Problems with the idle

[warrensark]

Hi guys - complete newby here, so bear with me. hubby has the love of his life (apart from me, lol) has a MX5 1991 mk1, only of late it's developed intermittent probs with the idle. Anybody got any ideas on how to sort? When coming to a standstill, the revs are just under 2000, he goes to pull away - and nothing. three garages have looked and unable to find/sort the problem, our local dealer with the diagnostic simply wont return calls. the ignition and leads have just been replaced as the plugs and other maintenance etc - initially we thought the problem had been sorted but now it's playing up again - i now have one very unhappy hubby who is using the bus to work - def unhappy. Keep reading lots of 'what it could be' but as yet, nothing seems to be working - chances are, it's really simple - all thoughts on a postcard to .... no, seriosly guys, if there is anyone who can offer a glimmer of hope on the horizon as to what the problem could be, would really appreciate it

[maser_spyder]

Air flow meter?

[bluetone]

Info' here on how to get fault codes from the car, as your local dealer is not picking up the 'phone for a diagnostic check:

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[maser_spyder]

If you can't read the diagnostics from this method, just us a 'proper' tool.

http://cgi.ebay.co.uk/D900-OBD-OBD2-CAN-BUS-Univer...

Or something similar. You can get cheaper ones if you shop around.

Surprised the garage couldn't work out the fault from a diagnostics, it's normally very reliable?

[pmanson]

Ok.

Make sure the leads/plugs are ok

You could also try putting some carb cleaner through the intake to give it a good clear out (that helped mine).

The Idle Control Valve can cause similar symptons so if the carb cleaner doesn't work you've either looking at a replacement (£400 new from memory) or taking it off and cleaning it up properly.

Maybe give the guys at Boundville/Autolink a call - they are very helpful!

[warrensark]

y'know i knew somebody out there would have some kind of answer to all of this, will tell hubby of this which will hopefully put a smile back on his face - will let you know how he gets on - cheers x

[franv8]

maser_spyder said:

If you can't read the diagnostics from this method, just us a 'proper' tool.

http://cgi.ebay.co.uk/D900-OBD-OBD2-CAN-BUS-Univer...

Or something similar. You can get cheaper ones if you shop around.

Surprised the garage couldn't work out the fault from a diagnostics, it's normally very reliable?

The Op's car is a 1991 - which I can say with (relative) authority will be OBD1 - so this tool won't work.

MX5 parts do a £5.99 book with the required 12V LED (or order just a 12V LED from Maplin for less) - then just follow the simple instructions.

Sounds like it could be AFR related to me. I have a sticky idle valve and it doesn't have trouble pulling away (except when very cold!)

OP - other thing to 'try' is tweak the idle air, this is a large slot headed screw on the throttle body under a plastic cap (or not if it's missing) - try unscrewing it half a turn at a time with the engine running, although I wouldn't get the idle too high with the engine warm ( think it should be 850 rpm, but going to 1000 sometimes makes it a little more 'resilient' to stalling)

Hope this helps...

[mikey P 500]

i have a good working spare air flow meter for a 1.6 model, £20 posted if you want to give it a try.

[maser_spyder]

franv8 said:

maser_spyder said:

If you can't read the diagnostics from this method, just us a 'proper' tool.

http://cgi.ebay.co.uk/D900-OBD-OBD2-CAN-BUS-Univer...

Or something similar. You can get cheaper ones if you shop around.

Surprised the garage couldn't work out the fault from a diagnostics, it's normally very reliable?

The Op's car is a 1991 - which I can say with (relative) authority will be OBD1 - so this tool won't work.

MX5 parts do a £5.99 book with the required 12V LED (or order just a 12V LED from Maplin for less) - then just follow the simple instructions.

Sounds like it could be AFR related to me. I have a sticky idle valve and it doesn't have trouble pulling away (except when very cold!)

OP - other thing to 'try' is tweak the idle air, this is a large slot headed screw on the throttle body under a plastic cap (or not if it's missing) - try unscrewing it half a turn at a time with the engine running, although I wouldn't get the idle too high with the engine warm ( think it should be 850 rpm, but going to 1000 sometimes makes it a little more 'resilient' to stalling)

Hope this helps...

Well spotted that man - I wrongly assumed this unit would be backwardly compatible and it's clearly not.

Looks like the LED option is the way to go here then.

[bluetone]

franv8 said:

MX5 parts do a £5.99 book with the required 12V LED (or order just a 12V LED from Maplin for less) - then just follow the simple instructions.

linky