Very high idle after changing the plugs

Tiny
JIMHAAS3
  • MEMBER
  • 2003 DODGE RAM
  • 4.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 177,000 MILES
I have a very high (1,100+ rpm) idle that began the moment that I changed all the spark plugs and turned on the ignition to check my work. Checked all hoses, they seem okay. Even changed the IAC valve; no change. A friend of mine has suggested that maybe a plug was simply poorly installed. Could this be a factor? (I've noticed that as the engine temp rises when running for a while, the idle goes past 1500 rpm - makes it VERY difficult to control the car and I am concerned about damaging the tranny)
Saturday, February 21st, 2015 AT 8:17 AM

8 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Hello,

This can happen if you have the wrong spark plugs installed here are the correct plugs and gap.

Spark Plug Type .................... RC12MCC4 (Champion)

1.01 mm (0.040 in)

Here is a video to show you how to set the gap

https://youtu.be/c9_NVXiwvYg

Please let us know what happens.
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Saturday, February 21st, 2015 AT 10:13 AM
Tiny
BOOPERIII
  • MEMBER
  • 1 POST
Thanks for this post I had the same problem had to get the correct plugs all fixed! I love this site.
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Wednesday, July 17th, 2019 AT 1:31 PM
Tiny
COWGIRLEMT07
  • MEMBER
  • 2 POSTS
  • 2003 DODGE RAM
  • 226,000 MILES
I replaced the coil packs and now having trouble with the truck not going above 3000 rpms it acts like a restricter is in place and it isnt gaining any power I went through the spark plugs are at proper gap checked all the wires and all are connected good a check engine light code of coil h primary and secondery circuit malfunction is appearing it does have a custom exhaust due to an accident 4 years ago.
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Wednesday, July 17th, 2019 AT 1:32 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Scan for codes and check fuel pressure first
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Wednesday, July 17th, 2019 AT 1:32 PM (Merged)
Tiny
COWGIRLEMT07
  • MEMBER
  • 2 POSTS
I had scanned for codes and the code was the coil h primary secondary circuit malfunction and I actually fixed the problem myself the coil connecting wires clips were broken so it prevented the from gettin a good connection but I fixed that and its now running great already an improvemnt in gas mileage
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Wednesday, July 17th, 2019 AT 1:32 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Great at least ti told you what was wrong by scanning instead fo just thowing parts at it. Glad it 's fixed.
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Wednesday, July 17th, 2019 AT 1:32 PM (Merged)
Tiny
SONOR30
  • MEMBER
  • 1 POST
  • 2003 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 50,000 MILES
My ABS and "brake" light is on, on my dash. Engine revs up and down and dash needles move up and down with it. Any help?
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Wednesday, July 17th, 2019 AT 1:32 PM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
4 wheel ABS or not
remove and replace rear ABS sensor

check wiring harness
remove ABS module electrical plug
inspect terminals and wires
clean and use electric grease on the terminals
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Wednesday, July 17th, 2019 AT 1:32 PM (Merged)

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