Does this sound like Idle Air Control Valve failure?

[Robb235]

I too thought the same thing, I had even replaced every vacuum line under the hood and still was running lean with high ltft's.

I think I might have found the leaky hose. I walked outside during lunch and I can hear a hissing coming from one of the hoses that has a nice long split in it. I think this hose goes to the evap or something, I don't remember. I didn't take a picture because I didn't want to reach into my khaki pants to grab my phone with dirty hands lol.

EDIT: Here's a picture of someone else's engine. It's the hose with the silver hose clamp on the left. Mine has a nice split in it.

As a side note ethanol itself does not burn like fossil fuels, it is a solvent. Most dual fuel vehicles lose mpg's when going E85 for this reason.

Ethanol actually has some nice burn characteristics. It burns cooler, and has more vaporization cooling than gas, cooking the intake charge. It doesn't have as high peak cylinder pressure as gasoline, but maintains longer overall cylinder pressure, taking advantage of better crank angle. Or so I've read.

Reason you lose mileage is because ethanol runs at a richer mixture than gas, thus burning more of it to maintain its stoich ratio. Gas is 14.7:1 while pure ethanol is 9.0:1. Ethanol also has lower energy density than gas (less BTUs per gallon).

Winter fuel blends already have increased ethanol here in CA and as you know adding corn to fuel doesn't but the corn industry which is another subject.

I think you've got some typos in here, not sure what you're meaning to say?

Hope you are able to solve the issue soon.

Thanks, me too.


Sent from my iPhone using Tapatalk

 

[firemanj92]

"Ethanol actually has some nice burn characteristics. It burns cooler, and has more vaporization cooling than gas, cooking the intake charge. It doesn't have as high peak cylinder pressure as gasoline, but maintains longer overall cylinder pressure, taking advantage of better crank angle. Or so I've read.

Reason you lose mileage is because ethanol runs at a richer mixture than gas, thus burning more of it to maintain its stoich ratio. Gas is 14.7:1 while pure ethanol is 9.0:1. Ethanol also has lower energy density than gas (less BTUs per gallon)."


I agree and was stating the same thing in less technical terms without having to repeat without references. :thumb:


"I think you've got some typos in here, not sure what you're meaning to say"

Autocorrect left some words out. I corrected it. Meant to say "it only benefits the corn industry."

 

[Robb235]

Noticed that autocorrect bit me too... "cooking" the intake charge, lol! Meant to say "cooling" the intake charge.


Sent from my iPhone using Tapatalk

 

[Robb235]

Update: Motor hasn't died since cleaning the IAC. Looks like all that gunk was the culprit.


Sent from my iPhone using Tapatalk

 

[96Runr]

having the same issue.... stranded in Randsburg this weekend after getting off the 395... engine lowered to 1K RPM and died...


for those who changed idle control valve, which one did you go with and from where did you buy... thanks much!

 

[Robb235]

having the same issue.... stranded in Randsburg this weekend after getting off the 395... engine lowered to 1K RPM and died...


for those who changed idle control valve, which one did you go with and from where did you buy... thanks much!

I only cleaned mine, I did not replace it.

Does the engine start? Can you keep it running by keeping your foot on the gas slightly?

 

[96Runr]

ended up cleaning it... had to drill out only one bolt

wondering if problem persisted with anyone after cleaning, how many just go bad after 20+ years no matter how much they are cleaned?