My ranger has been having weird idle problem and wanted to know if any one else has had this problem. The truck idles fine when it is completely cool or when its warm. But if i go into a store or something and the truck is allowed to cool for like 10 min the idle when i start it is very rough sometimes even shutting the truck off. And it has to run for a few min until its idle equals out...now the longer the truck sits in the parking lot while im shopping or wat not the better the idle is at start up. The longer it cools the better. IAC is brand new so i know its not that. My dad and I suspected leaky injector so we took it to his work one day and hooked it up to the computer and watched the graph. When the truck was Idleing normally the truck was randomly dropping cylinders. Even though it doesnt seem that way under normal conditions the truck is randomly picking a cylinder and dropping it. So the only thing we have come up with is the program in the trucks computer is faulty and is causing the rough idle at start up and the random cylinder drops...but I was just curious if anyone else has had a problem like this before i decide spend the money on another computer.

 

how old are the plugs/wires?

 

Have you recently tanked up at a ststion that doesn't sell much gas????

That maybe still has the winter blend (vapor pressure) recipe, thats maybe boiling & causing random vaporlock after the truck sits a few minutes & heat soaks????

 

what causes that.. ethanol?

 

Most fuels in Va don't ontain more than 10% ethanol, so that shouldn't pose a problem imo.

The oil companies normally lower the fuels vapor pressure point for winter, to help cold weather starting & improve driveability.

When the weather suddenly warms a lot & you get a really warm day in late winter or early spring & you have winter vapor presure recipe fuel onboard, especally if you have a return type fuel system & say the tank is below 1/4 remaining, it's not ucommon for the fuel in the tank to get so warm, eapecially after a shutdown heat soak, that it'll boil & vapor lock.

This often happens in our area this time of year, especially on really warm days like we've been having, to interstate traveling folks from cold country, heading south & low on their home cold country recipe fuel, or if someone has tanked up locally, from an out of the way station, or one that doesn't pump much gas & still has the winter recipe in storage.

So if this problem began shortly after the last fillup, maybe winter fuel vaprlock gets the credit.

 

so the thing to do would be loosen the gas cap ?

 

the plugs are only like 30,000 miles old but i eliminated that because if it was the wires it would be an all the time thing or just one or a couple cylinders...it wouldnt just randomly drop the cylinders. And as far as the gas station i stop at one that is quite busy all the time...especially at 5 in the afternoon and i dont let the truck drop below a half...so other then that im not sure wat it is.

 

If you think your suffering from vapor lock, open the hood & let the engine heat out. It might take 1/2-1 hour, depending on the air temp, for things to cool down enough to stop boiling the fuel. If the fuel lvel is low, cool the tank with water, to cool it down.

Once you get er started again, fill up at a quality brand name gas station, that pumps a lot of fuel, so your likely to be getting fresh fuel & fuel who's vapor pressure is up to date with the season.

With todays hotter running engines & stuffed up engine bays, with poor air circulation & especially on vehicles with a retun type fuel system, DON'T let the fuel level get below 1/4 remaining in hot early Spring, or Summer weather.

Remember the fuel pump is cooled by the fuel it's immersed in, so the cooler it runs, the longer it'll last. So when the pump runs, it too is adding to the heat load in the fuel tank, then when we let the tank level get low, the fuels temp can rise quickly with the added heat of the pump, higher than normal ambient air temp, a hot engine bay, then a hot soak cycle after engine shut down, makes us all set for vapor lock!!!! lol

But all that said, this doesn't likely seem to be jfarmers problem, as he tanks up at a busy station, so his fuel recipe should to be seasonly up to date & he doesn't let it get below 1/4 remaining, all of which is good practice, so in theroy we're not likely to find him beside the road with "vapor lock"!!!!

SO, what the heck is going on with his ride????

Well the next question, is this busy station a off brand, cost cutter type???? If so, there may still be a problem with the fuels seasonal vapor pressure adjustment, as many tank farms will sell off any remaining off season fuel at bargan prices, to move it out.

SO, jfarmer, if it's an off brand gas I wouldn't rule out fuel just yet. Maybe try another name brand top tier fuel, that runs good in your engine & see what transpires.

I don't think it's the computer, as mine will randomly drop a cylinder at idle too.

For polution reasons, the computer is trying to run each cyl as close to the stichometric 14.5:1 air fuel ratio as it can at idle, so when it leans things out too much at idle, it can drop a cyl.

So when it does, the computer will sense that & adjust that cyl's A/F ratio by adjustng that cyls fuel injector's on pulse & the cycle begins all over again, until the mixture gets so lean, that the cyl misfires again!!!! Thus the seeming random nature of the idle misfire.

This "heat soak" cycle, type of problem is also symptomatic of an electrical part with a problem.

Could be something in the ignition system, typically something in the high voltage or trigger circuit parts.

I suppose the computer could be included, seeing as how it's located under hood, high up, where it'll get plenty warm, a few minutes after a hot shut down.

Then after a half hour or more, it'll cool down under there enough for the problem to go away, until the next heat soak cycle.

I suppose you could try causing the problem, by heating different items with a hair dryer or heat gun & see if you can find the heat sensitive component.

Or maybe go the other way, when it's hot and acting out, cool different suspect items down with air, ect, & see if you can cause the problem to clear up.

Just some more thoughts for pondering.

 

Im running amoco fuels...which i nvr had a problem...wat other brand name do u recommend

 

You should be ok with BP/Amoco fuel.

If you want to try something else, I've used both Chevron & Texaco in your part of the woods, with good results, so why not run most of the current tank out & try either of those for 3-5 tankfuls & see if there is any change. If not, then you have probably ruled out fuel & vapor lock as problem.

It may be a heat soak sensitive electrical part & that could take some time to run down, as the temp range seems fairly narrow.

 

i have a problem when mines cold runs good when it warms up it misses bad pings going uphill and on acceleration no codes have ben showng and we suspect bad distributer on yours you got coils. try a camshaft position sensore if equiped it tells ypur injectores when to fire

 

i have a problem when mines cold runs good when it warms up it misses bad pings going uphill and on acceleration no codes have ben showng and we suspect bad distributer on yours you got coils. try a camshaft position sensore if equiped it tells your injectores when to fire