I give up!! Au missing at idle drives ok.

[bellagirl67]

Hi just wondering if anyone can help me. My AUII is missing at idle in gear and out. When I slow at the lights and it changes back to first it gives a shudder and the idles drop to about 400rpm. It doesnt do so every time but 60 percent of the time. Someone suggested it was the idle step up motor which I have had replaced( the car idles in gear at 500 to 600rpms) it has made no difference at all except idling in gear is a bit higher. We have done plugs, leads (just had the fuel regulator replaced cos it was overfueling).The longer you sit waiting at lights etc the worse the miss gets but normal driving the car is fine. Fords have said they cant find anything wrong. I dont know what else to do!

[FGII-XR6]

have the mechanics pluged in the diagnostic scanner?
there should be a fault code showing up. might be the map sensor but at $150 + you don't want to change it unless you know

[ratter]

A vacuum leak will normally only show up at idle, check your inlet manifold gasket for leaks or even just vacuum lines fallen off/broken

[LPGUTE]

have u gave throttle body and ISC a very good clean?

[bellagirl67]

Thanx everyone for the info I will have hubby onto it this weekend. And yes Ford have plugged it in and says theres nothing wrong and everything is within specifications. :

[TheSneakiness]

Would the O2 sensor cause any of these problems? I would think especially with a previous overfueling issue that the sensor could be shagged.

Which reminds me... I must get that replaced.

[Chippar]

Here is an answer from a mechanic to a question asking whether a faulty oxygen sensor could cause poor idling;

Oxygen sensors read the fuel mixture in the exhaust and send the information to the computer. The computer then adjusts the fuel mixture. By not replacing faulty oxygen sensors, you can expect erratic idle and poor running. Your car probably will not quit running but there could be damage to the catalytic converter

I don't know how many K's you car has travelled, but it wouldn't hurt to fit a new oxygen sensor anyway. You've nothing to lose and they do have a use by date.

[FGII-XR6]

Originally Posted by The_Axe

Would the O2 sensor cause any of these problems? I would think especially with a previous overfueling issue that the sensor could be shagged.

Which reminds me... I must get that replaced.

faulty O2 sensor would show up on the scan tool

[GK]

What about cleaning the throttle body?

Cleaning Throttle Body
http://www.fordforums.com.au/showpos...2&postcount=48

GK

[HLC]

mine is teh same.

ive done leads, plugs, ISC, throttle body, reset ecu and base idle, but still idles sh/t. drives good though.

[chrispie123]

mines the same also reversing out of drive way and slight steer it shudders when just idling out and pull up at lights a vibration,

[ef_classic]

Originally Posted by HLC

mine is teh same.

ive done leads, plugs, ISC, throttle body, reset ecu and base idle, but still idles sh/t. drives good though.

Fuel pump, fuel filter, injectors???

[5tumpy]

Hahaha... Seems like one of those phantom AU problems...


I have the exact same thing... Tried everything! Even replaced all my injectors...

[Eu-GenixX]

mine only started doing that after i used the flash tuner... car runs like a dream tho.. seems to be doing it less and less tho

[sly]

Originally Posted by au3xr6

faulty O2 sensor would show up on the scan tool

Should it also trigger the engine warning light in the instrument cluster? I've been chasing an AU phantom for ages, have noticed that idle smells rich ATM. Just disconnected the HEGO (O2) sensor altogether and the car starts and runs exactly as per usual. The $15K Korean s**tbox I used for a work car 10 years ago had the "stop engine" light come on when the "servicing" dealer left its HEGO sensor disconnected.

Would someone mind disconnecting their O2 sensor long enough to run their car up to operating temp and post back what happens?

TIA,
Tony.

Are the grounds ok?

[sly]

NFI. How do I check them?

[sly]

On second thoughts... a grounding problem would cause the speedo needle to shadow the tacho needle while giving the throttle a blip in Park? So how do I go about finding where the problem is?

[ratter]

Originally Posted by sly

Should it also trigger the engine warning light in the instrument cluster? I've been chasing an AU phantom for ages, have noticed that idle smells rich ATM. Just disconnected the HEGO (O2) sensor altogether and the car starts and runs exactly as per usual. The $15K Korean s**tbox I used for a work car 10 years ago had the "stop engine" light come on when the "servicing" dealer left its HEGO sensor disconnected.

Would someone mind disconnecting their O2 sensor long enough to run their car up to operating temp and post back what happens?

TIA,
Tony.

If the o2 sensor totally failed it would cause the eng light to come on, but they don't normally totally fail, they get very slow in their operation, which means, although they may not be operating correctly, they are still sending a signal to the ECU (although it is the wrong signal for what is actually occuring), the ECU does not recognise there is a problem so the light stays off.

