Whit80

Hi all

my first post here on SN,

Randomly the car wont start on the key, sometimes takes 20-30 seconds to fire up, and when it does its initially very lumpy / low revs for a second or two before it jumps up to 1400 idle.

Now it doesnt do this all the time, an example would be today..7am started on the button, drove 6 miles to work, parked up, get in car 16.30 to drive home does the above! (Morning start never a problem)

Car is UK STI ppp, fitted the following new parts.... denso maf / front o2 sensor , S5 battery, ngk pfr7b plugs, walbro 255 pump.
Also fully stripped and cleaned iacv / Tb all new gaskets.

Anyone ever had similar problems or any ides?

ps I can to some degree data log with ecu explorer

cheers

Dan

sivo

iTrader: (30)

Hi mate

I had those symptoms and after chasing it for a while and changing this and that I ended up having a compression test that showed low on 1 cylinder.
Turned out I had 2 unseated valves and decided to rebuild while it was all apart.

I'm not saying this is your problem but a compression test would rule out a lot of things and also set your mind at rest

Siv

Whit80

Hi Siv

Thanks for the reply, i was tempted to buy a compression tester when i bought my new plugs and check while they were out!
Ill see if i can pick one up at the weekend and check them.

Did you have any running issues besides the starting problems?

Dan

sivo

iTrader: (30)

Yes, every now and then when dipping the clutch when slowing to an island or junction the revs would drop to nothing like it was barely running, sometimes it would stall.
Other than that and the starting it ran pretty strong.

Siv

Whit80

Just ordered a comp tester to put my mind at ease
Ill get them checked on saturday.

Besides the starting i dont have any other problems, and runs like a champ, all be it the ppp map will soon be coming off!

Any idea of target psi range for sti cylinders?

Dan

Vxr2010

Give the Maf a clean , disconnect the battery pump the brake pedal 30 or so times , after about 30 mins reconnect and see if it helps , it is like an Ecu reset

Gooch89

iTrader: (1)

I have exactly these symptoms with mine at the moment. Although they only started after I replaced the MAP sensor. Also not making peak boost in lower gears (should be 22psi, seeing between 16-20 - weirdly makes 22 no problem in higher gears). Now I'm worried...

Vxr2010

Boost would be higher in higher gears as gets a longer time to build boost up , changed the Maf or map sensor ? Maf sensors do not show a fault cel but can cause many different issues

Gooch89

iTrader: (1)

Sorry, should have said in my previous post!

Aye, changed MAF and MAP sensor (stall/rev drop issues only started around the time the new MAP sensor was popped in). Both appear normal on Romraider logging sessions. Had an issue with slow spool up previously - found a crack in my up-pipe and replaced the actuator to be safe - which seemed to cure it. The car still spools up fine, just doesn't make peak. Coupled with the stalling out and rev drop is worrying me!

Whit80

Yes, ive recently swapped the maf for brand new denso oe sensor (around 2 weeks ago) along with ecu reset on ecu explorer, can seem to get rom raider up and running, thats another thread!

Dan

Whit80

On a side note, along with doing a compression test at the weekend, im also going to swap out the engine coolant temp sensor ( 22630AA161 ), some suggest this could also give a crap start up.......

Whit80

So just to clear this thread up a bit....
Did a compression test - fully warmed up engine, cooled for 1 hr as i removed all the airbox, plugs etc - test came back a near identical 140 on all 4 cylinders.

I also replaced engine coolant temp sensor (genuine)

Now in conclusion this seems to have done the trick 95% of the time.
I stll get the odd 'weird' start up and occasional drop of the revs when clutching/coasting, again this only happens within first few min of driving, i should also point out i let the car warm up for 5 min (revs drop to 600-700) before i set off.

Looking to get booked in asap for remap, hopefully the mapper could shed some light.
I just wish it would throw a code!