Looking for some help before I give up on my 88'
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
87 to 90 are Renix. OBD starts in 91. Besides the vacuum test, you can loosen the header pipe bolts. I did that once and it was night and day. Once the exhaust could leak out it ran supper. I tightened them back up, installed a new cat and all was fine.
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Do a vacuum test when warmed up.
CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.
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The guy at the shop was telling me they were trying to hook up the "scanner" so it could read the wires for something but since I bypassed the c101 they didn't want to take the time to do it.
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Joined: May 2012
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From: Fort Erie, CANADA
Year: 1987
Model: Cherokee
Engine: 4.0
Sounds better than stabbing the cat, lol. I'm going to try the vacuum test.
The guy at the shop was telling me they were trying to hook up the "scanner" so it could read the wires for something but since I bypassed the c101 they didn't want to take the time to do it.
The guy at the shop was telling me they were trying to hook up the "scanner" so it could read the wires for something but since I bypassed the c101 they didn't want to take the time to do it.
How old are the mechanics? A lot of shops have people that have never seen a carb and think they can put a scan tool on anything. I can only bring in my '67 to a local garage that has a mechanic older than me if I need advice on the carb etc. The "kids" don't know the older stuff very well (if at all). If they're 30 years old, they were only 3 when your Renix Jeep came out and their first car might have been a 2000+ cavalier! Gets scary when you think of it.
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
It's not OBD-I, Or OBD-II, it's a Renix,
< (scanner)
Eliminating the bad connections in your harness does not have anything to do with hooking up a scanner.
As far as exhaust restriction, what I meant was I loosened the bolts at the header pipe (where the exhaust connects to the exhaust manifold), to see if letting it leak there helped. In one case it helped allot, night and day. I've heard of guys removing there 02 sensor so it can leak there. Of course you only run it a minute to see if that does it or not.
Eliminating the bad connections in your harness does not have anything to do with hooking up a scanner.
As far as exhaust restriction, what I meant was I loosened the bolts at the header pipe (where the exhaust connects to the exhaust manifold), to see if letting it leak there helped. In one case it helped allot, night and day. I've heard of guys removing there 02 sensor so it can leak there. Of course you only run it a minute to see if that does it or not.
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I've done 1,2,3,4,5,7,8,11, and 27. I'm going to do the vacuum test in the morning. Was a little hot out here in CenCal this afternoon
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Ok so I did the vacuum line test. Wasn't too confident understanding how it should come about, so I took a video.
Not sure if it's supposed to stay around the starting reading or go up when I gave it the juice. Then it cam down slow so I'm not too sure.
Not sure if it's supposed to stay around the starting reading or go up when I gave it the juice. Then it cam down slow so I'm not too sure.
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Seems like there's quite a hesitation off idle.....And vacuum drops to nothing. I'll bet the EGR valve is opening when it's not supposed to.
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