If the o2 was left unplugged it will cause the light to come on, but maybe not immediatley, as the ECU does testing of all it's sensors by doing a test cycle called a trip. Different manufacturers have different trips and different sensors have different trips.

Basically a trip is a test cycle the ECU looks for, ie the car may have to run at operating temp for 5 minutes and in thet time perform x amount off accelration cyles and do a road speed of x amount (purely speclative cycle) for the ECU to determine whether the sensor is working correctly.

[sly]

Hmmmmm. Just took the car around the block twice (20 minutes / 26 km) with the O2 sensor disconnected. No red light, no LHM, just drove exactly as it has for ages. It was prewarmed too, I had it idling for 1/2 hr with the sensor unplugged before reading ratter's post, hoping to get it into closed loop and throw an error.

Not sure whether I drove it long enough to self-test, but surely going into closed loop and getting no O2 reading would cause a problem?

Have had issues of spontaneous stalling / immobilisation over the last 6-8 mths or so with no DTC's to give any clue. The bloke I get to scan it thinks there may be some dodgy wiring (he hates afermarket LPG installs, J3 chips etc). Sounds like the PCM may be getting a voltage on the O2 input that's coming from somewhere else via a dodgy joint or worn insulation?

This might give a sparky a starting point. I'd hate to take it to a sparky and have to say "check the entire engine bay and dashboard looms and all the sensors". Would cost a bit unless he was lucky.

[bellagirl67]

Well got my dad to clean the throttle body but it made no difference. Then he put the idles up so it idles in park at 750-800rpm. Now in gear with my foot on the brake it idles at 650rpms. Now it doesnt stall when I come to a stop at lights etc. Hooray!! Still has a slight miss intermittently when idling in gear but I suppose I will have to live with that. At least it doesnt stall now!!

[mik]

probably a long shot but coil packs might be worth closer inspection, how many k`s has the car done??

[HLC]

my car has only just ticked over 140 000. hmmm ill get some injector cleaner soon. but the injectors arnt ticking so i doubt they are that dirty.

[Mechan1k]

Originally Posted by mik

probably a long shot but coil packs might be worth closer inspection, how many k`s has the car done??

I had a coilpack start to play up ... and it was noticeable at idle ... but also played up while cruising and under load as well. It ended up being one of the terminals on the coilpack deteriorating ... but I would have though it could have caused issues while driving as well.

also being an EGAS model ... getting it to miss under load (ie: one hell of a decent backfire) scared the crap out of the cabbie driving next to me (no damage to the intake thank goodness).

It maybe a vacuum leak as mentioned (should have able to hear a sucking sound from the intake manifold usually) ... another thing it might be is the power steering switch ... this can cause issues with erratic and low idle too (someone mentioned a grinding sound as well).

[bellagirl67]

My car has only done 110,000kms. Heaps better to drive today only missed twice while waiting at the lights. Thanks everyone for your input. Much appreciated!!!!!

[ubuxkl]

My car has done 85,000km and started to miss occasionally at idle about a month ago. Has anyone licked this issue yet?

At the end of March I'm moving to Qld from Tassie and will be driving up towing my 4.55 metre boat. I don't want any hassles en route. I have had all the plugs and leads changed, had the injectors cleaned but nothing changes it. : :

I noticed that it occurs less frequently with the air con on - probably because of the higher idle speed.

[FGII-XR6]

sorry for thread mining but just noticed this response . you should never adjust the base idle it factory preset . if this fixed it i would say your ics is faulty

Originally Posted by bellagirl67

Well got my dad to clean the throttle body but it made no difference. Then he put the idles up so it idles in park at 750-800rpm. Now in gear with my foot on the brake it idles at 650rpms. Now it doesnt stall when I come to a stop at lights etc. Hooray!! Still has a slight miss intermittently when idling in gear but I suppose I will have to live with that. At least it doesnt stall now!!

[Uncle_Ken]

Are you using a high flow air filter?
UK

[INJECTED_250]

manifold gaskets tend to crack and split.. this causes a leak at idle giving a rough idle... Use some CRC / water hell anything and spray it over the manifold where its bolted to the head.. if u hear a loud hissing or it runs differntly then thats ya prob.. i

[Chamelion]

I've had a rough idle, but fine when driving issue.. an LPG conversion has fixed it. I can only put it down to something related to the petrol system.. Injector, pump, filter?

EDIT: If I switch back to petrol it idles rough as always, but LPG is nice and smooth.