Mazda Rotary Club

General => General Technical => Topic started by: gavink on April 23, 2005, 06:49:51 PM

Title: very uneven idle
Post by: gavink on April 23, 2005, 06:49:51 PM
Hi...

my car has just developed a problem..on idle the revs hunt up and down from 1100 to 1600 rpm constantly..

It done the same thing a week back but fixed its-self...anyone got any ideas

gavin
Title: very uneven idle
Post by: kev-yorks on April 23, 2005, 06:58:51 PM
You could aways try a ECU reset if your running the stock one. Disconnect battery press brake pedal for 30 secs then reconnect. If that doesn\'t cure it check for any vac leaks (easier said than  done)
Regards Kevin
Title: very uneven idle
Post by: gavink on April 24, 2005, 07:21:40 AM
Thankyou for the help :)  running an apexi ecu though..

I did look for any pipes that were off, and there are a few matal pipes that have no pipes on them but they  dont look like they ever have had a pipe conected...why did they put SO many vac pipes !!!! there\'s bloody loads   :mad:
Title: very uneven idle
Post by: rx7veilside on April 24, 2005, 03:14:03 PM
any pipe that is pulling air in shd not be open to atmosphere if in doubt put ur finger over the end if there is suction then it shd be attatched somewhere
Title: very uneven idle
Post by: gavink on April 24, 2005, 04:51:22 PM
QuoteOriginally posted by rx7veilside
any pipe that is pulling air in shd not be open to atmosphere if in doubt put ur finger over the end if there is suction then it shd be attatched somewhere


Hi....


Ok today ive been trying to sort it out but im not getting anywhere...none of the hoses that are open to atmosphere either suck or blow ( ;) )..

Ive got a commander linked to my ecu so i can check all the relevent sensors\'s voltages etc...ive disconnected the tps plug,map sensor,ecu and cleaned all contacts etc but that made no diference....
Ive check the vac pipes for leaks and they all seem ok
Checked the vac hose to the brake servo - all ok...
I really dont think it can be an air leak as the problem has happend once before but fixed its self...

Im a little stuck with this one...dont really know what to try next..any ideas ??

thanks

gavin :)
Title: very uneven idle
Post by: rx7veilside on April 24, 2005, 05:19:24 PM
apart from idle is car loosing power i am by no means an expert but uneven idle is one syptom of loosing a tip.with prob like thise pay an expert an hours labor to diagnose as many problems have multiple symptoms..where are u located
Title: very uneven idle
Post by: gavink on April 24, 2005, 06:58:47 PM
QuoteOriginally posted by rx7veilside
apart from idle is car loosing power i am by no means an expert but uneven idle is one syptom of loosing a tip.with prob like thise pay an expert an hours labor to diagnose as many problems have multiple symptoms..where are u located


Hi there..

No no power loss and the car boost\'s fine...

Just bein doin some research and found that a faulty clutch switch can cause uneven idle - ill borrow a multimeter tomoz and check it...:)

If that turns out to be ok i may have to pop it to a specialist as you say...im in evesham (about 15 miles from worcs)
Title: very uneven idle
Post by: jonrx7uk on April 25, 2005, 11:52:35 AM
When i got my Apexi i had the same symptons.

Check the clutch switch is working using the Commander.  If it\'s not, take the clutch switch out (dead easy, 1 nut).  

The clutch switch spring can break.  I replaced mine with a ball point pen spring!

Solid idle afterwards :)

Cheers
Jon
Title: very uneven idle
Post by: gavink on April 25, 2005, 05:25:35 PM
QuoteOriginally posted by jonrx7uk
When i got my Apexi i had the same symptons.

Check the clutch switch is working using the Commander.  If it\'s not, take the clutch switch out (dead easy, 1 nut).  

The clutch switch spring can break.  I replaced mine with a ball point pen spring!

