When i accelerate in 4 or 5 th at motorway speeds i am getting a violent hesitation like hitting a brick wall for a fraction of a second and then the car pulls away fine
any ideas please its a 93 wrx
cheers nick

 

Sounds like fuel cut, has the boost been tweaked at-all??

 

no mate not that i'm aware of its very similar to what the car was like before it was delimited and i hit 112 if thats any help

 

my 98 wagon seems to do this in 5th gear if you boot it from about 80mph
what is the likely cause ??

 

Id say the maf sensor could be faulty,

i had same prb, when you out your foot down in 3 and mostly 4th gear, the car hesitates and jumps, then starts pulling away,

do you have a boost gauge? whats it boosting at?

if you maf sensor is failing, i prob would drive with care unitl you fit a new one.



saying that, i could be something totally different, but just an idea,

oh another sympton of this, my exhaust seemed to pop a fair bit when you blip the throttle, since a nre maf was fitted, all fine.

 

No mate the maf was changed about 2 weeks ago

 

Sounds like overboost to me, I had this problem a while ago but found it to be a damaged pipe going to the boost solenoid so it had no idea what boost it was trying to control.

 

check the basics first like the plugs. It all to easy to blame the MAF. Just had a similar problem on mine, have posted elsewhere. Change of plugs sorted it. The other common thing is like Nezz10 says is overboost, which is commonly down to damaged or ill fitting pipes (without clips on)

 

thanks for the replies guys will check out the pipes and plugs when misses gets home with car
Nick

 

Id say its spiking, overboosting for a fraction of a second. I had mine on the rollers and the graph was a nice curve except for two bits at about 3 and 5k rpm where there was a really sharp spike.

It overboosts and then comes back down to normal boost again. mine only had a decat. power engineering stuck it on their rollers and tuned it, adjusted a few bits, throttle position sensor and actuator and it drove a lot lot better afterwards.

 

It sounds like overboost - Enable the diagnostic mode shown HERE which will pulse the boost solenoid, then spray brake cleaner in the ports of the boost solenoid to clean it then give the car another test

Cheers