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New MJ Owner


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Hello, all. I just acquired a 1990 Comanche, and have a few questions for ya'll. But first, a little about the truck...

 

It's a '90 SporTruck, 2.5L/AX4, 2WD, shortbed, 3.55's, with 181,000 miles. I hope to license it in the next week or two to use as my DD and runaround/work vehicle in place of my '85 GMC C3500; I'm still keeping the Oneton, but the Comanche is much better suited to the country 2-lane roads (less cumbersome and rides better) I do most of my driving on and will have to get better gas mileage than my current figure of 11.5. jamminz.gif (Hey, the 454 ain't all bad - I towed the Comanche home with it.)

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Cosmetically, a lot of the clear coat is flaking/wearing off, the bottom of both doors and rocker panels under the doors are rusty, and there are small-dinner-plate-size holes on the outside of the frame "rail" in the front of both floorboards, but it's still solid otherwise and the bed has almost no rust on it. Mechanically, it runs and drives, but the engine has a slight miss and an intermittent knock. I was told the engine had a rod knocking before I bought it so that wasn't a surprise, but I haven't positively determined it's a rod, as opposed to a lifter, etc. - as soon as it's licensed I'll drive it to my preferred mechanic and get his opinion on it. The tranny feels good and, aside from the track bar being worn completely out, it drives pretty well. I think I did pretty well for $450. :thumbsup:

 

I think I can handle the mechanical issues, but there are a few things I need some help on. First off, there are three plugs under the dash (see photo) that are unplugged. The Jeep had a few things robbed off of it (fan shroud, temp. sending unit) and I think whatever these hooked up to was one of those pieces. Any ideas?

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Also, when you shut it off, after the engine stops the TBI quickly "pumps" the throttle butterfly three times. I've never been around a Renix Jeep before, nor many other early EFI rigs; is it supposed to do this?

 

Thanks!

 

Alex

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Those plugs are for a number of different switches that were available depending on the options, model and year. They were for fog lights, bed cargo light, and power/comfort switch for earlier AW4s although I've never seen on on an MJ. Next time you're in a yard, go through the XJs and you'll likely find on with all the switches present, usually in Limited models.

 

It's not technically TBI, but it is a throttle body, not sure why it does that. Dig through the tech section for "Renix diagnosis", you should be able to find an answer. There's also a ton of good links in the FAQs and the stickies. One page with an excellent write up for Renix sensors is at the Lunghd site. http://www.lunghd.com/Tech_Articles/Eng ... ostics.htm

 

Other links: viewforum.php?f=9, viewtopic.php?f=9&t=7910

 

Its a nice straight looking truck too. Besides the rust in the frame rail you mentioned,,,better get on that pretty quick....Also, welcome to the club!!! :thumbsup:

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Welcome! I've got nothing to add here other than asking what the story is on the blue Chevy in the background. '67? '68? I'm kind of a sucker for that body style... Good looking MJ too!

 

Oh geez... :hijack: ... already?

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The 2.5l have a electronic idle control. When you shut the engine off the idle control resets itself for restart, that is where you see the movement. It should start with a fast idle and then slow down to normal in about 5 seconds. If you watch the plunger you can see it move.

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Welcome! I've got nothing to add here other than asking what the story is on the blue Chevy in the background. '67? '68? I'm kind of a sucker for that body style... Good looking MJ too!

 

Oh geez... :hijack: ... already?

 

Boy Ben you must study the heck out of the background of pics.... :rotf:

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Thanks for the links/references, Comanche County. I'll sift through those and see what I can find. FWIW, when you shut it off, you don't have to be looking at the throttle shaft to tell it does it - you can hear it pretty distinctively "rrrr, click-click-click". As to the plugs under the dash, the way they were dangling led me to conclude they were originally hooked up to something, but it doesn't look like the truck ever had fog lights, a bed light, or AW4. I'll probably replace the floorpans sooner rather than later - not immediately, as I bought the truck to be a functional, economical DD that I don't feel bad about getting/leaving dirty (unlike the all-original, 100,000-mile GMC) so I won't be putting a priority on making it cosmetically perfect anytime soon - but I won't let it get out of hand.

 

neohic: It's a '67 C10... ready? ...3-door Suburban. 327/4-speed with all heavy duty/tow options, PS/PB, and Custom trim. My dad bought it in the mid 80's and it was the family DD until '01 when its third 327 dropped a valve, and it's been out of service ever since. He needed to sell it last fall and I had the money/didn't want to see it go, so it's now mine and has a recently rebuilt '79 350 sitting in it that's just waiting on me to hook it up. :wrench:

 

airspeed: Yes, I've noticed the plunger is what changes the idle, and it does start at a higher RPM then settle down after a few seconds. It doesn't like to drop back to idle immediately when shifting gears (which may be related to this same system) but that's something to iron out after I get it running better and licensed.

 

Thanks for the help, and I'm sure I'll be back for more!

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The "rrrrr" of the idle stepper is normal...the "click,click,click"may be a signal that it is out of adjustment

 

any time a P.O. messes around behind the dash(or you hit a bad R/R crossing too fast) the factory harness will drop some of the previously tucked away un-installed options' plugs.

Also when someone gets around to ripping out that clear box for the emission reminder, it leaves behind one of those plugs.A few of those others are for the yellow cruise control box that may have been velcroed up under there

 

My 88 2.5 2wd AW4auto has the power/comfort switch. Just like the XJs.

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