What sensors does the compuer use at WOT.

[5ohCOUPE]

I have a 1991 5.0. I was just wondering what the computer reads at wide open throttle. I have heard that it doesnt read the mass air, or the O2 sensors and that it runs off of a preprogrammed fuel map. I think that this is wrong. Any ideas?? Im trying to figure out a problem with my car and this info might help me. THANKS

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91 LX COUPE, 3.73 gears, 2 1/2 inch full exhaust, 1 5/8 shorty headers, 73 MM C&L MAF, 70 MM MAC TB, LUNATI cam, Windsor jr heads, GT 40 intake with ported lower, world class T5 with PRO 5.0 shifter, Griffin aluminum radiator, Fluid Damper, SSM traction bars, 150 HP shot N2O kit, 190 GPH in tank fuel pump with T-Rex external pump. And more to come.
BEST TIME ON BOTTLE---11.51 @123
BEST TIME ON MOTOR---12.63 @109

[LX XLR8R]

it only looks at the mass air at WOT as far as i can remember..it has a preset curve that it follows but according to the mass air

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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

[WADS56]

MAF,ACT,ECT,TPS

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79 hatch w/ NA 347,stage 2 Canfield heads, out of the box Victor 5.0 intake, solid roller cam, Aeromotive fuel system, proshifted TKO II.MY CAR http://www.mustangworks.com/cgi-bin/...splay.cgi?1288
93lx all stock + tremec

[jimberg]

The computer uses the MAF, BAP, ECT and ACT sensors at WOT. The O2 sensors are active but only for the purpose of detecting a dangerously lean condition. They aren't used for adjusting the air/fuel ratio since the computer is trying to maintain a richer a/f ratio than the O2 sensors can measure.

The fuel map is based on a separate lookup table for WOT, but those numbers are adjusted according to numbers calculated during closed-loop control.

When the computer is reset, it will use some preprogrammed numbers based on RPMs and the amount of air being measured. It will use feedback from the O2 sensors to adjust those numbers. It stores these numbers in an adaptive strategey table in terms of an adjustment factor. If more fuel is needed, it's greater than 1. If less fuel is needed it's less than 1. That's basically close-loop mode. At WOT (open-loop control), those adjustment factors are multiplied by what the computer looks up.

What's the problem with your car?

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351W 89 Mustang GT Convertible

[5ohCOUPE]

The car runs good at times and sometimes it just runs slow. When it feels slow it doesnt sputter, pop, or run bad. It just is slow. It changes from a very stout car to felling like a stock car. Its the weirdest thing that i have ever felt. There are no codes stored. It has a mind of its own. The differance from when it feels good to when it feels bad is from a 12.63 @ 109 to a 13.21 @ 103. It will change from minute to minute. Any ideas ????????

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91 LX COUPE, 3.73 gears, 2 1/2 inch full exhaust, 1 5/8 shorty headers, 73 MM C&L MAF, 70 MM MAC TB, LUNATI cam, Windsor jr heads, GT 40 intake with ported lower, world class T5 with PRO 5.0 shifter, Griffin aluminum radiator, Fluid Damper, SSM traction bars, 150 HP shot N2O kit, 190 GPH in tank fuel pump with T-Rex external pump. And more to come.
BEST TIME ON BOTTLE---11.51 @123
BEST TIME ON MOTOR---12.63 @109

[90dpscoupe]

sounds like you may need a custom chip, im not sure though, i have always heard 5.0 owners say "some days it runs strong, others it runs like crap"

so i dont know what to tell ya, i know in good weather i sure notice a power increase in my coupe, bye the way, nice times on the bottle, is it the stock shortblock?

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90 lx coupe: 5spd, energy susp trans mounts, fms hd clutch, Mac coldair fenderwell, Mac h-pipe, supercoil, ADS chip, 160 stat, aluminum D/S, Black magic fan, 3.27grs.
Best time: 13.9116(on 225/60/15 firehawks)
Best mph: 98.17
Best 60': 1.9607

someday mods:4.10's, slicks.

[PKRWUD]

Work with Jim on this one. He's my go-to guy when I've got a question.

BTW, you said there are no codes. Have you tried both KOEO and KOER?

Take care,
-Chris

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Retired Moderator
MustangNet

My site: Peckerwoods Pit Stop



My teams site: Jim Porter Racing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN.

[5ohCOUPE]

Yeah its a stock short block with 168,000 miles on it. I wonder how much longer it will last. There are no codes with the KOER or KOEO. I was thinking last night that it could be the injectors because they are only 19 LB. Yeah, i know kill me. Im going to 24 LB. this week. What i dont understand is im not leaning out any on bottle with the 19 LB.

