Hesitation on Acceleration...???

JAMIE-TYPERV6

JAMIE-TYPERV6

Octane Boostaholics
Hey all,

What's the cause of a slight hesitation coming on boost...? The wagon has been doing this for a while... initally I thought it was a faulty lead.... but on closer scrutiny it appears to happen just as it comes on boost. When you plant the foot... and just as you hit 3250-3500 rpm... it stutters and then pulls strong again after that.

It's been bugging me for a while so any advice would be greatly appreciated. :thumbsup:

J..
 
[quote author=STi Brian link=topic=31879.msg365728#msg365728 date=1317974812]
maf or plug lead?
[/quote]#

Plug leads from Type R went into there recently Brian as they are fresh ones... but no luck... still have hesitation.

Anyone know if the Maf in my V6 STI is the same as the one in my V6 Uk WRX?? If it is I'll swap em over and see if that does the job.
 
[quote author=BazGF8 link=topic=31879.msg365730#msg365730 date=1317975189]
Could even be as simple as the plugs Jamie, how old are they?
[/quote]

No idea TBH... but I'd have thought dodgy plug would cause misfire and not hesitation only when coming on boost. :dontknow:
 
yeah try the MAF!

are you sure the coipacks are ok? the only happening on boost points me that way!!

o2 sensor? is it a bad stutter?
 
was thinking the same
Jamie can you not check if its giving a code
[quote author=KENC link=topic=31879.msg365787#msg365787 date=1318022420]
Knock sensor
[/quote]
 
I've a spare MAF and coilpack off the STI that should help me eliminate either. I know the knock sensor has been repositioned elsewhere on the block so I must check it's on a good contact point and if not move it back to factory fitment. Hope to get out and check codes shortly. Cheers all.
 
Is it running standard boost? If the revs it happens at is peak boost then I'd also check the plugs on a phase 2. Remember to reset the ECU when swapping MAFs around.

Richard
 
Thanks Richard... The car got mapped by a previous owner through Bob Rawle, so I'd imagine it's had the boost raised. Problem happens just as it comes on boost rather than at peak boost from what I can tell. I'll check the plugs to. How do you reset ECU?
 
from scoobypedia :thumbsup:
Classic (JECS) ECU Reset

Ensure engine is at normal operating temperature, turn engine off
Locate the two ECU connectors, located under the steering column and consist of a black plastic male and female connector, and a green male female connector
With the ignition OFF connect black to black and green to green.
Turn on ignition, do not start the engine, depress the accelerator pedal to full throttle, then return it to the half-throttle position and hold for a few seconds, and then release
Engine Check lamp turns on
Start engine and then drive for at least one minute, keeping road speed above 11 Km/h.
ECU is now re-set.
At this point the check engine light should start to flash the all clear signal (steady 1/2 second interval flashes). If the check engine light does not flash, or indicates some other sequence, there is a fault present in the system, and should be professionally checked for necessary repairs.
Stop the car and turn off the engine.
Disconnect the black and green connectors.
Job complete
 
Check

Top mount pipework/jubilee loose ,Header exhaust leak as in upipe, intake pipe damage like rip at jubilee turbo side, fuel reg issue, lamda sensor issues?

really need go spin whilst monitoring data live on diagnostics and judge from there.
 
As per both posts above. If you can, better get it connected to diagnostics before simply trying an ECU reset. If it is the MAF for instance, then an ECU reset can make matters worse as the car has to learn to control things with lots of knock happening.

Check to see whether the MAF has a green spot on it close to one of the securing holes - this indicates it has been replaced already at least (but does not mean it is not faulty!). If it doesn't have a green spot, then replace for sure. Also note that it is possible that both MAF and lambda (O2) sensor are faulty - the car runs fine in closed loop because the under reading O2 sensor means more fuel is going in which compensates for the under-reading MAF causing the ECU to think it needs less fuel.

Diagnostic check will highlight some of this - if MAF I'd expect the advance multiplier to be down. I have delta dash if you're anywhere near D4.

Bob's maps are amongst the best out there, so definitely worth getting it sorted :)

Richard
 
Thanx Richard.

Indeed Bob is regarded as one the best in business.
Although this is not a map issue.

Also check neutral position switch correctly working.
 
[quote author=Richard.D link=topic=31879.msg365936#msg365936 date=1318162574]
As per both posts above. If you can, better get it connected to diagnostics before simply trying an ECU reset. If it is the MAF for instance, then an ECU reset can make matters worse as the car has to learn to control things with lots of knock happening.

Check to see whether the MAF has a green spot on it close to one of the securing holes - this indicates it has been replaced already at least (but does not mean it is not faulty!). If it doesn't have a green spot, then replace for sure. Also note that it is possible that both MAF and lambda (O2) sensor are faulty - the car runs fine in closed loop because the under reading O2 sensor means more fuel is going in which compensates for the under-reading MAF causing the ECU to think it needs less fuel.

Diagnostic check will highlight some of this - if MAF I'd expect the advance multiplier to be down. I have delta dash if you're anywhere near D4.

Bob's maps are amongst the best out there, so definitely worth getting it sorted :)

Richard
[/quote]

Hey Richard... thanks for all the info.

Haven't had a chance ot do a single thing with the car this weekend... the joys of a 4 month old who's teething. I'll be down in the garage on wednesday and check for any codes and check for the green spot. :thumbsup: I won't be resetting the ECU till I get it checked on the diagnostics either.

Strangely it didn't do i this morning on the way into work :ponder2: and I was trying my hardest!! :icon_biggrin:

Thanks for the offer of the delta dash ... I might give you a shout bout popping down to you and getting it checked. :thumbsup:

Jamie.
 
[quote author=scoobycolm link=topic=31879.msg365900#msg365900 date=1318110590]
from scoobypedia :thumbsup:
Classic (JECS) ECU Reset

Ensure engine is at normal operating temperature, turn engine off
Locate the two ECU connectors, located under the steering column and consist of a black plastic male and female connector, and a green male female connector
With the ignition OFF connect black to black and green to green.
Turn on ignition, do not start the engine, depress the accelerator pedal to full throttle, then return it to the half-throttle position and hold for a few seconds, and then release
Engine Check lamp turns on
Start engine and then drive for at least one minute, keeping road speed above 11 Km/h.
ECU is now re-set.
At this point the check engine light should start to flash the all clear signal (steady 1/2 second interval flashes). If the check engine light does not flash, or indicates some other sequence, there is a fault present in the system, and should be professionally checked for necessary repairs.
Stop the car and turn off the engine.
Disconnect the black and green connectors.
Job complete
[/quote]

Thanks Colm! :thumbsup:
 
Did you try that knock sensor yet Jaime??? FFS get the finger out, there is a side bet running on your back man
 
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