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

 

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

 

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 😆

 

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'll give the fuel pressure a go, there's also a quite bad smell of petrol in the boot even with no leaking so would a bad sender gasket cause anything with the pressure. All the people I know have a green maf unfortunately and there's not even any second hand ones going on ebay etc
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

 

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

 

no leaks to be seen under the car, round the tank or under the seats. It was only once I could smell it in the boot but thought it could have been something lol

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

 

could also be you are being too 'keen' with the MBC..........

 

I've removed the mbc all together now mate and still doing it

 

So I've checked my maf sensor and I'm only getting 0.01v from the signal wire

 

AFAIK for MY97/98 EJ20G
Ignition switch on (engine off) 0-0.3v
Engine on idling 0.8-1.2v

 

I have a purple maf 3 wire, which wire is the signal just so I'm testing the right one, is it the middle ?

 

used the third wire

ignititon on/engine off 0.27v
​​​idling 1.19v

 

1- Green - signal
2 Black/green - ground
3 Yellow/blue - supply

See attachments

 

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

 

I'd put my money on it being the mushroom filter causing the problems, standard airbox with a good panel filter should be fine unless you're running big power and car is mapped according.

 

100% agree - put the standard air box back on.

 

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 😆😆

 

Please can you let me know where the cam and crank sensors are? Thanks

 

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