a kinda sorta question
#1
Thread Starter
CF Veteran
Joined: Dec 2011
Posts: 1,050
Likes: 2
From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
a kinda sorta question
Ok, so last week my 90 renix got a 98 motor, 99 intake and exhaust, it's all wired up and running like a dream. Two thing happened though. My idle air controller was bad from the get go, so I simply left it unplugged and manually adjusted it untill it idled at 800ish rpm. I used the same 'bad' iac on the new motor and intake, but it's idling around 1500. The other thing that happened is on the old motor removal, I neglected to remove the o2 sensor, so it got busted. So here's the questions
1- could not having the o2 sensor make the idle high? I know it helps meter fuel delivery, but does it do it to where high idle will happen?
2- when first started up, the jeep idled at 1k, then rises the idle as it warms. I'm assuming this is due to no o2 sensor so its running on presets once it gets to operating temperature?
I'm going to get a new iac and o2 come Friday, just curious if these two things have a correlation
1- could not having the o2 sensor make the idle high? I know it helps meter fuel delivery, but does it do it to where high idle will happen?
2- when first started up, the jeep idled at 1k, then rises the idle as it warms. I'm assuming this is due to no o2 sensor so its running on presets once it gets to operating temperature?
I'm going to get a new iac and o2 come Friday, just curious if these two things have a correlation
#3
Thread Starter
CF Veteran
Joined: Dec 2011
Posts: 1,050
Likes: 2
From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
Anyways, I don't see or hear any vaccuum leaks, only vacuum ports are for the brake booster, and fuel rail. All other ports are capped
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#8
Herp Derp Jerp
Joined: Nov 2011
Posts: 18,251
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From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Well you need a new IAC and O2 sensor but it's time to get out the spray bottle or carb cleaner and find that leak. Check around the TB, head mating area (you used a new gasket for the manifolds-to-head right?) and check for any missing vacuum hoses. I know the '99+ intake has an additional fitting that prior models to not use.
#10
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
#11
Thread Starter
CF Veteran
Joined: Dec 2011
Posts: 1,050
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From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
Grounds were actually 're done, ie factory end was cut off, the stud on the block was cleaned while it was out etc. I'm getting like .03 ohms between the intake and negative terminal if that's what your huntin cruise man
#12
::CF Moderator::
Joined: Aug 2011
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Used the 98 intake gasket, since its a 99 intake/exhaust.
Grounds were actually 're done, ie factory end was cut off, the stud on the block was cleaned while it was out etc. I'm getting like .03 ohms between the intake and negative terminal if that's what your huntin cruise man
Grounds were actually 're done, ie factory end was cut off, the stud on the block was cleaned while it was out etc. I'm getting like .03 ohms between the intake and negative terminal if that's what your huntin cruise man
Have you sprayed for vacuum leaks?
#13
Thread Starter
CF Veteran
Joined: Dec 2011
Posts: 1,050
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From: Roanoke, VA
Year: 1990
Model: Cherokee
Engine: 4.0
#14
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,563
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
#15
Herp Derp Jerp
Joined: Nov 2011
Posts: 18,251
Likes: 13
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II