70mm MAF causing backfire and Pop

Mackin1t · Jun 28, 2007

I bought a used 70mm MAF off of a 94 GT. The MAF was put in to my 93 LX 5.0 - I took it out for a ride after and it was very smooth through first gear driving slow but once I got out of the parking lot and went WOT, the car would bog then a LOUD pop comes from the passenger side of the car. I am sure it is the MAF that is causing the problem, just wondering how to reconcile the problem.

Any ideas? Thanks

2002BLGT · Jun 28, 2007

Mackin1t said:
I bought a used 70mm MAF off of a 94 GT. The MAF was put in to my 93 LX 5.0 - I took it out for a ride after and it was very smooth through first gear driving slow but once I got out of the parking lot and went WOT, the car would bog then a LOUD pop comes from the passenger side of the car. I am sure it is the MAF that is causing the problem, just wondering how to reconcile the problem.

Any ideas? Thanks

put the stock MAF back on , or get one that is designed to work on your car , C&L 73MM is a good upgrade for a stock car

vristang · Jun 28, 2007

Pulled codes????

Not sure what else it could be other than you bought a defective MAF.

What sensor is on the MAF tube?

jason

Mackin1t · Jun 28, 2007

it's the sensor that came stock on the 94GT on the 70mm MAF

so basically if it weren't defective, I could have just bolted it up and it would have worked without issue?

jrichker · Jun 28, 2007

It works that way for me. See http://forums.stangnet.com/showthread.php?t=616246 for input form other guys who tried it.

I am assuming you are still using the stock air box and a stock filter or K&N flat panel filter.

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see http://www.midwayautosupply.com/pc-7208-90-equus-digital-ford-code-reader-3145.aspx – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

HISSIN50 · Jun 28, 2007

Also, simply recheck the plumbing connections.

I suppose you could fart around with blowing through your tube and noting voltage changes in the signal wire reading.

No air filter bolted to the end of the MAF, right?

Good luck.

mantix33 · Jun 28, 2007

id also recommend trying to clean it, just shoot a little carb cleaner at it real quick

vristang · Jun 28, 2007

Mackin1t said:
it's the sensor that came stock on the 94GT on the 70mm MAF

There should be an F2VF in the part number...

This meter works very well on most Fox ecu's

What ecu are you using?

Mackin1t · Jun 30, 2007

That is the part number on the top of the MAF and I am using a stock computer with a basically stock mustang. So most likely a bad MAF right?

How expensive it is to just replace the meter because I had the square end machined to a circle so that it would fit with my CAI. Thanks for all your help guys

montegoman351 · Jun 30, 2007

Mackin1t said:
How expensive it is to just replace the meter because I had the square end machined to a circle so that it would fit with my CAI. Thanks for all your help guys

Whaaaaat? You had the square end machined to fit the CAI? To fit the filter or the CAI tube? If it was to fit the CAI tube, then you gots it backerds!

vristang · Jul 1, 2007

Mackin1t said:
That is the part number on the top of the MAF and I am using a stock computer with a basically stock mustang. So most likely a bad MAF right?

How expensive it is to just replace the meter because I had the square end machined to a circle so that it would fit with my CAI. Thanks for all your help guys

I realize that you don't want to pull the ecu out, but it would be nice to double check. A previous owner may have done something odd, you never know...

Regardless...
You should pull the diagnostic codes before you go any further.
I'm not trying to be rude, but this has been suggested several times in this thread... and for good reason.
Pulling the codes is a crucial step in finding the source of a problem.

Wouldn't it suck to spend the $$$ on a new MAS, just to have the problem continue?
Pulling codes can help prevent that.

Let us know what you get,
jason

chowbrow · Jul 2, 2007

Hey ...I too have run into idle problems, flat and missing during acceleration... I ran my ECU for codes and came back 11 KOEO.. ran the running car came back with 92,, too rich. I then thought my 73mm C&L was crap and thought the sample tube might be wrecked too... I checked and cleaned everything and it still idled bad and ran even worse .. popping etc. I solved the problem with and adjustable IAS motor spacer part # (F2PZ-9F939-A)... It was expensive at $35.00 and solved all my drivability problems. It took 5 minutes to install. Just a thought before you go hog wild. But again check all your codes first.

