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Unread 02-12-2013, 11:43 AM   #16
Que89YJ
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1989 YJ Wrangler 
 
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Acouple things. Be ready with your multimeter. You are going to have to re setup some of your sensors. IAC motor, tps, and wot switch. Take the time while you have everything ripped apart to clean the throttlebody.

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Unread 05-25-2013, 11:19 PM   #17
LJameson
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1990 YJ Wrangler 
 
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So I've had this thing running for a while now. The mechanical part of the engine is awesome. No noises, leaks or anything. It has a lot more power than before. I took it on a trip up north and even going up some steep grades it maintained 70-75.

However, I can't get the damn thing to idle right. It misfires at idle and is erratic, but when I'm driving the engine is perfectly smooth and runs just as it should. I replaced the O2 sensor (was rust welded in the old manifold), replaced the TPS (this was bad before I pulled the motor out), replaced Map sensor, checked fuel pressure (14 psi), checked for vacuum leaks with a smoke machine (none at all), replaced the EGR (which did help), replaced injector o-rings and checked the resistance in the injector, checked the resistance in the coolant temp sensor and intake air sensor (both good), and adjusted everything that can be adjusted so that it's all within factory specs. The only thing I haven't replaced are the spark plug wires (did put in new spark plugs), cap and rotor simply because they only had 5,000 miles on them before I started the rebuild. Distributor is timed right, so I'm just at a loss here. I'm starting to wonder if it's the ECU, but I'd hate to throw one of those at the Jeep when I'm not sure if thats whats wrong. :
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Unread 05-26-2013, 04:49 AM   #18
Que89YJ
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did you do the suspects for the idle motor, tps, and fuel pressure?
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Unread 05-26-2013, 06:22 AM   #19
snail81
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Quote:
Originally Posted by Que89YJ View Post
did you do the suspects for the idle motor, tps, and fuel pressure?
I would say tps also
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Unread 05-30-2013, 12:34 AM   #20
LJameson
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Quote:
Originally Posted by Que89YJ View Post
did you do the suspects for the idle motor, tps, and fuel pressure?
Yes, I checked and adjusted those. Fuel pressure is 14 psi, I replaced the tps and have it adjusted to 4.6V @ WOT, and the idle motor is good. I unplugged it with the jeep off and started it up, engine went up to 3500 rpm.

I also check the resistance on the fuel injector, 1.2 ohms (exactly what the service manual specifies). I'm probably going to pull it out this weekend and check the o-rings. Hopefully it's something that simple.
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Unread 05-30-2013, 12:34 PM   #21
Luuca
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Great thread but I kept looking at that engine and trying to figure out why mine looks so different. Then I realized.. 2000 TJ..

Welcome to the YJ forums.
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Unread 05-30-2013, 03:09 PM   #22
CrawlingForward
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Wait, are you implying that the OP's engine being rebuilt is from a TJ? We clearly saw it on the first post as a YJ...
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Unread 05-30-2013, 03:45 PM   #23
Luuca
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Originally Posted by CrawlingForward View Post
Wait, are you implying that the OP's engine being rebuilt odds from a TJ? We clearly saw it on the first post as a YJ...
Hmm, ya. You're right. I guess I just didn't recognize the 2.5l due to the valve cover and the beefy alternator hes got on there.

don't mind me.
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Unread 05-30-2013, 10:40 PM   #24
LJameson
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Quote:
Originally Posted by Luuca View Post
Hmm, ya. You're right. I guess I just didn't recognize the 2.5l due to the valve cover and the beefy alternator hes got on there.

don't mind me.
Heh, I got a chuckle out of your beefy alternator comment. It's the stock alternator, rated for something like 60 amps. You're just used to seeing the MPFI 2.5 and not the Renix TBI 2.5. Pretty much everything that bolts to the block is different, it's 100% AMC design as opposed to the 91+ YJs where Chrysler took the YJ and improved it.
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Unread 06-08-2013, 07:44 AM   #25
LJameson
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So I ordered new injector o rings and they should be here any day now.

In the meantime, I mounted a viair compressor under the hood. I've never had the factory jack for my jeep so I drilled out the spot welds on the bracket and drilled some more holes to mount the compressor. Gave it a quick and crappy paint job and bolted it up.

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"Anything to do with the land, I love."
"So it's probably eighty percent luck and twenty percent skill."

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I never could figure what the sky was thinking, but the soil, she don't keep too many secrets.
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Unread 06-08-2013, 01:41 PM   #26
metalhead
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I just bought a 94 wrangler. I got an oil filter from work (work at chrysler,jeep,dodge dealership) The parts guy didn't mention anything about the threads on the filter neck being different so do I need to swap the neck out for a standard thread neck?


Should have read further just found the answer.

