Agree with diagnosis/Rough cost of replacing spark plugs?

C

co11ingsworth

Member
Evening everyone,

Turned my car on to leave work today and instantly could tell a cylinder had gone offline. Car felt like it was jumping around, engine sounded rough as anything and the needle bobbling up and down.

Mr AA came out to meet me at home, diagnosed cylinder five had gone, and replaced the coil with a Bosch unit he had in his van. After 10 minutes of trying he still couldnt get the cylinder to re-ignite, and suggested that the issue could thus be with the plugs rather than cylinder.

As chucking it down at the side of the road, and as I live/work pretty close to a local indy, he suggested I take it in ASAP to get at least the fault plugs replaced, possibly all of them as I'm on 75k miles and theyre possibly due anyway. Swapped my original coil back in, and that's now where I'm at. Sadly this was all after 5.30 so the garage was closed - ringing first thing tomorrow.

All I'm asking please, is a) if you agree with what he's suggested & b) a rough guide as to what I can expect the parts to come to (try and pre-empt the teeth-sucking tomorrow :lol: )
 
Assuming you have a 6 cyl car (as you said issue was with cyl 5) a set of NGK Iridium plugs should be under £50 - labour should be £0 as anyone can change a set of plugs
 
Should the check engine light turn off automatically once I've changed the plug? What about the cylinder coming back online - it's still not firing. Is the electrical plug in doo-dah needed to reset everything?
 
I've just brought a set of 6x Bosch Super Plus Spark Plugs FGR7DQP+ off flebay for £29. As stated in the previous post they are very quick and easy to change. if you can't manage a spark plug change I wouldn't bother opening the bonnet at all.
 
Shouldn't you confirm the diagnosis first - I think you can test the plugs for continuity??
 
Dont rule out that the Coil could still be dead (his could be too) - very unlikely for a plug to suddenly completely fail.

Plug misfires are often due to contamination. Take them all out, remember their order and compare - look for oil or soot.

if you've never changed plugs before, its ok to take them out of a hot engine, but NEVER put a cold plug into a hot engine.
 
I perhaps should have written that better peter700 - I swapped the plug from cylinder 5 last night successfully but the cylinder still wasn't firing. (EdButler: it was cold plug into a cold engine, I assume this is ok!?) My three lines of possible reason for not still working are:

1) Coil had failed along with the plug, but as Mr AA had re-fitted the original one due to seeing no change the cylinder is potentially still fitted with a faulty coil. It is possible his was also faulty - he had mentioned how reliable these engines were as he'd had that coil in his van for 5 years, so yeah it could've easily degraded in all that time.

2) The ECU needs to be told to reset to allow the cylinder to re-fire (I've since discovered that this isn't the case. Been told that if the engine light is still on on start-up, then there is simply still a fault)

3) The fault was neither of these in the first place!

Rang an old work friend who races M3s (my go-to engine man), he said to look for cracks in hose lines, but I cannot see any, failing that a compression test. Sadly he is away currently and cannot look at it until next week, and as I need to drive a fair distance this weekend that is not an option. Booked it in with a local garage to have a look at tomorrow morning.

I shall post a reply tomorrow evening (hopefully) to say what the problem was... if I don't then it's because I'm busy consoling myself at the size of the invoice :cry:
 
It could be injector too.
Coil failures are really rare when we are talking about M54 engines.. which model and year your car is?
What was fault code?
 
EdButler said:
Dont rule out that the Coil could still be dead (his could be too) - very unlikely for a plug to suddenly completely fail.

Plug misfires are often due to contamination. Take them all out, remember their order and compare - look for oil or soot.

if you've never changed plugs before, its ok to take them out of a hot engine, but NEVER put a cold plug into a hot engine.
Click to expand...


WHY IS THAT THEN ? :?
 
Turns out that the coil was faulty after all :headbang: The garage owner wasnt too shy to share what he thought about AA mechanics!!

He did raise a concern about the replacement coil though, and I was wondering if anyone knew of a design change to the coil since my car was new in 2006? It is a Bosch part, looks identical except that the previous version clipped on to the top of the plug, whereas the new one just sits on top of it and relies on a friction fit only to stay in place. Is this correct? Seems like it could arise to the coil moving out of position and causing arcing between the contacts or losing connection all together
 
Sounds like your mechanic has fitted an incorrect coil, and he's got the cheek to criticise the AA! :roll:
Regards
 
I'm sure the bosch replacements from eurocarparts also clip in. I'm going to have all mine replaced along with the spark plugs when goes in for an inspection 2.
 
Just replaced all my coil packs after 1 went down. They definitely have to connect to the spark plug. The Bosch coils have a rubber outer with the connector slightly inside so they have to be pushed onto the plug securely thus preventing any arcing.

Also you can feel it "click" on to the plug which assures a good connection.

Never heard of a "friction connection" especially when high tension is involved. :o
 
tug said:
Just replaced all my coil packs after 1 went down. They definitely have to connect to the spark plug. The Bosch coils have a rubber outer with the connector slightly inside so they have to be pushed onto the plug securely thus preventing any arcing.

Also you can feel it "click" on to the plug which assures a good connection.

Never heard of a "friction connection" especially when high tension is involved. :o
Click to expand...

Yeah it did seem odd to me. As you've just changed yours, could you tell me what part number you used please and I'll compare that to what is on my invoice?
 
Hi mate, got the packs from Euro Carparts and part number is 413110187. Cheers.
 
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