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Lumpy idle and misfire

Started by SteveBB, March 29, 2018, 16:24:25 pm

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SteveBB

March 29, 2018, 16:24:25 pm Last Edit: March 29, 2018, 16:28:31 pm by SteveBB
This is a problem that is elusive but we don't want to throw money at it due to its age. We have a 2001 Ford Taurus (Basically the US version of a Mondeo of the same year but with a 3 litre V6 transverse lump in it). My missus has owned it since new and its pretty much been a reliable means of transport. Recently on start up the idle has had it running on five pots for about 30 seconds-minute until the cold choke has clicked off and it then settles down to the usual balance shaft assisted V6 imperfect smoothness. Being California spec it has tubes and pipes everywhere to comply with emissions; Essentially anything that could leak oil or petrol vapour into the atmosphere goes through the combustion process.

There's a pair of rubber elbows that connect to a couple of sensors and a diaphragm via pipes (I think vacuum) and over the years one has suffered the ravages of heat and cracked (replaced recently) the other has swollen, loosened up and the pipes going into it causing air leaks. Both go into the inlet manifold.

I've 'bodged' the loose one by putting heat shrink tube on the two rigid plastic pipes going into it at the bottom and cable tied it to the spigot on the manifold. (This particular part Ford no longer makes and without knowing it's name, I don't know what to look for as a copy-Its year specific, 2000 and 2002 are different)

I thought this would cure the issue, and for a couple of days it idled beautifully from cold. Success!!

But it doesn't seem to be the case, and its gone back to rough cold start and wasting fuel. The two elbows are tight but I'm now wondering if that was the right direction to be looking. Herself took it to her pet mechanic last week and he put it on the diagnostics which says "Recommend start with ignition wires (HT leads)" It has a coil pack rather than distributor and the rear three pots (and plugs) are a complete bitch to access needing to remove the inlet manifold.

I popped into the local car spares place yesterday and he suggested holding off buying a new set of leads as he wasn't sure it was the problem. I too am not convinced as if it was an ignition problem (On one or more cylinders) wouldn't the ignition get worse under load rather than smooth out after warming up?

Anyone have any ideas? A new set of HT leads is about 30 quid but you can appreciate that I don't want to throw money at it.

Thanks in advance.  :)
Rimmer: Step up to Red Alert!
Kryten: Sir, are you absolutely sure? It does mean changing the bulb.

PDR

The only thing that springs to mind would be that it's almost certainly an air leak somewhere, and that you'll need to find someone who really understands the actual details of the emissions mitigation stuff on the specific car. I'm reliably informed that ageing Californian cars are just a pain in the butt in that regard. I'm told that you'll need to find your nearest Taurus Whisperer!

But as an aside - I'm sure Lumpy Idle & Misfire was a satirical improv theatre trio I saw at the Fringe last year? They did a Brexit sketch called "big end gone" or something...

PDR

There are no shortcuts on the long, hard road to success. But if your dad's rich there could a limo service...

SteveBB

Quote from: Alan Smithie on March 30, 2018, 14:15:17 pm
The only thing that springs to mind would be that it's almost certainly an air leak somewhere, and that you'll need to find someone who really understands the actual details of the emissions mitigation stuff on the specific car. I'm reliably informed that ageing Californian cars are just a pain in the butt in that regard. I'm told that you'll need to find your nearest Taurus Whisperer!

But as an aside - I'm sure Lumpy Idle & Misfire was a satirical improv theatre trio I saw at the Fringe last year? They did a Brexit sketch called "big end gone" or something...

PDR


Cheers for that Pete, your research is appreciated. I had a feeling it could be in that vein but frankly its a nightmare unless you know what you're looking for and what you're doing.


As for the improv trio, they're doing a three night 'revue' here in Sacramento, entitled "Old Fords, and how to make them into your new home"..They're hoping to appeal to the local homeless population who will get concessionary tickets in exchange for a small amount of crack or a long draw on a bong. 
Rimmer: Step up to Red Alert!
Kryten: Sir, are you absolutely sure? It does mean changing the bulb.

keithl

Give the HT leads a wipe with a rag soaked in WD40.  If the problem goes away for a week or so before returning, then that is your problem.
Warning: objects in the mirror may be close than they appear (or I'm creeping up on you from behind)

pheasant_plucker

If the idle is lumpy from cold I would check the idle air valve which is usually located on the throttle body. It's sole function is to allow more air in to speed up the idle from a cold start. These are normally reliable but can get clogged with carbon. A good clean out will probably make a huge difference.

Gerry
Senior Administrator

The man serving me in the canteen said "Look, You can see the face of Jesus in the Margarine" The Asian guy next to me replied "I can't believe it's not Budda"

SteveBB

Quote from: pheasant_plucker on April 04, 2018, 14:12:45 pm
If the idle is lumpy from cold I would check the idle air valve which is usually located on the throttle body. It's sole function is to allow more air in to speed up the idle from a cold start. These are normally reliable but can get clogged with carbon. A good clean out will probably make a huge difference.

Gerry



We popped out to get a can of carb cleaner and I took off the flex hose to the throttle body and it didn't seem too bad (Car has done 175000 miles) but I sprayed some in and wiped out the bit of dirt in there...which is when I noticed a label stuck to the side of what looks like a sensor (metal cylinder shaped on side of throttle body) "Do not use cleaner on throttle body as it has a special coating"; Suspect a teflon type coating... Oh well... :banghead:
Rimmer: Step up to Red Alert!
Kryten: Sir, are you absolutely sure? It does mean changing the bulb.

The Saint. (Owen)

 ;D ;D ;D Sorry but I couldn't help it. ;)
Electrickery is the work of the devil.
Proper aeroplanes are powered by engines.

SteveBB

Quote from: The Saint. (Owen) on April 04, 2018, 16:23:21 pm
;D ;D ;D Sorry but I couldn't help it. ;)


Yeah, it's easy to laugh Owen, herself will be laughing like a drain if it's made it worse... The extra fuel its burning would have paid for a new car.
Rimmer: Step up to Red Alert!
Kryten: Sir, are you absolutely sure? It does mean changing the bulb.