Clonky Engine

[WonkyGibbon]

Hi There,

Every now and again - I hit a bit of a lack of power problem. The engine will tick over at idle unaffected, but when you put your foot down, next to nothing, then a wack when the engine kicks in, then a jolt when it kicks out. Somtimes it can go on for quite a while (ie: several miles - usually stopping when I reach my destination). It definately is not throttle pot as you can disconnect it and make no difference. I think the engine is being starved either of air or petrol. I've also noticed that it usally improves if I fill the tank up with reputable fuel and on one occasion started almost immediately after I went to one of the cheaper vendors (shall we say).

Assuming petrol, because its intermittent, I'm thinking maybe water is getting into the fuel somehow, or some crap from the tank is getting stuck in the jets ?

I just don't know - any thoughts ?

Thanks,

WG

[Barkychoc]

Obviously all guesswork - but airflow meters a possibility if you have them (Cat cars don't as I found out recently).
I think you can swap them over as I believe one meters the airflow and the other the temp of the air.

Fuel filter at the rear - any idea when it was last changed?

Maybe some kind of air leak on your air inlet side - though maybe not so likely if your idle is OK. Check your servo isn't rusted away underneath - what are the brakes like? If the servo is leaking they won't feel great.

Chris

[WonkyGibbon]

Barkychoc said:

Obviously all guesswork - but airflow meters a possibility if you have them (Cat cars don't as I found out recently).
I think you can swap them over as I believe one meters the airflow and the other the temp of the air.

Fuel filter at the rear - any idea when it was last changed?

Maybe some kind of air leak on your air inlet side - though maybe not so likely if your idle is OK. Check your servo isn't rusted away underneath - what are the brakes like? If the servo is leaking they won't feel great.

Chris

Thanks for this - its an S3 rather than an S3C so presumably has airflow meters. Will have to check the service records re: the fuel filter - no idea. When you say "servo" - I'm not sure which you mean ?> Surely not the brake servo ?

Thanks for your thoughts - much appreciated !

WG

[Barkychoc]

Yes the brake servo.
It works off the vacuum in the inlet manifold.
If the servo is leaking it is letting air straight into the inlet manifold and weakening the mixture.
I'm not so sure that it is this - I think your idling would be rough if it had a leak.

I'd try the airflow meters first.
I don't have the V6 but if the leads will reach just swap them over - you don't need to physically swap the airflow meters.

Another thought just sprang to mind - check the connectors on the fuel pump.

Chris

Edited by Barkychoc on Monday 3rd December 15:43

[WonkyGibbon]

Barkychoc said:

Yes the brake servo.
It works off the vacuum in the inlet manifold.
If the servo is leaking it is letting air straight into the inlet manifold and weakening the mixture.
I'm not so sure that it is this - I think your idling would be rough if it had a leak.

Wow - interesting, didn't know that. From your point earlier about the brakes though, they haven't changed in usage characteristics, so I'm guessing its not this.

Barkychoc said:

I'd try the airflow meters first.
I don't have the V6 but if the leads will reach just swap them over - you don't need to physically swap the airflow meters.

Another thought just sprang to mind - check the connectors on the fuel pump.

Chris

Given how intermittent it is - I may need to swap over for a week or so and then wait for nothing to happen (which is always fun !). I take it they can be left in this configuration ie: there's no significance to which is which.

If this turns out to be the problem - is it just a case of cleaning them up ?

Thanks,

WG

Edited by WonkyGibbon on Monday 3rd December 17:20

[Barkychoc]

I have to be honest with the airflow meters - I really don't know about repairs / cleaning.

[Harry1972M]

Regarding the air flow meters - all you can really do is check that the flaps are opening and closing easily and clean the wire sensor inside gently with a cotton bud and some carb cleaner.

Graham

[WonkyGibbon]

Car continued to splutter and clonk for most of the way home. Flipped the connectors to the two AFMs this morning and it ran pretty much perfectly. This isn't conclusive, as to prove it I need to swap them back - but it's certainly an indicator.

I shall probably try and take them apart to clean them at the weekend however one does that. Driving in London eveyr day, I could beleive they're covered in crap.

Cheers,

WG

[Harry1972M]

It is fairly straight forward to clean them - unclip your air filter, undo the 2 jubilee clips from the hoses, disconnect the wiring plugas and undo the 3 bolts on the bottom brackets and lift the whole assembly out - then simply check the operation opf the air flaps and gently clean the wire sensors you can see with carb cleaner and a cotton but or ten.

G

[WonkyGibbon]

Harry1972M said:

It is fairly straight forward to clean them - unclip your air filter, undo the 2 jubilee clips from the hoses, disconnect the wiring plugas and undo the 3 bolts on the bottom brackets and lift the whole assembly out - then simply check the operation opf the air flaps and gently clean the wire sensors you can see with carb cleaner and a cotton but or ten.

G

Great instructions - Thankyou !

[Barkychoc]

Could be worth investing - I know they are second hand but with a bit of luck at least one of them will be OK.

http://cgi.ebay.co.uk/Ford-Granada-Scorpio-2-9-Air...

