idle problems (could be fixed, I hope)

gjp

gjp

another post whore
I am running my truck at idle and after about 2 min it starts to almost stall out. the only thing I show in the DM is the rpm drops to 300 and the voltage drops. The voltage is low compared to what it was before the new alt. Its idleing at 12.2-12.4 volts. My fuel pressure is low because it used to run rich before. Should I bump the fp back up. No vac connected its at 38lbs. Running its at 30lbs. Everything is new. Just want ideas. WBO2 shows 14.7~ 15.5 when its stalling. At startup its in the low 13 range. Vac is at 19.48 and of course it drops too when it stumbles.
 
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WyoSyclone

WyoSyclone

Active member
Re: idle problems

Re: idle problems

Hey Gary,
What chip are you running?
Did you go with a new TB?
What are your IAC counts doing when the truck starts to stall?

EDIT...saw your mods list.... IAC count would be one question during stall...
 
WyoSyclone

WyoSyclone

Active member
Re: idle problems

Re: idle problems

Also...
Is the stall happening from a cold engine to warmer engine transition, or does the stall happen after two minutes when the engine is warm as well?

Does your voltage go up to about 13.8 off idle?

Just to try one thing at a time - maybe take your fuel pressure up a bit and see if it changes the timing of when the onset of stall occurs.
 
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gjp

gjp

another post whore
Re: idle problems

Re: idle problems

alt is a cs130 (stock style) with a 140amp upgrade, New.

Started it up again. turned FP up 5lbs. Idled great for 67 seconds then it started to stumle just a bit.
The iac counts are in the low 20's and they jump up to 35ish when it stalls. The nbo2 when its good are around 860ish and drop to the high 100's when it stalls. TP volts are .58 and do not change. nothing else realy changes.
 
gjp

gjp

another post whore
Re: idle problems

Re: idle problems

the o2volts look to be the key. They drop first before anything else. I know I only have less then a 1/4 tank and the gas is 8 months old but it was 95octane gas. I have yet to see what the FP does when it stalls.

And the engine is still cold at 135*
 
WyoSyclone

WyoSyclone

Active member
Re: idle problems

Re: idle problems

Just as a quick test.... adjust the stop screw in just a little bit on the throttle body to give the engine a tad more air at idle... even if the idle goes up to 900 or 1k, leave it and see if the stalling happens at the same elapsed time.
 
gjp

gjp

another post whore
Re: idle problems

Re: idle problems

now it wont start. looks to be a fuel problem. I show 45psi but when I run the fuel pump with the bleed off valve open on the fp guage the fuel just trickles out. FP is new so i am guessing its out of gas even though the guage reads just under a 1/4.
 
WyoSyclone

WyoSyclone

Active member
Re: idle problems

Re: idle problems

That's about how far my gauge is off, as well. So is my temp gauge.. pretty frustrating. I guess there is a method to remedy the fuel gauge being off.

Running out of gas would be a simple fix! :D
 
gjp

gjp

another post whore
Re: idle problems

Re: idle problems

I never let it go past 1/2 tank when I drive it. you know the boost thing. teaches me to trust a syty stock guage. i will fill it up and try tomorow.
THANKS ROB!!
 
WyoSyclone

WyoSyclone

Active member
Re: idle problems

Re: idle problems

Wonder if Phil would chime in and tell you if he thinks it's a code-related issue in his chip? As many things as you have new on the truck it will probably just come down to making sure each mechanical item is within spec.... then checking to see if the chip is managing each correctly.
 
sy#2921

sy#2921

BAMF
Re: idle problems

Re: idle problems

One thing I remember from somewhere is high amp alternators tend to sometimes put out less current at idle rpms compared to a stock alternator. So maybe it is turning off and then voltage drops to battery differential then maybe it needs a charge which could cause a hickup to stall. Maybe bump your idle tables up 100 rpm first before you mess with the idle screw and add some base fuel back in. 43psi vac dissconnected. If you need you can then have the f28 scaled down to make the difference
 
W

wantingasy

Active member
Re: idle problems

Re: idle problems

Is the pulley on the alternator the right size? I know when I was getting a new one for my old ty there was a couple different sizes and one put out less amperage.
 
gjp

gjp

another post whore
Re: idle problems

Re: idle problems

had a friend help me out today. noticed the fuel pressure would go up before the stall and my wbo2 would go way high. max out at 19.9.
 
gjp

gjp

another post whore
Re: idle problems

Re: idle problems

truck runs for a few min. and slowly gets leaner on the wbo2 till it stumbles and dies? the rear hose on the tb that connects to the pcv valve is sucking hard. when i unplug the hose the idle jumps. it still stumbles and will die. any ideas??
 
REVEREND HARMON

REVEREND HARMON

Party in a box!
Re: idle problems

Re: idle problems

Im having a problem with mine kinda the same, only mine will idle jump between 30-100 consistantly, very very annoying. it also runs lean when it drops and the voltage meter drops.im curious to see what your outcome is or my outcome.
 
WyoSyclone

WyoSyclone

Active member
Re: idle problems

Re: idle problems

Hey Gary, Do you have DataMaster?.... sounds like time to hook up some diagnostics and see where some base parameters are sitting.
Some things to check....
- TPS voltage
- IAC counts
- check fuel pressure during stall condition
- AFR's at idle before stall
- voltage characteristics before onset - slowly decreasing voltages?

questions...
- Checked for vacuum leaks with ether (starting fluid)? - be careful doing this one.
- Does the 2 minute stall happen when the engine is warm, or just during a cold startup?
- Did your new injectors call for the output driver modification to your ECM?
- Does your voltage go up to above 13 off of idle?

Leaning out can be caused by a decrease in fuel, or an increase in air, or a sensor/ECM mis-read of info during a warmup cycle. Once again, maybe get in touch with Phil and see if he has any ideas concerning how his tune (chip) may be issuing commands with the engine mods you have made (closed/open loop modes, F29 tables).

Take a breather, make sure all the mechanical aspects are within specs, then look at the tune/chip as the final factor... just my :2cents:
 
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