[Mk2] [Turbo] what happens at 2250 revs?

[Quigonjay]

or there abouts?
my car has always done this, full throttle the car flies, no hiccups or misfires or anything so quite sure i have no ignition faults (parts all new anyway)
part throttle/gentle acceleration, come 2250 (to about 2750 ish) revs it always feels like it has missed a beat or two, not enough to become a misfire or stutter, its just not as smooth as the rest of the rev range
this has always been low on my priority list but i'm on a roll at the moment with all those little jobs i've been meaning to do
so, my first guess would be ecu related
does anyone know if the ecu is doing anything in particular at 2250?
changing maps? switching from closed loop to open or vice versa?
i asked peter in passing but he couldnt think of anything off the top of his head
cheers
Jay

[Lewis Jay]

I would start with plug gaps and timing.

[Quigonjay]

i would have thought any fault like that would also show itself when on boost/full throttle but nothing at all

[Lewis Jay]

So they are o.k. then?

Next would be resistance checks on all EFI related sensors.

[Quigonjay]

So they are o.k. then?

Next would be resistance checks on all EFI related sensors.

to try and narrow it down a bit, i have tried paing more attention to wether or not it does this when cold and hot (the engine, i'm usually too busy booting it when warm)
it doesnt do it when fully warmed up
so, what does the ecu use when cold that it doesnt use when the car is warmed up?
thanks
Jay

[Quigonjay]

ok, so i changed the o2 sensor again and the problem was gone for about 24 hours, so either
A - i have blown another o2 sensor within 24 hours of fitting or
B - the sensor is getting that clogged up straight away it just cant get a reading
at the moment i am leaning towards B as it is still boosting fine
is there a local rev3 tubby owner that would be willing to meet up and swap o2 sensors so i can see if my sensor on your car is the same as on mine?
dont want to fork out for another one until i find out why this is happening
thanks
Jay

[ancient mariner]

if you can't get anyone closer jay,i am more than happy to help out.paul.

[RobCrezz]

I would try ECU coolant temp sensor.

[Quigonjay]

I would try ECU coolant temp sensor.

had thought about this but wouldnt the problem still be there when warm?
anyways, the problem went again after swapping the o2 sensor
i dont know if that means 100% that it actually is the o2 sensor but at the moment it seems to be the case

[Baker]

no, when warm the ECU sender would not show if faulty (usually), so defo change that.

[Quigonjay]

i'll add it to the list if my o2 sensor check doesnt work

[toxo]

I've had loads of problems with my car hesitating around 2500 revs when cold. In fact it was getting worse and worse the colder and colder the weather is getting to the point where driving the car last week I was worried that something was seriously amiss with my engine - it would not rev past 2200-2500 revs at all until warm. Having seen numerous posts from RobCrezz on here about ecu water temp sensors I bought a new one + crush washer from Mr T and changed it yesterday. Dead easy to change if you haven't got an ST205 CC on, otherwise you have to move the core first. Instant fix, car now feels perfect from start up and doesn't change all the way through to being at full temperature. Cured the problem of the car reeking of fuel from startup as well, as the sensor not working causes the car to think the coolant is up to temp at all times so it runs a warm fuel map from start.

My old water temp sensor fell apart as it came out, it was rusted all the way through.

10 points for RobCrezz!

[Quigonjay]

i've already bought one, but its 'kin freezing outside

[toxo]

lol, it only takes half hour if that! Unless you have a CC in the way...

Here's some encouragement, this is what mine looked like inside:



It can't have been telling the ECU much

[Quigonjay]

funny you should mention about it getting to the point of being undriveable as it suddenly got a lot worse this morning
i'll do it tomorrow if it is dry

[Quigonjay]

finally got round to changing this, first dry day for ages
no change from cold
in fact if anything, it has got worse
getting bored with this car now
so what else is there i can try changing?
does anybody know what sensors exactly the ecu uses from cold?
changed the o2 and ecu coolant temp (and sender), must use the one in the air intake so i'l try that but what else?

[Baker]

try a fuel filter replacement.
unlikely, but a tenner to change.

[Quigonjay]

did it last year mate, probably less than a 1000 miles ago

[Baker]

which o2 sensor did you fit?

only a genuine toyota sensor albeit they're expensive, are reliable.

whats your MPG like? noticeably poor?

[Quigonjay]

not noticed any change in mpg but i've never been one for taking any notice of mpg
i took out what i thought was a genuine o2 sensor (it wasnt) and put in a genuine second hand one