[Deadduck]

Hi everyone I have bought myself an i30 1.6L diesel auto and love it, but I have a slight problem. It will do it cold or hot and any speed braking or not, it's just complety random.

I will just be driving along then all of a sudden it will jolt (like someones tapped on the brakes hard for less than a second) it has 230 tho kms on the clock when it happens; the revs drop off and come back up. I have replaced the engine as the old one has bad timing rattle then i accidentally cooked it but i used the injector and pump that came on the new one. Got it all coded done diesel filter air ect; it did it on the old engine and also now the new one.

Anyone have any ideas where to look or what it could be? thanks

[Dazzler]

Welcome DD,

Jeepers, that's an odd one, especially as you can discount the engine. Sounds like you don't muck around when you have a problem. 

Sounds like something in the transmission is slipping or jamming maybe, but I'm no mechanic, so see what others say. 

Could it be the ABS playing up

[Deadduck]

I thought about abs so ive allready pulled the fuses to abs to eliminate that

[Dazzler]

I thought about abs so ive allready pulled the fuses to abs to eliminate that

Better put them back, you will be a dead duck if you need the ABS! 

[Deadduck]

I thought about abs so ive allready pulled the fuses to abs to eliminate that

Better put them back, you will be a dead duck if you need the ABS! 

Yes i only done that till it done it again then i put them all back in 

[tw2005]

Could be in the trans being auto. they are know to have valve body issues. Could it be the torque converter  lockup?

Last time the trans was flushed out and new fluid?

[Deadduck]

Could be in the trans being auto. they are know to have valve body issues. Could it be the torque converter  lockup?

Last time the trans was flushed out and new fluid?

Im not too sure but the trans oil looks good and nice and red no  burnt smell the valve body looks like it has been replaced as the sump has come off before and it having 230tho kms on the clock i hope its an easy cheap fix and not a replacement gearbox

[diesel1984]

How many kms on  replacment engine?
Injectors?correction codes? Ecu new old..
If you can drive it and record live data on obd you will be very close to answer yourself on

[Deadduck]

73 tho km's on new engine but all of a sudden today the gearbox is playing up its fine in reverse but as soon as I go into a forward gear it just fells like it's slipping like no drive I can't make it up a light incline it just revs up and moves slow it started working fine again then I have hopped back in it now and it's doing it again the fluid looks really clear kind of red/pink I hope I don't have to do the trans as well.

[tw2005]

73 tho km's on new engine but all of a sudden today the gearbox is playing up its fine in reverse but as soon as I go into a forward gear it just fells like it's slipping like no drive I can't make it up a light incline it just revs up and moves slow it started working fine again then I have hopped back in it now and it's doing it again the fluid looks really clear kind of red/pink I hope I don't have to do the trans as well.

Like I said , sounded like trans and sounds like Valve Body now. Possibly is failsafe 3 rd gear. Try selecting manual 2nd, if the electronic control has quite the shifts will be quite nasty.

If you have a scanner I'd expect some codes to be present. Could be other things like shaft speed sensors too.

I had sensor failure in mine and got by doing 300-400k on along trip with just 2nd and third manual shifting , not fun and not ideal.  Valve body alone if you got it from Korea yourself is about $1000 AUD deliverd here.

[Deadduck]

Hi works again now no codes present and when it was doing it it didn't change to first or second manually still smooth gear changes thanks

[tw2005]

Hi works again now no codes present and when it was doing it it didn't change to first or second manually still smooth gear changes thanks

Doubt this is the end of the story. Could also be broken connections(solders) on the flat ribbon that drives the solenoids in the Valve body(internal)

[Deadduck]

It done it again this morning it was fine I stopped came back 3 min after went to drive off and it was stuck in 3rd gear but I was actually driving it this time and I noticed the speedo was jumping around to all different speeds then it came right and it stared changing properly I have a Bluetooth scan tool no code comes up I'm not sure if it can read the trans but could it be the speed sensor where is that located on theses gearboxes? Thanks 

[tw2005]

It done it again this morning it was fine I stopped came back 3 min after went to drive off and it was stuck in 3rd gear but I was actually driving it this time and I noticed the speedo was jumping around to all different speeds then it came right and it stared changing properly I have a Bluetooth scan tool no code comes up I'm not sure if it can read the trans but could it be the speed sensor where is that located on theses gearboxes? Thanks

Was the scan tool attached when it went crazy? I had issues with my BT scantool on my car which caused havoc.

