Sounds like cylinders are loading up afte iat cleaning
04-24-2013, 06:18 PM
#1
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Year: 1989
Model: Cherokee
Engine: 4.0
Sounds like cylinders are loading up afte iat cleaning
Cleaned my iat and at idle it sounds like my injectors are pre-loading the cylinders with fuel for the first 30-45seconds after starting the jeep then the idle goes back up to normal. When it first starts revs are lower then they use to be so no sky rocketing idle at start up now but after that it stumbles. What would cause this and what am I missing?
04-24-2013, 06:50 PM
#2
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Year: 1999
Model: Cherokee
Engine: 4.0
Cleaned my iat and at idle it sounds like my injectors are pre-loading the cylinders with fuel for the first 30-45seconds after starting the jeep then the idle goes back up to normal. When it first starts revs are lower then they use to be so no sky rocketing idle at start up now but after that it stumbles. What would cause this and what am I missing?
Edit: Oops, I now see you have a 1989. This is best left to the RENIX experts.
04-24-2013, 07:05 PM
#3
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
04-24-2013, 09:13 PM
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Vacuum leak in the throttle body to MAP piping?
04-24-2013, 09:25 PM
#6
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Year: 1989
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I have rubber hose on a few pipings not sure what they go to tho lol. I did remove the vacuum hose on the fpr and didnt notice a difference in idle even reved up fine now that I think about it may have idled smoother with the vacuum line off of the fpr.
04-25-2013, 06:13 AM
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Year: 1990
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Low vacuum will tell the MAP that the engine needs more fuel.
Did you get the vac line for the MAP back in the correct hole on the throttle body?
Did you get the vac line for the MAP back in the correct hole on the throttle body?
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04-25-2013, 06:16 PM
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Year: 1990
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Check the connection at the MAP sensor and make sure a connector hasn't retracted or something. Wiggle wires/harnesses/plugs at idle and see if anything changes.
04-25-2013, 09:42 PM
#12
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
TESTING THE EGR VALVE FOR 87-90 4.0 ENGINE
Valve Opening Test
1) With engine at normal operating temperature and at idle,
rapidly open and close throttle. Open throttle sufficiently to obtain
at least 1500 RPM. Movement should be noticed in EGR diaphragm.
2) If diaphragm does not move, probable causes are: faulty
vacuum signal to EGR, defective EGR diaphragm or defective
backpressure sensor diaphragm (if equipped), or leaks in vacuum lines
or connections.
Valve Closing Test
1) With engine at normal operating temperature and at idle,
manually depress EGR valve diaphragm. RPM should immediately drop,
indicating that EGR valve is not leaking and had been properly cutting
off exhaust gas flow at idle.
2) If there is no change in RPM and engine is idling
properly, exhaust gases are not reaching combustion chamber. Check for
plugged passage between EGR valve and intake manifold.
3) If engine idles poorly and RPM is not greatly affected by
manually moving diaphragm up, EGR valve is not closing off exhaust gas
flow. Check for carbon between pintle, leaking EGR valve gasket or bad
EGR valve.
***************
Valve Opening Test
1) With engine at normal operating temperature and at idle,
rapidly open and close throttle. Open throttle sufficiently to obtain
at least 1500 RPM. Movement should be noticed in EGR diaphragm.
2) If diaphragm does not move, probable causes are: faulty
vacuum signal to EGR, defective EGR diaphragm or defective
backpressure sensor diaphragm (if equipped), or leaks in vacuum lines
or connections.
Valve Closing Test
1) With engine at normal operating temperature and at idle,
manually depress EGR valve diaphragm. RPM should immediately drop,
indicating that EGR valve is not leaking and had been properly cutting
off exhaust gas flow at idle.
2) If there is no change in RPM and engine is idling
properly, exhaust gases are not reaching combustion chamber. Check for
plugged passage between EGR valve and intake manifold.
3) If engine idles poorly and RPM is not greatly affected by
manually moving diaphragm up, EGR valve is not closing off exhaust gas
flow. Check for carbon between pintle, leaking EGR valve gasket or bad
EGR valve.
***************
04-26-2013, 03:53 PM
#13
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Year: 1989
Model: Cherokee
Engine: 4.0
TESTING THE EGR VALVE FOR 87-90 4.0 ENGINE
Valve Opening Test
1) With engine at normal operating temperature and at idle,
rapidly open and close throttle. Open throttle sufficiently to obtain
at least 1500 RPM. Movement should be noticed in EGR diaphragm.
2) If diaphragm does not move, probable causes are: faulty
vacuum signal to EGR, defective EGR diaphragm or defective
backpressure sensor diaphragm (if equipped), or leaks in vacuum lines
or connections.
Valve Closing Test
1) With engine at normal operating temperature and at idle,
manually depress EGR valve diaphragm. RPM should immediately drop,
indicating that EGR valve is not leaking and had been properly cutting
off exhaust gas flow at idle.
2) If there is no change in RPM and engine is idling
properly, exhaust gases are not reaching combustion chamber. Check for
plugged passage between EGR valve and intake manifold.
3) If engine idles poorly and RPM is not greatly affected by
manually moving diaphragm up, EGR valve is not closing off exhaust gas
flow. Check for carbon between pintle, leaking EGR valve gasket or bad
EGR valve.
***************
Valve Opening Test
1) With engine at normal operating temperature and at idle,
rapidly open and close throttle. Open throttle sufficiently to obtain
at least 1500 RPM. Movement should be noticed in EGR diaphragm.
2) If diaphragm does not move, probable causes are: faulty
vacuum signal to EGR, defective EGR diaphragm or defective
backpressure sensor diaphragm (if equipped), or leaks in vacuum lines
or connections.
Valve Closing Test
1) With engine at normal operating temperature and at idle,
manually depress EGR valve diaphragm. RPM should immediately drop,
indicating that EGR valve is not leaking and had been properly cutting
off exhaust gas flow at idle.
2) If there is no change in RPM and engine is idling
properly, exhaust gases are not reaching combustion chamber. Check for
plugged passage between EGR valve and intake manifold.
3) If engine idles poorly and RPM is not greatly affected by
manually moving diaphragm up, EGR valve is not closing off exhaust gas
flow. Check for carbon between pintle, leaking EGR valve gasket or bad
EGR valve.
***************
04-26-2013, 04:14 PM
#15
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Attachment 189080
Attachment 189081
Heres the pics of what and where its broke. My idle is **** now very very rough just barely idling :/
Attachment 189081
Heres the pics of what and where its broke. My idle is **** now very very rough just barely idling :/
LOL.
Pop the rubber plug out of the TB. Get the remaining piece out of the plug. Glue, without covering the hole in the tube, the tube back in to the plug.
Installation is a reversal of removal.