upside down MAF solves idle problem

FoxBuilder · 03-06-2001, 03:48 PM

Hey guys,
A buddy has a 306 with TFS heads, 70mm TB/EGR, 70mm MAF, TFS stage 1 cam. This past weekend we installed the TFS Track Heat intake and a 1" spacer. Car ran down the street great but would not idle. At first the only thing we found to make it idle was to give it a vacuum leak. We started playing around with the MAF and found that if the MAF is turned upside down the car idled perfect. Does any one know of a good price on re-calibrating a MAF sensor?

------------------
Barbie dream cam303
Easily mistaken for a real cam303
beast used with Fairy dust cam303
Xena warrior princess cam303
we wish "camZilla" wasn't a marketing ploy303

rtz · 03-06-2001, 08:16 PM

How can just turning it upside down have any effect at all on it?

rtz · 03-06-2001, 08:21 PM

This new C&L 76mm is the only one I would consider these days. It comes with that intake tube in the picture also.

http://www.jdsperformance.com/index....=196&fcmd=item

First hand account of the meter:
http://www.corral.net/Forums/Forum1/HTML/060269.html

LX XLR8R · 03-06-2001, 08:54 PM

unless c&l has a new way of making mass air meters they in a word, ah umm suck..go pro-m 77

------------------
1987 black notch(ex 4 banger)
DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..
AIM=onesillynotch

rtz · 03-06-2001, 10:46 PM

What's wrong with C&L meter's?

moosejaw · 03-07-2001, 04:04 AM

Many idle surging problems are caused by the air meter. Ever hear of "fan wash". Open filters in the engine compartment can catch waves of air from the stock fan and disrupt the air meter.

Non laminar flow coming in the filter and inlet bends at low rpms cause variations in meter readings. Moving the meter around may allow you to "catch" the air at a nice smooth air flow point.

Not all inlet tracks can be set up with a smooth straight length of pipe/tube before the meter. Therefore some experimenting is necessary to find the best location. When this doesn't succeed the in inlet air path must be straightened. Then when this is not the cause a voltage reading of the meter output signal should reveal whether the meter is at fault.

I have used both the Pro-M 77 and the C+L 80mm in supercharged and NA, in blow through and suck through modes. I like them both. The C+L is easier to service but the Pro-M comes with a better data sheet.

With any meter you need to be concious of how it is installed and how piping transitions into and out of them. Anyone with a 94-95 can testify how important this is.

Mike

------------------
Live near St.Louis?
Check out Mustang Muscle and Dyno in High Ridge, MO
Check out my ride.

FoxBuilder · 03-07-2001, 12:48 PM

Actually the meter is mounted in a BBK fender cold air induction kit, modified to fit I might add. The meter is just out of calibration. The motor idled fine given a vacuum leak, the motor just wasn't getting enough air. The motor was running rich but the MAF seamed to be in a lean condition. Putting the meter tube on the bottom (or weird position) in the air stream fooled the computer into a rich condition and opened the air bypass.

Electrical noise in the MAF due to fan wash, can be read by a digital voltmeter across pins C and D of the meter. The voltmeter should read between .600 and .900 volts on the D.C. scale at idle. On the AC scale the voltmeter should read less than .010 volts. With no shield between the air filter and the engine, the voltmeter will read above .010 volts and go to as high as .050 volts. This is known as the signal-to-noise ratio and is similar to trying to listen to someone whisper next to a jet plane.

So, what is the best price I can expect on getting this thing recalibrated?

------------------
Barbie dream cam303
Easily mistaken for a real cam303
beast used with Fairy dust cam303
Xena warrior princess cam303
we wish "camZilla" wasn't a marketing ploy303

moosejaw · 03-08-2001, 02:20 AM

I was not refering to S/N ratio when I spoke of fan wash. The Physical air flow from the fan will push air to an open filter and disturb what should be laminar flow. RF interference (using unshielded race wire) will cause high S/N ratios that you speak of. Perhaps we are using the same name for different things?

As for recal prices, isn't this the C+L/vortech meter on the BBK cold air kits? The only way to recal is with the different sample tubes. If there is problems with the electronics they are stock off the shelf no tampering required right?

I know pro-m meters or stock meters are ~$90 to recal through a dealer.

Mike

------------------
Live near St.Louis?
Check out Mustang Muscle and Dyno in High Ridge, MO
Check out my ride.

