New owner of an old Jeep...having issues - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Wrangler Forums > YJ Wrangler Technical Forum > New owner of an old Jeep...having issues

Stainless Steel Door Hinge PinsPoly Door Hinge BushingsDual Color LED Light Bars White/Amber

Reply
Unread 06-11-2014, 09:59 AM   #1
fchapma
Registered User
1993 YJ Wrangler 
 
Join Date: Jun 2014
Location: boerne, tx
Posts: 7
New owner of an old Jeep...having issues

Hello everyone! This forum has been a great and useful tool, unfortunately I believe I have exceeded my skill level. So, here we go.....It's been a rough 15 or so months, I was diagnosed with lymphoma and have been battling it for a while now. My wife has been keeping me busy with projects and bought me this old jeep that was once her fathers. He turned around and gave it to his son who put a used engine in it. Same engine 2.5L but it came out of a dodge dakota year unknown but seems to think 1998-2003. Anyway, when I received the jeep he said it had been sitting for a year and it had been rarely driven. We then got in and drove it around the neighborhood and it was great but really loud. It finally died on us and we looked over the engine and noticed the head gasket looked blown. I had a mechanic come over and disassemble the engine and had him replace both the head gasket and manifold gasket. He also took the valve head and had it milled down level. Got everything back in and could not get it started. He finally got it started and it ran at idle for a good 5 minutes and sounded great but as soon as he gave it gas it slowly died. The mechanic did say that the engine is in excellent condition. We thought maybe a fuel issue since it had been sitting for so long. We drained the fuel and changed the filter and put new fuel in the tank. 40 psi at the fuel rail.

1. New injectors and we are getting spark.
2. Changed all the fuses and relays.
3. Checked the ignition coil (put a new one in just to see), map, and most of the wiring.
4. New distributor with wiring.
5. New cam shaft sensor.
6. Timing chain is in good.
7. New battery.
8. New starter.
I thought after reading here maybe it was a o2 sensor but he didn't seem to think so. The o2 sensor has a wire that is severed.

He was able to get it started again and I drove it to his house where he could look at it when he had time. It ran great on that 15 minute drive and would start right up if shutoff. However, it will not start up and we are back to square one. We both came to the conclusion that it is either a bad computer, wiring or something with the flywheel. I'm not sure I understand how the flywheel could be the culprit in this situation but we haven't got there yet sooo.

The wiring- he has checked continuity between a lot of the sensors and that all seems to be good.

The computer is a problem for me because I don't fully understand how it works with vehicles. I have built several computers from the ground up and understand it from that point but with this jeep from what I have read might have some firmware issues that need to be fixed. Anyway, the original computer is in it and before reading fully I rushed over to ebay and bought a used computer that was pulled directly from an operating 1993 Jeep wrangler 2.5L manual transmission. The computer came in yesterday and we swapped them out and still have the same issue except now we don't have spark. I didn't think it needed to be reprogrammed because it came out of the exact same jeep but I could be wrong. After not having anything to do for the last 2 days and reading up on these computers it looks like I need to send my computer away to have it rebuilt. I saw a service on ebay that can do this. Is this the correct way to go? or do I go to a dealer and have it looked at. So, does swapping the engine out effect the computer and its timing signal?

My mechanic says the timing is good TDC and distributor but the computer is messing up the spark timing...

By the way when the key is turned the pump primes and the check engine light comes on normally and extinguishes. Checked codes by turning key 3 separate times and get 12 33 55....all are normal from my understanding.


I know this is long but I appreciate any and all help. Thanks in advance!

Last question....should I keep the second computer for a backup have it repaired and upgraded as well or return it?

fchapma is offline   Reply With Quote
Unread 06-11-2014, 10:27 AM   #2
superj
Registered User
1987 YJ Wrangler 
 
Join Date: Mar 2008
Location: corpus christi, texas
Posts: 6,321
i have no idea on any of your questions as i have never had a 2.5l jeep but someone should be able to come along and help you out.
__________________
Slow ride, take it easy
superj is offline   Reply With Quote
Unread 06-11-2014, 12:38 PM   #3
XJ93
Registered User
1995 YJ Wrangler 
 
Join Date: Apr 2009
Location: Michigan
Posts: 698
Looks like you've done everything but the crank position sensor. I have used an internet service for ecm rebuild and I would never go that route again. When my ecm failed again less than a year later I went straight to the dealer. I paid more for sure but I was guaranteed it would work.
XJ93 is offline   Reply With Quote
Unread 06-11-2014, 02:11 PM   #4
Que89YJ
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
Posts: 14,549
You have done a lot to it. Before you start sending anything for repair or throwing parts at it lets start with the basics. The O2 sensor is primary for air fuel and when it is warmed up has a huge effect on the way it runs. You must fix the O2.
The O2 does not have anything to do with a cold start unless it is shorting. The no start is air, fuel and spark.

Check to make sure you have spark at the plugs when you are cranking it.

You measured 40 psi at the rail. That is good. When it is running/starting it should drop down to 31 psi. If you turn the ignition off it should keep pressure above 20 psi for 20 minutes. Try shooting starter fluid directly into the throttle body.

Try disconnecting the battery for a long 10 count and reconnecting it then starting it.

One more possibility would be a plugged catalytic converter. Do you still have the cat on the Jeep?