[Deadduck]

It done it again this morning it was fine I stopped came back 3 min after went to drive off and it was stuck in 3rd gear but I was actually driving it this time and I noticed the speedo was jumping around to all different speeds then it came right and it stared changing properly I have a Bluetooth scan tool no code comes up I'm not sure if it can read the trans but could it be the speed sensor where is that located on theses gearboxes? Thanks

Was the scan tool attached when it went crazy? I had issues with my BT scantool on my car which caused havoc.

Yea it was it hasn't done it before with it in but I will pull it out and try thanks

[Deadduck]

I've pulled out the scan tool and all problems I was having disappeared no jolt or anything drove round for quite a while today then all of a sudden it lost 4th and 3rd took a while to get into I'd have to let off then let it get into gear then I can put the gas back on it would red up then change really weird but then I let it cool down and it's fine again would an external trans cooler help this get it out of the radiator
Thanks

[mickd]

I've pulled out the scan tool and all problems I was having disappeared no jolt or anything drove round for quite a while today then all of a sudden it lost 4th and 3rd took a while to get into I'd have to let off then let it get into gear then I can put the gas back on it would red up then change really weird but then I let it cool down and it's fine again would an external trans cooler help this get it out of the radiator
Thanks

Hi ,
Been following your thread.
Leave it as it is,  don't add external cooler. 
The root cause of  your problem has still not been identified.
 Do it when fixed if you wish,  but not really necessary.

[Deadduck]

I have put an external cooler on and it has made it alot better it does  it a lot less (losing 4th and hunting for 3rd) only on hot days and stuck in traffic for a while or after a decent hill climb but when  it starts and you get up to speed it goes back to normal again so cooling down is there something in the gearbox that would cause this when  it gets real hot?

[tw2005]

I have put an external cooler on and it has made it alot better it does  it a lot less (losing 4th and hunting for 3rd) only on hot days and stuck in traffic for a while or after a decent hill climb but when  it starts and you get up to speed it goes back to normal again so cooling down is there something in the gearbox that would cause this when  it gets real hot?

Hard to nail down this sort of issue. Honestly you need a specialist with good experience and I'd be looking at getting the line pressures checked.

The whole operation of the box is based on electronic controls, correct valving operation, correct pressures being controlled and regulated to the correct clutch packs and servos for the whole show to perform. that also means seals also need to be sound.

Given the distance the box has travelled and the two common known faults of valve body wear and/or bad solders on the harness to the control solenoids.

heat can change tolerances and clearances, including if  there are warped mating surfaces of the Valve Body as well. Iit can induce electrical issues as well particularly with poor joints, could also cause changes in pressures.

I would expect someone with the correct diagnostic interface could  run line pressure tests and/or command solenoids and watch the results achieved and see if they meet the specs.

Ultimately it would seem transmission is the culprit and if there are plenty of wrecked i30s in NZ maybe sourcing a relatively low K unit could be  an economic solution.

In other words how much time and money do you invest in the diagnostic phase  as opposed to biting the bullet and just replace it. Maybe it's just a valve body but a new one is pricey alone.

I'm not qualified but I have been through a particularly unpleasant wty experience with another make with  the internals wearing and jamming the Valve Body up which started to present with gears jamming, dropping into neutral and violent sudden gear re-engagement and eventual destruction.

Sorry for all the waffle .

[tw2005]

  @Deadduck Any updates with your problem?