Smoking twins and.....smoking twins?
03-14-11, 12:43 PM
#1
Smoking twins and.....smoking twins?
I had a set of stock JDM twins that started smoking after I boosted hard. Like do a hard 3rd and 4th pull, and it would blow smoke at the next stop sign you came to.
I was pretty positive that they were bad because My BOV was seeping oil and my intercooler piping had a good bit oil in it. Not to mention the fact that the #1 twin had oil in the compressor inlet when I took them apart.
Anywho, fast forward to now. I bought some used JDM hybrids with less than 5k miles on them and put them on the car. The car STILL smokes after a long boost run. Now, I did look in the intercooler and there was some oil in it, and I imagine there was some oil in the intake tract from the other twins. I didn't clean all the piping before I put it back together, but I made sure there were no puddles in it. Just a film.
Do you think I am still burning off old oil from the intake tract, or did I trade one set of blown twins for another? Its not looking good because it smokes quite a bit after a hard pull.
FYI, the car has very recent valve stem seals on it and does not seem to smoke at startup, just after boosting.
So do you think I have more bad twins, burning off old oil, or something else?
I was pretty positive that they were bad because My BOV was seeping oil and my intercooler piping had a good bit oil in it. Not to mention the fact that the #1 twin had oil in the compressor inlet when I took them apart.
Anywho, fast forward to now. I bought some used JDM hybrids with less than 5k miles on them and put them on the car. The car STILL smokes after a long boost run. Now, I did look in the intercooler and there was some oil in it, and I imagine there was some oil in the intake tract from the other twins. I didn't clean all the piping before I put it back together, but I made sure there were no puddles in it. Just a film.
Do you think I am still burning off old oil from the intake tract, or did I trade one set of blown twins for another? Its not looking good because it smokes quite a bit after a hard pull.
FYI, the car has very recent valve stem seals on it and does not seem to smoke at startup, just after boosting.
So do you think I have more bad twins, burning off old oil, or something else?
03-14-11, 02:47 PM
#3
Ok, here is what I found out through some testing. It does not appear to be related to boost so much as vacuum. If I just do a high rev low load run without getting into boost and then engine brake it down, it will smoke. If I do a boosted run and clutch it and use the brakes to slow down, it does not appear to smoke. Or if it does it is a lot less and I am not catching it.
Does this point to something else? VSS over turbos? Rings? It has me baffled and I am out of money
Very bad juju.
Does this point to something else? VSS over turbos? Rings? It has me baffled and I am out of money
Very bad juju.
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03-14-11, 04:16 PM
#8
For some reason, the turbos are only boosting to 11psi, and I was under the impression they were supposed to be set to 14psi out of the box. I will have to check to make sure it is the wastegate and not something else. So, I suppose I have a list of stuff to test.
03-14-11, 06:42 PM
#9
Driver School Candidate
If it was a N/A engine and it smoked after slowing down on compression/engine braking, then I would say it's pulling oil past the rings.
The fact that it's a turbo'd motor means that when your under boost, your putting a stronger load on the rings during acceleration. This causes the rings to deflect more and will cause more wear to the cylinders/rings/ring lands/grooves. It's not un-common to see an increase in blow-by as well as oil being pulled back into the cylinders during engine braking due to the wear on the affected parts and the vacuum created.
You may have noticed a slight puff of smoke when you shift or after you return to speed after a brief let up on the go pedal. The cats normally burn this small amount of oil smoke before you ever see it, if you still have them, but they can't keep up with larger volumes of smoke.
Rule of thumb: Smoke at start up; valve guide seals. Smoke at shift or engine braking; rings. There are some variables, but 9 times outta 10, it's true.
If you have ruled out the Turbo's and the residual oil in the intake track, the next step would be a cylinder leak down test. If it's bad, then maybe it's time to save some cash up and rebuild it. Bigger pistons X bored cylinders/more cubic inches = more horses in the stable : )
I know its clear as mudd, but it covers the ground. I hope it helps. Keep us posted as to what you find/do.