Solid idle afterwards :)

Cheers
Jon

Just checked the operation on the commander and its seems to be switching ok...What is port air control?
Title: very uneven idle
Post by: jonrx7uk on April 26, 2005, 01:26:48 PM
Port Air Control is when the ACV (Air Control Valve) directs some of the Air pump air into the exhaust (at certain oerating conditions).  To check if it is working okay, pull off the long 1" pipe that comes from the ACV to the air filter (runs alongside the 2nd turbo inlet pipe).  If you can smell exhaust gas something is wrong.  Do you think this has something to do with the surging?
Title: very uneven idle
Post by: gavink on April 26, 2005, 06:19:06 PM
QuoteOriginally posted by jonrx7uk
 Do you think this has something to do with the surging?



Maybe because on the commander it show it is switching on and off as the revs hunt...

Just took it up the road today and its a wright pig to drive..apart from the idle problem the throttle takes approx 1 second to shut off which is bloody dangerous and every time between gear changes  the revs go up approx 200rpm...
Title: very uneven idle
Post by: John Yorke on April 26, 2005, 07:28:21 PM
Time to get it to an expert
Title: Idle Speed Adjustment
Post by: jonrx7uk on April 27, 2005, 09:42:33 AM
Did you wind the screw in under the inlet elbow when you fitted the PFC?  I had to do this as the idle was all over the place.  I wound it all the way in, and then back out about 1 full turn.  Took a few goes before i got it right.

The port air will switch on and off as the revs rise/fall.  Normal IIRC

Cheers
Jon
Title: very uneven idle
Post by: gavink on April 27, 2005, 05:14:21 PM
Thank you for the info there jonrx7uk :)

No i have not touched any idle screws etc as having the PFC pluged in made no difference...

Anyway last night i stripped the plenum off and have found a split in the upper intake gasket,hopefully this was what was causing the problem...

Now to my next problem...are all mazda dealers  F**king useless ?

I rang them up with the part numbers (also want an intake temp sensor as this seems to read all over the plaice) but they want the chassis number...i go find it them ring them back..nope the system dont reconice that chassis number !! well thats what it says on the v5!!...Now that was at 9.30 this morning..they were supposed to be ringing me back within an hour !! well its now just gone 5pm ffs.......Sorry rant over :)

Where else can i order gaskets from ? can one of the specialists from this forum help?

thanks

gavin...
Title: very uneven idle
Post by: jonrx7uk on April 28, 2005, 11:57:37 AM
WGT got me my last UIM gasket.  Give them a ring, they may also have a 2nd hand temp sensor.

Glad you traced the problem.

Cheers
Jon
Title: very uneven idle
Post by: gavink on April 28, 2005, 08:08:04 PM
Ok well decided i would make a new gasket out of gasket paper to see if it fixed the fault...

Nope the bloody thing still hunts!!!   1000rpm upto 1750ish rpm then back down again constantly...when first started it also has a very fast idle speed of approx 2600 rpm...Now im not stupid when it comes to cars (been a mechanic for 9 years) but this has got me stumped....all sensors are reading fine on the pfc..

Even when driving it in first for example at 1000 rpm without touching the throttle it accelerates to 1750 ish rpm then drops back to 1000 etc etc..

It must have an air leak but where from i dont know... lower intake manifold gasket possibly but what a **** of a job that looks !!!!!

Think im going to drive about 20 miles away from home then ring the AA and get it taken somewhere....i dont like admiting defeat so any ideas would be great....:confused:

thanks

gavin....
Title: very uneven idle
Post by: Stu.Wilson on June 10, 2006, 06:01:08 PM
Hi Gavin i know this might be to late, but i have had the same problem on my car recently and it turned out the be the Air pump, as i don\'t run a cat i have just unplug\'d it and hey presto job done.

Hope you got it fixed though, if so what was it?

Cheers Stu
Title: very uneven idle
Post by: johnf on June 10, 2006, 06:58:27 PM
I had an eratic idle that turned out to be as simple as a plug lead arcing.

John