95wrangler Posted May 12, 2014 Share Posted May 12, 2014 Is it possible for a bad injector to fri the electronic control module/unit? I recently changed injectors,ran the truck about 400 mi.In a two day time span,truck ran great.On the third day first start-up ,rough idle. #5 not firing.Pulled the plug ,cleand the plug, replaced the plug.Ran the truck 40mi.while driving the truck started missing on 1 or 2 cylinders for about 2mi.then it shut-down.would not restart,wanted to but no.key-on fuelpump pressured-up then pressure droped,would not hold.I pulled the fuel-rail with the injectors attached,#5 injector was leaking fuel.blew out the injector, replaced everthing.Injectors would not fire.Traced everything back to the ECM/ECU.pulled the unit,Opened the unit found something like a double-stack diode cooked.Anyone ever have this prob? Link to comment Share on other sites More sharing options...
95wrangler Posted May 12, 2014 Author Share Posted May 12, 2014 1990 4.0 aw4 4x4 Link to comment Share on other sites More sharing options...
cruiser54 Posted May 13, 2014 Share Posted May 13, 2014 I can't see that happening.... Link to comment Share on other sites More sharing options...
95wrangler Posted May 13, 2014 Author Share Posted May 13, 2014 How common is it for ECM to go bad? I can't find anything shorted-out.Is there a fuel relay or fuse somewhere between the Injectors and the ECM? Link to comment Share on other sites More sharing options...
cruiser54 Posted May 14, 2014 Share Posted May 14, 2014 EXTREMELY RARE. Link to comment Share on other sites More sharing options...
95wrangler Posted May 14, 2014 Author Share Posted May 14, 2014 Thanks cruiser,you are a fantastic sorce for info :thumbsup: Somewhere something took-out the ECM/U. I'll keep looking. :hmm: Link to comment Share on other sites More sharing options...
cruiser54 Posted May 14, 2014 Share Posted May 14, 2014 What got moved during the injector installation? Any bare wires, harness crimped somewhere? Link to comment Share on other sites More sharing options...
mnkyboy Posted May 14, 2014 Share Posted May 14, 2014 I had the same issue on my old XJ, I put In some LT1 injectors. A few hundred miles later I lost a cylinder, traced it back to the ECU were I found the transistor that I'm guessing pulsed the injector on the dead hole had let the smoke out. I put in a new ECU and a fresh set of bosch yellow tops and never had another issue. Link to comment Share on other sites More sharing options...
95wrangler Posted May 14, 2014 Author Share Posted May 14, 2014 Thats exactly what happend.I got reworked injectors from precision auto injectors.They said they were for the year model I have.When I got there product I noticed they were 4-port,not single port. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 14, 2014 Share Posted May 14, 2014 You WANT 4 port. Link to comment Share on other sites More sharing options...
95wrangler Posted May 14, 2014 Author Share Posted May 14, 2014 Nothing was moved, No bare wires, I was very careful with the instal. Link to comment Share on other sites More sharing options...
95wrangler Posted May 14, 2014 Author Share Posted May 14, 2014 No sir, that's what they sent.I figured I'd try-em out.I'm in the process of putting the old ones back in.Also installed A1988 ECM.Still looking for A 89-90 ECM. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 14, 2014 Share Posted May 14, 2014 I've put the 4 port injectors in all my Renix Jeeps and in my neighbor's. . Link to comment Share on other sites More sharing options...
mnkyboy Posted May 14, 2014 Share Posted May 14, 2014 The 4 ports is what I use as well. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 14, 2014 Share Posted May 14, 2014 Did you bust the line from your throttle body to MAP sensor on install? Go look. Link to comment Share on other sites More sharing options...
95wrangler Posted May 14, 2014 Author Share Posted May 14, 2014 All I know Is that the injector instal was the only thing I have done.So I'll go back where I started, With the old injectors. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 14, 2014 Share Posted May 14, 2014 Don't jump the gun. Go look at that hose/tube. Link to comment Share on other sites More sharing options...
95wrangler Posted May 14, 2014 Author Share Posted May 14, 2014 Not on the injector instal, On bleeding the air out of the closed cooling.I did splice the line with electrical tape.Can't look at anything, cause the truck is 200mi. from me at presant. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 14, 2014 Share Posted May 14, 2014 Gotta be perfect or the MAP is telling the eCM that the vacuum is low and to "add a bunch of fuel". Link to comment Share on other sites More sharing options...
95wrangler Posted May 14, 2014 Author Share Posted May 14, 2014 I work out of town,200mi. from my home. when the truck quit I got my son-in- law to trailer it to his shop. Link to comment Share on other sites More sharing options...
95wrangler Posted May 14, 2014 Author Share Posted May 14, 2014 10-4 I will replace asap.With the 88 ECM and the 4-port injectors the truck still has a miss. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 14, 2014 Share Posted May 14, 2014 Can you isolate it? Link to comment Share on other sites More sharing options...
95wrangler Posted May 14, 2014 Author Share Posted May 14, 2014 I did not try to find the missing cylinder as of yet,Everything happend late sunday on my way back to the valley for work on monday.After the 88 ECM instal,and start-up, when it was still missing the time was 2am.I called it quits for for now.Trying to get info for the next round this weekend or relay info to the son-in- law.He can work on it when he has time.Thanks for your time & info :bowdown: Link to comment Share on other sites More sharing options...
95wrangler Posted June 1, 2014 Author Share Posted June 1, 2014 One bad injector DiD take- out the ECM. Link to comment Share on other sites More sharing options...
cruiser54 Posted June 1, 2014 Share Posted June 1, 2014 One bad injector DiD take- out the ECM. How did you determine that? Link to comment Share on other sites More sharing options...
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