Postman Pat

I know its been on here before but I was away and missed most of the answers.
My MY99 UK Turbo has got an intermittent uneven idle problem when hot. It varies from being perfectly smooth to hunting by about 100 revs to hunting by about 500-600 revs which shakes the whole car and just about keeps from conking out.
I've been to the dealer he put the diagnostic on her found no errors and hasn't a clue whats up.
Any ideas?

Cheers Pat

dmel

Very likely it's a MAF related. It doesn't show up on the Select Monitor yet because it is still partly functional. It will only show when it becomes completelt knackered.

Check your consumption. If it is MAF related chances are your consumption will increase. I had exactly the same problem.

[Edited by dmel - 2/21/2002 3:16:19 PM]

jmca

Pat,

I had the same problem & it wasn't showing up on the codes. SO I took of the MAF sensor & cleaned the sensor VERY GENTLY with a cotton bud & some electrical contact cleaner. It was quite grimy!

When I pu it back it was fine idled okay & has done since - 3 months ago since I did it.

Johny.

Postman Pat

Thanks for the answers lads.

Johnny where is the MAF sensor located?

Pat

lumby

Similar posts recently , could mean its your lambda sensor , I am having similar problems with WRX 94 , mainly from cold though , I am ordering a new lambda in hope its that , if its not its back to the drawing board.

I took off the MAF last weekend and cleaned it but no grime on it in anycase. So not that

s-man

I have the same problem on my MY95 - given the age I think the MAFs a candidate - anybody got a diy guide on how to locate and clean the MAF ?

many thanks

steve

WRX Youngster

iTrader: (1)

This could also be my problem with my 95 WRX, worst thing is that it is intermittent.

Luke

Mcbrun555

had a very similar prob with our my99 it turned out to be the C02 valve!

still under warenty so it doesn't bother me!

mcbrun555

Postman Pat

Thanks folks.
My yoke is still under warranty too McBrun555 that is until April. Knowing my luck though the bloody thing will wait until March before it throws it's toys out of the pram.
Cheers Pat

dmel

CO2 valve?
What is this? Are you sure you got it right?

jmca

Pat, I've got a HKS Powerflow Kit & it's just after that. It's got a connector to it, which can be taken off. Then it's just a case of loosening the clips, the nut holding it to strut tower & lift it off away from the intake.

The sensor looks like a bit of a square box after the air filter.

Hope that helps.

Johny

pob on the job

If your idle is uneven all the time, it is more than likely the MAF sensor. This is located just after your air box. It's the only thing in the air inlet pipework, just after the airbox, with wires coming from it. It needs a tamper proof bit to get it out. Clean very carefully with electrical cleaner. You may get some sucess with this since you will have the earlier hot wire version. Be very gentle though!
Next, and most likely if it's intermitant, or only when cold,is the O2 or lamda sensor. This is located in the exhaust downpipe. You should be able to see it if you look down between your turbo an intercooler, near the gearbox dipstick. Again, only thing on the exhaust with wires coming from it. It will only operate correctly within a certain temperature range. There is an inbuilt heater to quickly bring the sensor up to minimum operating temperature when cold starting. This may be where your fault lies. At the other end of the spectrum, following hard driving and abrupt stop, you may find that the car idles poorly for a short period of time. I believe this is due to the O2 sensor being too hot, outwith it's upper operating temperature. This being the case, a few seconds later, idle returns to normal as the probe cools to within it's normal operating temperature perameters.

Hope my limited knowledge is of some assistance, you really do know as much about it as me now.

Al

s-man

Al - many thanks mate...your info is definitely helpful to me. From what you say my car seems to follow the pattern of your last example - it doesnt happen all the time. Which makes it sound like its something I may just have to live with ? The only other relevant info is that the car seems to do it after/during long periods of idle (in jams etc) - is that still likely to overheat the O2 sensor ?

I'm not so sure i'll bother doing the MAF right now but your info is being saved for future use...ta

cheers again

steve

FOZ STiV5

My 99 STiV is rough on idle too...not enough for the rev needle to move much but rough. Also ata a steady speed it feels like it misses a beat???? However under any acceleration no miss can be felt at all.?????

I have just changed the plugs (NGK7's) and gapped them to 0.8mm ...the old ones set at .55mm ....anyway still no difference....

Can anyone help... I guess the MAF sensor looks suspect but it had done only 1500 miles ..and it cost £350!!!! I did run a Blitz SUS for 1000 miles?????

Any ideas appreciated

Julian

Postman Pat

Gentlemen thanks for all the gen. I'll check out the Maf when I'm off during the week though from you're discription Al it might be the lambada sensor. Anyway off to work I go.........

Cheers Pat

grahamstocker

Have you checked the idle switch ? just had the same trouble on my sti and gave the idle switch a good spray of carb cleaner following advice from a well known machanic , and it seem to do the trick . G.

