mx5cartalk.com

Hey everyone, the past year I've had a random problem with my na6 turbo. I was driving it and all of a sudden the car ran really rough (like it was running on 3 cylinders). Opened the bonnet and noticed heaps of smoke coming from the turbo. So i went and got the turbo rebuilt professionally and the insides enlarged. So now its an s14 turbo with s15 internals. So i put it all back together and was running alright for awhile. Then it starts to run rough again, a heap of white smoke out the exhaust again. I pull over, open the bonnet, couldn't see anything. Get in the car and drove it back home running normally again. Did a compression test and got these results: 190, 190, 200, 200.
Also after i rebuilt the turbo and it happened again. Luckily i was about 5 houses away from home, i checked the oil and it was empty, but full before i left.
Coil packs and leads are also new too.

Anyone had something like this before? I'm really stumped. I'm scared to take it anywhere and only drove the car max of 6 times last year..
Thanks

ok, a few things.

The compression numbers look about right for an MX5, I assume that was just a dry test? do a wet test as well and see if the numbers are similar.
If the wet test is substantially higher it's a sign piston rings arent sealing.

Spark plugs look normal? are they wet? black, white?

Coolant normal? no weird looking foam, or a milky look? no oil in it? (white smoke is often coolant/water being burned. head gasket most commonly)




The biggest concern is the oil level...
I'd be looking for a leak first, then find out if it's burning oil.
Regardless, it's got to be a farking massive leak to lose an entire sump worth in a short period.
To do that something has gone massively wrong.

hks_kansei wrote:ok, a few things.

The compression numbers look about right for an MX5, I assume that was just a dry test? do a wet test as well and see if the numbers are similar.
If the wet test is substantially higher it's a sign piston rings arent sealing.

Spark plugs look normal? are they wet? black, white?

Coolant normal? no weird looking foam, or a milky look? no oil in it? (white smoke is often coolant/water being burned. head gasket most commonly)




The biggest concern is the oil level...
I'd be looking for a leak first, then find out if it's burning oil.
Regardless, it's got to be a farking massive leak to lose an entire sump worth in a short period.
To do that something has gone massively wrong.

Thanks for the response, We did both a a dry and wet with a bit of oil in each and they were basically the same across them all.
The spark plugs just look black. they aren't wet or white.
Coolant looks normal to me, doesn't look milky or have any weird foam. level of coolant doesn't dropped either. Inside of the oil cap is normal too.
It's weird cause I took it for a 2hr drive and it ran perfectly. Went really good. Then picked the misses up (20min drive) and started playing up. pulled over and it started working again :/

But the last 2 times it happened the oil was still full.. Its beyond me whats going on.
I was thinking could it be a valve that's sticking or getting stuck? I'm not sure what the symptoms of that would be..

First off you need to find the oil issue.
It's gone somewhere, either leaked out, or been burned.

until the oil issue is sorted there's no point doing anything else, "hey I sorted out the misfire, but spun a big end from oil starvation"


A stuck valve is a possibility, but you'd likely hear a loud ticking from the engine as the cam slaps the lifter.
Easiest way is to when it does it next time let the car cool, take of the rocker cover and check that each valve is able to move freely (either finger press them in, or turn the engine over with a shifter and check they all move normally)

I presume you've done the usual check of air-fuel-compression-spark ? (I know compression yes, how is the rest?)

an intermittent issue would seem to me to be electrical/sensor related.

I'm gonna guess a cracked piston, even though you appear to have good compression. I'd be testing it again.
Also you should see a rise in pressure with the wet test. Shouldn't be the same as dry.
Do you run a catch can, how big and how full?
Is the oil return line actually returning oil to the sump?
Unless of course it was a turbo seal and hasn't been rebuilt properly. Possible regardless of how unlikely.

hks_kansei wrote:First off you need to find the oil issue.
It's gone somewhere, either leaked out, or been burned.

until the oil issue is sorted there's no point doing anything else, "hey I sorted out the misfire, but spun a big end from oil starvation"


A stuck valve is a possibility, but you'd likely hear a loud ticking from the engine as the cam slaps the lifter.
Easiest way is to when it does it next time let the car cool, take of the rocker cover and check that each valve is able to move freely (either finger press them in, or turn the engine over with a shifter and check they all move normally)

I presume you've done the usual check of air-fuel-compression-spark ? (I know compression yes, how is the rest?)

an intermittent issue would seem to me to be electrical/sensor related.

