90 xj running rough please help
#16
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,563
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I'd check the fuel pump pressure on the rail too. Just before my pump went, it would idle fine but the pressure would drop / become erratic when I gave it some constant throttle. Look at Cruiser's book of wisdom of course. Can't do anything until you go through the tried and true advice found there.
Good luck and be systematic (try one thing at a time).
Also, punctuation helps us old guys read your posts.
wehatehavingtoreadallyourpostslikethiswithoutanyco mmasperiodshyphenscapitalsetc.
Good luck and be systematic (try one thing at a time).
Also, punctuation helps us old guys read your posts.
wehatehavingtoreadallyourpostslikethiswithoutanyco mmasperiodshyphenscapitalsetc.
Read that disregarding punctuation and see how the meaning changes.....
#20
CF Veteran
Joined: Dec 2009
Posts: 1,882
Likes: 0
From: Oxford NC
Year: 1998
Model: Cherokee
Engine: 4.0L
you can almost certainly rule out iac if its idling fine. iac does exactly what its called idle air control. you said something about one plug looking like it got hit? was it a new plug? did u regap it and stick it in? did you recheck? also post a picture if it was an old plug.
#21
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,563
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
#22
Member
Joined: Oct 2012
Posts: 243
Likes: 0
From: Tallahassee Florida
Year: 89
Model: Cherokee
Engine: 4.0
#23
The plug was smashed no gap at all. It's like the piston slapped it I threw it away when changing plugs so no pic I've done the whole ground refreshing and electrical connections under the hood look fine and I cleaned them with contact cleaner no luck yet though
#24
Seasoned Member
Joined: Jul 2009
Posts: 275
Likes: 0
From: Lakewood, CO
Year: 1993
Model: Cherokee
Engine: 4.0 HO
It took 3 years to figure out my '90 gremlin .. sounds just like yours
was (-) battery cable to block .. oil soaked wet noodle .. never realized it because it was in that protective duct .. oil leak from filter adapter dripped directly into that duct
replaced cable .. all good
I replaced all kinds of stuff before that too .. $$$$$$ .. cable was free from scraps at work
its a renix? if so, did you replace the funky octopus lookin vacuum harness yet? mine had leaks galore .. dirty dirty inside .. new part wasn't too cool either .. hoses kept coming apart .. glued / taped / zip tied them tight
was (-) battery cable to block .. oil soaked wet noodle .. never realized it because it was in that protective duct .. oil leak from filter adapter dripped directly into that duct
replaced cable .. all good
I replaced all kinds of stuff before that too .. $$$$$$ .. cable was free from scraps at work
its a renix? if so, did you replace the funky octopus lookin vacuum harness yet? mine had leaks galore .. dirty dirty inside .. new part wasn't too cool either .. hoses kept coming apart .. glued / taped / zip tied them tight
Last edited by dogkatcher; 04-06-2013 at 10:46 PM.
#25
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
In ether in my, or Cruisers signature you will find info on adjusting that new TPS. You might start by getting that handled...You will need a digital meter. Even the cheap $4 Harbor Freight ones work, at least for a while.
It only takes a couple minutes to check the CPS, rule that out....that darn trickster thing can do about anything! (like a condensers use to)
It only takes a couple minutes to check the CPS, rule that out....that darn trickster thing can do about anything! (like a condensers use to)
I'd go ahead and adjust that TPS, gotta do it anyway. Unplugging the IAC just leaves it where it was..As said, likely not your problem.
As RT points out in post 2, did you gap your plugs to .035? New doesn't mean right. I'm cheap, I don't often buy rotors and caps. Scrubbed in the kitchen sink, and good and dry seems to work. Granted, it's hard to see a black carbon track on a black dizy cap though!
Spark might try to find another way, or just not make it across the gap at all under high compression. If it's is crisp and blue, it is most likely finding another way, or jumping the gap, (as intended)
So, plug gap, (& cap/rotor), adjust TPS, and the fuel pressure....does it always go like heck if you floorboard it?
Just my .o2!
Last edited by DFlintstone; 04-06-2013 at 10:55 PM.
#26
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 19
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
#27
I replaced the vacuum harness with all new lines, but without the egr valve hooked up. When I hooked the egr up right it just kept stalling out, the plugs are gaped right. No oil all my grounds are clean and nice and tight.
#29
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Joined: Aug 2011
Posts: 43,971
Likes: 1,563
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Clarify please. Clean and tight or did you remove, scrape, sand, polish til shiny?