MAF reading
Thread Starter
Staging Lane
Joined: Jun 2008
Posts: 65
Likes: 0
From: Ft. Rucker AL
I'm trying to figure out if mine is bad. In the morning the cars rpms bounce up and down from around 900-1100. Once it gets a little warmer out it stops doing this. But sometimes while I drive the rpms will stick around 1500 or 2000. Other times they drop to where they are supposed to be. I guess I should specify that it does this while driving and I put it in neutral or press in the clutch. When it does this it will do it for the entire time I'm driving then on e I shut it off and start driving again later it might drive normal then next time it might be messed up again.
it sounds to me like your idle airflow tables could be off...has the car been tuned or what mods are on it?
also, is your intake tract or the MAF dirty? DO NOT touch the sensors on the MAF they are really thin wires and can be broken easily
also, is your intake tract or the MAF dirty? DO NOT touch the sensors on the MAF they are really thin wires and can be broken easily
Thread Starter
Staging Lane
Joined: Jun 2008
Posts: 65
Likes: 0
From: Ft. Rucker AL
The car is basically a heads & cam package car. I have replaced everything except the lower end. It was tuned several years ago I then replaced the intake and ported the TB. I'm sure my idle airflow tables have been messed with A friend of mine hooked it up to his HP Tuner and said they looked pretty messed up but I don't think he could tune it the greatest cause I don't have a wide band. I tried cleaning the MAF not to long ago.
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On The Tree
Joined: Apr 2011
Posts: 181
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The car is basically a heads & cam package car. I have replaced everything except the lower end. It was tuned several years ago I then replaced the intake and ported the TB. I'm sure my idle airflow tables have been messed with A friend of mine hooked it up to his HP Tuner and said they looked pretty messed up but I don't think he could tune it the greatest cause I don't have a wide band. I tried cleaning the MAF not to long ago.
All you need is reading comprehension and an ability to follow directions.
Here: http://www.hptuners.com/forum/showthread.php?t=36318
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You don't need a wideband to tune idle configuration.
All you need is reading comprehension and an ability to follow directions.
Here: http://www.hptuners.com/forum/showthread.php?t=36318
All you need is reading comprehension and an ability to follow directions.
Here: http://www.hptuners.com/forum/showthread.php?t=36318
From the second paragraph of the link you posted...
"The following assumes that you have all of your other tables correct for your pre cam install set-up (IFR, Ve etc.). He means this too...don't skip straight to fine tuning your idle if you're unsure of your injector data or you know ahead of time that your VE table is garbage."
That takes a wideband... and if he changed the intake and ported the throttle body, the tune is now off...
Staging Lane
Joined: Jan 2009
Posts: 59
Likes: 0
From: Bella Vista, AR
You screwed the pooch when you ported the TB. It will take a competent tuner to get your MAF curve recalibrated which is the primary reason your idle is not acceptable. If the new intake flows a lot better than previous intake then your VE table is crap again and this must be dialed in for a good idle with cam and heads package. Check out ProM Racing MAFs, and talk to them about the best choice for your package. This will be much more reliable and easier for a tuner to dial in when you have the motor retuned - which you will now need to do. The tune you had previously is no longer going to be ideal even with a quality unharmed MAF; again, the ported MAF is what messed things up the most. This completely destroyed the accuracy of your MAF sensor which is the heart of your air measurement system and tells your PCM how the fuel injectors need to be pulsed for the proper AF ratio. Right now your idle is running WAY TOO RICH - is there any black soot shooting out of the exhaust during cold starts indicating this is the case?
Thread Starter
Staging Lane
Joined: Jun 2008
Posts: 65
Likes: 0
From: Ft. Rucker AL
I don't think I really ported to much out of the inside. Mostly polished it up so it looked nicer. I have never noticed black soot coming from the exhaust. I have never really driven it in the. Old until recently. It dosnt get very cold where I live. About 30's at best.
Instability is less likely an airflow settings problem, than
fuel (driven by VE table error, esp. MAP-axis, MAF improves
this, or O2 sensor heat issues indicated by weather sensitivity).
Airflow table, the best you can do is make it "guess high and
pull down". Maybe tweak the PID coefficients to mellow out
the idle loop response. But letting it run rich (which can be
indicated-stoich if you have enough air shot through the cam
overlap) is a good way to get unstable (one of several but
the first place to play).
fuel (driven by VE table error, esp. MAP-axis, MAF improves
this, or O2 sensor heat issues indicated by weather sensitivity).
Airflow table, the best you can do is make it "guess high and
pull down". Maybe tweak the PID coefficients to mellow out
the idle loop response. But letting it run rich (which can be
indicated-stoich if you have enough air shot through the cam
overlap) is a good way to get unstable (one of several but
the first place to play).