Chris

[WonkyGibbon]

WonkyGibbon said:

Harry1972M said:

It is fairly straight forward to clean them - unclip your air filter, undo the 2 jubilee clips from the hoses, disconnect the wiring plugas and undo the 3 bolts on the bottom brackets and lift the whole assembly out - then simply check the operation opf the air flaps and gently clean the wire sensors you can see with carb cleaner and a cotton but or ten.

G

Great instructions - Thankyou !

Using Instructions as above managed to get the Air Flow Meter's out for a clean. The higher of the two was in good clean condition, the wire needed no attention, so I did no more than clean the excess grime out of the tunnels and off the flap with a bit of kitchen roll. The lower sensor had the wire covered in wet crud. So in addition to wiping the tunnel down I needed to get in there and clean that up. However because of the plastic protective assembly that surrounds the wire it is quite tricky to get into. Too narrow to really use a cotton bud. In the end I very gently used a toothbrush to loosen and move the crud around a bit and then some canned air to blast it out which was very effective.

Reassembly was reverse of dissassembly

As the fault was intermittent - only time will tell if this has fixed it - but all was running smooth this morning.

I suspect the crud is coming from the seal around the air filter which isn't quite snug around the bottom, which probably lets moisture in in wet weather allowing the cokey like crud to then stick to the wire.

Cheers,

WG

[ketvrin]

Have you got your engine breather pipe routed to the side of the air filter ? a great source of crud I think... I couldnt bring myself to poke a hole in a perfectly good new Pipercross filter just to dump hot oily air into the inlet system in front of sensors etc, so simply removed it and put a breather filter on the Cap out of the rocker box.

have a think about that...

[WonkyGibbon]

ketvrin said:

Have you got your engine breather pipe routed to the side of the air filter ? a great source of crud I think... I couldnt bring myself to poke a hole in a perfectly good new Pipercross filter just to dump hot oily air into the inlet system in front of sensors etc, so simply removed it and put a breather filter on the Cap out of the rocker box.

have a think about that...

Oh crap - you could well be right. Do you mean the pipe that comes from (I think) the side of the Oil Cap and down to (I think) the side of the Air Filter ? I noticed this but didn't think twice about it. The liquid fraction of the crap could well have been oil too. That said - I had a bit of a feel around in the rest of the air filter and that felt largely dry and clean (for an old bit spongey stuff).

WG

[ketvrin]

Yes and thats the standard setup and maybe thats the way it should be... it just didnt look right to me so I changed my setup. If you keep that setup then just make sure you keep cleaning the crud off the sensors...

your spongy filter should have a light oil impregnation anyway (filter oil...) so that might explain why it feels oily ? how old is it ?

K

[Barkychoc]

Its all down to emissions regs - the crankcase gases are fed back into the air filter to be drawn back into the engine.
I'd just vent the pipe down to the ground - you'll only have an issue if your engine is really tired, then you'll get some smoke out of it.

Chris

[WonkyGibbon]

Barkychoc said:

Its all down to emissions regs - the crankcase gases are fed back into the air filter to be drawn back into the engine.
I'd just vent the pipe down to the ground - you'll only have an issue if your engine is really tired, then you'll get some smoke out of it.

Chris

Right - I guess the overall effect on the intake air temperature is pretty marginal anyway.

Had to take her for a longer spin down to the other office today - it's the best she's run in the last 6 months, smooth as silk, pulled like a train.

Brilliant.

Thanks for all your help guys,

WG

[clarenceboddiger]

WonkyGibbon said:

Flipped the connectors to the two AFMs this morning and it ran pretty much perfectly. This isn't conclusive, as to prove it I need to swap them back - but it's certainly an indicator.
WG

Just a thought,Could be that it was a bad connection on the AFMs, only saying this as although all the muck would certainly be detrimental I wouldn't have thought it would be intermittent.

[Barkychoc]

The way these airflow meters work is a flap moves an electronic variable resistor - like the volume control on your hifi.
Ever had a crackly volume control?
Well what happens is there is a contact on a carbon track (or it can be wire / other materials but lets not make it difficult) that varies the electrical resistance as is moves along the track - the track can wear away and / or get dirt on it - or even have a break so it moves so far and nothing - then bang the resistance value changes suddenly when it passes the break (sound familiar?).
I'd say its possible that on your meter that was used to measure the air flow that the track has had it - swapping them over means you are now using a good meter with a good track for the airflow, and as the other meter only measures air temp you've got away with it.
I'd try and source a meter or two for the future as they come up on ebay or wherever as spares.

Chris

[WonkyGibbon]

Sorry - I should have said that I did swap the conenctors back. it occurs to me that the other reason that it may be running well is that with the current cold snap, the meters are just sending "its bloody cold" to the ECU thus giving the engine more juice than usual.

Presumably the flap (and associated variable resistor) measure the air flow then whilst the wire measures the air temperature. For those who are interested I found this on wikipedia (fount of all knowledge !)
http://en.wikipedia.org/wiki/Mass_airflow_sensor

Edited by WonkyGibbon on Wednesday 12th December 10:13