always been, iirc. My boost seems fine too.

I didn't necessarily plan on doing much in the realm of tuning... or at least anytime soon I should say-

vacuum is normal.

It might be a dirty maf, just not being able to register the amount of air coming in.

But positive fuel trims like that also mean there's a vacuum leak, so something else to look for.

tbot wrote:vacuum is normal.

It might be a dirty maf, just not being able to register the amount of air coming in.

But positive fuel trims like that also mean there's a vacuum leak, so something else to look for.

I see, thanks for the info guys. Next warm day, I'll do a 'tut diagnostic examination'.

I don't know about vacuum leak, since his LTFT at idle are ok. What do your STFTs look like at idle? When your LTFTs go that positive at WOT, what do your AFRs look like? Without a tune it may just be trying really hard to hit the pig rich numbers the factory tune likes.

And yes, that -17.4 vacuum at idle is normal.

Yeah but at wot its open loop not closed loop. Regardless it should be a 0. I don't think a tune, or lack there of, would fvck up LTFT at wot like that. There's something else going on, as in a vacuum leak/boost leak. Its basically an issue of there's WAY more air entering the engine than what is being metered.


Read here:

http://www.mazdaspeedforums.org/forum/f9/trims-seriously-wtf-62774/

has really nothing to do with a tune if they're that outa wack, and a tune won't fix it.

erod550 wrote:I don't know about vacuum leak, since his LTFT at idle are ok. What do your STFTs look like at idle? When your LTFTs go that positive at WOT, what do your AFRs look like? Without a tune it may just be trying really hard to hit the pig rich numbers the factory tune likes.

And yes, that -17.4 vacuum at idle is normal.

Most recently, my LTFT at idle was +4.5, cruising was +14.0 and WOT was +18.5. Oddly enough, my STFT's seem to be between -3 and +4 (mostly) ... sometimes bumping up to 8's briefly. At idle, they are generally -3's.

tbot wrote:Yeah but at wot its open loop not closed loop. Regardless it should be a 0. I don't think a tune, or lack there of, would fvck up LTFT at wot like that. There's something else going on, as in a vacuum leak/boost leak. Its basically an issue of there's WAY more air entering the engine than what is being metered.


Read here:

http://www.mazdaspeedforums.org/forum/f9/trims-seriously-wtf-62774/

has really nothing to do with a tune if they're that outa wack, and a tune won't fix it.

Thanks for the link- I'll have a look when time allows. The car is parked. I plan on going over everything (BPV connections, and intake) next warm day.

Your Idle numbers look good but your Cruising and WOT does not. If you get +20 you'd trip a CEL so I'd check all of the connections again. I think most people with aftermarket intakes see around +10 for WOT.

RichB wrote:Your Idle numbers look good but your Cruising and WOT does not. If you get +20 you'd trip a CEL so I'd check all of the connections again. I think most people with aftermarket intakes see around +10 for WOT.

Interesting. Wouldn't this differ from the advice tbot offered up? That at WOT trims should be 0.0?

Oh, regarding erod's question about AFR's...I haven't looked at those as closely- but I recall them sticking around the 14's in normal crusing, then closer to 13's in spirted driving.

Technically they should be at 0 all the time but you'll never see it. Your goal is to get as close to 0 as possible.

Even when you drive a new MS3 off the lot you'll see somewhere around +5.

yeah something is up man...and RichB in all honesty, you don't know shit about what you're talking about.

WOT should be 0.0 regardless of the mods. There's an issue where you're getting unmetered air into the system and the ecu is trying to compensate for it by adding more fuel to reach target AFR's. The other possibility is an exhaust leak BEFORE the top O2 sensor.

Dude, what are you talking about! Every tuning solution out there tells you to calibrate your MAF with your mods before you adjust anything else including and especially WOT. It is known that even with a completely stock set-up you won't see 0.0. Check yours and plot it because I want to see this if you get 0 LTFTs