View Full Version : Any difference between 90 and 91 MAF?

08-27-2008, 11:31 PM
I have a 1990 35th SC, and noticed while looking at the MAF sensor it is a different design than the 1991 MAF I had access to. The '91 sensor has a much larger internal diameter, but has a center post. The 90 sensor has no such post, but a smaller main opening and secondary opening for the heated wire, both covered with a wire screen. For the sake of experimentation, I have been running the car (1990) with the '91 MAF. I have felt no discernable difference in driveability. I assume the redesign was for the better, but did not know if there were any compatibility issues that might cause driveability or mileage problems over time that aren't initially noticed. I did a search, and came up short. Any reason why I should not leave the newer style MAF on my '90?


08-29-2008, 12:50 AM
I'm surprised that no one knows about this. Any input?

08-29-2008, 01:47 AM
i think the maf with the post is slightly larger but not enough to make a difference, the post is big enough to only let about as much air as the smaller inner diameter sensor? Im prolly wrong but thats what i think

08-29-2008, 02:11 AM
The 91 & later got the 70mm MAF, 89-90 was a 55mm they are different & they do make a differance. If you want the best MPG dont mix without a tune. I did some testing & lost MPG, that's my line.

I did witness a Dyno run on an 89 with the 70mm & the OEM 55mm & the 55 won.

08-29-2008, 11:57 PM
So is it a safe assumption then that a C&L MAF for either year car would also need a tune to operate at its full potential power and efficiency wise?

Edit: Just out of curiosity, what was the difference in power on those dyno runs?

09-03-2008, 12:52 PM
I did a mileage comparison between the newer and older (factory stock) style MAF sensors on my '90. I made the same trip (110 miles) both ways, first running the larger '91 MAF, which the EEC had about a week to learn beforehand.

On this leg I acheived 28.6 mpg, averaging about 55mph.

On the second leg, I installed the stock 55mm MAF after unplugging the battery. I was returned 25.3 mpg at the same average speed.

Granted, unplugging the battery meant the EEC had to start from base tables on this leg, and the comparison is not an exact scientific one, but I think it shows that there are probably no serious fuel consumption or driveability concerns running the newer style MAF. (No discernable difference in performance, either)

09-03-2008, 06:07 PM
Well id been running with the 70MM one since i got my car, (89)
and got a consistent 20~ mpg and 35thauto pointed out to me at his house that i had a 70 so i switched to a 55mm and at 27.5 mpg checked last night.

I do a majority of highway driving so thats how i run my MPG tests