Failed Smog, Analyze my results please!
11-01-2012, 01:58 PM
#16
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Year: 1994
Model: Cherokee
Engine: 4.0 HO motor
i heard it passes easier with stock tires if you dont have them on then see if you can get ahold of a couple, a freind of mine was asking for just 2 back ones to take to the smog shop
11-01-2012, 02:25 PM
#17
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Year: Several
Model: Cherokee
Engine: 4.0
Combustion temp is a little hot at idle, causing an increase in NOx.
Do a smoke test in the intake - even 1 cylinder running a bit lean will drive up the NOx at idle. At above idle the vacuum leak has less effect.
Engine off - Disconnect a vacumm hose on the intake manifold - blow cirarette smoke down tne hose into the intake manifold. Fix where it comes out.
Make sure it's got a tankfull of fresh gas before testing.
And - add a 1/2 pint of DENATURED ALCOHOL just before you take it in. The alcohol will lower combustion temps slightly - and lower HC.
Denatured alcohol is available at paint stores - it's used as a cleaning solvent - $1. Same stuff as sold to pass smog for $12.
Do a smoke test in the intake - even 1 cylinder running a bit lean will drive up the NOx at idle. At above idle the vacuum leak has less effect.
Engine off - Disconnect a vacumm hose on the intake manifold - blow cirarette smoke down tne hose into the intake manifold. Fix where it comes out.
Make sure it's got a tankfull of fresh gas before testing.
And - add a 1/2 pint of DENATURED ALCOHOL just before you take it in. The alcohol will lower combustion temps slightly - and lower HC.
Denatured alcohol is available at paint stores - it's used as a cleaning solvent - $1. Same stuff as sold to pass smog for $12.
11-01-2012, 07:16 PM
#18
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Year: 1996
Model: Cherokee
Engine: 4litre
It will up my rpm's at the same speed, theoretically make me pass!
11-01-2012, 07:22 PM
#19
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Year: 1989
Model: Cherokee
Engine: 4.0L Renix Freshly Rebuilt!!
Originally Posted by rrich
Combustion temp is a little hot at idle, causing an increase in NOx.
Do a smoke test in the intake - even 1 cylinder running a bit lean will drive up the NOx at idle. At above idle the vacuum leak has less effect.
Engine off - Disconnect a vacumm hose on the intake manifold - blow cirarette smoke down tne hose into the intake manifold. Fix where it comes out.
Make sure it's got a tankfull of fresh gas before testing.
And - add a 1/2 pint of DENATURED ALCOHOL just before you take it in. The alcohol will lower combustion temps slightly - and lower HC.
Denatured alcohol is available at paint stores - it's used as a cleaning solvent - $1. Same stuff as sold to pass smog for $12.
Do a smoke test in the intake - even 1 cylinder running a bit lean will drive up the NOx at idle. At above idle the vacuum leak has less effect.
Engine off - Disconnect a vacumm hose on the intake manifold - blow cirarette smoke down tne hose into the intake manifold. Fix where it comes out.
Make sure it's got a tankfull of fresh gas before testing.
And - add a 1/2 pint of DENATURED ALCOHOL just before you take it in. The alcohol will lower combustion temps slightly - and lower HC.
Denatured alcohol is available at paint stores - it's used as a cleaning solvent - $1. Same stuff as sold to pass smog for $12.
11-14-2012, 04:41 PM
#20
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Year: 1996
Model: Cherokee
Engine: 4litre
well I got it to pass!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
It wasnt the o2 sensors, or the cat, or the MAF!!!
I went through all the usually **** people tell you to try and nothing worked.
What actually worked was a 180* thermostat and running colder Champion RC9YC spark plugs!
This works assuming you have good sensors and no vacuum leaks!
Hope this helps somebody in the future!
It wasnt the o2 sensors, or the cat, or the MAF!!!
I went through all the usually **** people tell you to try and nothing worked.
What actually worked was a 180* thermostat and running colder Champion RC9YC spark plugs!
This works assuming you have good sensors and no vacuum leaks!
Hope this helps somebody in the future!
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