Hesitation when cold?
#1
Scooby Regular
Thread Starter
Join Date: Jan 2001
Location: Down South to Ooop North to Back Down South again!!
Posts: 6,633
Likes: 0
Received 0 Likes
on
0 Posts
When cold the car hesitates at low revs nut stops doing it when warm & is no problem at all at high revs/boost. Any ideas/similar occurences?
Cheers
MAFFA
Cheers
MAFFA
#4
Not sure why they do it but over time and completely out of the blue Subaru's seem to develop this problem and to this day I am unsure of the fix or if there is even one.
One thing it could be is the knock sensor, it is a known problem that they can get too sensitive and it causes the engine to retard when cold because it thinks it is hearing knock. Most likely to be picking up mild piston slap, valve noise, or tappets of course until the engine warms up.
One thing it could be is the knock sensor, it is a known problem that they can get too sensitive and it causes the engine to retard when cold because it thinks it is hearing knock. Most likely to be picking up mild piston slap, valve noise, or tappets of course until the engine warms up.
#7
Scooby Regular
Thread Starter
Join Date: Jan 2001
Location: Down South to Ooop North to Back Down South again!!
Posts: 6,633
Likes: 0
Received 0 Likes
on
0 Posts
I think my post might have read wrong. I wasn't boosting on a cold engine but it was still slightly doing it when warm. Only when I booted it did the hesitation stop on a warm engine. It was worse when I was on low revs on a cold engine.
Steve - the lambda wasn't doing anything unusual.
Funny thing is the car seems to be fine now. I took a drive to Bedfordshire at the weekend & in case I couldn't find a Shell I took some octane boost with me. Filled up on Texaco Super (on my return) plus the octane boost making it about 99Ron and it was fine. Gone through 1/4 tank so far & there's been no problems so far.
Could I have got some dodgy fuel or something as I always fill up at the same Shell garage?
I'll keep you posted if it does it next time I fill up with Optimax.
MAFFA
Steve - the lambda wasn't doing anything unusual.
Funny thing is the car seems to be fine now. I took a drive to Bedfordshire at the weekend & in case I couldn't find a Shell I took some octane boost with me. Filled up on Texaco Super (on my return) plus the octane boost making it about 99Ron and it was fine. Gone through 1/4 tank so far & there's been no problems so far.
Could I have got some dodgy fuel or something as I always fill up at the same Shell garage?
I'll keep you posted if it does it next time I fill up with Optimax.
MAFFA
Trending Topics
#9
Scooby Regular
Thread Starter
Join Date: Jan 2001
Location: Down South to Ooop North to Back Down South again!!
Posts: 6,633
Likes: 0
Received 0 Likes
on
0 Posts
Must be one of those "unknowns" that we'll just have to live with every now & then. Lets just hope it's another 2.5yrs before it does it again LOL
MAFFA
MAFFA
#11
Scooby Regular
Join Date: Aug 2003
Location: Ayrshire
Posts: 201
Likes: 0
Received 0 Likes
on
0 Posts
MAFFA,
My own 1999 UK turbo is doing something similar to yours. Mine hesitates below turbo rev-band, almost like a mild flat spot, but mine is "cyclic" in nature. It is worse when cold but does it slightly even when warm.
But like yours, when the turbo comes in, its all dissapears and smoothens the whole thing out.
Somebody told me to change the plugs and it should fix it. Haven't got round to it yet. This might not be any help to you, but if your plugs are old, it might be worth a try.
My own 1999 UK turbo is doing something similar to yours. Mine hesitates below turbo rev-band, almost like a mild flat spot, but mine is "cyclic" in nature. It is worse when cold but does it slightly even when warm.
But like yours, when the turbo comes in, its all dissapears and smoothens the whole thing out.
Somebody told me to change the plugs and it should fix it. Haven't got round to it yet. This might not be any help to you, but if your plugs are old, it might be worth a try.
#12
Scooby Regular
iTrader: (1)
Join Date: Oct 2001
Location: South East
Posts: 1,300
Likes: 0
Received 0 Likes
on
0 Posts
the cyclic is normally the ECU rocking the mixture around stocih (sp?) 14.7:1 ...
on boost it just chucks fuel in & therefore doesnt care.
might indicate a nackerd (or nackering) Lambda ... ????
Steve
on boost it just chucks fuel in & therefore doesnt care.
might indicate a nackerd (or nackering) Lambda ... ????
Steve
#13
If you search for hesitation or surging you'll find that this is a common problem (if it's the same thing we're on about). My MY00 also had this problem. Changing the ECU from a 802 to a 801 helped slightly. Changing the O2 sensor made no difference, however, running the car with the O2 sensor unplugged removed the problem entirely and the car runs like a dream. I'm currently seeking advice as to weather running the car with this sensor unplugged could be harmful, see this thread http://www.scoobynet.co.uk/bbs/thread.asp?threadid=243085
Seeing as most of my driving is done with short journeys and the car not being given chance to warm up it makes my driving experience better but if you do long journeys and the car just plays up when cold then I'd just live with it until it warms up.
Regards
FC
Seeing as most of my driving is done with short journeys and the car not being given chance to warm up it makes my driving experience better but if you do long journeys and the car just plays up when cold then I'd just live with it until it warms up.
Regards
FC
#15
\m/ ^_^ \m/
have you checked your water temperature sensor? (under the inlet manifolds i think) if this fails, the ECU sees the engine temps as hot and doesn't use choke when you first drive the car from cold
i'm pretty sure this is the case, but don't hold me to it
kev
i'm pretty sure this is the case, but don't hold me to it
kev
#16
Former Sponsor
iTrader: (4)
Join Date: Jan 2001
Location: ECU Mapping - www.JollyGreenMonster.co.uk
Posts: 16,548
Likes: 0
Received 2 Likes
on
2 Posts
have you checked your water temperature sensor? (under the inlet manifolds i think) if this fails, the ECU sees the engine temps as hot and doesn't use choke when you first drive the car from cold
i'm pretty sure this is the case, but don't hold me to it
kev
i'm pretty sure this is the case, but don't hold me to it
kev
JGM
#17
Scooby Regular
Thread Starter
Join Date: Jan 2001
Location: Down South to Ooop North to Back Down South again!!
Posts: 6,633
Likes: 0
Received 0 Likes
on
0 Posts
Changed the water temp sensor a few months back coz mine was buggered. Pain in the ar$e to change and had to get my girlfriend (with smaller hands ) to help LOL
Thread
Thread Starter
Forum
Replies
Last Post
aaron_ions
General Technical
17
03 November 2021 11:07 AM