weird idle problem with pt 880's

sj-performance · Post by **sj-performance** » Sat Mar 07, 2009 1:14 pm

I have had the same problem for sometime, I just cant get my car to idle properly..... The car will only idle without bucking and poping when I have it extremly rich like in the 11-12afr anything higher and it starts to misfire... I have tried every combo with the battery offsets,egt and iat...when the fan comes on it will idle fine untill it shuts off, and its not just me I have a couple friends that are good at tuning and it leaves them scrathing there heads.... So far I have checked everyhing mechanical,made new ecu, new conversion harness,grounds, sent the injectors back to p.t and had them checked and cleaned etc etc.... I have no clue as to why it is doing this maybe I am missing something... I am using 880cc precision injectors,boosted b18c,gm 3 bar map, 255 walbroh pump, aeromotive regulator... Please help.....The only thing I havent really checked was the pump, I do have an extra but the fuel pressure looks good......

sj-performance · Post by **sj-performance** » Sat Mar 07, 2009 2:29 pm

my fuel pressure is at 42 psi I tried to lower the fuel pressur to 32 psi but I havent had a chance to try it..... Anybody using the 880s what pressure do you have them set

Post by **calvin** » Sun Mar 08, 2009 1:09 pm

up it to 52

sj-performance · Post by **sj-performance** » Sun Mar 08, 2009 7:25 pm

Thanks Calvin. Is that with the vacuum line off or on????

sj-performance · Post by **sj-performance** » Sun Mar 08, 2009 11:41 pm

Looks like I got it ....... so far I lowered the fuel pressure and losened up my valve lash a bit.....I haven't had time to tune it properly but I did get it to idle at 15afr with the odd pop.. next I will start a new tune from scratch then try to raise the fuel pressure and see how it goes.

hackish · Post by **hackish** » Mon Mar 09, 2009 8:53 am

With the vacuum line off they should be set to 43.5 psi. -Michael

sj-performance · Post by **sj-performance** » Mon Mar 09, 2009 10:45 pm

I will give it a try.

Post by **Bugermass** » Tue Mar 10, 2009 1:35 am

some injectors just suck at lower duty cycles.

Post by **calvin** » Wed Mar 11, 2009 11:43 am

BlindFashion · Post by **BlindFashion** » Sat Mar 14, 2009 9:46 pm

Bugermass wrote:some injectors just suck at lower duty cycles.

Yep. I have to idle my 1000's at 11 - 11.5 or else it wont idle under 1200 without poping.

Post by **Bugermass** » Mon Mar 16, 2009 12:12 am

its not gonna hurt anything to let it pop.. Id rahter have the poping than run it really rich for a smooth idle..

Adam Hopkins · Post by **Adam Hopkins** » Mon Mar 16, 2009 1:23 am

Bugermass wrote:its gonna gonna hurt anything to let it pop.. Id rahter have the poping than run it really rich for a smooth idle..

+1 As long as the car is not shutting off or wanting to die a little popping is better than 11.5 a/fs at idle. You do not want to wash the cylinder walls down with gas and possibly cause damage.

BlindFashion · Post by **BlindFashion** » Tue Mar 17, 2009 3:04 am

Adam Hopkins wrote:
Bugermass wrote:its gonna gonna hurt anything to let it pop.. Id rahter have the poping than run it really rich for a smooth idle..
+1 As long as the car is not shutting off or wanting to die a little popping is better than 11.5 a/fs at idle. You do not want to wash the cylinder walls down with gas and possibly cause damage.

Bah, Its really really hard to wash cylinders down, andd 11:1 wont do it. 40k and 4 raced years later I've never had my bottom end apart and in the winter she idles right at 11:1 Doesnt eat oil or smoke. 693WHP