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Just wanted to relay an important discovery. While tuning my new 350 with Scott Hansen, it was discovered that the aftermarket, "O'Reilly" MAF was the culprit in my rich condition all along. There are many threads on trouble after putting in Bosch D3's. I ended up having the car tuned because they apparently overflowed their rating. Turns out is was this dang MAF the whole time.
The problem with the non-Bosch MAF was that it was just wrong and innaccurate but it wouldn't throw a code though. It was puzzling to Scott, for both separate tunes to try to dial this pretty much stock L98 in as it was, like the previous original, refreshed LB9 running rich. With all his experience, he was perplexed but eventually got the LB9 dialed in. Once he started in on my new L98 with the same MAF and same Bosch D3's he was also having trouble with which would should be an easy tune. I had a functioning original MAF and put it in, mid-tune process, and it made all the difference for the better.
After doing some digging, I found testimony from a tech that works for Bosch that Bosch individually calibrates each hot wire MAF since they all come out slightly different. Their MAF's are accurate and respond quickly to rapid air mass changes. The replacement one I had used did not use the same technology and when looking at the differences I can see why these units could be very poor performers. Even when my LB9 was tuned, it never felt "sharp."
Just wanted to pass that along. Last I heard, Bosch will rebuild and re-calibrate original MAFs that are sent to them.
Here is a pic of the crappy MAF's internals. These will probably cause any engine they are used with to run poorly.
Last edited by Tootie Pang; Apr 19, 2020 at 09:52 AM.
With the availability and price of some of these sensors, it makes that much more sense to go speed density.
Sure the initial investment in a quality stand-alone might seem high, but never having to worry about expensive sensor failures, and having powerful tuning and diagnostic capabilities pays for itself over time.
