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Unread 08-09-2013, 06:25 PM   #16
tjwalker
It's the crank sensor!
 
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Quote:
Originally Posted by gunner_woody View Post
ok new development, while I was at work my son drove it to an interview. While he was driving it shook badly would not go over 55mph and now has codes P0300 (random misfire) P0302 (misfire cylinder #2) and P0305 (misfire cylinder #5). Back to the drawing board!
I agree. Now that you are seeing the P0300 and the P0305, that leads you in a different direction.

Generally speaking, whenever I see the P0300 (random misfire), my mindset begins to go to a common root cause for the misfires that you are also seeing on specific cylinders.

First thing I would do is to verify FUEL PRESSURE. For your vintage, you must have 49 psi, plus or minus 5 psi at idle.

The fact that you are now seeing other cylinders leads me to believe you have a "common component" that is suspect. I'd start with fuel pressure. You've gotta rule it in or out before moving to more complex possibilities.

Good luck and keep us updated. This is an interesting one!

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Unread 08-09-2013, 07:44 PM   #17
gunner_woody
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Here is the progress thus far. I put new NGK copper plugs in gapped at .035, re timed it (again) and it started up and idled great. I checked fuel pressure it holds steady at 49psi at idle and at 2000rpm. Erased all codes and took it for a spin. Got it up to 45 mph and accelerated fast to 55 mph, as it started increasing speed it hesitated almost like it was missing but leveled out at 55. I pulled off the road and it was a rough idle like it was missing on one cylinder. I shut it off and let set for 5 minuets, then headed back on the road. This time I slowly got up speed to 55 mph with no problems. I slowed to 5 mph then stepped on it hard and it threw a check engine light which ended up being P0305 (cylinder 5 misfire). So as tjwalker is saying I am leaning towards fuel problem, now where do I start with this one?
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Unread 08-09-2013, 07:44 PM   #18
CCKen
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Quote:
Originally Posted by gunner_woody View Post
ok new development, while I was at work my son drove it to an interview. While he was driving it shook badly would not go over 55mph and now has codes P0300 (random misfire) P0302 (misfire cylinder #2) and P0305 (misfire cylinder #5). Back to the drawing board!
The Cam sensor may have taken a dump.
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Unread 08-09-2013, 08:25 PM   #19
gunner_woody
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Quote:
Originally Posted by CCKen View Post
The Cam sensor may have taken a dump.
Wouldn't that throw a code?
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Unread 08-09-2013, 10:04 PM   #20
X-Rated
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Seems to easy but i like to pick on the easy stuff first.
02 sensors?

Only reason i bring it up is mine has a random miss at idle and im positive its the rear 02 sensor. I cant seem to get the damn thing out tho.
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Unread 08-09-2013, 11:41 PM   #21
tnc22
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Well, this is gonna be interesting.

Seems doing the cheap and/or easy tests first is always the best:
-swap ignition wires around, see if problem moves to different cylinders.
-swap injectors around, see if the problem moves to different cylinders. That's more in keeping with the fuel problem hypothesis.
-swap push rods around, see if the problem moves to different cylinders. (yes yes, I know....)

I am of the understanding that a cylinder with higher compression has less resistance to a good spark. If that is true then a weak coil, wires, cap/rotor may cause misfire on cylinders with less than ideal compression???

Do keep us all in the loop. Fascinating stuff.

Good luck.
Tim
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Unread 08-10-2013, 06:05 AM   #22
gunner_woody
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I monitored the engine and captured data with a obdII snapon diagnostic machine, all O2 sensors are operating, all fuel pressures are good, all injectors are operating normal, all coils are firing, cps is giving normal readings... and all parameters are right where they need to be, still idling bad... Now I am really stumped, I am calling for back up, I will keep everyone informed of what is going on today
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Unread 08-10-2013, 07:43 AM   #23
CCKen
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You may want to do some vacuum gauge diagnostics. Here's a couple links that will show you how to diagnose various problems that show up as vacuum related.

You could have a clogged exhaust sysyem, i.e., Cat(s) plugged. Both links show how to diagnose this.

http://www.secondchancegarage.com/public/186.cfm

http://www.autospeed.com/cms/article...nostics&A=2393

Youtube has several videos on this as well.
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Unread 08-10-2013, 08:57 AM   #24
dave564
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Quote:
Originally Posted by gunner_woody View Post
I monitored the engine and captured data with a obdII snapon diagnostic machine, all O2 sensors are operating, all fuel pressures are good, all injectors are operating normal, all coils are firing, cps is giving normal readings... and all parameters are right where they need to be, still idling bad... Now I am really stumped, I am calling for back up, I will keep everyone informed of what is going on today
At idle on the shop, or was this on the road?
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Unread 08-10-2013, 12:48 PM   #25
xjdantheman
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since everything checks out sensor and electrical like then i would look into a clogged cat.
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Unread 08-10-2013, 01:10 PM   #26
gunner_woody
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At idle on the shop, or was this on the road?
At the shop.
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Unread 08-10-2013, 01:11 PM   #27
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since everything checks out sensor and electrical like then i would look into a clogged cat.
If the cat was cogged, shouldn't I get a code?
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Unread 08-10-2013, 06:15 PM   #28
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Alright, here is the skinny on this problem. My expert helper suggested resetting the timing, leak down test on the head and changing the coil rail. So taking the path of least resistance I happened to have a spare coil rail from a previous 2001 XJ, even though the one on it tested fine, so I started there first, and low and behold, so far running and idling fine. Took it for a test drive with no problems. I will post and let everyone know if anything changes.
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Unread 08-10-2013, 06:30 PM   #29
Holder350
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Dang, and I thought about that....but I was probably thinking like you and saying no way 2 separate rails were both bad.

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Unread 08-11-2013, 02:08 PM   #30
gunner_woody
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Well day 2 and no problems so far. Here is the total list in order of the head swap and trouble shooting. Head gasket; radiator; coil rail; junkyard head; piston rings; radiator (again); remanufactured head; coil rail. This does not include the IAC, MAP, TPS, or the numerous timing adjustments. The one thing that is taken for granted that is not on this list is the pain and suffering like you all know!
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