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Chris Broster - Bristol & Bath AO

Wild idle on Zetec Blacktop

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Chris Broster - Bristol & Bath AO

Hello collective brain,

 

I am struggling to get this pesky westfield  back on the road after my fuelling/ignition issues.

 

 I too had this fault with my 1.8 Zetec - died on track at Castle Coombe - fixed in pits then spluttered on track so binned it.

ed on track so binned it.  Sadly died again and had to be recovered home 

 

After checking all electrics and fuel etc etc worked again? But then failed on M5 heading to Stoneleigh....

 

Same thing as you with spluttering and coughing then run down.

 

I did however find that one bolt from the throttle linkage mounting was missing on the ITB and this was causing the linkage to swing when accelerator pushed. Great service from Jenvey - replacement free and next day delivery.

 

I have now...

Replaced fuel pump with new Walbro one from Glencoe - Speak to Terry, great service https://www.glencoeltd.co.uk/  (Actually, higher spec for less)

Fitted new Sytec in-line fuel filter - again from Glencoe

Replaced all hoses with new Cohline fuel lines - Glencoe

Checked all relays are working when and how intended - pre-ignition and ignition 

Checked all fuses

Checked all Earth connections - removed, cleaned and refitted.

Refitted vacuum pipe to Fuel Pressure Regulator

Replaced all spark plugs and checked for spark etc

Checked injectors are firing ok.

The result so far is that the car now starts and runs but is currently ticking over at 3000! This has been adjusted down from 4000 by winding in the throttle cable seat (result of reattaching the throttle linkage).

 

So now it is firing again my remaining issue is that on start it races up to 3000 rpm and if I blip the throttle or accelerator pedal it rises but then settles back at 3000?

 

Engine is 1.8 Zetec Blacktop with Jenvey ITB and MBE ECU.

 

I have tried winding the throttle cable to absolute slack and no joy.

 

I tried, gently, lifting the throttle linkage back to try to 'back it off'. The best this did was drop revs by 200? As soon as took pressure off it went back to 3000 plus?

 

I’ll try to upload video of start, revving and fall back to idle.

 

I haven't messed with ECU since it was mapped at InterPro in April.

 

The only thing I think of left to check/change is Throttle Position Sensor.

 

Anyone  got any experience, ideas, Jenvey set up instructions or 'how to set idle guides'?

 

Cheers Chris

 

 

 

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Geoffrey Carter (Buttercup)

I don't understand engines but I had a similar issue with my revs for a couple of days.

 

I had a spring on my throttle cable return that was missing.

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Chris Broster - Bristol & Bath AO

 Cheers Geoffrey 

Don't suppose you have a before and after pic? 

Chris 

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Geoffrey Carter (Buttercup)
15 minutes ago, Chris Broster - Bristol & Bath AO said:

 Cheers Geoffrey 

Don't suppose you have a before and after pic? 

Chris 

 

I am on bike carbs but not sure if you would have a spring or not.

 

 

IMG_5297.JPG

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DamperMan

Reconnected Vacuum pipe to fuel regulator??????    I believe the regulator should be open to atmosphere on naturally aspirated engines.   The pipe tail is only connected with turbo/ supercharged engines as it allows fielding to be increased with boost pressure. 

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Kit Car Electronics

Chris, this should be quite simple- no matter what fuel or spark you have, the engine won't idle at 3000 unless you have air, and quite a lot of it. So you're looking for throttles that aren't shut, a throttle bypass channel that's open or a leak to the intake manifold. 

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ainsworth

Hi

 

I had a worn and fraying accelerator cable with the broken strands catching on the sleeve going through the bulkhead wall. That made mine idle at 3000 revs because the cable was not retracting enough.

 

So might be something simple to check.

 

 

 

 

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Chris Broster - Bristol & Bath AO
1 hour ago, DamperMan said:

Reconnected Vacuum pipe to fuel regulator??????    I believe the regulator should be open to atmosphere on naturally aspirated engines.   The pipe tail is only connected with turbo/ supercharged engines as it allows fielding to be increased with boost pressure. 

Ok will disconnect again and retry? 

 

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Chris Broster - Bristol & Bath AO
47 minutes ago, Kit Car Electronics said:

Chris, this should be quite simple- no matter what fuel or spark you have, the engine won't idle at 3000 unless you have air, and quite a lot of it. So you're looking for throttles that aren't shut, a throttle bypass channel that's open or a leak to the intake manifold. 

Aye that’s what I thought, but butterflies appear closed? I’ll get a torch shone down there and retry? 

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Chris Broster - Bristol & Bath AO
33 minutes ago, ainsworth said:

Hi

 

I had a worn and fraying accelerator cable with the broken strands catching on the sleeve going through the bulkhead wall. That made mine idle at 3000 revs because the cable was not retracting enough.

 

So might be something simple to check.

 

 

 

 

Hadn’t thought of that so will get down and check full run of cable. 

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the stoat

I also found a lack of lubrication on the cable can cause this.  It is amazing how little throttle opening is required to have a high idle. 

 

Can you easily disconnect the throttle cable to test?

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Trevturtle
On 07/07/2019 at 21:11, Kit Car Electronics said:

Chris, this should be quite simple- no matter what fuel or spark you have, the engine won't idle at 3000 unless you have air, and quite a lot of it. So you're looking for throttles that aren't shut, a throttle bypass channel that's open or a leak to the intake manifold. 

As said above.   3000 rpm means air is getting in.

If the throttle butterflies are all closed (check them all the left and right hand pairs may be out of balance ) the remaining options are 

1. Throttle  bypass  air bleeds.   On top of each throttle body

2. Leaking inlet manifold 

 

It will not take much opening  of the butterflies to get 3000rpm will no load

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Chris Broster - Bristol & Bath AO

@the stoat and @Trevturtle

 

Thanks again.

 

Plan for tonight is to:

  1. Disconnect Throttle cable and test
  2. Lubricate throttle cable at pedal, pedal box bulkhead, throttle linkage
  3. Lubricate all of Jenvey throttle linkage
  4. Clean internals of throttle body trumpets - some soot deposits in 1&3
  5. Cover/block and test throttle bypass bleeds
  6. Try to check Manifold air tightness??? not sure how but worth a try?

Stand by for feed back - if it fixes it you'll hear me whooping!!!! if not then I'll be crying into my air filter!

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the stoat

To test for leaks in the inlet spray the outside with something flammable like carb cleaner, if the revs rise you have a leak and if they don't there is no leak.

 

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Trevturtle
3 hours ago, Chris Broster - Bristol & Bath AO said:

@the stoat and @Trevturtle

 

Thanks again.

 

Plan for tonight is to:

  1. Disconnect Throttle cable and test
  2. Lubricate throttle cable at pedal, pedal box bulkhead, throttle linkage
  3. Lubricate all of Jenvey throttle linkage
  4. Clean internals of throttle body trumpets - some soot deposits in 1&3
  5. Cover/block and test throttle bypass bleeds
  6. Try to check Manifold air tightness??? not sure how but worth a try?

Stand by for feed back - if it fixes it you'll hear me whooping!!!! if not then I'll be crying into my air filter!

Apologies for the dumb/ insulting question  ...☺️  @Chris Broster - Bristol & Bath AO

You have tried turning the idle screw down?  Its in between the centre 2 throttle bodies..  I can send a picture of it if it helps.

 

Sorry if you've  done  this already And i missed  it

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