Mass Air Flow or Speed Density?

I have a 1988 F150 XLT Lariat with a 351w

From what I've read, Ford started using MAF in 89. Therefore my truck was made stock with a speed density system.

Here s where it gets tricky and what I don't exactly understand. The engine in it was replaced by the original owner. They replaced the stock 351w with a 351w out of a 1995 E-150. If it's a 1995 it should have a MAF right? It doesn't though. They re still running the stock speed density from what I can tell considering the lack of a MAF sensor.

Did they do it this way so they didn't have to change out the computer? How well does the 1995 engine communicate with the 1988 computer? Should I go ahead and convert it to MAF so the newer engine performs better since that s what it was made with originally? Would I have to change out the computer?

Basically what I Wana know is, did they do it correctly? Or should I convert to MAF for the newer engine?

Any info would be great thanks!

It's speed density for sure. For the F-Series. Mass Air didn't show until 1993 at the absolute earliest. It was in CA emissions vehicles only in 1993, everywhere else was speed density. In 1994, there was about a 50/50 chance of having it, all CA emissions trucks had it, but it was seen in other areas as well. In 1995 most trucks had mass-air you were more likely to have it than you were to see to speed density. More 302's were mass-air than 351w's were.In 1996, All trucks with the 300, 302, and 351W had it. 3/4 ton and 1 ton trucks with the 460 also had mass-air but only in CA emissions states.

"Did they do it this way so they didn't have to change out the computer? "

probably, doing a mass-air conversion isn't cheap.

" How well does the 1995 engine communicate with the 1988 computer? "

They are largely the same, the only different would be that the 1995 ECU would have provisions for communicating with the E4OD and/or AODE transmissions. The 1988 might or might not be able to do that.

" Should I go ahead and convert it to MAF so the newer engine performs better since that s what it was made with originally?"

There's no guarantee that it was mass-air. I'd be willing to bet that the 1995 351w you have was speed density form the beginning. Also stock for stock, there's no performance benefit in going to mass-air. Mass-air is really only beneficial when you start heavily modifying the engine. Mass-air engines tend to tolerate aggressive cams and new heads more better than speed density.

" Would I have to change out the computer? "

Yes you would.

"Basically what I Wana know is, did they do it correctly? Or should I convert to MAF for the newer engine? "

If it runs fine as is, then it was probably a speed density engine anyway, and converting to mass-air would cost you over a grand, and not get you much in return.

I would think that they would be using all the original bolt ons, sensors and manifolds from the original engine, otherwise you would have to change loom, ecu etc.

Hi add to this it is not a ford engine but a MAZDA engine so i let you take it from her.