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incompatability issue with aftermarket MAF's and microtuners

1408 Views 5 Replies 3 Participants Last post by  53wanab
Hey All,

Iv'e recently become aware of an issue that may save some of you some bucks.
Apparently, Crane cams has made the statement that their Powermax micro tuner will not work with high flow recalibrated Mass Air Flow Sensors(MAF), such as the Grannetelli MAF's.These computer tuners are incompatable with the recalibrated fuel/air/timing tables.
I discovered this for myself when I installed a Granetelli MAF on my 03 SSR.No matter how I programmed the computer, I kept getting Lean trouble codes on bank 1 and 2. I'd reset the DTC and it would come right back.
Also, when I accelerated at WOT, I was getting a real bad hesitation at the top end of the pwer band.
The good news is that all this went away when I removed the unit and reinstalled my stock unit.
No more hesitation and a solid pull all the way through the gears.
It cost me $350.00 but I stuck the Grannetelli MAF on my Silverado which I don't intend to tune.Seems to run good with the stock computer tune.
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53wanab: I am not at all surprised to read that this happened. You are fortunate that you did not do damage to your engine.

Microtuners, ALL of them, only work correctly when applied to powertrains whose PHYSICAL characteristics are known and precisley mapped for within the microtuner.

The Crane has more flexibility than any of the others I have encountered so far, in that its programming apprently includes parameters to use with certain PRE-IDENTIFIED aftermarket parts.

Once you replace a "known" part with a new part "unknown" to the microtuner part, or ADD a new part unknown to the microtuner, the preprogramming instantly becomes WRONG (unless the change made is so small as to not require re-programming, in which case it is not worth doing, right?).

This is an inherent limitation of the microtuner approach. If you want to use components not prepoprgrammed into the microtuner, you need to do one of 2 things:

1. Change the A/F ratio and/or spark advance characteristics by trial and error using the limited change capabilities of the microtuner (not recommended since you are working blind and could grenade the engine), or

2. Put the vehicle on a dyno, attach an exhaust gas analyzer that is accurate across a wide range of A/F ratios, and manually make incremental adjustments on the microtuner to the A/F and/or spark advance. If you are going to this trouble and expense, it of course makes much more sense to just use a proper full-featured tuning product (like LS Edit, HP Tuner, or EFILive) so you can do it RIGHT.

Microtuners are for folks who do NOT intend to make other changes that affect engine output. If your plans are grander than that, the microtuner approach is the wrong one.

By the way, the "hesitation" COULD have been your GM engine protection features saving your engine for you.

Jim G
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getting with the program

Thank you Jim G. for your input on microtuners.It was as if a light bulb went off in my head when I read the statement from Crane about the incompatability of modified MAF's and their tuner, I thought to myself, OF COURSE.
I don't intend on going any further than I have with the Headers and 1:85 roller rockers.The tune is doing great after removing the Grannetelli unit and going back stock. The plugs are reading nice. I think I'll shut up and drive!


I see in your post that you have installed 1:85 roller rockers.

It is claimed on the street rod shows, on tv, that rockers will free up a lot of power in our motors lost to drag.

What do you think, does it rev a little quicker with the rollers? Did the rollers require tuning as well, or did the tuning come after for other reasons?

sa15335: Our SSRs come with roller rockers STOCK, in order to reduce friction, to improve fuel mileage, which raises the corproate GM fuel mileage number. By getting aftermarket ones, what you get is

1. A better roller tip that actually rolls versus drags (if you buy good ones). Factory ones often do not roll so well.

2. A numerically higher ratio, which means that the valves are lifted sooner and higher and longer for more airflow. Note that this DOES decrease the life of the valvetrain, as you are applying significantly larger forces to achieve that.

Also, you don't just say "if a little is good, more must be betetr". If you lift too fast or too high for YOUR engine, you break valvetrain parts OR run the valves into the pistons (catastrophic failure!), so don't "try this at home" without someone experienced guiding your efforts.

Jim G
Rockin Rollers

Actually guys, the stockrockers are cradle type guideless and adjustless units with needle bearing fulcrums only.The tips are flat ground solid ends.I used the Comp Cams 1:85 fully adjustable guide plate/stud type with rollers at both the fulcrum and tip.The guide plates and studs came with the kit but I had to get the hardened push rods separately. The tech at Comp cams said no problem with the stock beehive springs because of their design and newness.
The Crane cams tuner I used allows to set spark curve up in 10% increments to take advantage of things like high lift rockers and open exhaust and headers.
This thing was a dog when i got it. I was very dissapointed with the performance,but now its' a screamer and is alot of fun to drive. Just enough to get me in trouble.I had a blast goofin with the kids in O.C on the boulevard.
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