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Old 11-25-2009, 01:24 PM
harleyboy07 harleyboy07 is offline
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Default 4 cyl. shaky idle

have 99 4 cyl. FI. when trk. start,all is ok. When it starts to idle down. It almost cuts off, idles up,slows daown and shakes, for about 2-3 mins. then levels out. seems to run ok. But idles down very low and almost cuts off. This up and down has no rhyme or reason. Other than at statrup. Have replaced idler air control on back of throttle body. And fuel pressure regulator valve in tank. Any ideas before I start replacing parts. 196,780 mi.
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Old 11-25-2009, 06:35 PM
zbinck2.3 zbinck2.3 is offline
Ford Ranger Owner
Join Date: Aug 2009
Posts: 58

i doubt its anything with the fuel. Which means air or ignition, i would just replace the plugs plug wires. Is there a check engine light ? for almost 200000 miles the possibilities are kinda endless.
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Old 11-26-2009, 02:24 PM
scooby stew scooby stew is offline
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Join Date: Apr 2009
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welcome from the uk
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Old 11-26-2009, 02:37 PM
DangerRanger01 DangerRanger01 is offline
Join Date: Oct 2009
Posts: 313

My 2.5l does the same thing. At idle it'll dip up and down to were its almost dieing. I guess its normal, lol. I'm at 51,000miles so...idk. Someone told me it was because i use synthetic oil, but i have no idea the truth behind that.
2001 Ranger.
2.5l of passionate fury.
Big brake upgrade.
Cobra wheels
Hurst Equipped.
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Old 11-26-2009, 04:00 PM
Fx4wannabe01 Fx4wannabe01 is offline
Ford Ranger Driver
Join Date: Sep 2009
Posts: 4,058

Disconnect the a/c compressor electrical plug. Could be totally possible that the load it puts on your engine when it cycles, causes enough of an rpm drop to cause it to almost die. If disconnecting it helps out a ton, I suggest putting in an in-line switch to interrupt the battery power to the compressor.

As said above, any check engine lights? How's the maintainence on the truck? At 200k, problems could be practically endless.
'01 XLT disguised as a '03 Fx4 Level II.
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Old 11-26-2009, 11:35 PM
FoMoCo FoMoCo is offline ban camp founder
Join Date: Apr 2009
Posts: 1,816

my 2001 2.5L did the same thing, now my 06 2.3L doesn't do it
2012 mustang premium v6 pony package
702 crew
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Old 11-30-2009, 07:38 PM
twinjetguy twinjetguy is offline
I hate Nascar
Join Date: Nov 2009
Posts: 51

I recently replaced my coil packs with Accell coil packs and cleaned the mass air flow sensor. I was amazed with how much smoother the truck ran. Might want to check those out as well. Summit Racing sells the coil packs for around $69 each pack. Don't need to get both, just get one for the intake side. Just make sure to use electrical parts cleaner on the mass air flow sensor also.
1998 Mazda B2500 Extra Cab 5sp manual
(1998 Ford Ranger 2.5 liter)

Cat back with Flowmaster
Headers (no name)
K&N intake
Power Aid TB spacer
JET Performance chip
Accel coils
Bilstein Shocks
Electric Fan coming soon!
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Old 03-21-2010, 11:43 PM
bnuts5150 bnuts5150 is offline
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Default Re: 4 cyl. shaky idle

My father in law uses carb cleaner on the intake is there anything wrong with that???
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Old 03-24-2010, 02:47 PM
Scott Scott is offline
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Join Date: Jan 2010
Posts: 24
Default Re: 4 cyl. shaky idle

I'm guessing here, but it sounds like you have a leaky gasket somewhere in the intake. The way you describe it sounds to me like a cold gasket leaking air until the block warms up, which warms the gasket up, expanding the gasket and therefore eliminating the leak/surging. I replaced the cylinder head in my 2.3 awhile back and had this problem. I over-torqued the lower intake manifold gasket and cracked it. Mine was pretty bad though, it would surge constantly. I finally took the intake off and it was pretty obvious that I had created a HUGE vacuum leak. New gasket - CAREFULLY torqued (23-25 ft/lbs i think) - and it runs like new now. I'd use some high temp silicone on the new gaskets too. Good luck.
1997 Ford Ranger XLT short bed regular cab
2.3L Lima
5 speed manual
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