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nelmo

Misfire

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Hi, had a breakdown over the weekend - driving along, engine started misfiring just a little but soon degenerated into power loss and major kangarooing down the road. I called the AA and the guy who came out was an ex-Ford mechanic, so knew his onions ( I run a Zetec with FI and no other fancy bits).

However, he spent 3 hours and couldn't fix it (although it was good enough to get me home). He swapped out the coil pack, 2 of the 4 HT leads (all he had in the van) and the spark plugs which improved it but misfire still there. To be accurate, idle seems fine and gentle acceleration is OK but sudden or hard acceleration really shows up the misfire.

An old thread on here for someone who had the same problem was eventually traced to his HP fuel filter being blocked but I don't have one.

Initially, I'm getting a replacement set of HT leads and a new coil pack - I didn't keep the one the AA guy had because he wanted £60 for it, which seemed steep and it didn't fix the problem. However, found an NGK part (his was Delphi) for half that price - is it ok?

https://www.burtonpower.com/weber-4-cyl-coil-pack-ford-zetec-e-se-1998-wic141.html

Thought at that price, a new one is worth another shot...

After that, any other suggestions? To clarify, 2L Zetec, FI, external swirl pot, plenum only.

I'm concerned it may be electrical - on my way home, at a constant 60mph, all was fine until I went through a hefty pothole and suddenly the misfire was back with a vengance - felt more like the entire engine was switching off rather than just 1 cylinder. Got off the motorway (2am, no traffic, luckily) and nursed it down the road - lots of revs, feathering the clutch and then it just suddenly went away and back to 'normal' - gentle acceleration OK. Did the initial pothole loosen a weak connection and the violent shuddering of the engine 'loosened' it back to working, if you know what I mean?

 

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I think I'd be looking at a wiring issue as well, especially considering you've just done a trackday. 

Look for chaffing wires and loose earths. Can anything move under cornering and braking that might put a strain on the harness or connectors. Can you start the engine and have a good poke around at the wiring and connectors to see if it makes a difference to how it runs. 

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Why no high pressure fuel filter?  These are critical to stop any crap getting into and blocking your injectors. 

Do you not what grade your fuel hose is?  With modern unleaded having an amount of ethanol in, if your rubber lines are not ethanol safe they can break down fairly rapidly, which combined with no high pressure fuel filter would cause your injectors to become blocked.

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I've got an LP filter before the swirl pot (and it's clear) - shouldn't get any crud after that? Fuel lines are R9 which I believe are Gillette (the best a man can get 😉)....

If injectors were blocked, wouldn't it run crud all the time? Or not even start? Idle is smooth as ever....

BTW, is that NGK coil pack ok? Or is Delphi (OEM?) much better?

Edited by nelmo

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If it is injectors, it would run worse under heavy load, so high revs, accelerating etc. Which fits what you are saying, plus if it is the fuel line breaking down, it could be even though the LP filter is clear.  Also LP filters alone arent good enough for fuel injection as they generally arent as fine a filter.

As for the R9 fuel hose, I'd still remove some and check it, there was a lot of fake stuff knocking about, even from reputable retailers! Even though it is better than the older spec hoses, its also still not completely ethanol proof, so will deteriorate over time.  
 

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Hi I'm in agreement with the AA chap and I'd be looking at the spark side of things  - something is breaking down under load start with the wiggle test on connections 

Can you limit it to one cylinder ??

The zetec is known to eat spark plugs - go and buy four new plugs - they can be fine on idle and when out the engine sparing but fail under load 

 

Edited by blue

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My gut is also saying ignition, check leads Zetecs eat plugs and eventually cheap leads can break down under load especially when warmer. Even better borrow some off a good running engine, someone must live near you. 

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4 hours ago, blue said:

Hi I'm in agreement with the AA chap and I'd be looking at the spark side of things  - something is breaking down under load start with the wiggle test on connections 

Can you limit it to one cylinder ??

The zetec is known to eat spark plugs - go and buy four new plugs - they can be fine on idle and when out the engine sparing but fail under load 

 

AA guy fitted 4 new plugs.

 

2 hours ago, MarkBzero said:

My gut is also saying ignition, check leads Zetecs eat plugs and eventually cheap leads can break down under load especially when warmer. Even better borrow some off a good running engine, someone must live near you. 

New leads on order but AA guy did fit 2 new ones (all he had) and tested the other 2 and said they were OK. 

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Have you checked the vacuum hoses? May be a small leak causing miss timing at higher revs.

Not sure on Zetec what goes where but I had problems with silicone hoses getting small holes in them and making the engine run badly, have replaced all for braided types and all good.

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1 hour ago, MrToad said:

Have you checked the vacuum hoses? May be a small leak causing miss timing at higher revs.

Not sure on Zetec what goes where but I had problems with silicone hoses getting small holes in them and making the engine run badly, have replaced all for braided types and all good.

My Zetec is FI, no carbs...

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No air reference on the fuel rail pressure regulator? 

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2 minutes ago, richyb66 said:

No air reference on the fuel rail pressure regulator? 

Que? 🤔 - no fuel pressure gauge, if that's what you mean?

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There should be a vacuum line from the inlet to the fuel pressure regulator

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What he said. 

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Really? Balls, I've never had one of those...what is it supposed to do?

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