TB got my car slower

[aleborjas]

hi
i have my car with a 306, stock heads ported, stock intake ported, 30pound inyectors, 75mm maff, 274HR cam. the problem is that i tried a lager TB 65mm with spacer and my car ran lot slower why? i had to put back the stock one again! lot of people i called told me to change the intake and put 70mm TB but i dont whant to spend my money and probaly my car is going to be worst!!!!
what should i do and why my car ran slower with more air i think it was going to be better because i have big inyectors.

 

[Foxfan88]

does the car pull a bit better up top???
i always thought it was expected to lose a tad of low end when swapping TBs?? but the loss in low end means gain in high end, which is where your engine is running 95% of time ( when racing)

 

[90mustangGT]

I would check your TPS voltage or something because I really don't see how it could hurt power, most of the velosity is made in the intake runners.

 

[aleborjas]

my tps is ok 9.80 and my car with the big TB is veryvery bad on top and low end

 

[DMAN302]

Going to a 65mm TB with stock intake should not change anything performance wise, as stated earlier I would look at the TPS sensor setting, also check for vac leaks while your at it. In stock form I have run stock/65/70mm TB's and not noticed any change in performance. Check over the engine bay to see if you forgot anything. Now the real question is why your running injectors that are too big..you may be running too fat in the A/f department.

 

[Black1987Stang]

Yea i agree with Dman, you certainly dont need 30lb injectors, Maybe 24's but im sure the stock 19's would be fine, THEN when you do start upgrading the intake manifold, heads, then you start upgrading the injectors also. Have you tried pulling ur codes lately.

 

[aleborjas]

dont know how to pull codes what do i have to do?

 

[v8only]

dude, you're KILLING yourself with those 30 pound injectors. Before you do anything, stick a stock set of 19 pounders back in, as they're good for up to 300 horse or so, and you're at 260-280 tops with your current combo. that throttle body should work fine with your combo, but those injectors won't.

 

[jackchan]

i fully agree with these other guys........tb shouldnt be the problem, injectors are whats hurting you! go back to 19's until you can get some 24's!

 

[Paul Perreca]

i say for the time being, save the throttlebody, and put on the stock one, so your back where you were, than save your money, get heads, cam n intake, and you'll use the throttlebody then, and your injectors will still be a little too big...

LOL just keep buying parts till your injectors are just right, throw a supercharger on it lol

 

[Michael Yount]

aleborjas - give us more detail -- all you changed was the throttle body? You didn't change anything else at the same time? Are you absolutely certain you got everything hooked back up/plugged back in the way it was supposed to be? Was the throttle body new? In addition to checking your initial tps voltage (you mean .98?) did you open the throttle to see if it climbed smoothly to 4.5V-5.0V at w.o.t.?

The only way you should've lost any power OR drivability with that swap is if you forgot to connect the throttle cable. Every Explorer and Mountaineer ever built came from Ford with a 65mm throttle body --- it should work just fine on yours, top end and bottom. Something else is wrong - it's not the throttle body causing the problems.

 

[mooktank]

maybe its all in your head...

 

[aleborjas]

the only thing i changed was the TB and put the TPS on .986 and WOT 4.65 even my iddle got better but the car was lot slower i had to put back the stock one, i have base timing 14* with cobra computer and pass the finish line on 5500RPM and with the 65mm one i pass on 4900-5000RPM.... all this with 30pounds and 6000RPM powershifting and street radial tires 245/45-17...

 

[90mustangGT]

Oh, I didn't read that, you don't need 30#injectors. I would do what Michael said, check to be sure the throttle opens all the way when the pedal was on the floor. I had a car come into work with a messed up throttle linkage. The guy said "I bought it used, I wondered why it seemed so slow" TPS voltage being proper is vital too. Make sure the MAF is clean and everything being hooked up.

 

[mooktank]

Maybe you disrupted the gonculator switch. Haha jk Umm I would recommend checking for leaks like everyone else said.

 

[aleborjas]

i checked all that it opens all tha way full!
i bought a RPMII and 70mm TB for very cheap price 300$ all. what happens if i put it with my combination?
i plan for a 347 but not now like for february!
can i got on 12' s with my 306? what do i have to do?

 

[IntenseBlue]

It augtta run better, but get some 24s when you do the intake.

 

[aleborjas]

It augtta run better, but get some 24s when you do the intake.

what happens if i put the RPMII and 70 TB on my aplication?
and wich inyectors 19? im going to leave the 30lbs for the 347!

 

[ninety15.0]

I think that the RPMII is a high rpm manifold 1500-6500...and normally used in bigger inch motors with large cams, so it should be great for that 347 your planning but if u put it on your motor now you will be dissapointed with low end grunt. Your setup is very similar to mine...im running stock injectors and my A/F is fine...i think thats your biggest problem way too big. what MAF are you running? why are you running a cobra computer? and do u have a chip?

 

[aleborjas]

I think that the RPMII is a high rpm manifold 1500-6500...and normally used in bigger inch motors with large cams, so it should be great for that 347 your planning but if u put it on your motor now you will be dissapointed with low end grunt. Your setup is very similar to mine...im running stock injectors and my A/F is fine...i think thats your biggest problem way too big. what MAF are you running? why are you running a cobra computer? and do u have a chip?

i have 75mm maff, cobra computer and i have a chip but not on i am goin to try it is diablo!
i have a large cam!