Jump to content

Pinto 2.0 EFi rough idle when cold


peter_m7uk
 Share

Recommended Posts

Hi All,

My Pinto 2.0 EFi idled absolutely fine when cold, until recently.  I used to start it and it would automatically rev at about 1200-1500 rpm until it warmed up a bit, then drop to 800rpm, nice and stable.  These days, I start it and it almost stalls, then the revs pick up for a few seconds, before it almost stalls again, then it finally settles into an 800rpm idle.

Once it's hot the idle is fine, so what's going on specifically when cold?  And where has my initial high idle speed disappeared to??  🤨

Thanks,

Pete

Link to comment
Share on other sites

Idle Air Control valve is sticking.

It is an electricaly controled valve that gives bypass air round the throttle body. (efectivly it changes the throttle stop by allowing more air post the butterfly valve, the ECU takes care of the petrol)

It is held on by 2 screws and has a single electrical connector.

Remove the 2 screws and spray carb cleaner into the body, refit and if I am correct the idle will be back.

Too much carb cleaner is better than not enough, 20 second squirt should do.

Link to comment
Share on other sites

4 minutes ago, IanS said:

Idle Air Control valve is sticking.

It is an electricaly controled valve that gives bypass air round the throttle body. (efectivly it changes the throttle stop by allowing more air post the butterfly valve, the ECU takes care of the petrol)

It is held on by 2 screws and has a single electrical connector.

Remove the 2 screws and spray carb cleaner into the body, refit and if I am correct the idle will be back.

Too much carb cleaner is better than not enough, 20 second squirt should do.

Hi Ian, thanks for the suggestion.  It's one thing I'd considered, but doesn't that valve work when the engine is hot as well?  My thinking was that, if it was the idle valve, it would always idle badly, not just when cold..   As it's pretty easy, I will have a look anyway.

Cheers

Link to comment
Share on other sites

  • 3 weeks later...

Thanks, but the idle valve certainly doesn't seem to be stuck, I'm inclined to look elsewhere before I consider a new one.  I will try measuring the voltages given on page 3 of Derek's article...

Edited by peter_m7uk
Link to comment
Share on other sites

  • 3 weeks later...

Update - I measured the coolant sensor voltage..  When cold, it was 4.4v.  Just after I started the engine, it actually rose above 5v.  Then when hot, it dropped to around 3.4v.

This is obviously pretty different to the 3.5v cold and 0.5-0.8v hot in the article above!  So I suspect that's the culprit, the voltages are way out of range. Now where do I buy a replacement??  Mine needs a spade connector, but a quick online search so far shows sensors with round connectors...  🤨

Link to comment
Share on other sites

Are you sure your looking at the right sensor? There's one in the cylinder head near the dizzy with a spade connection and one in the middle of the inlet manifold with the round connector. Cylinder head sensor is for temp gauge and manifold sensor is for efi.

Link to comment
Share on other sites

I checked my sensors recently after an unrelated fault in the injection manifold loom. I got ~4.4v cold and it turned out it was completely disconnected. You ought to rule out a wiring fault before replacing the sensor. Disconnect the multi plug on the sensor (on the inlet manifold between cyl 2 & 3) and measure the continuity/resistance of the wires to the ecu.

Edited by Grim
Link to comment
Share on other sites

  • 7 months later...

I measured the voltages, but they seemed to be about the right ballpark, so I left it for a while...   Now the engine won't idle at all, never mind when it's cold!   So probably not temperature-related and I've ended up ordering a brand new idle control valve for £35.  I opted not to clean, as I cleaned the existing valve before and it's plumbed in without a connection to the cam cover, fresh air intake only.  It's a 33 year old valve that had already done 100,000+ miles, so let's try a new one!  Fingers crossed that does the job, anyway  🤞

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...