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Discussion Starter · #1 ·
OK - i need some help.
2004 disco 2 - maybe 100k miles.
I had a rough running idle - down a cylinder or two, random misfire codes, so I bought 2 coil packs, magnacor wires and 8 new plugs, took off the intake and swapped everything out. I don't think it was coil packs, but the job was so onerous, I just did them while I was in there.
Also, replaced valve cover gaskets, swapped the part of the abs unit to address my 3 amigos, and changed coolant.
plugs were really worn, that was probably most or all of my issue.
So... put it all back together and it idled awesome, great, right?
Well, when I went for a test drive, it has no power. So sluggish. OBD now shows a number of cylinder misfires, it smells all wrong - mixture must be off.
- I've searched all over trying to find a vacuum leak or disconnected sensor. I did find that I had a temp sensor not hooked up, but reconnecting did not solve my problem. Used some propane to try to find any leaks, but no leads from that
- may be a red herring, but the IACV unit noticeably buzzes/hums when the engine is off, but the key is in ignition (i disconnected it and the engine idled at about 500 rpm and threw codes for IACV open circuit fault)
- may also just be me not fully bleeding the brakes (those vacuum-draw tools are awful - didn't have anyone else around to help me pump brakes), but you need to stand on the pedal to get the brakes working. Thats what caused me to initially think vacuum leak
- I figure it HAS to be something dumb I just forgot to reconnect - any ideas to help narrow troubleshooting?

at least now I know why these valve cover gaskets leak - these mating surfaces look like they were hand carved :eek
 

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Sorry no one has been able to respond with a direction. It is so frustrating when things don't turn out, especially after covering as many issues as you have.

I would wonder if perhaps the firing order has been confused with the plug wire orientation.
If there are no vacuum leaks - that is my first suspect.

Hope you have some luck getting it sorted.

Please post back at that happy moment to let us know how it was resolved.
 

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Yeah, my money is on the wires being installed to the coils incorrectly. Use the diagram in RAVE, do not deviate.
 

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Discussion Starter · #4 ·
Thank you both for the advice / encouragement
I don't think I could have gotten wires crossed, since I was prety thorough in marking which was where. I labeled the new magnacor's too. I had the coil packs out so I didn't do it blind. I heeded the advice to make sure each one had a definite 'click' when it seated.
Besides - it wouldn't idle evenly with wires swapped, right? an improper seat could probably prompt higher rev misfires I suppose.

I did a swisher sweet vacuum leak test by blowing cigar smoke into the intake with the inlet plugged. I got a little smoke out the inlet tube to throttle body seal so I tightened that. Also a little out of the brake booster line, where it meets the intake, but I'm assuming from the design of that connector that it expects vacuum and not pressure to work properly. Didn't find any other leaks.
I'm going to look up vacuum specs on it and hook up a guage to the intake tomorrow to see if I can get something a little more scientific.

My mechanic friend mentioned clogged cats - anyone have experience with this or have a good test? It really doesn't seem to fit my symptoms prior to the plug change, though.

Pulled codes:
P1300 powertrain
p0302,3,5,8 - Cylinder misfires
P1319 powertrain
pending codes:
P1551 powertrain
p1510 powertrain
p0300 random/multiple cylinder misfire

-Mike
 

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Discussion Starter · #6 ·
Ha! Ok. Pass side coil pack plug was not fully seated- reached in with a screwdriver and snugged it in. Runs great now. I will give you a run down of lessons learned.
1) double check - no triple check all your connections upon reassembly
2) before I replaced wires I had multiple cyl misfires across both packs- afterwards I had multiple misfires but it was limited to just one pack. Even if codes look similar - remember to look at them with a Fresh set of eyes- may be a different issue.
3) apparently a v8 will idle smoothly on one bank of cylinders- I am accustomed to 4 cyl where you need each cylinder for even balance. If you have 1 bank down you're getting miserable power and insufficient vacuum to boost brakes.

Thanks for these posts and also for the folks that posted before - reading a dozen archive posts about vacuum leaks and other gremlins really helps to frame up a better understanding that can even help with a peripherally related problem

-Mike
 
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