Blood of a Jeep Posted December 9, 2014 Share Posted December 9, 2014 Hey everybody. Its been a while since I've been here, mostly because all is well in Jeep land. Well not anymore. My 89Xj will not run. The 90Mj will and I have been parts swapping to trouble shoot. The Xj is a 4.0 auto np242 3.73, power everything. In short its a Waggoneer. Currently the Xj has good spark, OK compression, and fuel, including injector pulse. The timing has been set and reset a bunch. I've been battling this for about a month or so. I'm at my wits end. I've done so much searching that I can guarantee it is not an evident issue. The story though is pretty short, so I've had the xj for 8 yrs. Most reliable rig I own. This past summer I caught the illusive Mj locally. So I did the stupidest thing. Made the Mj run with parts from the Xj. Fast forward to now. No combination of anything fixes anything. Any advice will be taken. Specific questions will be thoroughly answered. Thanks in advanced. Link to comment Share on other sites More sharing options...
Dom U Posted December 9, 2014 Share Posted December 9, 2014 After swaping a 89 xj engine into my MJ I had very similar symptoms. After a lot of wasted money on this and that and this item, it ended up being the CPS. If your MJ is currently running try swaping the CPS and see if it works. I'm by far no jeep tech or as educated as others around here just simply speaking from my own recent experiences. Also if you haven't gone over Cruisers renix tips I'd highly suggest it. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 9, 2014 Author Share Posted December 9, 2014 I wasn't going to go that route because it has spark. But I will anyway because its one thing I cannot guarantee. Thanks for your input. Link to comment Share on other sites More sharing options...
Dom U Posted December 9, 2014 Share Posted December 9, 2014 Let me know how it works. It only took me about 15 mins to remove and install the new one. Link to comment Share on other sites More sharing options...
Eagle Posted December 9, 2014 Share Posted December 9, 2014 Can you see the timing mark on the front cover? You have spark, but have you confirmed that #1 is firing when #1 is supposed to fire? Spark plug wires in the correct firing order (1-3-5-6-2-4, IIRC)? Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 9, 2014 Share Posted December 9, 2014 Can you see the timing mark on the front cover? You have spark, but have you confirmed that #1 is firing when #1 is supposed to fire? Spark plug wires in the correct firing order (1-3-5-6-2-4, IIRC)? This. It's really easy to be 180 degrees off. I suggest: Cut a window in you dist cap at number 1, pull your VC, manually turn your engine over and watch the rockers/valve and make certain you are on the compression stroke of #1 TDC, your rotor should have just swept #1 on the cap. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 9, 2014 Author Share Posted December 9, 2014 Can you see the timing mark on the front cover? You have spark, but have you confirmed that #1 is firing when #1 is supposed to fire? Spark plug wires in the correct firing order (1-3-5-6-2-4, IIRC)?Yes. I have done and redone this multiple times, I suspected issues with it myself. The odd thing I noted, is that it appears my engine hits tdc based on valves and timing mark, but the piston has passed tdc when everything lines up. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 9, 2014 Author Share Posted December 9, 2014 Can you see the timing mark on the front cover? You have spark, but have you confirmed that #1 is firing when #1 is supposed to fire? Spark plug wires in the correct firing order (1-3-5-6-2-4, IIRC)? This. It's really easy to be 180 degrees off. I suggest: Cut a window in you dist cap at number 1, pull your VC, manually turn your engine over and watch the rockers/valve and make certain you are on the compression stroke of #1 TDC, your rotor should have just swept #1 on the cap. Done an done. Link to comment Share on other sites More sharing options...
Brickmiata Posted December 9, 2014 Share Posted December 9, 2014 possible for the timing chain to have slipped? Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 9, 2014 Author Share Posted December 9, 2014 possible for the timing chain to have slipped?I would think not. It was driven until it was parked. Link to comment Share on other sites More sharing options...
Eagle Posted December 9, 2014 Share Posted December 9, 2014 Let's take it from the top. You wrote that you took parts from the XJ to get the MJ running. What parts did you take? And, since it ran before and doesn't run know, what did you use to replace the parts you "borrowed" from the XJ? In theory, the three things an internal combustion engine needs to run are fuel air, and spark. You have all three, so the answer has to be somehow related to timing, either of the ignition or of the injection. Have you tested the fuel pressure in the rail? Have you tried starting it with starting fluid, or by pouring a SMALL amount of gasoline directly into the throttle body? Link to comment Share on other sites More sharing options...
