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Unread 02-21-2014, 06:29 AM   #31
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
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I reread it. So you have and are holding pressure. You have spark. It started but was flooded and immeadiately died.(You can use the wot cutout to prove if it is the flooding of even pull the fuel pump relay and try to see if it cranks over and dies with some starter fluid). The TPS was a little low but not enough to through everything out of wack. Your map reading according to the readout says you are just shy of outerspace vacuum when you are starting it, but your live data from before shows a normal atmosphere.

Try one thing for me. I know it is a stretch but the speedo on the tcase has a common ground and is known for a no start issue like you are describing. It will not throw a code and basically is railing the ground when it shorts. Disconnect the sensor on the side of the tcase.

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Unread 02-21-2014, 07:07 AM   #32
Boothe
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1993 YJ Wrangler 
 
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Location: Clinton, MO
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Que89YJ - Yeah, I know a little something about control systems...I've been working on them, mostly in power plants, since 1981. Before that I knew a little something about Air Force electronic countermeasures systems. Once I got my hands on that Factory Service Manual over at Morrix 4X4 The Goob put me onto, all bets were off. Unless Mopar's own info is wrong, the timing is non-adjustable. The PCM sets ignition timing based on crank position and sets injector timing based on cam position. The fact that the PCM is not throwing a code, spark appears to be happening in the right time at the right place, the PCM sees the MAP, sees the TPS, sees the CPS and the scanner shows all of them moving during cranking is a good thing. The timing shown live on the scanner is being set to 4.4 deg. BTC. All of this along with visibly wet spark plugs point to a wide open injector or injectors. I didn't put a stop watch on the fuel pressure gauge when I had it on the rail, but at better than 10 minutes the pressure still hadn't dropped below 25 PSI (that's on the first page of this thread). So I'm leaning toward a grounded injector rather than a mechanically stuck injector. I should know for sure this weekend.
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Unread 02-21-2014, 07:34 AM   #33
Que89YJ
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The timing is computer controlled but and a big but the timing is sequenced by the cam/crank and uses the sensors to locate the the position of the cam/crank with the sensors. The problem is that you have 2 critical failure points in the timing that the ecu cant and wont make up for if they fail. The timing gearsin the front held together by a chain. Slop in the chain gets bad enough that it will allow the gears to slip past and you have an out of time engine. The other is the distributor. It can advance and retard timing by using the map input just like a vacuum advance on the old school engines, but it assumes a base location of #1 for pointing to do the control. If the gear is engaged at a point other then pointing at #1 on the compression stroke the ecu cannot correct the timing because it assumes that the distributor is at #1 compression stroke. Your timing can be off if you have played around with the distributor or the timing chain has slipped.

The PCM for OBD 1 is crude at best. It looks for a response in a range. Voltage and signal occuring in that range are assumed to be normal. It wasnt until OBD 2 that it started to look at rate change to know that a failure can occur withing normal paramaters like a coolant temp sensor stuck at a given temp and never deviating as the engine warms.
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Unread 02-21-2014, 07:42 AM   #34
Boothe
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Que89YJ - I missed seeing your later post. Yes, we already pulled the fuel pump relay and that's when we got it to start, run fine (no poppingj or backfiring indicating a timing issue) and then immediately die from lack of fuel. After it sits for a while it will fire off and then immediately die / plugs wet with gas. I'll check that sensor on the transfer case too this weekend.
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Unread 02-21-2014, 08:35 AM   #35
Que89YJ
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You dont need to if it fired right up and then died. The control systems have to be good. The sensor ties into the crank ground and wouldnt allow spark so no need to waste your time. You can still be 1 tooth off and not get the backfiring. It will advance the timing and the ecu will think everything is ok.
http://www.jeepforum.com/forum/f12/t...05/index1.html
When the guys run a cam they shave off the ear and twist the disributor to get the timing right for their stroker 4.0L. Did you replace the distributor? Is it possible the distributor was put in 1 tooth off?

