Impreza 98 uk2000 acceleration hesitation/bucking
#1
Scooby Newbie
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Impreza 98 uk2000 acceleration hesitation/bucking
Hi guys, so I've recently bought a 1998 uk2000 and I've been having the issue where when I go to acceleration at half throttle or slowly shes bucks and hesitates always between 2k-3k but if I drive it spiritually its fine. The weird thing is though it only starts to do it after driving for a while, like last night I was out driving and stopping at places for a good 2 hours and only started doing it when I was half hour from home but some times its just 30 mins of driving.
Its got:
new coil pack
New plugs
New boost solenoid
tps is reading .5v closed 4.39v open(both engine off)
cleaned the throttle body and icv
cleaned the pvc valve
new fuel filter
maf sensor has been cleaned and cuts the car out when unplugged(good sign its fine).
mods are boost gauge, hks mushroom filter and catback exhaust and mbc (top pressure of 1.1bar)
its making me really scratch my head now especially which it it only doing it once its been driving for a while
Its got:
new coil pack
New plugs
New boost solenoid
tps is reading .5v closed 4.39v open(both engine off)
cleaned the throttle body and icv
cleaned the pvc valve
new fuel filter
maf sensor has been cleaned and cuts the car out when unplugged(good sign its fine).
mods are boost gauge, hks mushroom filter and catback exhaust and mbc (top pressure of 1.1bar)
its making me really scratch my head now especially which it it only doing it once its been driving for a while
#2
Scooby Regular
my money is fuel pump so check fuel pump pressure vacuum on and off , or the maf is not working correctly 👍 my maf was on the way out and i had similar issues
#3
Scooby Newbie
Thread Starter
Whats the best way to test the fuel pump pressure? Also do you know what voltage the maf should be reading at idle ? I hope its not the maf as its the blue one so alot more expensive then the green 😆
#4
Scooby Regular
i bought a 12£ fuel pressure gauge on ebay then put it on to the fuel supply lines , i thought the classic mafs were the cheaper mafs ? any one local to you ? maybe do a swap see if the problem is cured , try re cleaning again as it had a temporary impact on mine but if it’s broken it’s broken as i found out on mine
#5
Scooby Newbie
Thread Starter
i bought a 12£ fuel pressure gauge on ebay then put it on to the fuel supply lines , i thought the classic mafs were the cheaper mafs ? any one local to you ? maybe do a swap see if the problem is cured , try re cleaning again as it had a temporary impact on mine but if it’s broken it’s broken as i found out on mine
I was thinking it could be air related as when I was out yesterday it was fine til temperature dropped at night so I don't know if the hks mushroom is letting too much air/cold air through pr if the cold airs throwing the maf off
#6
Scooby Regular
it’s sounding like a fuel leak as unless you are filling it there should be no smell of fuel 👍 the petrol tank pipes are under the rear seats via an access hatch , as i assume it’s same as the new shape cars , worth taking a look as there are quite a lot of rubber hoses around the tank
#7
Scooby Newbie
Thread Starter
it’s sounding like a fuel leak as unless you are filling it there should be no smell of fuel 👍 the petrol tank pipes are under the rear seats via an access hatch , as i assume it’s same as the new shape cars , worth taking a look as there are quite a lot of rubber hoses around the tank
Definitely thinking its got something to do with air though as it im normally driving later in the day so its when temps are dropping , I've just been out now and its fine but I'm 99.999% sure it will be back later tonight
Last edited by Scoobs_19998; 03 August 2021 at 01:17 PM.
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#9
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#11
Scooby Regular
AFAIK for MY97/98 EJ20G
Ignition switch on (engine off) 0-0.3v
Engine on idling 0.8-1.2v
Ignition switch on (engine off) 0-0.3v
Engine on idling 0.8-1.2v
Last edited by Don Clark; 03 August 2021 at 03:50 PM.
#12
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#13
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#14
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#15
Scooby Newbie
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So I cleaned my maf sensor and took the mushroom off and put the standard box on, cleaned the map sensor and the brown sensor that goes into it as I checked my codes and had code 45, also cleaned my cam and crank sensor and everything seems to be absolutely mint now, not using as much fuel now too, rev drop on first start up doesn't take anywhere near as long to drop off now too
so something I cleaned today fixed the issue 😆
I'll report back in a day or two if it has stopped for other people
so something I cleaned today fixed the issue 😆
I'll report back in a day or two if it has stopped for other people
#18
Scooby Newbie
Thread Starter
So guys after a few days from the last update I experienced a little bit of hesitation on the first drive however after foing well over 100 miles the ecu has fully learnt to the clean sensors and standard airbox and I'm glad to say she is a nice smooth ride now no hesitation or jerking and engine also sounds alot better and a better exhaust note too, so I guess it was throwing fueling off or timing. Well at least she's fixed now anyway 😁 can finally cruise about without being thrown about it and bonus is the fuel saving from not having to put my foot down to skip past the hesitation 😆😆
#19
Scooby Regular
So I cleaned my maf sensor and took the mushroom off and put the standard box on, cleaned the map sensor and the brown sensor that goes into it as I checked my codes and had code 45, also cleaned my cam and crank sensor and everything seems to be absolutely mint now, not using as much fuel now too, rev drop on first start up doesn't take anywhere near as long to drop off now too
so something I cleaned today fixed the issue 😆
I'll report back in a day or two if it has stopped for other people
so something I cleaned today fixed the issue 😆
I'll report back in a day or two if it has stopped for other people
#20
Scooby Regular
crank sensor is mounted in the top of the oil pump and site centrally underneath the alternator...........
the camshaft sensor on the non AVCS cars is located at the outermost top of the LH rear cam cover
the camshaft sensor on the non AVCS cars is located at the outermost top of the LH rear cam cover
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