87MJTIM Posted December 9, 2014 Share Posted December 9, 2014 Let's take it from the top. You wrote that you took parts from the XJ to get the MJ running. What parts did you take? And, since it ran before and doesn't run know, what did you use to replace the parts you "borrowed" from the XJ? In theory, the three things an internal combustion engine needs to run are fuel air, and spark. You have all three, so the answer has to be somehow related to timing, either of the ignition or of the injection. Have you tested the fuel pressure in the rail? Have you tried starting it with starting fluid, or by pouring a SMALL amount of gasoline directly into the throttle body? Exactly what I was thinking. Was the XJ running before you cannibalised it? When was it running last? How old is the fuel? Did you take the MJ parts and put them on the XJ? Which parts? My 2¢. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 9, 2014 Author Share Posted December 9, 2014 Let's take it from the top. You wrote that you took parts from the XJ to get the MJ running. What parts did you take? And, since it ran before and doesn't run know, what did you use to replace the parts you "borrowed" from the XJ? In theory, the three things an internal combustion engine needs to run are fuel air, and spark. You have all three, so the answer has to be somehow related to timing, either of the ignition or of the injection. Have you tested the fuel pressure in the rail? Have you tried starting it with starting fluid, or by pouring a SMALL amount of gasoline directly into the throttle body? Exactly what I was thinking. Was the XJ running before you cannibalised it? When was it running last? How old is the fuel? Did you take the MJ parts and put them on the XJ? Which parts? My 2¢. In response to all of this^. The Xj ran well before the parts swapping. I removed the distributor, coil, icm, ecm, cps, oil pressure sensor, temp sensor in the head, and recently valve cover to retime the engine for certain. Everything removed was reinstalled with the same part. all of the parts are original to the Xj. except the cps, but I have spark. I put 10 bucks in it yesterday to cover that base. I know the rail has pressure, but I don't know the exact number. I have poured fuel in the TB to check if it was a delivery issue, as well as starting fluid. Not at the same time. When i did these things there is almost no change in the cranking, almost, on occasion it does cough. But no backfiring out of intake or exhaust. By cough I mean seems like it wants to run but doesnt, Link to comment Share on other sites More sharing options...
Eagle Posted December 10, 2014 Share Posted December 10, 2014 Sounds like either weak spark or out of time. Check out Cruizer's list of sensor checks for how to determine if the CPS is putting out the correct voltage. Just because it's new doesn't mean it's good -- there's a lot of DOA stuff in the way of electrical components. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 10, 2014 Author Share Posted December 10, 2014 Well here's some clarification. Timing mark is at 9 o clock piston is at top of stroke valves are not being depressed. What the heck Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 10, 2014 Author Share Posted December 10, 2014 Double post oops Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 10, 2014 Author Share Posted December 10, 2014 Upon further, more intensive inspection, I'm pretty sure the timing chain jumped. I'm gonna dig into that in the next couple day . I'll update when I know for sure. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted December 10, 2014 Share Posted December 10, 2014 What was your compression numbers ? Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 10, 2014 Author Share Posted December 10, 2014 Compression was 120ish on all. The last thing last night the Xj did fire, ran like total trash backfiring an such but it was alive. Link to comment Share on other sites More sharing options...
Strokermjcomanche Posted December 10, 2014 Share Posted December 10, 2014 You're at the lower end of the allowed compression 120-150 ( I don't know when the cutoff is that the engine will not run at all) . Someone correct me if I'm wrong, but if your timing jumped your engine would have much lower compression numbers . I'm not saying the chain / gears don't need replacement but as eagle said: air, fuel ,spark . Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 10, 2014 Author Share Posted December 10, 2014 Well here's some clarification. Timing mark is at 9 o clock piston is at top of stroke valves are not being depressed. What the heck I'm curious if this means anything significant to anyone. Clearly I have a few timing issues. I'm not discounting anyone's opinions, just trying to gather things I haven't thought of or checked. As far as minimum allowable compression, idk what it is, but I know 120s enough to run a 4.0, at least the ones I've checked. Link to comment Share on other sites More sharing options...
Blood of a Jeep Posted December 11, 2014 Author Share Posted December 11, 2014 OK I tore into the area. Found that my harmonic balancer piece spun inside of the outer ring. Got into the timing chain and found a roller style chain,like a bicycle has. I don't think that's stock the marks line up on the gears, but I'm curious about the amount of deflection on the roller style, is it still half an inch like the factory chain is? Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 11, 2014 Share Posted December 11, 2014 OK I tore into the area. Found that my harmonic balancer piece spun inside of the outer ring. Got into the timing chain and found a roller style chain,like a bicycle has. I don't think that's stock the marks line up on the gears, but I'm curious about the amount of deflection on the roller style, is it still half an inch like the factory chain is? Yes......and I was going to mention the HB this morning but my ideas generally fall on deaf ears anyway....... The factory chain is a POS...just my opinion. You can get a double roller if you want. Your dist is a tooth or two off, use a screw driver or some other 'feeler' to find TDC on the piston....forget the HB for the moment..........NOW go index your dist. Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 11, 2014 Share Posted December 11, 2014 BTW, the key on your crank at 12 o-clock indicates TDC.......just go by that. Link to comment Share on other sites More sharing options...
Eagle Posted December 11, 2014 Share Posted December 11, 2014 The factory chain is a POS...just my opinion. You can get a double roller if you want. The factory timing chain is NOT a POS. It's a single roller, which is more than adequate for a torque engine that doesn't see high RPM and doesn't have dual coil, high-pressure valve springs. I pulled the timing assembly from my '88 XJ at 200,000, not because I was having problems but because I remembered that the cam sprocket on my AMC V8s had nylon teeth, and they liked to strip after a few years or a hubdred thousand miles or so. So I figured I was living on borrowed time and that a full replacement would be a preemptive strike. When I took it apart, the old timing set was in perfect condition. I learned that the large sprocket on the 4.0L is all steel, so no worries about stripping the teeth. The original chain was tight enough that there was virtually no difference between it and the new one. I was in these so I installed the replacement, but I kept the old timing set and I wouldn't hesitate to put it in an engine that needs a timing chain. Link to comment Share on other sites More sharing options...
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