It was running good then you had a sudden and you are flooding and you have spark and you are 100% the timing is right then it can only be an air/compression issue. A compression test would show it but again I have never hear of a compression issue failure like that unless you have a slipped timing chain which would show up as a timing issue when checked. If you have spark and fuel is compressed it will ignite. Your fuel pressure indication says that you are getting the right pressure. The injectors are ground switched and constant 12 volts from the asd so there is no way you have an injector issue because they are opening and closing. The ais does allow air to pass for idle but I have never heard of a no start because of the ais. The throttle plate will allow air through if the pedal is pushed. It just dies real quick after. The only thing left would be a bad ecu in a failure way I am not familar with.
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Unread 02-21-2014, 10:44 AM   #36
Boothe
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Quote:
Originally Posted by Que89YJ View Post
It can advance and retard timing by using the map input just like a vacuum advance on the old school engines, but it assumes a base location of #1 for pointing to do the control. If the gear is engaged at a point other then pointing at #1 on the compression stroke the ecu cannot correct the timing because it assumes that the distributor is at #1 compression stroke. Your timing can be off if you have played around with the distributor or the timing chain has slipped.
I read the timing thread you referred me too. Good stuff. I did swap the distributor and I thought I was pretty fastidious about it, but I'll go back, pull all the sparkplugs and get #1 back to TDC. I won't have any help, so I'll stick a foam earplug in #1 sparkplug hole and when it pops out I'll know I'm on the compression stroke. I can tweek it from there with a wrench on the harmonic balancer and dial indicator shaft through the spark plug hole to get it dead on. Then go by the FSM and Alfons' recommendations to be sure it's all correct. It can't hurt.

As an aside, that #1 plug is a real bear to get to because of the air conditioner compressor. Since the top stays off all summer anyway, I'm about on the verge of putting that whole (aftermarket) air conditioning system on ebay... It would make it a lot easier to change plugs and especially to get to things under the dash. The other unpleasant discovery I've made is that a SunTech compression tester fitting will not fit far enough into the spark plug hole recess in a 4.0L head to thread in. Can you recommend a brand of compression tester with a fitting diameter that is known to be small enough to go? Or do I finally have an excuse to buy a small engine lathe so I can turn that fitting down?

I find your comment about the MAP very interesting. The MAP sensor value is moving around more than I'd like to see and doesn't seem to be repeatable. The first thing my compadre and long time Mopar aficionado said when he saw all that gas on the sparkplug "Was pull that MAP sensor." He'd said he'd seen a bad MAP cause flooding on a Dakota and some of the mid - late 80's Chrysler cars. When I put the MAP on the bench though, it didn't seem like there was a problem with it (of course I don't know the calibration range, so I couldn't reference it to known cardinal points). But it responded in a linear fashion and didn't leak down with static vacuum applied. That original reading of 29.4" Hg I saw on the scanner was erroneous. If you cycle the ignition switch with the AutoXray 6000 connected to the diag. connector, it locks up with bad data displayed. You have to exit out of live data mode and restart it. My bad.

That being said, the new Borg -Warner MAP started out 3.4 "Hg static, then dropped to 2.4" cranking, then went to 10.5" static. When I cranked it over again, it went to 2.4" and then went to 7.5" static. I think that may be a clue. I'm going go through the whole timing thing again with a fine tooth comb just to satisfy my and everyone elses curiousity. If that's doesn't fix it, and I have my doubts since it tries to run with low / no fuel pressure and doesn't backfire, then I'll start looking for ground / wiring / PCM issues.
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Unread 02-21-2014, 11:31 AM   #37
lakeobum
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Boothe, I was reading your thread and just realized we live in the same town. I have a spare computer if you are thinking that may be your issue. It is for a 92 so not sure if it is the same or not. If it is, look me up and you can try it out as to eliminate that as the problem.
Mike
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Unread 02-21-2014, 11:44 AM   #38
Que89YJ
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The map is dealing with advance. Even with the map sensor disconnected it should start. The lack of advance will make it run like crap and stall, but it should start and stall...
I dont know the HG other then the standard 1 atmosphere amnient and running is 16" of vacuum. The Map sensor should have about 5v out before start and about 1.5 when running. I guess you can check the voltage at the input to the ecu to see if you have the same reading as the output of the sensor to make sure the wiring is good. I am just not sure with the hg reading what it translates to for voltage.
As far as the timing goes if you got it to start and stall then the most you could be off is 1 tooth. I dont think you need to use the thumb method but look at the rotor position and mark it, slide the distributor back in and see. There is an easy way to get around under the hood without the second set of hands. The starter relay in the pdc can be removed and jumped between 30/87 in the relay socket with a piece of wire and it will work just like turning the switch.

