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        General >> Problems >> Strange idle
        
(Message started by: tintin on Sep 2^nd, 2006, 10:36am)

Title: Strange idle
Post by tintin on Sep 2^nd, 2006, 10:36am

ok, having survived the plug blowing up, here is the ongoing problem with my engine.

when i start the car, the idle jumps to 1300 rpm then after a few seconds drops to 900. i drive around, and when i stop and put it into N/P it jumps up higher (the longer its drive, the higher it goes, the highest so far has been 1900 rpm). after 10 seconds it drops straight back down to 900rpm, sometimes there is a click, but may be unrelated. the drop is like the ECU is making a decision and dropping it, not like a sticky cable, as its always the same amount of time to drop, and doesnt drop gradually but all of a sudden.

this started happening after a garage replaced the Fuel Pressure Regulator, and i asked them to check the IACV (because the idle was 800rpm but lumpy)

i have replaced with IACV with another one, cleaned the MAF, checked the acc. cable, had a scan with scorpioman, and we are stumped.

whats next to check? unmetered air loss? cats/manifold/sensors?

Title: Re: Strange idle
Post by Malcolm73 on Sep 2^nd, 2006, 1:23pm

Our sons Ford Focus had an idle poblem with increasing and erratic idle speed. I cleaned the MAF and the IACV which was dirty but this did not cure the problem. Yesterday a garage replaced a faulty rubber hose (1076244) and the problem is now cured. I would have 'phoned the garage to find which particular hose this is but they are now closed, however someone may be able to identify the part number.

73's Malcolm

Title: Re: Strange idle
Post by Eric_R on Sep 2^nd, 2006, 1:52pm

TinTin,
The Idle monitoring certainly seems out of synch. This can be caused by reconnecting the battery while the ignition is switched on. The Throttle Position Sensor (TPS) can also lose its static setting and can cause problems like this. (see http://www.fordscorpio.co.uk/obd2scan9.htm) This may show a P0122 error code, but not always.

As a start, force a system reset by disonnecting the battery for 30 seconds. Make sure the ignition is 'off'. Be prepared for poor running for a while while the system recovers its fuel trims and you can help this by giving it a short run for a few miles.

If the problems persist, then it wasn't that. Check for DTCs again. A racing idle can be caused by an unmetered air leak, so check the air inlet trunking carefully, as well as the vacuum system pipes, the EGR, and make sure that electrical connections to the engine sensors are tight; they may have been disturbed during the work.

If that hasn't sorted it, get back to us. If you can meet with Scorpioman again I can suggest some RT scans to do.

Title: Re: Strange idle
Post by tintin on Sep 2^nd, 2006, 3:25pm

Hi Eric,

Yep, had done a scan with Andy after the FPR which showed that problem was fixed. We checked the TPS and it was normal. No error codes (apart from a post-cat sensor....).

I have been avoiding disconnecting the battery as the last time i had it done the stereo locked out with a 10+ code ??? had to get it reset by a stereo company. however may have to bite the bullet.

engine sensors? can you be more specific, im not an expert on these, but should be able to check them if pointed in the right direction

Andy, any chance of another meet-up next weekend and scan, maybe look at the EGR?

cheers

Title: Re: Strange idle
Post by scorpio_man on Sep 2^nd, 2006, 5:02pm

hi sam

next weekend should be fine.

hth

Title: Re: Strange idle
Post by howiedintheplace on Sep 2^nd, 2006, 9:21pm

My favourites to check would be:

Air leaks (that T conector for one)
Could be a split pipe etc as they have been messed with recently.
EGR system
clean the idle valve
& the ECU temp sender.
Oh & get it scanned of course ;)

Title: Re: Strange idle
Post by tintin on Sep 3^rd, 2006, 6:06pm

Andy, email sent, i cant host pics, but i suspect Geoff might be interested if you can post them....

Howie, yep gonna get a scan, check EGR and pull octopus off to see if there are any leaks. interested in the electrical side of things, what is this ECU temp sender you speak of? and where do i find it? i know there are a few on the cossie....

the drop seems to be regularly 10 seconds after stopping, and straight down not gentle, more electrical than mechanical.

have noticed it also "drops" when in gear and stationery, just that as its in gear the revs dont change the car just sits down as its not trying to get away

thanks for everyones help, btw

Title: Re: Strange idle
Post by howiedintheplace on Sep 3^rd, 2006, 8:55pm

Well if you look at this pic it's the white sensor
http://i20.photobucket.com/albums/b228/DavidHoward/Scorpio/TT280008-1.jpg

It gives a water temp reading to the ECU, if cold it revs higher, a faultly one will fool the ECU for a bit, could be somthing to do with that but it does sound like a air leak at the moment.

Title: Re: Strange idle
Post by tintin on Sep 9^th, 2006, 3:49pm

Hiya,

ok, as everyone seems to be having idle problems at the moment, i thought i would give you all an update. Just had a scan again, more codes >:(

Pre-cat sensor B2 is coding both too rich and too lean ???
Pre-cat sensor B1 is coding too rich

Interestingly, the Inlet Air Temp is reading 150F (internal computer reading 50F), which seems very high, and perhaps telling the ECU to do something strange. Andrew and I are fairly sure this is an electrical problem, due to the regular 10 sec then drop. Does anyone know the correct IAT reading, and could a faulty one read high? I need to get a 10mm thin socket so i can take the lid off and see if the darn thing is even plugged in after the FPR was done.....

Any thoughts appreciated, andrew is checking the scans and im sure will post anything i missed :-[

Title: Re: Strange idle
Post by scorpio_man on Sep 10^th, 2006, 2:00pm

hi sam

had a look at all your scans. your car is running +200/250 rpm at idle. :( i wonder if the settings on the throttle body have been touched? :-/ i'd do a battery reset. see if anything alters.

you still need to look at the iat. might need replacing.

have a look at the wiring/plugs to the lambda sensors. just to confirm they're ok.

let me know how you get on.

Title: Re: Strange idle
Post by tintin on Sep 26^th, 2006, 8:14pm

hi all, update time,

cars back from the garage, o/s wishbone and n/s droplink done, steering is tight again and no clunks, but still pulling to the left >:(

for the sticky idle, they fitted the s/h AIT sensor and cleaned/fitted the throttle body (they wouldnt grind off the screws for me), no difference. they checked the trunking on the octopus and found the last garage had fitted it on trapping the rubber >:( new rubber and the car is idling more smoothly, but the idle is still "sticking" at 1500 rpm then drops to 900 rpm after 10 secs.

at least that lot only cost me £130 for the labour (and new rubber) !

any other ideas?

Title: Re: Strange idle
Post by tintin on Jan 31^st, 2007, 8:05pm

ok, it only took 6 months, but i think Highlander has got to the bottom of my strange idle. the IACV was on back to front !!! i am surprised it fits the wrong way, and even more surprised that the car didnt throw a complete wobbly...

so, if you have a high and "sticky" idle, and have had the IACV off, this is worth a check. mine was fitted back on incorrectly by a garage >:(

Andy, Bruce, im saying nothing.... ;D

Title: Re: Strange idle
Post by twinturbo on Jan 31^st, 2007, 8:43pm

Is that the same garage that made a pigs ear of the VAC system?

TT

Title: Re: Strange idle
Post by tintin on Jan 31^st, 2007, 9:49pm

yup >:( see the first post, i asked them to also check it, i guess they did..... :D

at least the FPR seems to be holding ;D