Hot start idling problem
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Post Fiend
Joined: Jul 2005
Posts: 8,462
Likes: 4
From: Durant, OK (SOSU)
Hot start idling problem
Occasionally, when I restart my truck after a short period of sitting (it will not do it if the truck is turned off, then virtually immediately turned on), the truck starts fine, but as the idle drops to normal, it goes down to around 600 RPM and runs rough.
At first, I figured fuel pump or fuel relay, but it runs strongly when key is turned to run, and hitting the gas causes the truck to rev up normally, but still run rough.
It will do it for a short amount of time (perhaps 20 seconds at max), then suddenly it's back to a normal smooth idle. The roughness is enough to feel in the general hind quarters.
No CEL, any suggestions?
Thank you.
At first, I figured fuel pump or fuel relay, but it runs strongly when key is turned to run, and hitting the gas causes the truck to rev up normally, but still run rough.
It will do it for a short amount of time (perhaps 20 seconds at max), then suddenly it's back to a normal smooth idle. The roughness is enough to feel in the general hind quarters.
No CEL, any suggestions?
Thank you.
New User
Joined: Mar 2007
Posts: 9
Likes: 0
yes it would, see if an injector was bleeding down ever so slightly over night, that cylinder would have more fuel in it on start up than the others. once it burns off that extra fuel it would clear up and run good. I have the same problem on my truck. The best way to tell on those trucks os to let it set over night and one morning when you have nothing to do, start it let it miss for a second, don't let it clear out that would defeat the purpose, then shut it off while it's still missing. Then pull all your spark plugs keeping track of which ones go where. The cylinder with the bad injector will look different than the others.
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Post Fiend
Joined: Jul 2005
Posts: 8,462
Likes: 4
From: Durant, OK (SOSU)
But it's not an overnight problem. It happens only on hot starts where the truck has been setting less than probably 20 minutes. And it doesn't always happen.
The vacuum also is around 15-16 in Hg and varying when it happens, as soon as it clears up the vacuum is back steady at 19 in Hg. The idle can dip quite low and oscillate as well some.
The vacuum also is around 15-16 in Hg and varying when it happens, as soon as it clears up the vacuum is back steady at 19 in Hg. The idle can dip quite low and oscillate as well some.
Senior User
Joined: Feb 2006
Posts: 311
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From: Ellington, Connecticut
H-s-i-p
Hi RangerPilot,
I feel also that danger_ranger26 is in the correct ballpark.
When is the last time injector cleaner was added to your fuel?
As for the low Hg it follows suit from the engine not running efficently.
Or It also may be a matter of a tune-up?
Whatever may be creating this "brief intermittancy" is why I ask the above questions.
I feel also that danger_ranger26 is in the correct ballpark.
When is the last time injector cleaner was added to your fuel?
As for the low Hg it follows suit from the engine not running efficently.
Or It also may be a matter of a tune-up?
Whatever may be creating this "brief intermittancy" is why I ask the above questions.
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Post Fiend
Joined: Jul 2005
Posts: 8,462
Likes: 4
From: Durant, OK (SOSU)
Tune up (new plugs, wires, fuel filter, all fluids) has about 10K on it.
Oil has less than 1K on it.
Injector cleaner at oil change (STP brand).
The widely fluctuating idle also comes from this I assume? It hasn't ever died on me when doing this.
About to leave, just went outside and started it cold, and once again, no problems.
Oil has less than 1K on it.
Injector cleaner at oil change (STP brand).
The widely fluctuating idle also comes from this I assume? It hasn't ever died on me when doing this.
About to leave, just went outside and started it cold, and once again, no problems.
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Posting Guru
Joined: Jun 2006
Posts: 1,019
Likes: 0
From: Slatington PA
If that doesn't fix it, try getting some 93 octain and running it through. make sure you have an almost empty tank. dont put alot in, if this solves your problem, than you had the same problem i use to have. solution, run higher octain fuel in it.
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