rough idle after driving

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kygpn

NAXJA Forum User

Location

louisville ky

• Oct 19, 2007

• #1

On my 89 4.0 i have been plagued with an rough idle after driving. however it is not consistant. I have tuned it up recently as well as replaced the throttle position sensor and checked for vacumn leaks. these have not seemed to effect this issue. I have hooked it up to a scanner but still have not located this problem. can anyone give me direction to solve this problem?

 

C

comanchekid

NAXJA Forum User

Location

puyallup

• Oct 19, 2007

• #2

What did you put in it for spark plugs? Is the throttle body clean? Is your o2 sensor working properly? How are the rest of your tune parts?

 

K

kygpn

NAXJA Forum User

Location

louisville ky

• Oct 19, 2007

• #3

I just recently replaced plugs, wires, cap+ rotor. then due to a worn ditributor, replaced it and module. the o2 sensor and knock sensor has been replaced ealier. It does start easier and idle better in the morning after these items, but the rough idle after driving problem has been unaffected.
another item to note, is that it has not had a catylitic converter for some time

 

Stihl029

NAXJA Forum User

Location

San Diego, CA

• Oct 19, 2007

• #4

The 4.0 likes the Cat not to mention that its federally mandated.

 

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comanchekid

NAXJA Forum User

Location

puyallup

• Oct 20, 2007

• #5

4.0 doesn't need a cat they don't care about it..... What did you use for spark plugs Renix's don't like bosch platinums. good old champions work better in them....

 

K

kygpn

NAXJA Forum User

Location

louisville ky

• Oct 21, 2007

• #6

they were champions(dont recall which #), not bosch. but the problem was there and after the change.
the engine runs very well at highway speeds and gets reasonable mileage, considering it has 33s and 4.10s. we drove it on a trip recently(250 miles ea. way)it averaged 17.5mpg. but pulling if for a rest stop it would spit and sputter and idle rough. after it cooled for a minute it was better. but still idles rough. back on the highway with cruise set @ 70mph it ran fine. the next stop no spit and sputter. this is anoying and frustrating. Someone help:dunno:

 

M

megabyte5689

NAXJA Forum User

Location

Kansas

• Nov 12, 2007

• #7

4.0's are fine with Bosch, probably some other sensor

 

87manche

NAXJA Forum User

Location

Ohio

• Nov 12, 2007

• #8

check the EGR system.
after you'r eon the highway it may not be closing properly, and that would lead to a serious hesitation/idle problem.

You might also seriously consider replacing all the grounds, after 20 years they're not in good shape. A lot of the roughness/random issues went away on my 87 after all of the battery cables were cleaned or replaced.