FOZ STiV5

Thanks G,

Where exactly is the idle switch....?

Cheers,

Julian

lumby

FAo grahamstocker

How did you remove the idle switch , was it easy ?

Kevin Groat

Graham,

What was wrong with your STi ?, my ver 3 is idling at about 1500 rpm once warmed up after a long steady run. Switch it off for a couple of mins and it's back to normal. After reading the above I was going to look at the MAF sensor tomorrow. Likewise to above, where do I find the idle v/v ?

note to myself - must get damned manual for this thing !

Kevin.

grahamstocker

You dont have to remove the idle switch , but just remove the hose to it from airbox side and spray some carb cleaner in . G.

Kevin Groat

Graham,

Thanks for that - sorted now. MAF sensor was clean, took me a couple of goes with the carb cleaner to clear the problem with the idle v/v. Now idling happily @ 900 rpm again. Now that I've sussed where the idle v/v is, the whole job takes about 1 minute.

Kevin.

Kevin Groat

double post

[Edited by Kevin Groat - 2/24/2002 4:42:30 PM]

Stuart Taylor

Where is the idle valve located?

Thanks Stuart

[Edited by Stuart Taylor - 2/24/2002 5:14:09 PM]

Kevin Groat

Stuart,

It's an STi3 engine so don't know if it's different to yours ?. The v/v is on the rear of the inlet manifold to the righthand side of it. There's a rubber hose about 3/4 inch diameter runs from the inlet ducting, after the MAF sensor housing, across the top of the manifold to the v/v. Theres no hose clip so it pulls off easily. If you have the car idling and pull the hose off, the engine dies. A piccy would be simpler but I don't know how to upload them. Hope this helps.

Kevin.

Kevin.

grahamstocker

Glad i was of some help Kev ! but dont be supprised if it happens again it did to me . Just repeat with the carb cleaner again and all should be ok. Bit cheaper than a new maf which i nearly went straight out and baught when i had this prob last time. G.

lumby

Graham,Kevin

Any ideas where idle tube is on an early WRX ??

Kevin Groat

Lumby,

No idea. But I reckon you could find it by tracing all the hoses that come off the inlet tube just after the MAF sensor. As I mentioned above, if you remove the hose to the idle v/v with the car idling, the engine will die. On my car the hose is about 3/4 inch diameter and looking again it's actually a short rubber hose from the inlet pipe after the MAF sensor. Then it's actually a metal pipe that runs cross the top of the engine. Then a short rubber hose to the idle valve. Make sure it's an airhose before pulling anything off ! - there were no securing clips on my hoses. The second time I used the carb cleaner I actually filled the inlet to the v/v with cleaner and started the engine - it took some time to fire up till the cleaner worked it's way through the valve but once it fired up it was back to normal.

Kevin.

jmca

Lumby,

Graham & Kevin are right about spraying the tube with carb cleaner. I had to do it but it didn't cure it properly. I would spray the carb cleaner into the air feed pipe & at the same time get a friend to hold the rpm at approx 2000.

I have a MY95 & expect it's the same as yours. I had trouble with the idle valve before. You can check it's exact position using the following link.

http://www.shell.linux.se/wkc/subaru/ecu.htm (sorry don't know how to make the link active!)

Clink on the link "Comfirm trouble code" & then on the link for sensor 10 "Idle air control solenoid". This will show you where it is.

Standing at the front of the car facing the engine, it's located on the inlet manifold, to the right & to the rear. It has a light coloured plastic top connector.

Unplug the connector, mark the current position (I drew around it with a thin felt pen. Unscrew the two screws - take care as I think these can be tight & soft! Take the plastic top off & check that the spindle turns okay. If it doesn't then it needs cleaning!
Just unplug the bottom hose & spray some carb cleaner in it, then gently twist the spindle about until it frees up. Put everything back the way it was & see does it idle better.

Hope that's of help.

Johny.



Edited to make link active - found out how...


[Edited by jmca - 2/25/2002 4:41:54 PM]

lumby

cheers peeps thanks for the help

Scoobynet is invaluable when it comes to these techy questions

Postman Pat

Just got back from work chaps. I've checked my MAF and it's clean as a whistle mind you with std filter etc I can't see how it should get grimy.

Some of you lads have been talking about a sticky idling regulator. Maybe I'm looking at the wrong thing but I think mine is on top of the metal inlet manifold and I can't see an easy way to squirt carb cleaner into it. I'm fairly sure I'm looking at the correct piece of kit as I had to change the same thing on the wife's 405 just before Christmas. Mind you her car has 100,000+ miles on it versus my 32,000. I thought these Scoobs were supposed to be ultra reliable. I for one am beginning to change my mind on that issue (reading this BB etc)