First time it leaked It was coming from the turbo so I thought a seal went in the turbo as it was smoking out of the turbo, but sort of looked like it was coming from the manifold.
I thought you would definitely hear something too. It's really annoying cause when i get home the car ends up running perfect again. Hopefully it stuffs up and i can turn it off stuffed up at home so i can take the rocker cover off and check. The rest are good too. I'm not sure which sensor would cause it though. Can't be maf since i don't run one now. If it stuffed up all the time I could fix it but being intermittent is just annoying. Seriously just thinking about buying another engine lol

Could be valve stem seals? Or a sticking PCV valve.

You need to drive your car more often.

I expect you'd notice smoke on start up if valve stem seals but I don't know how much smoke you're talking about. I presumed that it was a lot since no oil.

We should all drive our cars more often

Thanks for the responses everyone. Sorry been busy at work.

I really do need to drive the car more often
I think there was a rise in the wet test but not much though.
I don't run a catch can. Should I be running one :/ ?
Yeah the oil line does return oil back into the sump.

The engine does make a ticking noise a fair bit. could that be the head gasket? When it first happened it looked like oil might of been coming in from the manifold. might be a small crack in the gasket on that side, just cant really see with the manifold and heat shield there. I'll have to take them off and have a look.

When I turbocharged the car, I replaced the PCV valve with the 323 gtx ones. pretty sure I did anyway. I still have the original one in the garage somewhere too.

When I start the car, there not really any smoke at all. When it does happen, there is an epic amount of smoke, can barely see behind me lol. Feels like its running on 3 cylinders too.

I might take the engine cover off and have a look. Might paint it while im at it too.

So sometimes it has full power and sometimes it is down and blows white smoke?

Can you post a pic of engine bay? (just because I like pics) and to see how you are running vent breather pipe.

If you did have a blown turbo seal (now fixed), you may still have oil in you exhaust system, which could explain some smoking on a longer drive. Still thinking on the loss of power issue though.

MasterZ wrote:The engine does make a ticking noise a fair bit. could that be the head gasket?

Given it's only dríven occasionally, it could be HLAs, which is very common on the NA6 & NA8.

Yeah, Most times it has full power. But then all of a sudden, car struggles to stay alive. White smoke everywhere, cant even see the cars behind me.

Here are some pictures of the engine bay. The engines ticking is pretty loud. If I clean the HLA's, do you think it will help? The car seems to have a bit of white smoke when i press the accelerator, but when it's idling it doesn't some at all. Ill try upload a video of it soon. Just editing it, the files were huge.

IMG_1495 by Michael Zammit, on Flickr
IMG_1494 by Michael Zammit, on Flickr
IMG_1493 by Michael Zammit, on Flickr
IMG_1496 by Michael Zammit, on Flickr

MasterZ wrote:The engines ticking is pretty loud. If I clean the HLA's, do you think it will help?

Don't think it will help with the white smoke issue, & probably won't even help with the HLA noise, if that's what the noise is. HLA cleaning is very time consuming with no guarantee. manga_blue has tried various things to fix HLA noise & has posted about it. Sometimes an oil change or couple of oil changes can help. Sometimes using the correct spec of oil also helps. Nulon Lifter Free can also help.

Just finished editing the video and uploading it.
By the way, does anyone know why I could edit my last post so I didn't have to post again?
I can't seem to find an edit post button :/

If you watch it on youtube, it should be 1080p.
Thanks everyone that has helped so far.

Posts can only be edited for 30 minutes after posting.