i have been having stalling and running rough issues so i tryed to set my idle speed by using tunerpro and watching the iac steps. i was aiming for 20 steps but couldnt achieve it since there must be a vacuum leak. i smoke tested my intake to check for a leak and couldnt find anything external. when i pulled the ccv hose off the throttle body there was alot of smoke coming out.

I thought that was suppose to be a fresh air source for the ccv system, so why is it directly linked to the intake? i have a professional products throttle body and am wondering if they gave me the wrong year or if this was for speed density since on a maf car any vacuum leak before the maf would cause issues. maybe i am wrong or dumb but i am stumped now and need some help.

 

THE CCV should be hooked up just behind the throttle blades. if its anything like a stock TPI.

 

That is curious. You are correct that the PCV hose going to the TB is make up air. The manifold side of the system connects midway on the driver's side of the manifold base. Are you sure that the smoke isn't just coming out through the idle air passage and the minimum air gap of the throttle blades? Did you try the smoke test with the inlet air tube removed?

 

im an idiot, it was coming out of the air passage. i had it blocked at the maf sensor so the smoke was collecting in the elbow and coming out the ccv. so now i cant find any vacuum leaks but my iac steps are so close to 0 and i cant get them any higher since the throttle plate is all the way closed. i just replaced the iac with a cheap one and think it may be the iac itself causing this problem.

 

if i have the blades closed completely shouldnt the iac steps be very high to let air in. the car is getting only 10 mpg and stalling. when i come to a complete stop the idle hangs around 1000 for a couple seconds then down to around 700 but every so often it wants to stall when it drops to 700. i still think there has to be a vacuum leak but ive tryed everything i can think of to find one with no luck. starting to think it may be the lower intake gaskets even tho i just replaced them when the engine was rebuilt about 5000 miles ago

 

Connect your smoke machine to the PCV hose into the manifold base, with the PCV valve out of the valve cover. Run the smoke and watch for smoke to come out of the valve cover opening. That is strong clue that you have an internal intake leak.

 

Right so I have a 88 l98 tpi 350 stock. when I pull the CCV hose from the throttle body and put my thump over the hose there is very little suction is this normal.Why I am asking is that I had an 87 350tpi about ten years ago and remember there was a lot of suction on that hose .This 88 isn't like that at all is there a blockage.The PCV is good on the drivers side.

 

An engine with blowby may not develop significant suction in the crankcase. It is also important to use a proper and functional PCV valve. Many aftermarket PCVs are rather generic, where the pintle taper and spring package are inappropriate for a TPI system.

 

Thank you for your help Vader. I will change the valve for what it costs its probably been there since 1988.