buckwheat Posted December 8, 2014 Share Posted December 8, 2014 My 87 MJ 4.0L BA10-5 has decided to have its first major problem. I figured it was time to clean the C-101 and ground at the dipstick. Took both apart no problem, wire brushed them till shiny, sprayed with brake cleaner, polished some more, then stuck them back together. When I tried to start my MJ to back it out of the garage it would crank but not catch and run. After playing around a little bit I realized I could floor the gas pedal and it would start and run, but VERY rough, like it was missing on multiple cylinders. Also, if I quit feathering the gas it would idle down until it died. The exhaust was also very rich, smelling strongly of gas. I pulled my spark plugs and the back three (closest to the firewall) were black. So I replaced all 6 with champion copper plugs, but that didn't help. I checked my TPS and it was properly adjusted per Cruiser's Renix Tips. I have looked over all the vacuum lines and can't find anything that appears to be out of place or missing. I changed my MAP sensor from a known good vehicle to this one, as well as the vacuum line on it. No change. I unplugged my O2 sensor and tried to start and run it, again no change. The vacuum line to the fuel pressure regulator doesn't seem to smell like gas (hard to tell with the exhaust being so rich). I have tested the CPS and while cranking it would read .75-.8 AC volts. I thought it was only supposed to read .5? Is this an issue? I plan on renting a fuel pressure gauge to see what it is at with the key on. I also will check to make sure I have spark on all cylinders. Does anyone have any ideas or recommendations of other things to try? Could I have messed something up cleaning the C-101? I'm really at a loss, any help is appreciated. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 8, 2014 Share Posted December 8, 2014 My 87 MJ 4.0L BA10-5 has decided to have its first major problem. I figured it was time to clean the C-101 and ground at the dipstick. Took both apart no problem, wire brushed them till shiny, sprayed with brake cleaner, polished some more, then stuck them back together. When I tried to start my MJ to back it out of the garage it would crank but not catch and run. After playing around a little bit I realized I could floor the gas pedal and it would start and run, but VERY rough, like it was missing on multiple cylinders. Also, if I quit feathering the gas it would idle down until it died. The exhaust was also very rich, smelling strongly of gas. I pulled my spark plugs and the back three (closest to the firewall) were black. So I replaced all 6 with champion copper plugs, but that didn't help. I checked my TPS and it was properly adjusted per Cruiser's Renix Tips. I have looked over all the vacuum lines and can't find anything that appears to be out of place or missing. I changed my MAP sensor from a known good vehicle to this one, as well as the vacuum line on it. No change. I unplugged my O2 sensor and tried to start and run it, again no change. The vacuum line to the fuel pressure regulator doesn't seem to smell like gas (hard to tell with the exhaust being so rich). I have tested the CPS and while cranking it would read .75-.8 AC volts. I thought it was only supposed to read .5? Is this an issue? I plan on renting a fuel pressure gauge to see what it is at with the key on. I also will check to make sure I have spark on all cylinders. Does anyone have any ideas or recommendations of other things to try? Could I have messed something up cleaning the C-101? I'm really at a loss, any help is appreciated. Higher than .5 on the CPS is wonderful!! Re-open the C101 and tweak the connectors so they grab the pins better. Link to comment Share on other sites More sharing options...
buckwheat Posted December 9, 2014 Author Share Posted December 9, 2014 I was reading your tips and thinking that the only way to be sure the C-101 is not an issue is to eliminate it. Are there any downsides to eliminating that connector? And is it really as simple as taking one wire from opposite sides and soldering them together? Plenty of slack in the loom to manage this correct? I hope to get to it this weekend. *fingers crossed* Link to comment Share on other sites More sharing options...
cruiser54 Posted December 9, 2014 Share Posted December 9, 2014 I was reading your tips and thinking that the only way to be sure the C-101 is not an issue is to eliminate it. Are there any downsides to eliminating that connector? And is it really as simple as taking one wire from opposite sides and soldering them together? Plenty of slack in the loom to manage this correct? I hope to get to it this weekend. *fingers crossed* No downside at all. Solder and shrink tubing, one wire at a time. Link to comment Share on other sites More sharing options...
buckwheat Posted December 17, 2014 Author Share Posted December 17, 2014 So I have been (slowly) working on the C-101 elimination. I have the first row of wires looking down at the C-101 soldered and shrink wrapped. However, below that there seems to be wires without matches on both sides of the connector. I was under the impression that every wire had a counterpart on the other side of the connector. Is this not the case? Kinda worried I've screwed myself somehow. . . Link to comment Share on other sites More sharing options...
cruiser54 Posted December 17, 2014 Share Posted December 17, 2014 Not the case. Keep on trucking. Link to comment Share on other sites More sharing options...
buckwheat Posted December 19, 2014 Author Share Posted December 19, 2014 Alright. C-101 bypassed. Truck runs no better than before. Still sounds like its missing on multiple cylinders / timing is off. And it still has no idle. I have to put the pedal to the floor to start it, and if I quit feathering the gas while it is running it will die. While running and feathering the gas it is running VERY rich. I can smell raw gas from the exhaust. To this point I have: Eliminated C-101 Changed TPS from a known good vehicle (haven't calibrated it because I can't get it to stay running) Cleaned TB Checked CPS Changed out the ICM and Coil from a known good vehicle Changed spark plugs Changed MAP sensor and vacuum hose from a known good vehicle Checked spark at each plug These things are not in order, but I have tried them all. Everything looks good. So to me it seems like a timing issue. Is it possible that my ECU is bad? Link to comment Share on other sites More sharing options...
