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Unread 12-15-2011, 12:12 PM   #31
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
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Hey Shaef, how goes it? The CTS needs to be replaced. It effects advance and injector pulse so you do need to get it strait. You still need to adjust the tps too. If you are falling flat on accelleration the tps would make the most sense. I would do the fuel pressure test before I replace the pump. You can get the guage from any good parts store with a refundable deposit. You should see 14 psi.

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Unread 12-16-2011, 07:50 AM   #32
schaef89
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1989 YJ Wrangler 
 
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I adjusted the TPS last night. It was actually set at 4.02v at WOT instead of the 4.6-4.7v recommendation. I got it to 4.64v when it was all said and done. It's kind of a pain the in the *** to adjust since the wiring harness, fuel lines, and vacuum piping are all right in the way.

I also replaced the CTS with the original. I took a reading and it was around 550 ohms before the thermostat cycled coolant. I'll have to look into a Mopar replacement from the dealership

I also think I need to re-adjust the ISA motor as well to account for the proper TPS setting.
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Unread 12-16-2011, 08:03 AM   #33
Que89YJ
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Keep us posted. I am following this one close because my 89 needs some tlc and i am going to have to do this when I am done with the body stuff.
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Unread 12-16-2011, 09:09 PM   #34
schaef89
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Just an update.. I readjusted the ISA motor today after work and it seemed to make the situation worse.. It cuts out maybe 60% less and has more power during acceleration, but the idle is god awful. It seems to get better as it gets to operating temp but it's not by much. This makes me think the CTS is to blame here since it has been tested bad. I'm also going to have to go through all the vacuum hoses per the FSM and double check placement.. at this point I want to replace all of the hoses to rule that out completely. The search continues..
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Unread 12-16-2011, 09:44 PM   #35
oldtime_ironman
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There's no question in my mind anymore about the CTS. I would simply get a fresh one in there - yesterday. The hoses and vac leaks is always a good idea
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Unread 12-19-2011, 08:18 AM   #36
Que89YJ
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Any update?
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Unread 12-23-2011, 02:32 PM   #37
schaef89
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I had to put this on hold for a little since I decided to fix my DD's head gasket.. long story.

But today I went through and took readings on all the sensors. Here's what I found

MAP - confirmed 5v feed, 2.35-2.49v at temp (idle) - acceptable was 1.5-2.1v
TPS - confirmed 5v feed, 4.64v output at WOT (adjusted last week)
CTS - 288 ohms at temp before coolant circulated (acceptable is 185 ohms at 210degF)
MAT - 150 ohms before coolant circulated (acceptable is 185 ohms at 210degF)
WOT - infinite resistance closed, 23.2 Mohms open (good per FSM text)
o2 Sensor Heater element test - 7.3 ohms (5-7 acceptable)

Looks like I got a bad MAP and o2 sensor from the store. I'll replace them and report back
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Unread 12-31-2011, 03:16 PM   #38
Que89YJ
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Schaef, how goes the Jeep?
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Unread 01-01-2012, 08:28 PM   #39
schaef89
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It goes slow.. i replaced the o2 earlier today which seemed to help smooth it out a little. I also retested the MAP sensor and it ended up being fine, I guess my reading was off during the first measurement.

I want to test the fuel pressure next but forgot to grab my gauge when I was home for the holidays. I should be getting that in a couple weeks and I'll go from there.

If the fuel pressure is good I'll be doing a compression test after that, and start looking into the possibility of it being a mechanical problem.
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Unread 01-03-2012, 09:29 AM   #40
Que89YJ
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I have given it some thought Schaef. It sounds like the stuff you did has had an effect which is good, but it still hasn't solved the root problem. How many miles you have on it? I have an idea. Your sensor readings seem fine and I doubt that the fuel pressure is giving you the problem because if it was the acceleration would show the issue worse than any other of the conditions. Compression is always a good thing but the more obvious to me is the distributor and the timing chain. Especially the timing chain. Loading the engine down like accelerating tightens the chain while unloaded like idle will allow play. Check the movement of the rotor while you move the nut on the crank pullley and see how far you move the crank moves in both directions before the rotor spins on the distributor. That will tell you the amount of play in the timing chain. Do you hear any chain slap at idle? Also, check the distributor out for play and wear on the gear and the bearing.
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Unread 01-03-2012, 11:04 AM   #41
schaef89
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Quote:
Originally Posted by Que89YJ View Post
I have given it some thought Schaef. It sounds like the stuff you did has had an effect which is good, but it still hasn't solved the root problem. How many miles you have on it? I have an idea. Your sensor readings seem fine and I doubt that the fuel pressure is giving you the problem because if it was the acceleration would show the issue worse than any other of the conditions. Compression is always a good thing but the more obvious to me is the distributor and the timing chain. Especially the timing chain. Loading the engine down like accelerating tightens the chain while unloaded like idle will allow play. Check the movement of the rotor while you move the nut on the crank pullley and see how far you move the crank moves in both directions before the rotor spins on the distributor. That will tell you the amount of play in the timing chain. Do you hear any chain slap at idle? Also, check the distributor out for play and wear on the gear and the bearing.
That's a good theory.. however i replaced the timing chain and sprockets back in August, as well as the Distributor cap and rotor in July.

All that being said, I did not replace the tensioner since I've just done the timing chain a year before and didn't see the need to replace it again. (All this is explained in my build thread, but the timing chain was a pin off which is why i ripped into it again this summer)

There is a possibility the worm gear on the distributor shaft or camshaft is worn though. I think that's more likely than the timing chain being worn already

edit: youre coming up with some good ideas though
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Unread 01-03-2012, 09:22 PM   #42
schaef89
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I started it today (as i periodically do during the winter) and noticed some carbon in the snow below the tailpipe.. looks like it's running rich
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Unread 01-04-2012, 09:28 AM   #43
Que89YJ
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I have a couple links for you.
http://www.jeepforum.com/forum/f12/h...switch-368246/

and:

http://jeep.zerok.ru/index.php?page=19
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Unread 01-04-2012, 09:51 AM   #44
89WhyJ
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Quote:
Originally Posted by Que89YJ View Post
After reading that last post about running rich, this is exactlyu what I was thinking as well. I know my engine is running very rich, and I found (during my intake manifold gasket replacement) that my WOT switch will not physically spring back anymore. So, the ecu has been assuming a WOT condition since I've had it. Any ideas on a replacement? You can't find these things anymore.
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Unread 01-04-2012, 09:58 AM   #45
schaef89
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My WOT switch seems to be in working order and tested OK per the FSM test procedure, and all my vacuum lines seem to be good. Grounds were cleaned up as well

The only things I haven't tested yet are:

Fuel Pressure
Compression
Purge Solenoid
Crank Position Sensor (replaced this past summer, reason why I didn't test)
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