Crappy start ups....IAC/AIS and speed sensor functions?!?

[89ShelbyGuy]

Hey guys, recently ive been getting weird cold starts on my shelby....it wont even idle and will just die unless i give it some gas for a few seconds and then it feels like the iac kicks in and then runs normally.??? On warm starts i have no issues....i reset the base idle already...i thought i took care of it but its doing it again. I also noticed on decels it stays in the rpms alittle longer then it usally does..

Last nigt i took the TB out and took the air controller out and cleaned it all...there was very little crap on it......basicly no build up of anything....

My qeustion is would the AIS or IAC (which ever you call it) do that? And also with the decel...(ex. i shift from 2nd to 3rd and it stays on 3k rpm alittle longer and then comes down) would that have to do something with the speed sensor?

Tom

[shackwrrr]

it can but difficult cold starts on a FI car alot of times are attributed to the temp sensor not reading correctly.

[89ShelbyGuy]

Thanks for the tip..i wouldnt of never thought that..

[89ShelbyGuy]

After reading some more..i geuss after you reset the AIS sensor is might take alittle bit for the smec to learn it....i am assuming thats why on my decels its staying a little higher then i'd like?...

[shadowdude]

What is it throwing for codes ??

[89ShelbyGuy]

Nothin....

Last night i started it up after it sat all night and day and it chugged in the beginning so i gave it some gas...and then it felt like something kicked in and the idle shot up to where it should be......fine after that...i am leaning towards a faulty ais motor....

[89FerrariShelby]

I had cold start issues for 3 years after my car got built. Of course i didn't know about this site at that time....

Mine ended up being the CAL wasn't providing enough fuel...or at least that's what i think it was.

I had someone reprogram the CAL to add fuel and i don't have the issue anymore...but i have new ones!!!

i think i might check some stuff mentioned in this thread to see if it wasn't the issue way back then....

good luck, hope its fixed for you.

[89ShelbyGuy]

Let me ask everyone this,

I've been running 55psi static fuel pressure for a while now with my +20s on a stock cal....before this started happening i decided to turn it down from 55psi to 50 to help so i am not so rich......now that i think about it, i havn't had problems since i did that...i think....you think that would cause bad starts? i would think +20s would give plenty of fuel on start up?

Tom

[89FerrariShelby]

for what its worth i had +40's and slightly below 50psi when i had the cold start issues....

but my car has always been FUBAR...finally getting it right (i hope i hope i hope)...

Just adding my experience, i'd defer to more knowledgeable minds for actual advice...

[Mysterio]

My car was doing the same crappy startup thing when using redone LM and i'm pretty sure it had to do with lack of fuel. I went back to stock injectors& stock LM and it fired right up without requiring any gas. Then it started doing the same holding rpms for a while after letting go of the gas which I assume was since the LM was freshly plugged in it was learning things. Maybe bad AIS but we'll see once I drive it some more and let it get used to things.

[89ShelbyGuy]

Well, its not the feul pressure...i put it back up to 55psi...no change in cold starts...i check my plugs and wires and cap and rotor and found my fork that holds the distribtor down was loose which made me move the assembly unwillingly...causing my timing to be off....i then tried to time it but every time i unplug the coolant sensor the car refuses to idle...i have a feeling that the timing has jumped a tooth causing my bad cold starts....this weekend i am going to rip it apart and re do it....hopefully thats the issue here.....cause my 3bar, +20 cal is ready to go in...

[shackwrrr]

I replied to your other post but I will add some here. You say that your +20s were working fine before and they just now started causing problems? Did you unhook your battery anytime around when it messed up? If so Id say that before your adaptive fuel took care of the +20s but your o2 sensor was good. Now after the batt being disconnected your O2 is bad and your computer cant learn your injectors. I would replace your o2 when you install your cal (Which I recommend you do now)

O2 sensors on these cars dont cause a check engine light as soon as you would think. Ive been running without an o2 for about a month and Ive never gotten an o2 code. I even got 30 MPG on the highway I only get a few misses when its cold and thats it.

[89ShelbyGuy]

Its probably due for a sensor....havn't changed it for years....since about 2 rebuilds ago..lol....

Do you recommend that i let the engine warm up before attempting to loosen that o2 sensor?

[shackwrrr]

Just break it loose cold. When its warmed up everything expands so it would be tighter. O2's usually break free fairly easy anyway. What wideband do you run? does it have a narrowband sim?

[89ShelbyGuy]

Thats the next toy i will be buying...a wideband gauge...just have the crappy narrow right now....i planned on putting that cal in but only boosting stock until i hook up that wideband...i plan on running about 20psi...that should wake it up some...actually, i can't go above 15 psi anyways cause my clutch slips...that another upgrade...lol...i am shooting for next tax return...

[89ShelbyGuy]

So yea..my car is a POS...half the time it will start up fine, the other it wont...i geuss it will idle fine...but you know its suppose to be right:

You start up a nice and cold car that been sitting in 40 degree weather...
It starts right up...and idles at 1500 and graduly comes down as it warms up...

In my opinion, thats a good cold start....but i've been starting it up and sometimes it will do that or it will idle at about 800...and just stay there....almost dieing...the check engine will flash as the rpms come down so low....


Next step...replace o2

Tom

[shackwrrr]

take it to the next level. Pick yourself up a wideband, it is a definite must with any upgrades and would say it should be required with any "cal"

A LC-1, Zietronix, TechEdge, and AEM uego are all good setups with some sub 200 and they all have narrowband output options so you can just trash your stock sensor and run just the wideband.