We will get you going!
Que89YJ is offline   Reply With Quote
Unread 06-11-2014, 08:15 PM   #5
fchapma
Registered User
1993 YJ Wrangler 
 
Join Date: Jun 2014
Location: boerne, tx
Posts: 7
update....so we have narrowed it down to the distributor or cam shaft....The distributor is moving or shaking out of place during idle or driving and prevents further starts. We move it over one notch and it starts right up. We will be taking it apart tomorrow to see if the cam shaft needs to be replaced. Also, there is alternate wiring for the alternator because it looks as though the PDC took a beating and melted away the fuse spot for the alternator charge slot. There is now an inline fuse with a 50 amp fuse on it. We have 12v coming out of one tooth and 48v on the other which is blowing the fuse for some reason. I am assuming the alternator is going bad....That will be checked tomorrow as well....thanks for the responses
fchapma is offline   Reply With Quote
Unread 06-12-2014, 07:57 AM   #6
Que89YJ
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
Posts: 14,549
No, the alternator is before the fuses not after. If you are blowing the fuse its on the load side. 48Vdc is impossible. I don't know where you are measuring. The alternator has 2 50 amp output fuses in the PDC. If those are blowing you have a dead short and I would be looking at the bottom of the PDC first. Pull all the fuses in the PDC and see if you are still blowing the fuse.

So you are getting spark? If the pickup or distributor are bad the spark is usually intermittent and more common at the wrong time.
Que89YJ is offline   Reply With Quote
Unread 06-12-2014, 10:24 AM   #7
XJ93
Registered User
1995 YJ Wrangler 
 
Join Date: Apr 2009
Location: Michigan
Posts: 698
You said the distributor is shaking out of place, is the hold down not tightened down all the way?
XJ93 is offline   Reply With Quote
Unread 06-16-2014, 09:35 PM   #8
fchapma
Registered User
1993 YJ Wrangler 
 
Join Date: Jun 2014
Location: boerne, tx
Posts: 7
so it's not the distributor. We can start, turn off, start, and turn off but come out the next day and it wont start. So, I took some advice from above and disconnected the battery and let it sit for an hour. I came back out and it started right up but slowly died after a few minutes. I want to say its the ECM but its been replaced by a used ecm that came out of a working replica of my jeep. The engine wiring harness is in disarray due to the previous engine overheating and part of the PDC is melted and like said above new wires have been added and rerouted around the pdc. I bought a used engine wiring harness from ebay and it should be here sometime in the next few days. I am hoping that takes care of the problem.
fchapma is offline   Reply With Quote
Unread 06-17-2014, 05:38 AM   #9
Que89YJ
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
Posts: 14,549
Its not the ecm. The OBD 1 computers are very simple. There is no programming the ecu, the are all eprom and all the OB1 ecu's are the same with the exception of the security on the XJ ecu's. When you say it starts and slowly dies, how long does it take? Does the temp gauge get up into normal operating range? I will guarantee if you are patient and we go through this we can fix it.
Que89YJ is offline   Reply With Quote
Unread 06-17-2014, 05:57 AM   #10
Michaelgoesrawr
Web Wheeler
 
Michaelgoesrawr's Avatar
1988 YJ Wrangler 
 
Join Date: Nov 2009
Location: Waco, TX
Posts: 6,531
Quote:
Originally Posted by Que89YJ
I will guarantee if you are patient and we go through this we can fix it.
This man speaks the truth. Widely respected man for being a cool dude. And he's forgotten more than I've learned so far in life.

One step at a time, use the forum like a repair manual and don't throw good money after bad unless you've got a lot to spare, in which case throw it at me.
__________________
Adopt your pets. Don't shop for them.
Michaelgoesrawr is offline   Reply With Quote
Unread 06-25-2014, 08:31 PM   #11
fchapma
Registered User
1993 YJ Wrangler 
 
Join Date: Jun 2014
Location: boerne, tx
Posts: 7
so the engine wiring harness came in and it doesn't look like its going to fit. It's from a 1991 jeep wrangler yj manual 2.5L. I thought 91 - 95 were interchangeable but I guess not. The adapter to the computer will fit and connect but there is one extra wire coming up for something. The bulkhead connector will connect but the plug pins don't match up like the old one or there are some missing. I can return this wiring harness but what are the years I need to be looking for to get an exact match. I saw a 95' harness with the same engine but don't know if it will work. Help!

Last edited by fchapma; 06-26-2014 at 07:22 AM..
fchapma is offline   Reply With Quote
Unread 06-25-2014, 09:26 PM   #12
Que89YJ
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
Posts: 14,549
Plug teeth? You mean the pins on the connector?
Que89YJ is offline   Reply With Quote
Unread 06-26-2014, 07:05 AM   #13
fchapma
Registered User
1993 YJ Wrangler 
 
Join Date: Jun 2014
Location: boerne, tx
Posts: 7
yes....just starting reading and learning the terminology.
fchapma is offline   Reply With Quote
Unread 06-26-2014, 07:09 AM   #14
Que89YJ
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
Posts: 14,549
Why are you replacing the harness?
Que89YJ is offline   Reply With Quote
Unread 06-26-2014, 07:18 AM   #15
fchapma
Registered User
1993 YJ Wrangler 
 
Join Date: Jun 2014
Location: boerne, tx
Posts: 7
I have downloaded the bulkhead connector diagram for a 91' and a 94' because I could not find it for the 93'. There are some differences as far as the pins. Right off the bat I see A4, A5, and A6 are different plus several more.
fchapma is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.