i put all s5 manifolds on and now i cant get my car to idle below 1400 rpms. please help me with this

 

oh god, i know exactly how you feel. i just did the same thing and had to take it to chris sanders to get it to idle. make damn sure you have the vac lines right, i triple checked mine and they still were not right. chances are you are running rich, check to see the the vac line on your fuel rail is connected in the right spot or it will just dump fuel. there is a lot of things that it could be but if you give me a good description of exactly how it runs i will try to help. also, what do YOU think could be the problem?

 

a high idle and not idling any lower is usually running lean, not rich. Chances are you've got a vac leak or mixed up vac lines (as mentioned above). That or your throttle is being held open too far. It all depends, does it die under 1400 or just sit there forever?

 

ya my problem was that it would not run below about 1800 so i assumed he had the same problem. if its just a high idle than congradulations, easy fix

 

Yeah, a lot of people swap everything and don't adjust their throttle cable afterwards and it holds it open slightly and thus high idles, so I figured I'd mention it. Hopefully it's an easy fix, troubleshooting everything else sucks!

 

when i did the swap, it took 3 months to get it to run. i didnt have my license so i had no real urge to work on it. but still took 3 months

 

well, i have my vac lines right, cause i dont have emissoins and have done tb mod there isnt mutch to get confused, at one point i did have a vac leak between the upper and lower manifolds but thats taken care of, and it will run below 1600 all the way down to 700rpm, BUT the car runs fine i can stand on it and have no problems, i have adjust everything tps. throttle cable everything i just cant figure it outl

 

Be VERY sure you have the gaskets on right!! Good, clean mating surfaces with good condition gaskets, especially with that copper-gasket-spray (I love that stuff).

Make sure the bolts on the intake manifold are torqued to spec (They need a LOT of torque)

MAKE SURE YOU HAVE NOT PLUGGED THE FUEL INJECTOR PLUGS IN BACKWARS!!!!!!!!!

Putting the primary plugs on the secondary injectors will cause some MAJOR problems!

 

lol i bet it would, but thats not the problem , Like i said the car runs very nice and strung throught the rpm range, but it just wont idle below 1600. and im pretty sure a vac leak big enough between manifolds would affect how good it runs

 

so your problem is just a high idle? no other problems? if that is the case, what have you tried as far as adjusting the idle? did you connect the initial set connector when you tried to adjust it, if you dont i think the bac just raises the idle again when you try to lower it. have you checked the variable resistor, pressure sensor,afm? and did you do any porting when you did the swap?

 

i did no porting, I have no bac valve, afm is fine. i dont no anything about the variable resistor or how to chek the pressure sensor

 

the specs are in the fsm and haynes, use an ohm meter. what have you tried to get the idle lower that hasnt worked

 

i messed with tps, standard idle screw on the top of manifold, throttle cable, off the top of my head thats all i can think of

 

Possably there are other reasons, maybe your throttle plates not closing all the way... maybe because of:
A) An obstruction
B) Incorrectly set throttle stop screw or dashpot
C) Incorrectly set thermowax (I've never seen this, but I bet it could happen)

 

Here's an often overlooked issue with this swap. The s4 block has an edge on the rear iron, where the inspection cover plate sits. ON the s5 block, the intake sits lower, so the put a dimple in that spot on the block, and there is no point sticking up where it used to be on the s4 block. So, to put the new intake which sits low, on the old block, you must grind down that hump on the rear iron. Take about 1/4" of material off, then reinstall it. use a light to be sure your LIM-to-UIM mating surface is nice and tight. The issue is that the intake will hit the hump and won't bolt together all the way because of it, so you have a massive vacuum leak that is not the result of a loose hose or open nipple. Most people are blind to it, since none of this is visible with the engine in the car.

 

ahh, that is some intelligent stuff, at one point i did have the major vacuum leak from from the upper to lower manifold but thats fixed, and there is no leak between the lower and block, but i will double chek once i have the chance. also in my opinion i dont think it is a vacuum leak, i think it might have something to do with what Tofuball was saying with throttle plates not closing all the way