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Old 04-29-2015, 08:14 PM
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OBD I issues

Hi all,

First off, I'd like to say thank you for all the information that this forum has provided me with so far. You Folks are Awesome.


I have a 1990 2.5 5sp AX-5.
There's alot going on that's not right with my rig. I've had it for about 9 months, and have fixed most of the major issues from previous owners...new starter(old solenoid held on with bungee cord, rebuilt rear end(had enough play in it that it should have disintegrated on the 60 mile drive home), replaced exhaust manifold (not cracked...broken in three pieces). And a whole bunch of other little stuff that mostly I found by reading this forum.

I read alot on this forum, which is where I find most of my fixes or workarounds for stuff on my jeep, I am not real big on asking questions if the search button gets me info, but, I am now at a point that I must ask a pointed question, and hope somebody has an Idea. (I've been searching for a couple of weeks now)

Currently, I'm running really rich, but cannot figure out why, I also have a charging issue (I think)...But need to find out what the computer is seeing/thinking. I've got a funny felling that they are linked but need to access the ECU.

I've tried Cycling the key 3 times to no avail. The only time my check engine light comes on is if I ground it manually with a test light.

Is there a tester that I can purchase...or make... that will allow me to talk to the magical boxes next to my battery?

Any insight or suggestions would be really helpful.

Thanks,
Ross

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Old 04-29-2015, 08:35 PM   #2
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Scanners sold in auto parts stores are useless on OBD1 , the only scanners that will help you are the old school ones like the Snap-On MT2500, they will read a real time data stream. If the check engine light doesn't come on when you turn on the key you have a problem that needs to be addressed first possibly a bad fuse. Most importantly you need to address things like vacuum leaks and tune up issues before you even think about the computer. The first place I look for an engine running rich is a bad vacuum supply to the MAP sensor.

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Old 04-29-2015, 09:32 PM
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Quote:
Originally Posted by Mowrangler View Post
Scanners sold in auto parts stores are useless on OBD1 , the only scanners that will help you are the old school ones like the Snap-On MT2500, they will read a real time data stream. If the check engine light doesn't come on when you turn on the key you have a problem that needs to be addressed first possibly a bad fuse. Most importantly you need to address things like vacuum leaks and tune up issues before you even think about the computer. The first place I look for an engine running rich is a bad vacuum supply to the MAP sensor.
Thanks for that. I know I have a vacuum problem with my brake booster, I'm waiting for payday to fix that. All fuses are good...that's the first thing I checked when I found out the only way to turn my MIL light on was by grounding the bulb to the body. Shortly after fixing the big stuff on the list, I did a full tune up...plugs, cap, rotor button, wires, fuel filter and oil change

There's just so much that's wrong with this Jeep that I need to see what is going on with the computer to get an Idea where to start. I'll start the search for the Snap-On MT2500.
I have a Snap-on Solus and launch tech scan pad at my shop...only nobody knows where to find the OBD I Attachments to connect to.
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Old 04-30-2015, 06:18 AM   #4
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I wasn't aware that the Solus would even work with OBD1.
As far as the running rich problem goes try clamping off the hose to the brake booster and see if it runs better , I have seen bad brake boosters create havoc with the way a vehicle runs.
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Old 04-30-2015, 04:34 PM
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This may have been part of the problem.
I also clamped off the vacuum leak, I'll report back after the drive home.
Those plugs have less than 5000 miles on them.
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Old 04-30-2015, 08:02 PM
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I'm going to do a compression check, leak down test and then test my spark plug wires at work tomorrow. I ran out of time today...man I hate it when work gets in the way...
But, after seeing the #4 Plug covered in oil, and observing the amount of blue smoke coming from my tailpipe on the way home today...I have a nasty feeling that an engine rebuild is in order. Maybe I'll get lucky and just need new valve guide seals, but I'm betting on the worst.
On the bright side, I located an old school Snap-On scanner with all the OBD 1 adapters for $100, so I'll also be able to see what else is malfunctioning with my jeep.
Thanks for the help thus far.
Ross
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Old 05-05-2015, 04:04 PM
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So, I finally got around to doing a compression test...and the results
#1-55 psi
#2-75 psi
#3-90 psi
#4-10 psi

I didn't even bother checking the other stuff after this. Time for a rebuild, or, a 6 cyl...
I found a 6 that the guy kind of fell into and has no use for, and will let me have for $300. Supposedly it's rebuilt by PO, but the fellow doesn't know what year Wrangler it came out of. I haven't laid eyes on it yet, but am wondering if it will bolt up to my transmission? Or will I need a new bellhousing etc.?
Is there a difference in bolt pattern, of the eng/trans between CJ and YJ? He gave me the serial # off of it, but I don't know where to run it to find out what year it came out of.
Any insight would be appreciated. I realize that there are probably several things I haven't covered, and apologize in advance for that.

Thanks
Ross
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Old 05-05-2015, 08:21 PM   #8
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No a six isn't a direct bolt in. You will need a transmission , bell housing, a different transfer case input shaft , different drive shafts , computer and motor mount brackets welded to the frame.
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Old 05-05-2015, 09:14 PM
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Mowrangler, thanks for the idea to clamp the vacuum line to the brake booster off. It completely cleared up the running rich issue. I thought about it earlier, but didn't want to not have power brakes. I really wish I'd listened to myself earlier...the gross vacuum leak lead to a nasty set of backfires that I'm sure are what finished off the rings in Cyl #4.

I had a funny feeling that a 6cyl wasn't going to be the easy solution (I'm still fairly new to jeeps). I discussed the matter with my better half, and we're not prepared to go that route for my "daily driver/play toy".
So, I'm going to rebuild. However, I would like to build something that makes a little more power. I was looking at the Summit Racing site, and, apparently I can get flat top pistons and a little larger cam.
This is all at first glance, I have not done a ton of research yet.
I realize that if I start making changes that I will have to get a carb instead of FI. I'll have to change the Distributor, etc, but these parts can be purchased over time to complete the build.
Additionally, going this route, I will cut the computer out of the equation and will no longer need a scanner to figure out WTF is going on with my motor. A vacuum guage and timing light will be my new best friend again.
The idea of building up a 4 banger probably sounds stupid...at best. But, the tuner crowd does it all the time. I figure why not give it a shot.

Thoughts anyone?

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