As most here know I have been having Mick Stevens (mseven) doing my tune on my new 383 for the last few months. Things have been going great with every new chip I would get improving the performance noticable. About 2 weeks ago I had to replace the MAF sensor with a rebuilt unit, then a few days ago I did another datalog and sent it to Mick so he could burn me a new chip..Yesterday morning I get a call from Mick saying the datalog I sent him showed my car running very,very, lean and I shouldn't drive it until this problem was corrected..Come to find out replacing the MAF sensor with a different (rebuilt) unit changed my blm from 128,(which is perfect), all the way up to 145 to 148 which is very lean . Thank goodness Mick saw this and let me know quickly or I could have done serious damage to my engine..This post is just to let you guys know that changing a major part on your engine may also change your tune enough to do damage to it. Im just glad that Mick was there watching my back.. My suggestion is anytime you change a major part on your engine, do a scan to make sure you haven't changed your tune to the point that it could do damage..Thanks Mick, good job.... ...Wayne

Glad you caught it before it caused any damage. Goes to show you the quality/reliability of some aftermarket electronic parts

Matthew

I just found out yesterday these MAF sensors have to be calibrated when there rebuilt. I guess this is where they can differ, a lot...WW

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I've been doing my tune for the past 2 years, all the guys I know at third gen, and myself included leave the ecm out on the floor, we learn, and burn all the time the only way to learn about your car, now that you got the car running,take your time , buy the gear and learn how to do it yourself... it aint that hard, then you'll know why it drives the way it does when and in what mode, cruise idle wot part throttle.

and you'll be surprised the computer does a very good job of compensation all by itself.

pull your plugs and tell me if it's lean, how does it drive?


cheers

Wow. Mick sure is the man when seeing detail is the key!!!

You go!!!!

Thanks for the words guys and no problem Wayne.
Typically going that lean from a known good blm/fueling would indicate vac leaks or possible fuel delivery issues. Because I had him check for the latter, I think in Waynes case the aftermarket maf is calibrated differently. I have tuned others cars who had to replace the MAF (with a gm version), but I would only see a couple of point deviation and nothing of any huge significance. Bottom line in this case is that it's going too lean/edgy for my taste, and I don't want to see anyones motor get hurt.

What is too high of a BLM count?

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What is an easy way to tell if you are running lean via the spark plugs without having to wait for engine damage? I know one way is to look for metal pieces on the center piece. But I wouldn't want to wait that long to see if it is actually running lean.

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Once in upper 140's and soaring is too lean, using a wide band I have seen 145 + start to go over 15:1+.

The problem you encountered is simple the ev6 (design III) delivers fuel mass differently (fuel mass v.s.injection time in m.s.). When comparing the ev1 (older style)to an ev6 of the same lb. rating, the fuel mass below 6 m.s. is quite a bit different. Once above that they start to look similar. Unfortunately 0-6 ms. represents typical street driving. When vendors speak of flowing an injector, it only refers to what might simulate WOT, and not how much fuel mass is being delivered at lower m.s. or predicted pulse width....not to mention other various effects of slope gain, injection time to deliver the same amount of fuel, etc.etc.

They can be made to work well but requires extra work in the tune to compensate. Your old accels were an ev1 style, and the tables set-up in tune favor that style injector. I am not a fan of tuning through increasing or decreasing the f.p. Most injectors we use are designed to operate at 43.5 or 39.15 delta. That combined with the proper offsets (available from ford racing) for a particular inj. is were I start and then I begin actually tuning.

Bosch IMO has always made a great product, but one must remember that the ev6 style is designed for the newer motors. Valve angle, injector distance from the valve etc.etc. also plays a role in the "whys" of how this inj. delivers fuel. Many seem to think think that look of "fuel frothing/misting" in a tube means better atomization, performance or a better injector..it does not. The "spray patterns" were developed due to the type of engine design. Unfortunately ev1's are discontinued. Therefor, if one still wants to use a Bosch injector the option is to work with the ev6/new body design (this means giving the ecm more info than just the offset and linear flow rate), or perhaps find some new ev1's (old style).

To me, regarding performance the idea of "feel/sotp" means very little until all the data has been established. Feel does not always tell you if it is rich or lean..or how lean/rich it truly is.
You keep data logging, that is the right thing to do..