im trying to compile a list of things that can keep a car from idleing

i recently replaced the afm with a new one and now the car starts everytime i crank it, but it wont stay running ..
if i give it gas i can keep it alive, but once it drops below 700 or lower RPM it just stalls out ...

now i need to know EVERYTHING that can cause a car to not hold an idle ...
i know the TPS isnt too crucial, ive adjusted the idle screw on the back of the throttle body ... all the way in and all the way out .. no change ...

i know the fuel pump works, but i still need to check to see how much fuel is actually making it thru the filter..

if its a vaccum leak that wont allow the car to stay started, it would have to be a pretty big vaccum leak right? what could possibly be big enough to cause that?

would injector emulsifiers have anything to do with this?

 

After pulling my hair out for months trying to solve the no-idling on my S5 NA, I found a broken wire leading to an air bypass valve. 2 minutes and a strip of electrical tape later I was driving around, purring like a rotary kitten.

 

Stalls unless you pedal it - Partial list:
low compression from high mileage or bad seal(s).
Vac leak.
Primary injector problem (wiring or flow).
AFM problem.
Idle stop screw or bleed screw adjustment.
Leading coil problem.
ECU problem.
Even weak grounds.

 

Sounds annoying.

 

i know this will sound kinda goofy but check for a vac leak on the check valve.. located under the thoratal body. there is a vac line that goes under that and conects to a choke on the front side... mine was broken and i put a new vac line in and it worked fine and it was showing the EXSACT same thing yours is doing...
good luck...

 

I've seen this problem on my boys 86 N/A. It was a vaccuum leak. Two lil hoses he forgot to hook back up.

 

ive removed all emissions so i have no spit air valve ...

and can you describe that check valve a little more for me?

anyone else?

 

did you check the dashpot on the side of the TB like i said earlier? that sounds like the prob to me... just try adjusting it to where you hold a 1k idle and then adjust the TPS... i wish i had somebody tell me that and saved me a month of grief

 

ive removed all emissions so i have no spit air valve ...

and can you describe that check valve a little more for me?

anyone else?

 

dont you remove the dashpot with the tb mod ... or is that just the thermowax

i wish i was at home

 

it is optional but people like me for instance only remove the thermowax when doing the TB mod because if you remove the dashpot it makes it about 10 times harder to drive.... the motor will just stall out every time you stop... im working on a way to remove mine but still retain the mechanism there to stop the throttle cable at 1 k rpms... the reason im doing this is because what the dashpot does is slowly returns your car to the idle speed instead of just dropping it.... when you eleminate this and just let it fall back fast its much easier to throw flames!!

 

hmmm
so say its a vaccum leak ... how big of a leak would it take to keep the car from idling?

 

fitness stain- these are probably self-induced problems you're having- you took all of the components off that help the engine maintain an idle through varying loads, then you fight with idle problems for days- see any connections here? you're just gonna have to rig/adjust the items you still can on the TB, that's what these guys (cwsttu) are trying to tell ya...

 

Isn't it supposed to idle around 750RPM?

I forget.

 

no man ... ive only removed everything that anyone has removed by getting rid of emiisions... nothing more nothing less ... there are way too many people on this board that have removed EXACTLY what i have and have not had a problem ... ive only removed emissions ...

BAC
ACW
SPLIT AIR
DONE THE THROTTLE BODY MOD (WHICH I DID BEFORE MY CAR DIED) so i know it works

 

is that list the stuff you've removed, or the stuff still on the car?

 

*removed*
here is the full list that i can think of off the top of my head

BAC
ACW
ACV
EGR
SPLIT AIR
i have removed the accerleated warm up crap
throttle body mod ... did that following the write up so i know its good
and im pretty sure thats about it ... as far as emissions , if theres something else related to emissions then i have removed it ... cause i have NOTHING relating to emissions

 

could too much slack in the throttle cable cause this?

 

what about dirty injectors ... seems like it would'nt run good in higher rpm though ... cause the rpms go up real smooth ... the car just dies anywhere from 1000 - 50 rpm
i can let it drop pretty far below 1000 rpm and then blip the gas to get it back up ... would the CAS or timing affect it this much ??

 

O.K., the BAC's only function in life is to help the idle with moderate loads- not really an emissions function, eh? I can't understand the fascination with removing all this stuff that some guys have- together, the components don't weigh squat, most have nothing to do with horsepower gains, and most are there for driveability concerns. O.K., now that rant's over...too much slack in throttle cable shouldn't have any effect on idle...if the timing is off, that could be it, but you said the remainder of the rpm range is good, so that's not likely...

 

what about the CAS

would too much MMO in the engine cause this?

 

if its a vaccum leak it would have to be huge right?

like a intercooler elbow loose or something wrong with the intake for it to be this bad .. wouldnt you think?

 

******* server. Remove the damn swear thing too. It's just an added load it can't handle already.

We remove those things because it cleans up the engine bay and makes it easier to install.

Besides. I know the PCV,Fuel,and wiring systems like the back of my hand now.

CAS is what does your timing. Just borrow/rent a timing light and check it. I bet your fine.

MMO(Marvel mystery?) should not have any affect on it running at lower rpms.

 

just thought of something

when im revving it up ... the boost guage doesnt move at all .. i do have an fcd , but when the car was running (before the previous engine blew) it still moved, im sure it was inaccurate, but it moved none the less ...

while im revving it the boost guage doesnt even flicker now ... is this a clue?

i also have the BOV vented to the atmosphere
the side with the vaccum connection is the one that has a hose going to it ...

the other end is open?

could that cause anything
i actualy have pictures of it .. let me get them real quick

 

CAS is not hard to read out to verify serviceability, but you probably wouldn't be running at all if it was bad...MMO in the oil? don't see how that could affect idle...dirty injectors, maybe, if the spray pattern is totally shot...after all this conjecture, I still believe it's the removal of those certain components causing your prob (BAC, Air bypass valve...)