SURGE/MISS WHEN COLD?

[Guest]

Had this same problem on my 2000 foz and 99 wrx. when cold it jumps like its running out of gas. really noticeable when accelerating uphill. its not afm or o2 sensor i replaced both on both cars. im replacing temp sensor but ordered the wrong one and plug wouldnt fit. is this a possible cause or is this just a subaru thing?

no cels either and ive reset ecu

also it doesnt make sense for me to warm my car up in the morning coz i work 2k away and its still cold wen i get there juz cbf walking.

[Swindog]

adjusted your tps? if its out of spec this is also a cause of surging.

[Guest]

would this throw a code? just weird both cars did/do it?

[Swindog]

depends, more than likely not though.

surging normally comes from out of spec afm or tps. but as always theres other reason. Be the first two id look at.

TPS should be .48v. can check with a multimeter. three wires, use a paper clip or something to get in behind the wire and put the multi meter on the clip and get the reading. adjusted via two screws on the side. long handled electrical screw driver makes it easy.

[Stoffa]

Coolant temp sensor also causes some cold drama. cheap to replace to rule it out. think its just a v5/6 tging

[darren23]

my 93 rs has same problem.

[Sequence]

I have the same problem

[Timmah]

I do too. AFM and o2 were tested to be sweet. TPS was also altered. It has mitigated the issue though. I suspect cold unhappy clutch or just my tired engine. Never worries me as I nana it when cold

[Guest]

all intake is standard and downpipe too. definitly no problems with afm or 02 sensor.

will update when i change coolant temperature sensor.

its just real annoying and being on both cars which run identical ignition/engine setups i thought it might be a cold start thing like running off afm till 02 sensor heats up. but its is a 3 wire heated 02 sensor...

[madmike]

Let them warm up a little people...

[Guest]

 madmike said:

Let them warm up a little people...

so it is a problem on subarus where you have to warm them up first?

i dont jump in my car and quartermile everywhere i go i warm up before i thrash ;D but ive driven a shit load of cars and never had this problem before on any car. havent driven many subarus lately though only foz an wrx.

just remembering the forester used to be quite bad and was idling funny so i changed afm and 02 made it way better but still fully noticeable. it never threw a code though.

subaru suggested leads, plugs just all ignition common for people too break leads when they change plugs but wasnt any of that.

[madmike]

Put it this way..

My company car is a 2008 Ford mondeo.

If i jump in it and drive it cold it drives like a pig....

There is no harm in starting your car and letting it warm up for a couple of

Min..

If you start it cold and drive for 2kms twice a day you will be causin more harm than letting it warm

Up a little..

I ALWAYS warm up and cool down all our Subaru's

Just my way of thinking.

[Guest]

the car wakes my kid when i go to work or i would warm it up ;D

i warm up and down on any other drive.

thats random in laws got a 2004 mondeo its sweet from cold.

theres got to be a reason that only newish cars do it just interested to know why? it must be a change in the system...

[gazzy2000]

yea its hard to let them (our noisy subarus) sit an idle on a quiet morning, the whole neighborhood must get p1ssy aye..

My work is like 6km away, so i either let it warm up a tad/alot or sometimes go the longer way to let the old girl get nice an warm.

[Swindog]

Check the tps anyway. its a free instade of chucking money at it.

mine surges slightly when cold too but then again my afm is bung.

[Sequence]

I always let my car sit once started for a couple of minutes, Never boost until the car is at its normal temp. Car always cooled down also. Car has only done 15000kms on new motor.

[Guest]

 Sequence said:

I always let my car sit once started for a couple of minutes, Never boost until the car is at its normal temp. Car always cooled down also. Car has only done 15000kms on new motor.

i think i said above why i dont warm it up above and its only once a day. im not saying "f#ck warming up your car bro" i normally do above but im just interested to know why it surges. im not the village idiot just asking something no one seems to know. it seems to be a common problem just bugs me as ive only had the problem on subarus.

do you know why?

also did you forge your motor when it was built? forgies do take longer to warm up too

like the wheels on your wagon too very different you should keep them ones on

[B4 2000]

i think this could be caused by moister/water on AFM (only my speculation)

i had this on my B4, would only happen when car is cold or when it heavily rained, took it to Subaru to get checked, i even left the car with them for couple days and they couldn't find a thing wrong.

