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Unread 01-04-2010, 12:33 AM   #1
Registered User
1988 YJ Wrangler 
Join Date: Dec 2008
Location: Georgia
Posts: 192
Runs Rich and Runs Rough

I have 1988 YJ with a 1989 258 4.2L engine. It has a GM Computer and TBI with Jeep ignition. The TBI swap was done on the engine before I bought the engine. I tried to "clean up the engine bay and get rid of some cut wires that were from the old Jeep wiring harness that weren't being used anymore. Also the local Jeep 4wd shop told me I could get rid of acouple things like an extra distributor connector that wasn't being used. Alot of the cut wire were going to the connectors and relays attached to the side of the battery tray. People have told me that since I am running a TBI I don't need those connectors and relays anyway.

The YJ has always runs alittle rich but, now after doing all that above its runs real rich, idles rough, hesitates and sputters while driving. Also backfires sometimes at running low speeds

I checked the spray pattern at the injectors with a timing light and the spray pattern was sporadic. Then I started checking continuity of each wire at the computer and the sensor. I also hooked a scanner up to the AL/DL connector under the dash and the showed "NO" problems execpt under Knock sensor it said yes and I know I have no Knock sensor.

I know the Computer came out of a 89-93 Chevy truck/van. I have a wiring diagram from Mitchell On Demand but my wiring harness has been cut into. Meaning the GM and the original Jeep harness have been integrated.

One last thing when I put the engine in the Jeep I installed Headers and had to relocate the stock placement of the O2 sensor and had to extend the wire going to the O2 sensor over to the other side of the engine. I also just replaced the O2 sensor realizing it was broke. When I bought a new one it was for my year Jeep and the single wire kind.

Just giving everyone all the info I can think of. If ya'll can think of anything please let me know or if youy need me to give you more info as well. Thanks

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Unread 01-04-2010, 12:27 PM   #2
Registered User
1988 YJ Wrangler 
Join Date: Dec 2008
Location: Georgia
Posts: 192
Any ideas. I'm at a stand still
madjeep1 is offline   Reply With Quote Quick reply to this message

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