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91 LX COUPE, 3.73 gears, 2 1/2 inch full exhaust, 1 5/8 shorty headers, 73 MM C&L MAF, 70 MM MAC TB, LUNATI cam, Windsor jr heads, GT 40 intake with ported lower, world class T5 with PRO 5.0 shifter, Griffin aluminum radiator, Fluid Damper, SSM traction bars, 150 HP shot N2O kit, 190 GPH in tank fuel pump with T-Rex external pump. And more to come.
BEST TIME ON BOTTLE---11.51 @123
BEST TIME ON MOTOR---12.63 @109

[Rebel79]

Originally posted by 5ohCOUPE:
The car runs good at times and sometimes it just runs slow. When it feels slow it doesnt sputter, pop, or run bad. It just is slow. It changes from a very stout car to felling like a stock car. Its the weirdest thing that i have ever felt. There are no codes stored. It has a mind of its own. The differance from when it feels good to when it feels bad is from a 12.63 @ 109 to a 13.21 @ 103. It will change from minute to minute. Any ideas ????????

My car does the same thing! Its driving me crazy! Only I don't know of its related but my fuel pressure drops with the throttle.

I have to reset the EEC once a week, because as the EEC learns how to run the car it seems to make it run worse.

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1994 Mustang Cobra
308ci, Vortech S-trim 11#, ported GT-40 heads, E-303 cam, FMS 1 5/8 headers, BBK Offroad H-pipe, 2-chamber flows, and several other goodies.
Rebel Racing. Home of Bay Area Mustangs

[5ohCOUPE]

WHOOOOAAA, I finally got a code. I decided to check the codes one more time and i have one code. Its 67 neutral dirve switch open. i dont think this will make the car do what its doing though.

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91 LX COUPE, 3.73 gears, 2 1/2 inch full exhaust, 1 5/8 shorty headers, 73 MM C&L MAF, 70 MM MAC TB, LUNATI cam, Windsor jr heads, GT 40 intake with ported lower, world class T5 with PRO 5.0 shifter, Griffin aluminum radiator, Fluid Damper, SSM traction bars, 150 HP shot N2O kit, 190 GPH in tank fuel pump with T-Rex external pump. And more to come.
BEST TIME ON BOTTLE---11.51 @123
BEST TIME ON MOTOR---12.63 @109

[jimberg]

Thanks for the vote of confidence, Chris.

The only thing I can think of is that you are falling victim to the computer's adaptive strategy. How you drive before doing a race run will determine how your computer responds. If you're cruising around driving conservatively to save on gas and then try to race, your computer will need to take some time to readapt for performance. If, however, you always drive somewhat aggressively, your computer will pretty much be race ready.

What you need to do is isolate a pattern. Is it sluggish under certain weather conditions? Have you not raced in a while? Did you use gasoline from a different source? Did you race recently with the nitrous on? Things like that. Maybe keep a notebook where you record the things you do and note when the car is running strong or running sluggishly. This might help figure out what's the cause.



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351W 89 Mustang GT Convertible

[5ohCOUPE]

I think that is it !!!!!!! On saturday nights we all go out driving around looking for racing. i usually drive normal for about an hour then get hooked up with a race and it runs sluggish. After a couple of races the car starts to run better and better. Then drive around again and it starts to run sluggish again.

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91 LX COUPE, 3.73 gears, 2 1/2 inch full exhaust, 1 5/8 shorty headers, 73 MM C&L MAF, 70 MM MAC TB, LUNATI cam, Windsor jr heads, GT 40 intake with ported lower, world class T5 with PRO 5.0 shifter, Griffin aluminum radiator, Fluid Damper, SSM traction bars, 150 HP shot N2O kit, 190 GPH in tank fuel pump with T-Rex external pump. And more to come.
BEST TIME ON BOTTLE---11.51 @123
BEST TIME ON MOTOR---12.63 @109

[PKRWUD]

Try resetting the ECM before you race next time and see what happens.

As far as your code 67, go see your other post.

Take care,
-Chris

------------------
Retired Moderator
MustangNet

My site: Peckerwoods Pit Stop



My teams site: Jim Porter Racing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN.

[jimberg]

Chris' suggestion is a good one, but I would like to add a little more info to it.

Fuel delivery decisions by the computer will affect your performance the most. The best thing to do would be to get an adjustable fuel pressure regulator if you don't have one and then go to a dyno to tune your engine. You will need to reset your computer between dyno runs. Keep adjusting fuel pressure until you get the most power. Then, reset your computer before a race and you can be sure that your computer will be running exactly the same parameters and give you near the same results.

This, of course, will not work for cruise night since resetting your computer will be impracticable.

The best thing to do would be to drive aggressively.

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351W 89 Mustang GT Convertible