dont know if i need another MAF again and it was only changed about 3 months ago everytime i go out in the car now it always seems to have the engine spluttering at about 2000rpm ive checked the lamda sensor on the commander and that seems ok. but idle even dropped to 600 rpm today as well is there any simple way i can find out if its the maf sensor

 

You have a PFC don't you? What is the MAF voltage at idle and what does it get to at full boost (what ever that is?). Should be around 1000mV @ idle and i'd expect it to be at least 4800mV @ peak boost. Probably a lot more if highly modified.... but if the MAF is knackered it will be far less.

Tony.

 

go for a reasonable drive Steve to get the car up to full operating temp.
then pull up, and read the airflow voltage from the monitor display options.
Tony said 1000mV as a guide which is good, but I know that my own car runs nearer to 1290mV (my99) and it was only changed two weeks ago.

could always try the old disconnected MAF when warm trick?
(I think its detailed in a fairly long MAF thread on here)

 

Probably best compare your voltage to the one above if you've got a MY99/00. Mine is pre97 and the Subaru diagnostic manual says it should be between 0.8 and 1.2V . So quite a range.

Tony.

 

its a V reg, i'll take it out for a spin on saturday and check over the sensor setting then

 

took the car out for a spin today and i checked the AFL sensor , i hope thats the right one. it averaged from about 1.0vlt on idle up to about 4.2 vlts on full boost which was hitting about 1.7 bar with all this cold weather. does that seem about right .

this is the 1st winter ive had an apexi ecu, so are these bad starters in the cold cause it might be more down to that, think ill change my plug leads as well just to eliminate a fault

 

I dream of 1.0V at idle
no matter what I do its 1300mV or just below.
however, at 6k rpm and boost its nearer 4.6V so maybe your a bit low as mine is only 1.3bar

 

i never took the car past 5000rpm too much traffic

 

If your hitting 1.7bar i'd expect more than 4.2V to be honest.... but then again i only have experience of pre97 MAFs.

As for the ECU being a bad starter... mine has been as good as the OEM ecu all year round. Compared to my old Link it's a joy!!!!

Tony.

 

agree with Tony,
my car has never behaved so well/felt so good as on the pfc, quieter/less knock, better starting.
generally all around good show.
I do wait for the lambda to get up to temp before pulling away though, as before if I used to pull away I got a little knock count (8/9) early on before falling back to <6 normal driving

 

Have to say, one of the most noticeable things about mine was the starting. Much quieter and quicker. Sorry Steve, not helping...

 

Steve, are you sure your fuel pressure has not moved ? Is the vac pipe to the fpr intact ? I've had them before where the external braiding looked fine but the rubber inside was actually leaking air in/out and causing fuel pressure instability on vac and load.

Are you actually having starting problems or just asking the question? Unheard of on the Apexi to my knowledge.

FWIW, someone else recently had a misfire issue and it was traced to a bad connection on the throttle position sensor plug.

Andy

 

Forgive me Steve:

Andy, I have emailed you on Hotmail for a mapping date! (at long last)

911.

 

Replied last night !

 

I was that someone lol

As Andy stated, i have a UK97 with an Apexi PFC, the car has been fantastic since Andy installed and mapped the PFC.

On Friday it began misbehaving a little, hicupping and around 4.5k rpm and juddering past that, cutting out etc. I used the hand commander to check the sensor readings and found that the throttle position sensor voltage was all over the place when on full throttle it would momentarily read 4.23v then for no reason drop to 3.00v and sometimes drop to 0.02v. Gave all the connections on the Throttle sensor a clean and jiggle, and have been able to stablised the voltage for the time being, and the car now revs cleanly through.

My Air flow voltage is 1.1v or there abouts at tickover and 5.04v at 6800rpm (higher because of extensive tweaks to the inlet system) this is at 1.23 bar @ 6800rpm.

Throttle position sensor now at 0.40v with no throttle, and 4.23v at full throttle, with no fluctuations.

O2 sensor takes a long time to warm up on my car as the heater element has gone, but once up to temp it oscillates as it should, and shows 0.86 - 0.84 v at full throttle.

I checked my leads and plugs and they were fine

Just my findings

Cheers



Iain

 

andy its only a couple of weeks till im at yours and i dont drive the car much anyway so will it be alright for you to have a look

 

right ive just been out and checked the fuel pressure and its just short of 4bar, im sure you set it at 3.5 bar when you mapped it, it wasnt that long ago the car was in for a service so i wonder if they have disturbed it. havent a clue how to check the other things you said as i only put fuel in the things i pay everyone to do things to my car

 

No problem Steve