High idle problem, drill and tubing modded 58mm bbk IAC counts at zero???
04-20-2010, 10:05 PM
#1
High idle problem, drill and tubing modded 58mm bbk IAC counts at zero??? I admittedly do not have a cam. The buttwrench previous owner put this POS 58mm throttle body on, without headers either. I read a lot about the BBK's and the issue with the casting/iac and split blms, so I did the drill mod with an 11/64 hole while I had everything apart changing the alternator. I do have the tube sandwiched into the back of the throttle body to separate the IAC air from the plenum air.
Long story short, TTS Datamaster says my IAC count is at 0, my engine is trying to idle at 650 in Park (closed loop) it says my fuel trims are 16 (what is fuel trim?) and the TPS voltage is .63
actual rpms is motherfucking 1353, give or take! What is going on here? What should I check out? This **** is driving me up a wall. Vacuum leak maybe?
Long story short, TTS Datamaster says my IAC count is at 0, my engine is trying to idle at 650 in Park (closed loop) it says my fuel trims are 16 (what is fuel trim?) and the TPS voltage is .63
actual rpms is motherfucking 1353, give or take! What is going on here? What should I check out? This **** is driving me up a wall. Vacuum leak maybe?
04-21-2010, 01:36 AM
#4
im thinking i just might need to. I'm going to leak test this thing tomorrow, I've got a pretty good hunch that there is a vacuum leak going on here. The tube on the pass side valve cover to the throttle body just pops right out with no effort, I haven't checked the PCV valve, the IAC may have had some solvent sprayed on it, and the previous owner looks to have drilled a hole in the intake elbow and just sort of stuck the opti vent tube in there to let it hang on loosely. Plenty of air getting in there. The brake booster line was all pinched and looked to have been replaced with non-vacuum line and no hose clamp. I'll get more on it tomorrow and let you all know what's up.
That IAC counts are zero with such a high idle, even when i load the stock tune, is indicative of a vacuum leak or a bad IAC right?
That IAC counts are zero with such a high idle, even when i load the stock tune, is indicative of a vacuum leak or a bad IAC right?
04-21-2010, 02:08 AM
#5
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A 58mm throttle body may not be beneficial on a stock motor however it should be able to be adjusted to run as well as stock regardless. Tons of people use them with no adverse effects. I would be hesitant to blame the throttle body while you addmittedly have unmetered air being sucked into the intake from potentially a few different areas. Fix the vacuum leaks then try and nail down your idle issues.
04-21-2010, 02:19 AM
#6
A 58mm throttle body may not be beneficial on a stock motor however it should be able to be adjusted to run as well as stock regardless. Tons of people use them with no adverse effects. I would be hesitant to blame the throttle body while you addmittedly have unmetered air being sucked into the intake from potentially a few different areas. Fix the vacuum leaks then try and nail down your idle issues.
04-21-2010, 02:46 AM
#7
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I think the manufacturer's warranty on either of those models has long since expired 
You will undoubtedly be forced to wrench on those as well, don't get discouraged yet
You will undoubtedly be forced to wrench on those as well, don't get discouraged yet Trending Topics
04-21-2010, 02:49 AM
#8
Anyhow, going to try a whole slew of **** tomorrow to get this thing running right. damnit it's 4am and i want waffles.
04-21-2010, 11:00 AM
#11
Close the blades all the way and reset the TPS voltage to .50. and see if the IAC counts go up.
The IAC is fully closed and still cannot drop the idle, so there is a lot of extra air going in.
The IAC is fully closed and still cannot drop the idle, so there is a lot of extra air going in.
04-21-2010, 11:25 AM
#12
I pulled the TB off again to check and there is gasoline all over the back of it. The blades are fully closed. Obviously the pcm is trying to correct, and if my understanding is correct, just pissing through fuel because of the high idle and the IAC unable to correct it. I exposed propane all over the areas where I suspected leaks and nothing changed. I ordered a new IAC just in case, and I will change the TPS voltage in a minute. If none of that works, I will assume that the 11/64ths hole I drilled is too big and plug it up with something. If that works, I'll just sell the TB to somebody with a cam and get a ported stocker, which will be nice when I do long tubes.
04-21-2010, 12:25 PM
#13
No luck with the TPS at .45 volts, the IAC count is still ******* zero and the RPM is still ridiculous. For the record I did not have this problem until I drilled the hole. I followed the instructions exactly. I am about to pull it off and plug it and see what happens.
04-21-2010, 01:38 PM
#15
No luck with the TPS at .45 volts, the IAC count is still ******* zero and the RPM is still ridiculous.
UPDATE!
I plugged that cunting hole that somebody told me to drill with jb weld and made it smooth again. I guess do not drill the motherfucking hole???? It works fine now. Idle at less than 1000 in park. I am going to buy a stock throttle body that's ported to 52mm and return the idle air controller valve I just bought. Can anybody explain why the hell the hole made this car do what it did? I'm interested to compare the casting to a stocker and see if my BBK is the same as the ones in the hole drilling tutorials.
UPDATE!
I plugged that cunting hole that somebody told me to drill with jb weld and made it smooth again. I guess do not drill the motherfucking hole???? It works fine now. Idle at less than 1000 in park. I am going to buy a stock throttle body that's ported to 52mm and return the idle air controller valve I just bought. Can anybody explain why the hell the hole made this car do what it did? I'm interested to compare the casting to a stocker and see if my BBK is the same as the ones in the hole drilling tutorials.
04-21-2010, 04:52 PM
#17
Mostly the only point of drilling the hole is when you have a cam it will take in more air and be able to idle easier before getting it tuned. there is absolutely NO reason to ever drill the hole bigger when you dont have a cam it will just suck in more air and make your car idle higher, hence what your car did.
04-21-2010, 07:30 PM
#18
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Mostly the only point of drilling the hole is when you have a cam it will take in more air and be able to idle easier before getting it tuned. there is absolutely NO reason to ever drill the hole bigger when you dont have a cam it will just suck in more air and make your car idle higher, hence what your car did.
I agree. I have a 93' ta, h/c/i. the cc306 cam, and on my holley 58mm. tb I had to drill a small hole in each blade to get the car to idle decent,and to get the split blm's alittle closer. but like this above, it didn't need drilled w/a stock cam.
04-22-2010, 12:39 PM
#19
I was under the understanding that because bbk cheaped out and used one casting for both the tbi and lt1 that the lt1 throttle body was lacking that hole that the stocker had, and drilling it with the same size hole as the stock unit would smooth the idle a bit with no ill effects. Actually heard of and confirmed with a few folks that if the hole's air was directed into that smaller hole on the intake, it would be a decent thing to do. Drill the hole dey sez...it'll run better dey sez. I sez dey full of ****... but hey you live and learn. I'm going to keep this tb but devise a better way to plug the hole, fabricate a removable part with replaceable ferrules and who knowsm maybe make a little cash selling them to people who change cams often or who don't want to worry about damaging their tb with the hole mod.
