Throttle Body Question ... Speed Density

AnthonyR23 · Apr 22, 2007

Hi.. I have a cold air intake.. with the throttle body... if I had to replace my throttle body would there be any benefits of getting a 65mm throttle body. My car doesn't currently have mass air.. still just speed density.. any possible hp gains??

Daggar · Apr 22, 2007

It will depend on where your bottle neck is. If you're running the stock upper and lower intake, you'll likely not gain anything noticable. If you're running a better intake then opening up the TB would be a good thing.

stang&2Birds · Apr 22, 2007

Going up to a 65mm TB won't hurt. But, don't expect much, if any, gains.

5spd GT · Apr 22, 2007

stang&2Birds said:
Going up to a 65mm TB won't hurt. But, don't expect much, if any, gains.

I agree...

AnthonyR23 · Apr 23, 2007

k thanks guys.. well I am having idle issues and a new iac was about 50ish from mustangs unlimited.. I got a iac, tps, 65mm throttle body, egr spacer, with egr valve for 145. which I think is good because some new 65mm throttle body's are more than that alone.. so I thought I may aswell upgrade to something other than stock.. if I am going to replace them in the first place.. thanks guys

irvgotti · Apr 23, 2007

I thought the car would run differently with a bigger TB... i was under the impression that changing the flow of air would make the computer go out of wack,and the car would not run as smooth....i guess im wrong....thats whats good about reading these forums lol...

donsbad68 · Apr 23, 2007

Your fine with speed density til you start changing vacuum levels

v8only · Apr 23, 2007

I run gt40p heads with a PORTED explorer efi intake, and a 65mm t/b and speed density, and it runs fantastic.

as for the poster of this thread, I wouldn't bother throwing it on in an effort to troubleshoot your idle problems, it could potentially only enter an unknown variable into the mix and complicate things.

what vacuum are you pulling at idle?

AnthonyR23 · Apr 23, 2007

about 22

AnthonyR23 · Apr 23, 2007

Says vacuum is in normal range on the vacuum gauge I use.. I am pretty sure 22 is pretty good. The reason I think the new throttle body will help is because it comes with a new throttle position sensor and idle air control motor..

v8only · Apr 23, 2007

that's great vacuum, I run good with only 18-19,....what is your tps set at right now?

AnthonyR23 · Apr 23, 2007

tps is between .9 and 1.0

AnthonyR23 · Apr 23, 2007

and I cleaned out my iac.. only errors I am getting right now are related to egr valve solenoid and secondary bypass solenoid. I bought a kit that should be arriving soon.. so hopefully those errors get cleared up.. Not sure why my idle won't drop below 800 with the iac unplugged... Weird... Anyways though the car is actually running pretty good.. just chasing down a exhaust leak that is making me so irritated.. Replaced the headers... so that is rulled out.. I think it is coming form the collector where h--pipe meats the headers.. really tightened it but I think there could be a hole in the h-pipe itself.. when I save up enough money I am gonna replace it with the pro chamber from mac... so hopefully that solves the problem.

v8only · Apr 23, 2007

thumbs up for REALLY doing your homework!! I'm assuming it won't adj below 800 with the iac unplugged?? I had an oddball situation where the bracket holes were hogged out a little, and physically pushing the bracket forward contacted the screw better and fixed my high idle problem.

dragnazz5.0 · Apr 23, 2007

most high idle problems on speed density systems are caused by vacuum leaks....but with 22" of vacuum i dont see a vacuum leak to be the problem.

AnthonyR23 · Apr 23, 2007

ya I have noticed that I can loosen that stop screw and there is a point where the actual bracket won't seem to go back any further.. actually got stuck though at one point.... I had to take off my cold air intake and push the throttle body plate thing back open probably because I backed the screw off to much.. but 800 seems to be as low as I can get with the iac removed.. I have a 65mm throttle body.. egr spacer.. tps.. and iac on the way.. so maybe that will resolve it.

AnthonyR23 · Apr 23, 2007

otherwise I am leaning towards it probably being a cable problem or something... who knows... but I have pretty much been through the surging idle checklist... no more surging.. only thing I haven't checked is the timing..

AnthonyR23 · Apr 23, 2007

I also ordered a kit from a late model restoration place that comes with new o2 sensors.. which I don't need.. but I'll have extra.. a new egr, tab, and tad solenoid.. that will probably clear up some of those error codes I'm getting.. and I'm not getting any errors that my tps is out of range anymore... I think once I get these new parts installed my problems may go away... if not.. only other thing I can think of is getting a new cable... and I am definetely going to check the timing. Not sure if that would make a difference..

AnthonyR23 · Apr 23, 2007

has anyone ever had a bad throttle cable?

Roland69 · Apr 23, 2007

not me but I have replaced them on costomers cars.

Throttle Body Question ... Speed Density

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