Mr. Rustypwnz · Jul 2, 2007

its bad, ive had 4 of these sensors, when one goes bad it does this, do this for me: take the sensor off your old maf: the stock 55mm unit, and put it on the newer 70mm piece, it works great!! ive done it three times, no ill effects.

vristang · Jul 2, 2007

slow95gt said:
its bad, ive had 4 of these sensors, when one goes bad it does this, do this for me: take the sensor off your old maf: the stock 55mm unit, and put it on the newer 70mm piece, it works great!! ive done it three times, no ill effects.

I cannot emphasize how BAD of an idea this is

Unless you have datalogs of AFR and/or KAMRF's, then you have no business saying how great it works...

Please... do not do this...

jason

93tealstang · Jul 2, 2007

I don't know if this has been brought up yet or not, but maybe try disconnecting the battery to reset the computer? When I put my 70mm on, it ran rough because I forgot to reset the computer. After resetting, it works great.

Mr. Rustypwnz · Jul 2, 2007

I cannot emphasize how BAD of an idea this is

Unless you have datalogs of AFR and/or KAMRF's, then you have no business saying how great it works...

Please... do not do this...

jason

believe me I thought it was stupid as well, look at both of the meters, you will find that they both have the same sample tube size, as long as the sample tube is the same, the computer thinks its running right. Ive had mine like this for 3 months no ill effects, shifting a 6k when the need comes, ive tried this on 3 cars so far, cauleys 89gt, my 86gt, full h/c/i to boot! and my 90 lx 5.0. Ill get a vid up soon of it, to prove this, but all in all it works hands down, and my a/f meter stayed the same as well, so it works for me.

Mr. Rustypwnz · Jul 2, 2007

look at this closely, this is the 94-95 meter, the only thing that is different is that the hole is bigger not the sample tube, the meter compensates for the extra air, it would be like if you cut out a stock 55mm to a 70, with the stock sample tube, up top it still reads the computer fine and is calibrated for stock 19's, so it works fine, thats all I know about it, but it works, runs fine, idles great. if anybody has a stock meter and a 70mm lying around, just swap the meter's and go drive it, what is amazing is it drives competely the same.

vristang · Jul 2, 2007

slow95gt said:
believe me I thought it was stupid as well, look at both of the meters, you will find that they both have the same sample tube size, as long as the sample tube is the same, the computer thinks its running right. Ive had mine like this for 3 months no ill effects, shifting a 6k when the need comes, ive tried this on 3 cars so far, cauleys 89gt, my 86gt, full h/c/i to boot! and my 90 lx 5.0. Ill get a vid up soon of it, to prove this, but all in all it works hands down, and my a/f meter stayed the same as well, so it works for me.

You can't tell crap by looking at the externals of an electronics black box!!!
(unless you want to talk part numbers... Ford changed part numbers for a reason... )

Sample tube????
What meter are we talking about here???
Ford did not EVER use a sample tube....

What you are proposing is pretty risky.

I encourage anyone following along in this thread to proceed with great caution.
Mixing and matching the MAS to MAF tubes is not recommended!!!!!

Again,
Datalogs...
I don't care about your 'vids' or even what your dash mounted afr gauge seems to 'show'

Datalog, both before and after, using a WB O2...
Until then, it is just theory...

jason

vristang · Jul 3, 2007

slow95gt said:

Please elaborate on your point...

I am trying real hard to hear you out, and not be a smart @$$, but it isn't easy at this point.
Please don't get offended, but honestly... I'm not buying it...

jason

Mr. Rustypwnz · Jul 3, 2007

I know your not, lol. The part im talking about would be A in the diagram, this is what I call the sample tube, correct me if im wrong though... both the stock maf and the 94-95 piece have the same size tube,

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