I guess for S & G pulling the VSS on the tcase couldnt hurt.
relay.gif

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Unread 02-21-2014, 11:59 AM   #39
Boothe
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Quote:
Originally Posted by lakeobum View Post
Boothe, I was reading your thread and just realized we live in the same town. I have a spare computer if you are thinking that may be your issue. It is for a 92 so not sure if it is the same or not. If it is, look me up and you can try it out as to eliminate that as the problem.
Mike
Awesome Mike. I appreciate the offer and I may take you up on it. We ought to lay eyeballs and a handshake on each other anyway since we're both local and into Jeeps. We've probably already waved to each other and didn't know it.
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Unread 02-21-2014, 02:26 PM   #40
Boothe
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Que89YJ - Thanks for the tip on the relay. I'll wire up a pushbutton switch with a couple of spade lugs.
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Unread 02-26-2014, 06:48 PM   #41
Boothe
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Update: I had to run about 600 ft. of fence last weekend so I didn't get a chance to look at the Jeep. Tonight I stopped by Autozone after work and picked up an Actron compression tester. The 14mm long reach adapter fits in the narrow spark plug recess nicely. Even on the #1 cylinder with that hard line off the water pump and the A/C compressor in the way. That's the good news. The bad news is the first effort to crank the engine (with the fuel pump relay pullled) resulted in #1 cylinder compression at <85 PSI. I bled off the pressure and tested it again, twice. Both times it was right at 60 PSI. I think I'll pull the valve cover next to see what the valves are actually doing when #1 is TDC. If both valves are closed, I guess an overhaul is in the works. If the valves aren't completely closed it's off with the timing cover. My wife did make the comment that when I was leaving the last day I drove it she could hear something that sounded like rattling in the engine. Hmmm.
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Unread 02-26-2014, 08:22 PM   #42
Que89YJ
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Timing maybe the chain skipped and it's not the rings.
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Unread 02-27-2014, 05:20 AM   #43
Boothe
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Que89YJ - That's what I'm hoping for. Maybe the rattling my better half heard when I was leaving the other day was timing chain slap. My Ford and Chevy compadres all thought a loose timing chain would wear a hole in the cover before it would jump time. But as I pointed out, this ain't a Ford or a Chevy. Maybe now is a good time for 4.6 stroker...
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Unread 02-27-2014, 11:20 AM   #44
Que89YJ
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Lol you know that is where I was going at page 1. If she heard the slap then you are lucky. Replacing the chain and gears are quick and easy.
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Unread 02-28-2014, 07:39 AM   #45
Boothe
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Que, I hope you're right. I've spent too much time around jet engines and power plants over the years, so I'm lucky to hear wind noise at 60MPH with the top and doors off these days. Much less something as obscure as a rattle under the hood. OTOH, with 161K+ on the ticker as well as little oil on the shop floor at the front & rear of the engine, now might be a good time to go through the motor. Let me bounce this off you; if the previous owner(s) weren't a conscientious about changing the oil and filter as I am (I bought the old girl at 100K+), that may be the reason the timing set is worn to the point of jumping teeth. Right? It that's the case, how much better shape do you think rings & bearings are going to be in? Just asking...
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