Dyno Problems

[Focker420]

K so i go yesterday to get my car dynoed, We strapped it down and on the 1st run as soon as he started to drive it turned the steering wheel 90 degrees to the left. and the car would bob and weave on the dyno. So he checks all the straps and gives it a go anyway. He had to hold the steering wheel straight and he used 4th gear from about 80km to 120mph (215km) @ 7000 rpm. And the dyno results were worse than before i did the under-drive pulley and the cam gears. WTF by like 10 whps to the wheels?He was all sketchy about doing a second run he keep saying it was my alignment and that toe was out.But i just did my outer tie rods and the alignment like 3 weeks ago. So i don't think it is the toe because there is no pull while driving . And so he couldn't tune the cam gears so instead messes with the safc2 the low and high throttle setting and now runs worse WTF.

Please help!!!

NateDizzle

 

[baxsom]

What gear was it ran in before the mods. Gearing makes a difference on numbers. A 3rd gear pull will give different numbers than a 4th gear pull.

 

[DSMcrazy3]

Baxsom is right. Also, even if you did align the car recently, there isn't really anything else that could have caused that. Have it rechecked.

 

[BigRand]

What kind of dyno is he using. Certain dyno's (ie dyno dynamics) it won't matter what gear you pull because of how they can maniupulate the ramp rate.

As for the dyno runs. Are you sure you don't have any type of flat spot or an irregular wear pattern that wouldn't make it stay stragight.
No offense but after working with guys who work on dyno's, I know there are ways to strap it down so that cars with extreme horsepower don't bob up and down or move side to side. Different knots they use, and different ways of strapping it down.

Case and point.


http://www.horsepowerconnection.com/images/Multimedia/daldyno04.wmv

 

[Blitzeclips]

What was your tire pressure? THAT could've played some role in your dyno problems...

 

[baxsom]

There is an issue of Cycle World that came out a few months ago talking about how dyno shops will fool customers. I wish I would have bought it.

Things like using different gears before and after mods to exaggerate differences.
Riding the brake on decelleration is supposed to give a higher number as well.

 

[Focker420]

Ok i am sure the alignment is correct and i don't know what gear they used the first time because i wasn't there and i'm leaningmore towards a tire issue i have a new tire on the right front and the rest have a summer on them so that might be it. I'm thinking they used third gear the first run fastest gear in my opinion. I think its a dyno jet or dynamics they have a web site called www.apexmodified.ca what do u think they trustworthy?

It would crank the steering wheel 90 degrees to the left and then straightn out as it climbed.?

I don;t know i am running toyo proxies and they are like $400 a tire .

 

[bullettdsm]

For what it's worth. On the Dynojet you should be doing pulls in 3rd gear. Not that I know that much about dyno's because I'm old school and don't go that often. BUT I did just go and the dyno guy (owner of the company) said that it is a 1 to 1 ratio to give you the most accurate pull. As for the 90 degree jerk, tire pressure or a broken interior belt could do that but you should notice it on the road. I'm also concerned with him adjusting you safc (unless he just did low throttle with wideband) without the dyno and no pulls.

MB

 

[Focker420]

Your totally right about the third gear pull would be way better and also u don't have to rev the hell out of the engine and take it to 120mph in 4 gear . But ya he tinkered with the low throttle before there was no + or - on the a/f ratio now he bumped it to -13% and the thing idles funny and runs way different. so i backed the a/f to 11%at like 2500rpm and as it gets higher i add more fuel and at high throttle its all messed up and takes a bunch away at like 3000rpm and the goes to like +15 at 4500 all of a sudden is there any way to figure out the best tuning without using the dyno? As for the pull im going to get a new tire anyway so that could be the only thing.

 

[DSMcrazy3]

Street tuning is basically the only way, run a pull, make some adjustments, rinse and repeat. Dyno tuning is perferred though because you aren't on the streets for one, and you get to see how productive what you're doing is.

 

[Focker420]

So i was takin to some other people about this dyno shop and i think hes an idiot now so trial and error is my only hope now for the safc tuning and the cam gears are useless till i find a new dyno guy/ tunner.