Boost issue? Engine stutter.

[individual]

Hey guy, just got myself a 1999 Legnum tonight, and I've noticed an issue on it.
When I put my foot down more than 1/3rd the way, the car develops a stutter at about 4000, sometimes earlier and later, but usually 4000.
Any ideas? Hitting fuel cut, boost cut, leaks?
It's an automatic with tiptronic.
It feels like its producing a lot of power for the throttle position also, the TPS seems to have been possibly repositioned, has white paint marks on it.
Could this be causing any issues?
Any help would be greatly appreciated.

Cheers, Mitchell.

[MarkSanne]

Boost/intercooler/vacuum hoses. Probably under load one (or more) of the connections takes false air and messes up. Search for stutter on here and you'll find a complete how-to topic.

[Anderz]

Check also condition of plugs and ignition coils.

[Davezj]

is it stuter or is it fuel cut, e.g. the boost solenoid is disconnected from the wastegates, and as soon as you put your foot down you hit fuel cut.
does the car boost really really quickly and then all power disappears then comes back, if you keep your foot down.

do you have a boost gauge fitted does it boost to over 0.8 bar?

[kiwigalant]

Any codes? If the TPS was that bad, from my experience, it would idle very badly and go into limp home mode as well as causing trouble code 14 to show up.

[individual]

First thing's first, this car is bone stock, done 121k and has been serviced very regularly since import in 2009.
I've only bought the car 30 hours ago. I'm just in my fault finding mode.

took it for a burn in the morning, first couple of minutes it went without issues.
As it started to heat up, it started again.

I got it checked and serviced (transmission) today and it turns out it was a faulty reading on the dip stick due to a nasty build up :/ was reading full when there was almost nothing.
SO, the serviced improved it a lot, but not completely.

when I try and put my foot down in first gear, its almost as if the trans is backing off the pressure plate and delivering half the power.
until it reaches about 30-35 it takes of great, when it hits 40 it's like it's slipping (around 4-4.5k rev), the engine revs it's tits off, but doesn't go anywhere much, till it slips into second
The transitions from gear to gear a smooth and still quick, but still through second and third when it gets to a higher rev range (4k+), when the pedal is to the metal, it feels like it's slipping and "stuttering"

I haven't checked the hoses, neither did the service center, but we both think it's transmission related.

I haven't checked the TPS or played with it, but it might make sense.
The car does hit boost fairly fast even at low pedal depression. (this is me guessing, being my first turbo car, my general understanding is that boost comes on a fair bit later. mine starts audible winding up at around 2.8k)
Anything where the pedal is depressed more than.....3/4 of the way, it develops the stutter.
Could be the ECU is reading the TPS as "oh ****, 130% throttle son, better boost it up at 130%, oh **** I can't, hold up a sec" and repeat.

I haven't checked any codes yet, I'm fairly new to the car world. Been doing nothing but research on here for the last 2 days.

I'm aiming to get Steve Knight Racetech (ex mitsi engineer) to do some diagnosis on his dyno within the next couple of weeks, then i'll have an answer.
Until then, if worse comes to worse and so I can start sourcing, what after market transmissions and diffs "plug and play" with minimal work?
I've heard evo's do but I heard old series. What does old series mean, 5-6 series or newer/older? And what kind of power do they take? (given that I'm aiming for 220kw at all 4.)
Please be specific if you know haha I don't know much about imports or the history of them.

[Nick Mann]

Can you record a video?
Transmission slip and engine stutter are two very different things to me. When you did the service did you do the transfer box? If so, what did the old oil look like?

[nos monkeys]

lol sounds like what mine is doing, im waiting for my cable to arrive so i can do some data logging. at first mine had 3 vacuum lines taken off including fuel pressure regulator and no wastegate lines. i hooked those up and the car got alot better but i still have the same problem just not as bad

[individual]

Can you record a video?
Transmission slip and engine stutter are two very different things to me. When you did the service did you do the transfer box? If so, what did the old oil look like?

