Hey I'm trying to install a Edelbrock 70 mm throttlebody on my 87 gt. Its mostly stock with gt40 heads, flowmasters, and 24s injectors. I know 24s are a little much for my setup but I needed injectors and I gottem cheap. Anyways, my question is how do I setup the tps and idle screw? Right now its surging. It comes and goes. Sometimes I can hear some hissing like its got a vac leak someplace but I can't locate it. Its only done that since i put this other throttle body on. Sprayed oil around the area with no effect. Maybe it just breathes differently. I've adjusted the tps from .90 up to 1.10. Anyone got some ideas?
Throttle body
- Thread starter stang0f87
- Start date
bock
Founding Member
well the idle should be around 750rpm. adjust the screw with the engine running and hot.
for the surgin idle, maybe clean de maf, with a q-tip and alcool.
for the surgin idle, maybe clean de maf, with a q-tip and alcool.
well i was gonna wait till i build my 347 to do it but my stocker is going bad. butterfly is sticking. just wore out i guess due to wear. hate to pay for a stock throttle body when i've got this brand new 70 mm edelbrock just sitting in my garage. would really like to make this work for now. any more thoughts?
bock
Founding Member
install the 70mm... you wont have any trouble.you wont have any gain.maybe a lost in power.... but not much...
i checked the plugs and they actually looked ok. it would have been simpler if they were extremelly lean or rich. that would at least give me a clue. i'll clean the maf. perhaps i'll try dropping the tps down a little. i've heard whats supposed to happen is adjust idle screw till it makes contact. then use 10/1000s feeler gauge plus quarter turn. then adjust tps from .95-1.05 i'm thinkin. thats what i originally tried anyways.
Black1987Stang
Active Member
Did u take the intake off to change the throttle body, if so one of the vacuum lines are probably leaking. If you have a vacuum leak THAT could be causing your surging problem, the tps should be set at .98 volts a little under is ok but def. dont go over 1 volt. Try pulling some codes, BTW when my maf was bad it was surging really bad like i had a huge cam in it
Black1987Stang
Active Member
The reason Starting Fluid works for finding vac leaks is that it is Flammable. unless you spray directly on the headers, or allow large pools to gather on the lower intake, this is not a big risk. Using oil is useless.
The larger/aftermarket TBs are notorious for the whistling that you describe.
I always use brake cleaner when cleaning the maf. First reason, it dries with NO residue. Second, I do not have to make contact with the delicate wires with a Q-tip.
With the couple of vac leaks I have had, I have yet to experience surging idle. I have had the idle surge due to a bad tps, dirty maf, and dirty iac. My vac leaks have always produced a high idle (but consistent), and very poor fuel economy.
just my experiences
jason
The larger/aftermarket TBs are notorious for the whistling that you describe.
I always use brake cleaner when cleaning the maf. First reason, it dries with NO residue. Second, I do not have to make contact with the delicate wires with a Q-tip.
With the couple of vac leaks I have had, I have yet to experience surging idle. I have had the idle surge due to a bad tps, dirty maf, and dirty iac. My vac leaks have always produced a high idle (but consistent), and very poor fuel economy.
just my experiences
jason
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