weird idleing problem
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Fleet Mechanic
Joined: Sep 2003
Posts: 1,980
Likes: 2
From: central ohio
weird idleing problem
my '93 ranger has developed a strange idle problem i just havent been able to get a fix on. its a 4.0 std trans and it will start fine, has plenty of power but just doesnt idle down right. when i dump the clutch to come to a stop it will rev and hold at about 2,500. but as i get to 10 mph it drops to 1,500. if i shut it off and restart it will be at about 1,000, dip down to 600 and go back up to 1,100. my scan tool said it was running lean on both banks and couldnt do a cyl balance test due to a uneven idle. i have replaced both oxygen sensors, the idle-air control valve, the coolant temp sender and the throttle postion sensor. i guess all thats left is the mass air sensor, but i doubt that would do anything. every time i changed something i had the battery unhooked, it would start fine and idle at 1,000 i dont have a check-engine light on, the truck has 103,000 miles on it. has no engine mods. any ideas? i seem to be at a impass.
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Fleet Mechanic
Joined: Sep 2003
Posts: 1,980
Likes: 2
From: central ohio
im wondering......if i used a propane torch (no flame, just gas on) could it help find a leak? heck, whats a torch kit compared to all the other stuff ive put on that aint worked. what puzzles me the most is the rpm drop from 2,000+ to 1,500 as soon as the speedo drops below 10 mph. that just doesnt make sence.
Elder User
Joined: Feb 2007
Posts: 771
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From: Aurora
Originally Posted by racsan
im wondering......if i used a propane torch (no flame, just gas on) could it help find a leak? heck, whats a torch kit compared to all the other stuff ive put on that aint worked. what puzzles me the most is the rpm drop from 2,000+ to 1,500 as soon as the speedo drops below 10 mph. that just doesnt make sence.
More Turbo
Joined: Dec 2006
Posts: 624
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From: FL
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Fleet Mechanic
Joined: Sep 2003
Posts: 1,980
Likes: 2
From: central ohio
new pcv valve and hose, stilll the same has codes 172,136, & 538 in memory. only three things left, mass air sensor, map sensor or the computer processor itself. havent found any vaccum leaks, checked the vapor canistor as well. may have to visit a stealership.
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Thread Starter
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Fleet Mechanic
Joined: Sep 2003
Posts: 1,980
Likes: 2
From: central ohio
finnally got it figured out, turned out to be a failed gasket. the fuel rail which is sandwiched between the upper and lower intake had the gasket between it and the lower intake pulling into the intake ports at the front and rear. idles fine now, i ran a compression check before i started to see if i had a problem there, its looking good for 104k with 185 on 4 cyl and 175 on the other 2. glad i didnt need to pull the heads. i pulled the lower intake just because i was that close and had the gasket, no issues there, looked good and clean. had the camera but ran out of battery before i got it compltely tore down. had the hood off, that made things easier but who knew a ranger hood could weigh so much.
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