Semper Fi!
The fact that it's a turbo'd motor means that when your under boost, your putting a stronger load on the rings during acceleration. This causes the rings to deflect more and will cause more wear to the cylinders/rings/ring lands/grooves. It's not un-common to see an increase in blow-by as well as oil being pulled back into the cylinders during engine braking due to the wear on the affected parts and the vacuum created.
You may have noticed a slight puff of smoke when you shift or after you return to speed after a brief let up on the go pedal. The cats normally burn this small amount of oil smoke before you ever see it, if you still have them, but they can't keep up with larger volumes of smoke.
Rule of thumb: Smoke at start up; valve guide seals. Smoke at shift or engine braking; rings. There are some variables, but 9 times outta 10, it's true.
If you have ruled out the Turbo's and the residual oil in the intake track, the next step would be a cylinder leak down test. If it's bad, then maybe it's time to save some cash up and rebuild it. Bigger pistons X bored cylinders/more cubic inches = more horses in the stable : )
I know its clear as mudd, but it covers the ground. I hope it helps. Keep us posted as to what you find/do.
Semper Fi!
Last edited by USMC; 03-14-11 at 07:02 PM. Reason: Misspells
03-14-11, 07:18 PM
#10
Yeah thanks. I really hope its not rings. I am going to do a leakdown and check the IC piping again to see if its the turbos. I will also try the pcv bypass to see if that helps. It happened suddenly, so I kinda doubt its rings, but who knows.
03-14-11, 07:53 PM
#11
Driver School Candidate
How many miles on the engine? How many miles with the turbos? If it happened suddenly, that could be both a good and bad thing. It could be a good thing because it might be something simple and easy to fix, but I'm not too optimistic about that. I saw you have recently replaced the valve guide seals, so I figure it's got a few miles on it. A cylinder leak down test will also show you if your compression is even between all cylinders as well, very useful in catching problems early. They should all be very close, no more than a 10-15 lb variance.
A broken oil control ring will not show up as easily as a broken compression ring will under the test, but if you pull your spark plugs shortly after a moderate down hill coast, in gear, you should be able to read the plugs and determine if that's your source of the smoke and which cylinder is causing it.
Also, a broken ring will sometimes cause a "tick" sound in the engine. Kinda hard to hear over the injectors and everything else making noise though a stethoscope can make it a little easier.
On older engines, you can pull one plug wire at a time or ground out one cylinder at a time and the "ticking" will stop on the one with the problem. I don't know that you can do that with the newer ones. Too many sensative electronics.
My son just had a similar problem on his MX-6 GT. But his was pretty easy to solve though, almost an 1/8" of play in the turbo shaft. Lots of oil running by
Semper Fi!
A broken oil control ring will not show up as easily as a broken compression ring will under the test, but if you pull your spark plugs shortly after a moderate down hill coast, in gear, you should be able to read the plugs and determine if that's your source of the smoke and which cylinder is causing it.
Also, a broken ring will sometimes cause a "tick" sound in the engine. Kinda hard to hear over the injectors and everything else making noise though a stethoscope can make it a little easier.
On older engines, you can pull one plug wire at a time or ground out one cylinder at a time and the "ticking" will stop on the one with the problem. I don't know that you can do that with the newer ones. Too many sensative electronics.
My son just had a similar problem on his MX-6 GT. But his was pretty easy to solve though, almost an 1/8" of play in the turbo shaft. Lots of oil running by
Semper Fi!
03-15-11, 04:32 AM
#13
Well, the turbos had some shaft play, but they were not hitting the housings. With only 4k miles or so on them, I would be very disappointed if they were dead. The compressor wheels on them looked brand new, and both inlets were spotless.
The motor has about 100k on it supposedly. I am going to do a leakdown for sure and see whats up.
The motor has about 100k on it supposedly. I am going to do a leakdown for sure and see whats up.
03-15-11, 09:33 AM
#15
I wish you the best on your problem and I hope it isnt too costly to repair.