Idle's high when I come to a stop

88_ranger · Dec 29, 2009

Hey there everybody...I have an 88 Ranger with the EFI 2.3L 4 cylinder and four spark plugs. The truck runs great but I am having this issue with the idle. When I'm driving down the road and I come to a stop light and I push the clutch in sometimes the RPM's will stay up at like 1700 and not come back down. But if I turn the truck off and restart it the RPM's will come back down to about 750 after a second.

I talked to someone about this and they thought it could be the EGR valve sticking. I replaced both the Idle air controller motor and the map sensor and this problem still persists. What do you guys think is going on? Thank you in advance for any help! :icon_confused:

master hec0 · Dec 29, 2009

is it cold outside? is your vehicle getting to operating temperature?

88_ranger · Dec 29, 2009

weather

It is cold outside and it actually seems to have gotten worse since winter came. But it does it when it's hot out too. And yes it does get up to operating temperature and the heat blows hot from the vents.

Like I said if I cut the truck off and restart it the idle comes down fine.

multiranger · Dec 29, 2009

88_ranger said:
It is cold outside and it actually seems to have gotten worse since winter came. But it does it when it's hot out too. And yes it does get up to operating temperature and the heat blows hot from the vents.

Like I said if I cut the truck off and restart it the idle comes down fine.

The idle air bypass valve sounds like she is sticking... or the butterfly is sticking.. Clean both with teflon safe TB cleaner... or You have a vaccume leak... I use starting fluid to find them myself but TB cleaner should work too...

ForOffRoadDriving · Dec 29, 2009

mine has done the same thing multiple times, once i come to a complete stop it will settle back down to normal again. it has always been a vaccum leak, usually around the 'vaccum tee tree' that comes out of the intake on the drivers side. ive found that the vaccum caps offered by the chinese (nealy every available cap out there) only last a year or 2 before they start to crack.

88_ranger · Dec 30, 2009

vacuum leak

I'll check on that vacuum leak. But mine is acting the opposite of yours. It's fine when I'm driving but when I come to a stop that's when the rpm's go up. But I will check for vacuum leaks on the tree.

88_ranger · Jul 12, 2010

I know it's been a while but I just now found a possible fix to my high idle issue's that i've been dealing with for the past year. I decided to replace the TPS (Throttle Position Sensor). When I put it on and the started the truck back up, it actually got worse. Then I found out that it was adjustable from another post on this site. I made the adjustments and knock on wood the truck seems to be idling like it just rolled off the assembly line. I'll post an update in a couple days. Again thank you for your help everybody!

bluepowerranger · Jul 12, 2010

same problem

mine just does it with a 1998 ranger 2.5 8 plug.

drives me nuts, and never does it when i take it to the mechanic..haha :icon_confused:

88_ranger · Jul 12, 2010

same thing

Mine was doing exactly the same thing...very intermittent! I replaced the idle air control valve, map sensor, egr valve control sensor, checked for vacuum leaks, and still could not figure it out. Then I replaced the TPS (Throttle Position Sensor) and it got worse. That's when it dawned on me that it the TPS is adjustable. With a Multimeter I belive the signal is supposed to read about .5 volts and when the throttle plate if fully open it's supposed to read about 5 volts. Well since I couldn't figure out how to use my multimeter I just kept adjusting it until the truck seemed to run good again. I've been running it for the past 2 days and knock on wood it hasn't returned after a full year of dealing with it! :yahoo:

TheTopher · Jul 13, 2010

88_ranger said:
Mine was doing exactly the same thing...very intermittent! I replaced the idle air control valve, map sensor, egr valve control sensor, checked for vacuum leaks, and still could not figure it out. Then I replaced the TPS (Throttle Position Sensor) and it got worse. That's when it dawned on me that it the TPS is adjustable. With a Multimeter I belive the signal is supposed to read about .5 volts and when the throttle plate if fully open it's supposed to read about 5 volts. Well since I couldn't figure out how to use my multimeter I just kept adjusting it until the truck seemed to run good again. I've been running it for the past 2 days and knock on wood it hasn't returned after a full year of dealing with it!

I'll keep my fingers crossed for ya, mate.

Desert Rat 23 · Jul 13, 2010

Glad I saw this thread. Mines been doing the same thing but only when the a/c is on. Tps is only $24, might as well toss in a new one. Did you change the gasket too?

disciplerocks · Jul 13, 2010

Vacuum leak unless you didn't clear the ecu after replacing the IAC.

Desert Rat 23 said:
Glad I saw this thread. Mines been doing the same thing but only when the a/c is on. Tps is only $24, might as well toss in a new one. Did you change the gasket too?

Yours is likely the IAC. Replace, clear ecu, then run it for at least a few days without the ac or defrost.

Desert Rat 23 · Jul 14, 2010

Sweet, that'll be fun. It's 110-112 here on a daily basis. I'll just have my wife drive it for a while.

no no. I'm just serious. Of course I would do that.

579 · Jul 19, 2010

My 94 idles real rough when I stop . 4cy auto. It does it consistently, hot or cold. The steering wheel vibrates real bad . it's not that bad in park.

88_ranger · Jul 19, 2010

Rough Idle

579 said:
My 94 idles real rough when I stop . 4cy auto. It does it consistently, hot or cold. The steering wheel vibrates real bad . it's not that bad in park.

Have you checked your timing lately? Just an idea... :icon_confused:

Idle's high when I come to a stop

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