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Poor Tickover Problem

 
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tommosredone
SD1 User


Joined: 28 Feb 2007
Posts: 100
Location: Mold North Wales

PostPosted: Wed Jan 09, 2008 7:11 pm    Post subject: Poor Tickover Problem Reply with quote

Hello dears, and Blwyddyn Newydd Da, or Happy New Year!
I have a problem that has just presented itself on the Vitesse:
Starts fine, but when cold, runs VERY rich and lumpy. Will stall instantly if left to idle. A bit of throttle and it'll clean up around 2500/3000 rpm. During warm up, coasting off throttle, as it slows to around 1000/1500 rpm, an awful jerking sets in. Small throttle application cures the jerk.
When fully warm, tickover varies between 0 - 450 rpm. It mostly just cuts out, so I have to drive carefully in traffic. Tickover used to be EITHER like this, or fine, at about 650 rpm (it had two distinct running modes!).
I'm thinking CSI could be staying on, could that be possible? Apart from this, she's been going REALLY well!
During the really cold weather, start-up has been (and always is). Could the thermotime sensor have gone dud, causing CSI to run, or possibly AFM giving dodgy temp readings?
Any help welcomed before I start swaping things around (which I'm loath to do, as it's the best she's run since I've had her!!!
Cheers,
Tommo

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ramon alban
SD1 Regular


Joined: 14 Feb 2006
Posts: 478
Location: Bedford UK

PostPosted: Wed Jan 09, 2008 8:05 pm    Post subject: Re: Poor Tickover Problem Reply with quote

Goodness Me Tommo, you are in another Irish (Welsh) stew!

tommosredone wrote:


Starts fine, but when cold, runs VERY rich and lumpy.

Do you know its a RICH problem by checking condition of spark plugs? If yes, think about all the possibilities that can make the system run VERY rich.

* Broken component or wiring to Temp Sensor.
* Ditto Throt-pot - particularly if badly worn carbon track.
* Thermotime switch faulty if not opening its internal contacts.
* CS injector weeping.
* Pressure regulator not responding to manifold vacuum due to broken membrane or leaking vac pipe.
* AFM flap sticking open causing random overfuelling.


Will stall instantly if left to idle. A bit of throttle and it'll clean up around 2500/3000 rpm. During warm up, coasting off throttle, as it slows to around 1000/1500 rpm, an awful jerking sets in. Small throttle application cures the jerk.

Clearly unstable mixture problems as the engine is unable to cope. Air leaks can also be a reason for unstable idling, and this is not due to being rich, but uncontrolled mixture caused by rogue air getting into the plenum.

When fully warm, tickover varies between 0 - 450 rpm. It mostly just cuts out, so I have to drive carefully in traffic. Tickover used to be EITHER like this, or fine, at about 650 rpm (it had two distinct running modes!).

Two running modes tends to indicate an intermittant fault, which is more often than not down to wiring or electrical connection probs.Components do not normally go intermittant. Except perhaps the ign amp and ECU.

I'm thinking CSI could be staying on, could that be possible? Apart from this, she's been going REALLY well!

Probably not - as the engine would be totally flooded and would not run at all.

During the really cold weather, start-up has been (and always is).

What?? is this an Irish (Welsh) thing??

Could the thermotime sensor have gone dud, causing CSI to run,

See Above

or possibly AFM giving dodgy temp readings?

No.



Unfortunately, all the above questions and answers represent the classic "scattergun approach" to fault finding.

But we can do better than that.

Read the component descriptions, follow a structured test schedule and "Presto" you will be running again in no time.

And remember that the vast majority of all Efi system faults are due to Wiring/Connector and Air Leak problems.

Happy Days

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tommosredone
SD1 User


Joined: 28 Feb 2007
Posts: 100
Location: Mold North Wales

PostPosted: Thu Jan 10, 2008 1:18 am    Post subject: Reply with quote

Nice work Ramon!
She was playing up on the way home, so I pulled up and had a fiddle about (in the dark and rain!). Pulled the wires off the CSI, and no change in engine note, so that's off the list. Had a wiggle of the TP wires (I've put on an RS jobbie, and the wiring was not great) and it settled down to a nice tickover (still stone cold though at this point). Didn't stall once on way home, though I did have to keep an eye on the pedal just to make sure. I think this weekend I'll try and investigate the TP wiring.
AFM, FP Reg are all known good, as is ECU. Temp sensor is new too. I've got almost all spares to substitute, so should be easy.
This has only started since I changed the plug leads... (back to the old scattergun again, eh??)
Cheers,
Tommo
PS Sorry about the typo; she ALWAYS starts on the button I was trying to say!
Just thinking about the jerking off load; I bought a Rangie ECU for a fiver a while back, and that gave me that symptom, so I shelved it and got one off Hugh Chambers which has been fine. He did say that there were (possibly) three distinct warm-up phases, and he always checks his ECU's through the warm-up cycle to ensure no hassles. Does this make sense?
It's an easy job to put my old one back in I suppose!

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ramon alban
SD1 Regular


Joined: 14 Feb 2006
Posts: 478
Location: Bedford UK

PostPosted: Thu Jan 10, 2008 3:23 am    Post subject: Reply with quote

Nice Work to you to Tommo.

[quote="tommosredone"]Nice work Ramon!
She was playing up on the way home, so I pulled up and had a fiddle about (in the dark and rain!). Pulled the wires off the CSI, and no change in engine note, so that's off the list. Had a wiggle of the TP wires (I've put on an RS jobbie,

Regarding the RS unit, bear in mind they are not hermetically sealed so unless you specifically do something about that they have a shorter life as a result.

Para #2 Page 9 on the Throt Pot PDF here:

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and the wiring was not great) and it settled down to a nice tickover (still stone cold though at this point). Didn't stall once on way home, though I did have to keep an eye on the pedal just to make sure. I think this weekend I'll try and investigate the TP wiring.

Check all the wiring/connectors while you are at it

AFM, FP Reg are all known good, as is ECU. Temp sensor is new too. I've got almost all spares to substitute, so should be easy.
This has only started since I changed the plug leads... (back to the old scattergun again, eh??)
PS Sorry about the typo; she ALWAYS starts on the button I was trying to say!

Yup, I alway find my lack of clairvoyance a big problem - tee hee.

Just thinking about the jerking off load; I bought a Rangie ECU for a fiver a while back, and that gave me that symptom, so I shelved it and got one off Hugh Chambers which has been fine. He did say that there were (possibly) three distinct warm-up phases, and he always checks his ECU's through the warm-up cycle to ensure no hassles. Does this make sense?
It's an easy job to put my old one back in I suppose!

Ah Ha, the old RR vs Vitesse ECU conundrum. Read this and decide for yourself. As Dirty Harry says - "Do ya feel lucky?"

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[quote]

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kerosene
SD1 Regular


Joined: 21 Dec 2006
Posts: 266
Location: IRL

PostPosted: Sun Jan 13, 2008 3:28 am    Post subject: Reply with quote

FAO Ramon


Ramon Alban wrote:
you are in another Irish (Welsh) stew!

What?? is this an Irish (Welsh) thing??


Another cheap dig eh ramon? Laughing sad
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