S@m

I know this topic has been done to death but here goes, engine hesitates/surges when driving normally whorse whilst under heavy load.
No error codes showing but diagnosed as MAF sensor so getting replacement, ecu reset doesnt cure it either, but just disconnected O2 sensor as discussed in other threads and hesitation/surge disappears.
Question - If the MAF is faulty why does the problem go when the O2 sensor is disconnected.

Grateful for any replies.

Mark.

[Edited by S@m - 7/27/2003 11:30:51 AM]

S@m

Hmmmm ok

I'm gonna go see if I can get a universal O2 sensor but would like to hear from anyone who's fitted one to a JDM. The MAF sensor can only be obtained from japan (nearly 3 weeks and still not arrived ) and I was wondering if any problems had occured fitting a universal O2 sensor to an import.

Mark.

S@m

Kinda therapeutic this talking to yourself, sitting on the porch watching the tumble weed rolling down the high street, beer in one hand, other poised over the trusty 6 shooter just waiting for them pesky critters to............. gonna go now


Mark.

LHD Ver1

Check the voltage from the MAF and the O2. They should be as follows:
MAF= 10-14 volts
O2= 10-14 volts
O2 heater= 0.1-1.0 volts

vulnax999

iTrader: (7)

Hmm a bit odd in Lancashire then I take it ?

nom

If it's up to no good at a cruise, it's likely to be the lambda.
If it's doing something wierd under acceleration, it's like the MAF.
If disonnecting a sensor clears the problem, it's likely that sensor's buggered.
If disconnecting a sensor makes it worse (or no different), the sensor's probably ok.
If disconnecting all potentially iffy sensors doesn't make a difference, do a reset & have another go.

I think that sort of covers things, albeit in a bit of a vague way

nom

Oh - and the lambdas are 'disposable' things (anything over 30,000 miles should be considered knackered or, at best, misreading). MAFs should generally be ok unless it's a UK99/00.
I think. I suppose the sti 5 might use the same MAF? Dunno

S@m

Ta ppl,

Got a new MAF sensor today and it hasn't made any difference to the way it runs so I guess I'm looking at a new O2 sensor. At least it removes them from the equation if the problem persists.

Thanks for the replies

Mark.

greasemonkey

For future reference Nom, both the STi 5 and 6 use the 99/00 "troublesome" type MAF sensor.

nom

Ta.
Always handy to know these things

S@m

Managed to get an O2 sensor from a main dealer, fitted this morning and in combination with a new MAF it seems to have cured the surge/hestation when driving at normal speeds but the problem is still there when driving at motorway speeds specially when you put you foot down.
This starting to depress me.

Mark.

tweenierob

What MY mate?

Rob

S@m

Looks like I neglected to mention this is on a JDM MY99 Legacy B4 with a 2.0 Ltr Non-turbo engine.


Mark.

tweenierob

Might be worth ckecking plugs mate, if not failed then maybe they are gapped wrong.

Rob