dyno'd in open loop?

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Dec 1, 2003 | 12:37 PM

WicketMike

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From: Killa Cali

dyno'd in open loop?

I went to a dyno day last week and i didnt warm the car up before it got on the dyno.

the car would fall on its face at 5500rpms and on the dyno graph you could see the hp drop by 20-30hp.

when i got home i looked at my a-tap log from the dyno and all the 3 runs where in open loop because they did all 3 runs within the first 2-3 mins after it started. i saw it go into closed loop on the a-tap right after the 3rd pull.

would open loop hurt any horsepower? and is my dip at 5500rpm because of it or does the MAF need to warm up also? you could see the maf frequency drop big time also at 5500rpm

thanks

Dec 1, 2003 | 08:13 PM

WS6FirebirdTA00

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From: North Carolina

i would think it woudl need to be in closed loop so the engine could monitor everything right or something, but i dont know so to the top!

Dec 2, 2003 | 01:49 PM

strokedls1

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From: Venice, Ca

Maybe you tires were slipping on the dyno. I was at that dyno day in the morning and they did not know how to dyno. Only use two straps on the back which doesn't load the rear enough. Mine weren't even that tight. He kept flooring mine and making it downshift into second before third so I only got 5000 to 7000rpm data. Car had a 30 hp difference between 1st and 3rd pull based off the tires heating up. You car sounded fine to me. Have you logged any street info to duplicate the maf issue on the dyno? The car runs in open loop when you go wot so that is not a factor.

Dec 2, 2003 | 11:10 PM

GrannySShifting

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From: Glen Burnie, Md

You only need two straps in the front and two in the back. im willign to bet you werent spinngin the tires it takes 600-800 rwhp to do that

Look at your 3-2 downshift tabel and 100% tps start from a mph thats higher than the one listed there or set them to 10 mph and it wont downshift, no problems. Just remember to chang it back

All wide open thottle is done in open loop, it means its not using the O2s to correct ot 14.7 (stoich) a/f at 5500 did you pickup knock retard (pitching timign into the dumsp) or did cat over temp kick on and send the a/f into the pitS?

Dec 2, 2003 | 11:55 PM

strokedls1

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From: Venice, Ca

Well the car is putting down 500 lbft torque, and on street tires it does not hook up. The trac light comes on everytime I punch it.

Dec 3, 2003 | 01:02 AM

Ed Blown Vert

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From: Sunny San Diego

@ WOT you are in open loop.

Dec 3, 2003 | 04:00 AM

Slowhawk

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From: Bridgewater,Ma

Ummm,Are you saying you started the car and blasted it to redline when the engine was ice cold?Good way to toss a motor.

And yes at WOT the car runs open loop.