P38 4.6 Thor 1999 engine missing on 2 cylinders

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boycie

boycie

Active Member
Posts
538
Location
Silver end Braintree ESSEX
Hi Folks I need your help again my p38 started missing a couple of days ago,I removed the spark plug leads one at a time and on cylinders 3 and 5 it made very little difference I have replaced the spark plug leads and plugs with some spare ones I had in the garage which has made no difference I did a compression test and cylinder 3 has almost 9 bar and cylinder 5 has almost 10 bar pressure.There is what looks and feels like a strong spark and if you lay the plugs on the head they spark quite well ,I have ordered a new set of plugs and leads and I have a spare coil pack I will try next week but I can’t help but feel by the size and feel of the spark it’s not the ignition ,any ideas what the problem could be ?.
 
Coil pack has gone "pop"? 3 & 5 are on the same pack maybe the spark you are seeing is weak compared to the others?.
post-21981-0-88128200-1328460460.jpg
 
My first thought was the coil pack 3 and 5 that’s quite a coincidence I found a spare one in the garage I’ll change it tomorrow, my nanocom is recording misfires on cylinders 3 and 5 .When I pull the plug caps there seems to be a good spark but it’s hard to tell .I will change the coil pack in the morning and come back to you ,thanks for the reply’s.
 
V8 uses the lost spark principal, it fires two plugs at the same time. One at TDC cylinder firing and one on the other cylinders exhaust stroke.
 
Well I fitted the spare coil pack this morning and changed plugs 3 and 5 for plugs 1 and 7 no difference it’s still not firing on cylinders 3 and 5 .I am not sure if this related but Jackie came out as I started the car to try it and she said that stinks it’s like sulphur it did really stink I’ve never noticed that before.I have new plugs leads and coilpacks on the way which I’ll fit next week if that doesn’t work any ideas what to try next ?.
 
Have you checked compression? Also worth checking if both sets of valves are opening properly, ie worn cams. If one cylinder hours bad it can negatively affect the other
 
Thanks Kermit ,I will recheck the compression when I pull the plugs out to change then next week if the new bits don’t work then I’ll remove the rocker covers and have a look .I have a brand new cam and all the necessary parts to change it in the garage so I can do that at the same time but it would be nice to sort this problem first .Is it likely that 2 injectors are playing up at the same time ?.
 
Thanks guys (should I say and girls )I am retaking my domestic gas next week (for the last time ) so I won’t get a chance to work on the car until the weekend then I’ll fit the new coilpacks leads and plugs and hopefully that should rule out the ignition side of things while the plugs are out I will check the compressions and report back if that’s ok .
 
boycie said:
Well I fitted the spare coil pack this morning and changed plugs 3 and 5 for plugs 1 and 7 no difference it’s still not firing on cylinders 3 and 5 .I am not sure if this related but Jackie came out as I started the car to try it and she said that stinks it’s like sulphur it did really stink I’ve never noticed that before.I have new plugs leads and coilpacks on the way which I’ll fit next week if that doesn’t work any ideas what to try next ?.
Click to expand...
Check the wiring to the injectors maybe?
 
I am not sure how to check the injectors I had a look earlier it didn’t look damaged ,I seem to recall there is a type of test light but I can’t remember what they are called .
 
Never had to use them but you need the correct 1 for the system and I believe plug into the injector plug 1 at a time
Or follow instructions on the box when you buy usually works as a last resort:D

You can get a kit with loads in but you only want your type.

J
 
Not worked/got a Thor so couldn’t say.
You may have to wait for a big boy with long trousers to confirm that:oops:

J
 
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