03-06-2001, 03:48 PM	#1
FoxBuilder Registered Member Join Date: Sep 1999 Location: Columbus, Ohio Posts: 233	upside down MAF solves idle problem Hey guys, A buddy has a 306 with TFS heads, 70mm TB/EGR, 70mm MAF, TFS stage 1 cam. This past weekend we installed the TFS Track Heat intake and a 1" spacer. Car ran down the street great but would not idle. At first the only thing we found to make it idle was to give it a vacuum leak. We started playing around with the MAF and found that if the MAF is turned upside down the car idled perfect. Does any one know of a good price on re-calibrating a MAF sensor? ------------------ Barbie dream cam303 Easily mistaken for a real cam303 beast used with Fairy dust cam303 Xena warrior princess cam303 we wish "camZilla" wasn't a marketing ploy303

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03-06-2001, 08:16 PM	#2
rtz Registered Member Join Date: Feb 2001 Location: Edmond, OK Posts: 180	How can just turning it upside down have any effect at all on it?

03-06-2001, 08:21 PM	#3
rtz Registered Member Join Date: Feb 2001 Location: Edmond, OK Posts: 180	This new C&L 76mm is the only one I would consider these days. It comes with that intake tube in the picture also. http://www.jdsperformance.com/index....=196&fcmd=item First hand account of the meter: http://www.corral.net/Forums/Forum1/HTML/060269.html

03-06-2001, 08:54 PM	#4
LX XLR8R Dirk Diggler Join Date: Feb 1999 Location: SLOATSBURG, NY Posts: 1,931	unless c&l has a new way of making mass air meters they in a word, ah umm suck..go pro-m 77 ------------------ 1987 black notch(ex 4 banger) DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one.. AIM=onesillynotch

03-06-2001, 10:46 PM	#5
rtz Registered Member Join Date: Feb 2001 Location: Edmond, OK Posts: 180	What's wrong with C&L meter's?

03-07-2001, 04:04 AM	#6
moosejaw Registered Member Join Date: Apr 1999 Location: St.Louis,MO Posts: 274	Many idle surging problems are caused by the air meter. Ever hear of "fan wash". Open filters in the engine compartment can catch waves of air from the stock fan and disrupt the air meter. Non laminar flow coming in the filter and inlet bends at low rpms cause variations in meter readings. Moving the meter around may allow you to "catch" the air at a nice smooth air flow point. Not all inlet tracks can be set up with a smooth straight length of pipe/tube before the meter. Therefore some experimenting is necessary to find the best location. When this doesn't succeed the in inlet air path must be straightened. Then when this is not the cause a voltage reading of the meter output signal should reveal whether the meter is at fault. I have used both the Pro-M 77 and the C+L 80mm in supercharged and NA, in blow through and suck through modes. I like them both. The C+L is easier to service but the Pro-M comes with a better data sheet. With any meter you need to be concious of how it is installed and how piping transitions into and out of them. Anyone with a 94-95 can testify how important this is. Mike ------------------ Live near St.Louis? Check out Mustang Muscle and Dyno in High Ridge, MO Check out my ride.

03-07-2001, 12:48 PM	#7
FoxBuilder Registered Member Join Date: Sep 1999 Location: Columbus, Ohio Posts: 233	Actually the meter is mounted in a BBK fender cold air induction kit, modified to fit I might add. The meter is just out of calibration. The motor idled fine given a vacuum leak, the motor just wasn't getting enough air. The motor was running rich but the MAF seamed to be in a lean condition. Putting the meter tube on the bottom (or weird position) in the air stream fooled the computer into a rich condition and opened the air bypass. Electrical noise in the MAF due to fan wash, can be read by a digital voltmeter across pins C and D of the meter. The voltmeter should read between .600 and .900 volts on the D.C. scale at idle. On the AC scale the voltmeter should read less than .010 volts. With no shield between the air filter and the engine, the voltmeter will read above .010 volts and go to as high as .050 volts. This is known as the signal-to-noise ratio and is similar to trying to listen to someone whisper next to a jet plane. So, what is the best price I can expect on getting this thing recalibrated? ------------------ Barbie dream cam303 Easily mistaken for a real cam303 beast used with Fairy dust cam303 Xena warrior princess cam303 we wish "camZilla" wasn't a marketing ploy303

03-08-2001, 02:20 AM	#8
moosejaw Registered Member Join Date: Apr 1999 Location: St.Louis,MO Posts: 274	I was not refering to S/N ratio when I spoke of fan wash. The Physical air flow from the fan will push air to an open filter and disturb what should be laminar flow. RF interference (using unshielded race wire) will cause high S/N ratios that you speak of. Perhaps we are using the same name for different things? As for recal prices, isn't this the C+L/vortech meter on the BBK cold air kits? The only way to recal is with the different sample tubes. If there is problems with the electronics they are stock off the shelf no tampering required right? I know pro-m meters or stock meters are ~$90 to recal through a dealer. Mike ------------------ Live near St.Louis? Check out Mustang Muscle and Dyno in High Ridge, MO Check out my ride.