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Discussion Starter · #1 ·
My sons escort is burning a lot of gas, even when I drive it so its not just because he's a teenager. I recently had the engine apart (replaced head) so everything was cleaned up when reinstalled. I hooked up my ODB tool and monitored while my son drove. O2 sensors looked good.

What seemed strange was during times of light load/acceleration, the load level on the ODB tool read much higher than it should, a few times, the load read 40-45% and we were standing still at idle (700-800 rpm). So question #1, what determines the load level? Is it the MAF sensor reading or something else? When I checked the MAF reading during acceleration, it was a linear climb from about .50 lbs to about 3.0-3.5 lbs depending on how fast we were going.

Another question. What should the timing be when crusing at 70 mph steady speed? Mine read 18-20, I was expecting it to be much higher, certainly over 30.

BTW, my ODB tool works fine, the parameters on my other cars are all normal.

Can anyone help or give clues.
 

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does the engine sound normal? is it running rough, etc? or does it sound like its running fine?
 

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Have you checked to make sure all the vacuum lines are in good condition and on their connection? It wouldn't hurt anything to get a can of MAF cleaner and give it a good cleaning. I would say check the brakes to make sure none of them are dragging, but that wouldn't be the problem if it's under load at idle.
 

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Engine load is calculated by the PCM. It takes into account various things like the MAF flow, throttle position sensor, RPM and the vehicle's speed. I can't recall what my car's engine load reads at idle... It's late now, but I could go out and look at it tomorrow.

FWIW, I have an Actron CP9180 scan tool that lets me record live data and then copy it to my computer.. Below is a snapshot of my 1998 Escort traveling at 62 MPH with the cruise on... You can see the ignition timing is advanced 30 degrees. Out of curiosity, what does your long term fuel trim (LTFTRM1) show at a steady cruise? (It shouldn't be too far off zero)..

-----------------------------------
ENG SPEED RPM 2403
VEH SPEED MPH 62
ABSLT TPS % 30.5
CALC LOAD % 55.2
MAF FLOW GR/SE 21.16
COOLANT TEMP F 199
IAT TEMP F 41
IGN ADVANCE DEG 30.0
ST FTRM1 % 2.3
LT FTRM1 % 0.7
FUEL SYS 1 CLSD
O2S11 V 0.115
O2S12 V 0.690
----------------------------------
 

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I plugged my scan tool into the Escort this morning....

At warm idle.... 760 - 780 RPM

TPS: 18,.8%
Engine load: 32.5%
Ignition Advance: 21.0 degrees

Note that the AC compressor adds to the load... When the compressor cuts in, the load at idle jumps to 45%.... If you have AC, then when checking the engine load, the dash switch should be in the "Off" position to make sure the compressor isn't kicking in and out.
 

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Discussion Starter · #6 ·
Thanks for the replys. I will check my engine parameters against those posted. Based on memory, mine looked similar except for the timing. The thing about the a/c adding to the load makes sense and also explains why sometimes it spikes and others it doesn't. The car idles a little rough but not too bad. It seems to run just fine though at normal speed. There nothing obviously wrong with the vacuum hoses, I don't hear any leaks but I need to take a closer look. I'll do another post when I know more.

Is there something sold in stores specifically for cleaning MAF sensors or can I use carb/brake cleaner?

Hey 98_Jim are the units for your MAF reading pounds per minute?
 

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My Scan tool reads all imperial, but for some reason they go metric with the MAF. It shows grams per second. FWIW, to convert grams per second, you multiply by the number below:

1 gram per second = 0.132277357 pounds per minute

So at 62 MPH, the 21.6 grams/sec my scan tool shows = 2.798 Lbs/Min

There's an article on cleaning the MAF on a Ford F150 forum that I follow.. It might be of some help:

http://www.fordf150.net/howto/clean-maf ... sensor.php
 

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Other than maybe the timing belt being a tooth off, it could be a fuel injector or two that are sticking. Check to see if you're getting fuel in the oil, the oil level would be rising above the normal mark due to fuel washing past the rings.
 
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