Last edited by metalhead; 06-08-2013 at 01:46 PM.. Reason: more to add
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Unread 06-13-2013, 10:07 PM   #27
LJameson
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Well, I put the new o-rings on the injector today. The bottom smaller o ring was torn so I was happy thinking I've found the problem, but alas theres no change.

I'm wondering of the ICM is bad. The rough idle is somewhat intermittent, sometimes its high (~1200 rpm), sometimes its at the normal speed but still somewhat rough. Sometimes when I shut off the Jeep itll do some dieseling. When it is idling high, I'll give it a quick jab at the gas and then it goes back down to normal. The only other thing I can think of is the closed throttle switch on the ISA is bad and not showing closed throttle all the time when it should be.

However, I'd like to add that aside from the idle issue, the engine runs AWESOME. The more it breaks in, the more power I'm feeling. Sure, it's still a 4 banger, but I'm going up hills in 5th gear whereas before with the old motor it would be 3rd gear to the floor. I took it on the 14 freeway the other day from Santa Clarita to Palmdale which has a long steep grade. Before I'd be bouncing between 3rd and 4th gear averaging 60 mph and revving the crap out of my engine, not this time. It held 75 up the whole grade in 5th gear and partial throttle.

I also was thinking about the 4.0 throttle body swap that the MPI 2.5 guys do and have good results with it. Well, if you look at the TBI throttle body bore, its considerably smaller than the 2.5 MPI throttle body. So I was thinking about getting all the parts to swap on the MPI system and adding a 4.0 TB. With the added size of my engine being bored .060 over, I'd imagine that the power increase from what I have now would be noticeable. Plus, the added reliability and driveability that the MPI system adds would be a nice benefit.
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"Anything to do with the land, I love."
"So it's probably eighty percent luck and twenty percent skill."

-Chris LeDoux

I never could figure what the sky was thinking, but the soil, she don't keep too many secrets.
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Unread 06-14-2013, 01:27 AM   #28
tommy450r
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I'm getting ready to do the same to my little 2.5 in a few weeks... Good to know about the oil filter stud
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Unread 06-14-2013, 08:56 AM   #29
LJameson
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Quote:
Originally Posted by tommy450r View Post
I'm getting ready to do the same to my little 2.5 in a few weeks... Good to know about the oil filter stud
If your rebuilding your 94, then it should already have the stud. It's the 87-90 YJs that use the metric adapter.
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"Anything to do with the land, I love."
"So it's probably eighty percent luck and twenty percent skill."

-Chris LeDoux

I never could figure what the sky was thinking, but the soil, she don't keep too many secrets.
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Unread 07-01-2013, 01:51 PM   #30
LJameson
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I had this saturday off so I decided to head up to Shaver Lake to escape the heat and try out my little YJ on the Strawberry lake trail. I debated if I should have just toughed it out with my Jeep and the heat so I could enjoy having it up at Shaver for the weekend, or if I should just take my Saturn so I can enjoy nice cold A/c, and spend less on gas...

Well as you can see by all the crap thats piled on top of the Saturn, the Jeep won the honor of going


Before I left I decided to take the sway bar off since I wasn't sure if it was going to make it even with it disconnected. I left work early around 2 o'clock and started heading up the 5. 105 degrees outside, no top, no A/C, and I was already working in the heat before leaving. It was hot, sticky and I had to stop every 30 minutes to pee because I was drinking so much water. But my little 2.5 was putting along quite well. I was cruising up the 99 at 75 mph no problem, and even maintained that speed going up the Grapevine. As soon as I got up the Shaver Lake, I knew it was worth fighting the heat the whole way up. The weather was perfect and I couldn't wait to get out on the trail on Saturday.


My dad decided to take his CJ7 and his dog Raz up to so we can both go wheeling together. After going over both of our Jeeps to make sure everything will work smoothly, we headed up. Got to the trail head, air'd down our tires and started on our way. My Jeep was conquering the trail like a champ, didn't get stuck once nor did it lose traction at all. My only problem with it was not having power steering makes wheelin a real workout. Needless to say, thats next on my list.




Raz really had a good time too. He's 10 years old now, but you swear he was still a puppy with how playful he was at the lake


The next morning I decided to head back home at 5 in the morning to beat the heat, which was smart on my part because I didn't feel hot the whole way home. Unfortunantly though, as I was slowing down to the street to my house, I started to hear a squeek come from under my Jeep. U-joint is going out. Luckily it waited until I made it home before it started to do anything. But on the bright side, brown santa left me a present while I was gone.


Speaker pods. I'm going to start shopping around for some good speakers and start collecting parts to add power steering to my Jeep.
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"Anything to do with the land, I love."
"So it's probably eighty percent luck and twenty percent skill."

-Chris LeDoux

I never could figure what the sky was thinking, but the soil, she don't keep too many secrets.
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