violent jolt at speed.
 

hi i was goin work yesterday and i put the boot down goin up the slip road to join the motorway when all of a sudden my car jolted violently, it scared the sh#t out of me. i eased off a bit and it was fine. it did it again this morning in fifth gear on motorway. ive drove round this evening and boosted it and its fine. hard to explain what i mean. any ideas please.:confused:

jolt
 

have the same problem with mine think its boost spike gota take too api for um ave look. mayb the oxyjen sensor or need remap try diong the check engine test and see if you get any flash codes up. best of luck let me no if u get sorted good luck:thumb:

yep a boost spike leading to fuel cut> the cold damp air causes an overboost more ofter than not in top gear>

is it bad ? or is it down to the wet foggy weather weve had the past two days ? its only done it twice. ive recently put new piping on the t-piece on the turbo actuator and a new restictor pill which fits inside the pipe. went to blackpool last week and it was fine.:confused:

its not ideal> the ecu should not let it get to the fuel cut> i'd reccomend getting it checked out. It might be the restricter pill just needs altering in size a little

the pill was ordered from the numbers on the vin plate.but my car isnt standard it has full decat.

Most likely the decat is causing the spiking. What MY is your car? Assuming it has a two port solenoid, you'll need to increase the size of the orifice in the restrictor a little. How much is down to trial and error, so get some 0.05mm interval mini-drill bits from a model shop/Maplin/etc and open it a tiny bit at a time until the overshoot is cured.

Boost gauge would obviously be of assistance in this, assuming you don't already have one.

its a 1997 uk turbo. decat has been on for three years. problem started yesterday. pill was put in four weeks ago.

sounds like a boost spike correction to me too. Ecu cutting the fuel.... Check the solenoid (upgrade) lower the boost setting in cold weather .

Have you got a VTA dump valve fitted as these can cause sudden jolts in high gears with low revs and trying to boot it.

yes its a baileys but its been on for a few years. im starting to think its the restrictor pill. car is a lot quicker since putting it in i dont think there was one in before. but the one thats in now is for standard mine is decatted with induction and dump valve. maybe i need the next size up.:wonder:

Is it like hitting a brick wall? and it only happens when you put ya foot down even in high gear?
It happened to me when I had my decat exhaust fitted! It really scary. If its the same thing I had to the boost adjusted. :)

yes very scary. only started recently. restrictor pill affects boost so may need a different size one.

Yeah sounds like it! You had it fitted 4 weeks ago you said? Is this the first time you've really pushed the rev's since you had it done?

not really though i did notice it was overboostin a bit at about 80mph on way home from the blackpool light run but i thought this might be because i was in first gear for over an hour in blackpool an car was very hot.

Definitely sounds like the boost. You cant do any damage so dont worry about it. I was having a bit of a chase when it happened to me. i was doing about 6500 rpm in 5th gear at ??? mph (best not say) when it happened. It drove fine after though, until I pushed my foot down again and it happened again. The whole car, including me jolted forward. See the guy who changed the restrictor pill. Im sure he can sort it :thumb:

Do not say it cant do any damage because thats quite wrong.. its hell for your transmission to fuelcut like that.. know of at least one guy here in iceland that broke his transmission while fuelcutting

Im not saying run it like that. Im saying take ya time with it until he can get it back into the garage. I ran mine for a few days until I got it into the garage, driving it sensibly. If its the same problem as mine its ok until then!

its ok to drive it like that.. just dont put your foot down.. boost as little as you can, this can break your tranny

Mine did this when the oil level was upto max and the car was under load (5 up, full of luggage, going up big hill at 3.5k foot to floor accelerating in top). Turned out to be the boost control solenoid which needed replacing, drop too much of oil was all it took . (That was on a 03 WRX PPP)

What model is it?

did you try cleaning the boost solenoid out?

roger

if you find that it's your boost soleniod i have one for sale just drop me a pm.

97 uk turbo. ive just changed the pipe from the solenoid to the t-piece where pill is. i changed the two small pipes on the t-piece when i put in the pill but didnt change the long one. now they are all the same size. see what happens tmorrow on the way to work.

Thanks Phil. :thumb:

sorry to jump on the post but my MY00 seems to have a little hesitation - not quite brick wall ish but its pretty noticeable. I don't know what classes as violent though, im a pretty big lad so violent for one of you guys may be a nudge for me! ;)

The car is a UK MY00, fully d/cat exhaust turbo back but ended up having a new sports cat welded in to the mid section to aid MOT etc. No other mods bar a panel filter. Replaced MAF about 3 months ago. Realistically the downpipe is straight through as cat is now on the mid section.

Assuming this could still cause boost spiking - you mention about enlarging the restrictor - is this advisable? and if so how can it be done? - i am not 100% what the restrictor is or how to go about it. I have a two port solenoid and was planning on cleaning it out this weekend. That seems easy enough. Ist here a walk through anyones done?

sorry to butt in lads, but couldnt decide between opening another thread or just being annoying and joining in this one! not sure if ive got the same issue...on the way home from work today in 1st, 2nd and 3rd gears (diddnt even try 4th or 5th) around the 4k mark planting my foot down then all of a sudden it was as if the engine just lost power and i lost compression for a second, almost like it had a flat spot...(did jolt me and the mrs foreward) then once id eased off it was fine again, driving sensibly its absolutely fine... its just been motd and emissions were fine but it does smell oil'y if you know what i mean theres no evidence for head gasket failure, leaks, smoke etc. its a N reg WRX imported in 07, completely standard engine wise, other than a new battery its had no work done recently....anyone got any ideas?! what sort of problems are caused on subaru's with things like coil packs going?! havent check the turbo out yet either its a bit dark!

sorry again for the input dont mean to take over thread, im assuming its only going to get worse! any advice gratefully recieved, cheers guys.

dale.

your hitting fuel cut, due to overboosting, mine done it after i upped the boost a bit so had to turn it down a bit.

why would it be overboosting? boost solenoid jamming or something?! nothing on the engine has been touched for the past 11months ive owned it (other than monitoring and checking levels) and its run fine, so i can only assume its a component gone down?!

thanks.