They tried a different AFM, changed plugs, reset TPS, changed fuel filter, O2 was checked, and had no codes when ECU was checked and few other things they've tested as well. All that and found nothing. They didn't charge me anything except for new plugs and fuel filter, no labour or even for their check over, as they said they found nothing but they did experience the surge.

So i thought it could be water/moister on afm so on a really cold winter morning i tried unplugging AFM and went for a drive and it didn't surge. Then parked the car for couple hours and went for another drive with AFM plugged, surge was back even tho my AFM was working perfectly fine :-\ .

 Sequence said:

I always let my car sit once started for a couple of minutes, Never boost until the car is at its normal temp. Car always cooled down also. Car has only done 15000kms on new motor.

Normal temperature doesn't equal optimal oil temperature, engine would only need bout 5 mins to reach "normal temp" but your oil would need bout 20+ mins to warm up.

[Guest]

i work in parts so the first time when i bought foz i changed leads, plugs, afm, 02 sensor, coil, fuel filter, everything that it could be coz i got them for cheap as. had a mate with 1998 foz with same problem but he spent 1500bux and hes just replaced tps or tcs now and it goes way better would have to check which when he gets back to me.

mine seems to only be when its cold but worse in the morning so not sure on moisture.

you definitely have a good mech if he doesnt charge if he doesnt fix the problem.

ha how many people will sit in their cars for 20 minutes tomorrow morning...?

[madmike]

Not me... The Mondeo gets 6000rpm stone cold!!!!

Give it assholes!!!

[G-unit]

this is what mine was doing, replaced plugs,coil pack,o2sensor cleaned the afm, put new panel filter in, put in another temp sensor and was alot better but still has the od miss/surge only when cold tho

where is the TPS on a ver5 motor

[Timmah]

 B4 2000 said:

i think this could be caused by moister/water on AFM (only my speculation)

i had this on my B4, would only happen when car is cold or when it heavily rained, took it to Subaru to get checked, i even left the car with them for couple days and they couldn't find a thing wrong.

They tried a different AFM, changed plugs, reset TPS, changed fuel filter, O2 was checked, and had no codes when ECU was checked and few other things they've tested as well. All that and found nothing. They didn't charge me anything except for new plugs and fuel filter, no labour or even for their check over, as they said they found nothing but they did experience the surge.

So i thought it could be water/moister on afm so on a really cold winter morning i tried unplugging AFM and went for a drive and it didn't surge. Then parked the car for couple hours and went for another drive with AFM plugged, surge was back even tho my AFM was working perfectly fine :-\ .

Pretty good theory there.

[Sequence]

 evowrx']

[quote name='Sequence said:

I always let my car sit once started for a couple of minutes, Never boost until the car is at its normal temp. Car always cooled down also. Car has only done 15000kms on new motor.

/quote]

i think i said above why i dont warm it up above and its only once a day. im not saying "f#ck warming up your car bro" i normally do above but im just interested to know why it surges. im not the village idiot just asking something no one seems to know. it seems to be a common problem just bugs me as ive only had the problem on subarus.

do you know why?

also did you forge your motor when it was built? forgies do take longer to warm up too

like the wheels on your wagon too very different you should keep them ones on

Yea Man understand, I have no idea why they have the surging. My car was rebuilt to factory STi spec.

I would like to keep the mags but Im doing a brembo conversion and the rims dont clear ;D

[Swindog]

 G-unit said:

this is what mine was doing, replaced plugs,coil pack,o2sensor cleaned the afm, put new panel filter in, put in another temp sensor and was alot better but still has the od miss/surge only when cold tho

where is the TPS on a ver5 motor

On right side of throttle body in front of intercooler. Three wires two screws.

[G-unit]

the idle control valve?