Good Idea, I'll record a video later this morning. I'm not sure if it's slip or stutter lol so hopefully the video will make it clearer.
I'm not 100% sure if the transfer box was done too.

lol sounds like what mine is doing, I'm waiting for my cable to arrive so i can do some data logging. at first mine had 3 vacuum lines taken off including fuel pressure regulator and no wastegate lines. i hooked those up and the car got alot better but i still have the same problem just not as bad

3 lines lol wow. Well if i find an answer I'll let you know I just hope i don't have to replace a trans :/

[wintertidenz]

I'd suggest checking plugs first and doing a basic service.

When they serviced the transmission, what fluid did they use? It NEEDS to be MM-SPIII or something compatible - Dexron-III will cause it to slip and rip itself to pieces.

[individual]

the plugs and leads were all replaced in December '13 on the last full service, they shouldn't have any issues.
I'm unsure what fluid they used, have to wait till monday to find out.

[nos monkeys]

I just tried taking a video of mine but its impossible to tell in the video the only difference is when its at 4krpm it sounds way different and there is no power at all. its like its just reving and nothing else happening. but my trans aint slipping because mines a manual lol and today its doing it worse than it has for ages =[ =[ =[ my cord needs to hurry up so i can see if anything abnormal shows up on data logging.


here is a link to my video as well. https://www.youtube.com/watch?v=Ugvv...ature=youtu.be

don't mean to hijack your thread but i think we have the same problem. watch the video over and over and you'l start to hear the different sound it makes at 4k rpm. has no power at all doesnt even feel like its accelerating but it is because its a manual, has no error codes no boost leaks and only does it after the car is warm the more i drive the worse it gets, to start with it just feels like fuel cut and loses power for a split second but then it turns into this and doesnt get the power back. ill get a video of what its like when it runs good in the morning when i first start it so you know the difference.

I've check my tps, intake temp sensor, coolant temp sensor, coil packs with a ohm meter, coil packs with water to see if it got worse ( never made a difference) checked the front 3 plugs because i forgot how to take the manifold off and wasnt sure if i needed a gasket. checked for error codes, checked fuel pressure. Its even been to the mitsi dealership but since it only does it when its hot they told me theres nothing wrong and couldnt find a problem yet as soon as i left it was doing it . . .

my list of things i still need to properly check is my fuel pressure regulator just because it was disconnected for over 8 months from the previous stupid owner so it might be broken now and not adding extra fuel or something. Apart from that i really have no clue at all. i brought a cable and evoscan to do some data logging and learning about that and hoping my a/f ratios and all that are fine because i dont want to drive it til i find the problem incase its running lean and ill melt a piston or something silly like that.

[individual]

I haven't checked much myself yet, literally only just started getting into cars. I'm a mech Engineer/Fitter and turner by trade, so I should be able to fix whatever is wrong myself. It's just finding whats wrong.
What power are these trans good for? 400bhp?

[individual]

This is the first video, foot now flat down.
https://www.youtube.com/watch?v=x7EWtPUlsJE

[individual]

Second video, foot flat.
https://www.youtube.com/watch?v=xMw_pdoLuK4
Sorry I took so long, had a mate look at a car.
He things it may just be a tuning issue, turbo sync. said it seemed like the second one wasn't coming on with the first one.

[Nick Mann]

It looks more like a small misfire to me.

If you have a turbo issue then you will be down on power, but the delivery should still be smooth.

I'd suggest spark plugs (check them at least) or leads or maybe a failing coil pack.

[individual]

SOrry for the late reply, again lol. been looking at it myself and there is an oil leak somewhere. looks like engine oil because of the colour, but seems to be coming from the trans.
This could be leading to the problems a bit, low oil levels. that and once the leak is taken care of I'm going to fit an aftermarket oil and trans cooler and see how it fairs.

[nos monkeys]

im not sure with these engines but on my 300zx i have oil leaking around the trans because my rear main seal is leaking and due to be changed. it could be that but not sure where the main seals are on these engines. mine has oil everywhere around the engine but doesnt leak on my drive and doesnt use oil so never bothered getting new gaskets yet.

[wintertidenz]

Rear main seal on our engines requires removing the transmission - they don't seem to leak from there all that often though.

More common is the torque converter seal.

[individual]

Yeah so confirmed it's the rear main seal, 1200 buck service. Gonna just add some stop leak additive and get the lifters, pistons and rods replaced at the same time.