cruiser54 Posted December 19, 2014 Share Posted December 19, 2014 Index the distributor then. Tip 12, then 13. Link to comment Share on other sites More sharing options...
buckwheat Posted December 19, 2014 Author Share Posted December 19, 2014 I don't really understand #13. If the rotor is at the #1 post when the engine is TDC, isn't that exactly what we want? Why do you have to remove the distributor, and what is happening here: "Place the distributor housing upside down in a soft jaw vise. Scribe a line 1/2 inch from the end of the distributor locating tab. Cut the distributor locating tab at the scribed line with a saw. Remove any burrs and metal filings from the distributor."? Not that I don't believe it needs to be done, but I would like to understand what I am doing first. Thanks for the help so far! Link to comment Share on other sites More sharing options...
cruiser54 Posted December 19, 2014 Share Posted December 19, 2014 Get the engine to #1 TDC. The rotor needs to have it's trailing edge about .020" past the #1 dizzy cap terminal. Here's why. The CPS tells the ICM when to fire. If the rotor is too far away from the dizzy cap terminal when it fires, the spark has a hell of a jump to make, resulting in poor running. Link to comment Share on other sites More sharing options...
buckwheat Posted December 27, 2014 Author Share Posted December 27, 2014 Sorry its taking me so long to try these things. Everything gets busy around the holidays. Also the wife decided to put gas in the diesel truck and drive it till it died. But for now I am back on the MJ problem. Distributor is indexed, no change. Other things I've noticed: When I pulled the O2 sensor plug apart while the truck was running nothing changed. Sounds really rough and has no idle If I pull the wires off the MAP sensor while it is running the rpms will go up by about 1000 and it will even out for 2-3 seconds. Then the rpms will drop and it will go back to being rough. If I manually move the EGR valve it will choke the truck out. Is this supposed to happen? Any other ideas or paths to send me down? Thanks so far to Cruiser for his suggestions. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 27, 2014 Share Posted December 27, 2014 Have you done Tip 5? Link to comment Share on other sites More sharing options...
buckwheat Posted December 27, 2014 Author Share Posted December 27, 2014 I have done the Sensor Upgrade by bringing the six brown wires together and soldering and shrink wrapping them. Tomorrow I will look at the ohm reading and see what it says. Link to comment Share on other sites More sharing options...
buckwheat Posted December 27, 2014 Author Share Posted December 27, 2014 Tip 5 done. Got a steady ready of .9 ohms. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 28, 2014 Share Posted December 28, 2014 Good to know. Link to comment Share on other sites More sharing options...
buckwheat Posted December 28, 2014 Author Share Posted December 28, 2014 So anyone have any ideas on what I can check or try next? Link to comment Share on other sites More sharing options...
cruiser54 Posted December 29, 2014 Share Posted December 29, 2014 So anyone have any ideas on what I can check or try next? Bad solder joint when eliminating the C101? Link to comment Share on other sites More sharing options...
buckwheat Posted December 29, 2014 Author Share Posted December 29, 2014 Cruiser, That would make sense if the problem was new. But I had the same issues before I got rid of the C-101. Trying to fix the problem is why I bypassed the C-101. It just doesnt seem like the causality works right for me to have the same issue before and after AND it be related to my solder joints. Not saying that they are good joints, it just doesnt make sense to me. What I'm wondering if why disconnecting the wires on the MAP sensor will raise the RPM by 1000 and make it run smoother for 2 seconds, followed by it getting rough again. Is that a normal thing when you disconnect the MAP wires? Link to comment Share on other sites More sharing options...
cruiser54 Posted December 29, 2014 Share Posted December 29, 2014 Usually when you disconnect those wires, it floods. I'm wondering if your ECU connectors are in need of attention at the plug. Link to comment Share on other sites More sharing options...
buckwheat Posted December 29, 2014 Author Share Posted December 29, 2014 Do you mean the where the wires plug into the ECU unit in the cab? I have already taken those connectors apart and cleaned them. I have also tried putting in a new ECU from a 90 jeep cherokee. I had the same issue with the new ECU that I had with the old one. It made no difference. Link to comment Share on other sites More sharing options...
54bobby Posted December 29, 2014 Share Posted December 29, 2014 does it run smooth once warm? Link to comment Share on other sites More sharing options...
cruiser54 Posted December 29, 2014 Share Posted December 29, 2014 I'm wondering if you've got an injector issue. Like clogged ones. Link to comment Share on other sites More sharing options...
buckwheat Posted December 29, 2014 Author Share Posted December 29, 2014 does it run smooth once warm? No. It runs rough the entire time. Cruiser, injectors was the next thing I was gonna try. But I am not having any luck getting ahold of programbo on cherokee forum. Is there another place I could get the Volvo 746? If I am replacing them, I might as well do an upgrade. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 29, 2014 Share Posted December 29, 2014 Complete part number is 0-280-155-746.. How are you trying to contact Programbo? Link to comment Share on other sites More sharing options...
buckwheat Posted December 29, 2014 Author Share Posted December 29, 2014 I made an account on http://www.cherokeeforum.com/private.php and sent him a PM. Other ideas I wanted to bounce off of you: CTS: How can I test this when I can't get the truck up to temp? I know it controls injector pulse and ignition advance, so if it was bad and reading infinite resistance that could cause my super rich and rough condition. And where can I get a replacement at? MAT: Same questions as the CTS. How to test, could it be my problem, and where can I get a replacement? Injectors: I found the following site http://www.injectorwarehouse.com/injectors/volvo/mp5060.htm for the injectors. But that seems kinda pricey to me. What do you think? Link to comment Share on other sites More sharing options...
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