Help! My engine is sideways!!
 

Need a little help. Finally installed my 2.7l 5 chain in my 99 Boxster. Initial startup had 3-4 bad injectors. Finally got that sorted and started it yesterday. Big smoke on initial startup. Not unexpected. Let it idle for 3-5 minutes and noticed that bank 2 was producing all of the smoke. Vehicle ran fine above idle. It a little rough at idle. Lots of smoke from bank 2 (no muffler installed so I could compare). Shut down for about 10 minutes. Started back up. Longer it ran the more smoke. I believe it is either the valve stem seals or stuck oil control rings. AOS and all related piping is brand new. Less than 20 minutes of runtime on them. Pulled the hose off of the AOS and only residual oil present. Borescope showed no bore scoring. Not significant oil in the combustion chamber except for maybe 1 cyl that appeared to have only a few ml of oil. I would like to do the old seafoam trick and let the rings soak overnight. Problem is obvious, the seafoam will not sit in the rings due to the nature of the flat 6. Don’t want to do a full tear down to replace the rings. Suggestions welcome.

PS- pressure test was about 160 psi on all cylinders. Ran out of time to do a leak down test. May get to that on Monday. I’ll post results if I do. In the meantime, what say you??

Thanks in advance
-Ric

What is the history of the 2.7?

Fairly unknown. Bought it from a guy who was converting a Boxster to electric. Prior to install, I replaced most of the external things like thermostat, water pump, AOS, AOS pipes. I bore scoped, pulled the pan, and replaced the IMS bearing. The only thing that raised a red flag was some sludge in the pan but it did not go higher than a couple of inches in the sump. My hunch is that the oil rings are stuck and that is only because I don’t believe that stem seals could leak that fast to create the amount of smoke that is being produced. My next idea is to kill each cyl 1 at a time by disconnecting coil and injector to see if any 1 cyl smokes more.

How is your oil level it's been recommended to half way up the stick ? Frank

Fresh oil change. 1st start of the transplanted engine. I have seen inside and everything looked good(clean). It did burn about 1/2qt of oil when I ran it for about 5 min. Did I mention LOTS of smoke. 😬

That’s a good plan.

I am concerned (as I suspect you are) about your comment about the amount of oils sludge in the sump. Are you literally saying it was a layer a couple of inches deep? The AOS pickups are down there, I think.

Update: one of my students posed the question, “does oil burn hotter or cooler than gasoline?”. Great question. Answer is cooler. “Can’t we just use a thermal camera to see which exhaust port is cooler. Great idea although it won’t answer the larger question it will isolate the problem. Ran the car with better ventilation and checked with a thermal camera. Unfortunately, there was not difference in exhaust temps.

We then ran a quick smoke test just to make sure all intake components were sealed. Found 2 major vac leaks post MAF we fixed those and should be able to run more tests tomorrow.

If oil is burning, the injector is still providing the same amount of fuel (putting aside flow differences unrelated to oil burning). In other words, it's only more fuel for heat - you won't just see a lower exhaust temp on that cylinder.

I agree. My thought was that because oil burns at a much lower temperature, the overall cylinder temp would be lower. None of that matters though. They were all the same temperature

So latest update. We noticed that when the engine started, we lost all communications to the DME. Checking the communications line today.

so yesterday we went exploring for the dropout of data when started. Turns out that my alternator was "glitching" and occasionally dropping below 11V causing the diagnostic tools to reset. New alternator ordered and on the way. Update after that.

UPDATE 5/22/26: Replaced the alternator. no longer see a voltage dropout when started. the communication still drops once started leading me to believe that an ignition voltage somewhere is suspect. took a look at the diagnostic port and did some voltage readings. I found the following:

Pin 1 - 11.98V

Pin 2 - Empty

Pin 3 - K-Lead 11.7V

Pin 4 - Ground good

Pin 5 - Ground good

Pin 6 - Empty

Pin 7 - K-lead 8.6V

Pin 8 - K-Line 7.5V

Pin 9 - TN Signal - 11.4V

Pin 10 - KVA?? - 8.8V

Pin 11 - Empty

Pin 12 - Software Voltage?? - 0.4 fluctuating

Pin 13 - Empty

Pin 14 - Empty

Pin 15 - Empty

Pin 16 - 12V

Not sure what 9, 10, and 12 are. I could use some help in identifying what they are for. Without knowing, I'm going to take measurements from my other 99 Boxster and compare but in the meantime, Please help.

Maybe this will help (or maybe not)

https://autotech-wss.com/blogs/our-blog/a-guide-to-obd2?srsltid=AfmBOorpX3hHSM3hRq4UFiaBayOhHjsstNbv_ T9MAS-P1s7IWW_XBubr

9 is tachometer.

Should there be 11.4V on 9 then if the car is not running?

Pin 3 - K-Lead 11.7V

Pin 7 - K-lead 8.6V

Pin 8 - K-Line 7.5V

Pin 9 - TN Signal - 11.4V

Pin 10 - KVA?? - 8.8V

Pin 12 - Software Voltage?? - 0.4 fluctuating


These are the ones I'm concerned with was wondering if someone had known good values for them.

I found a bit more detail on what the lines are for here

https://rennlist.com/forums/996-forum/954526-99-obdii-pinouts.html

I’ll try to get you some numbers from my ‘03 today.

Engine off
Pin 3 - battery
Pin 7 - 7.95V
Pin 8 - 0
Pin 9 - 46mV
Pin 10 - 0
Pin 12 - 0 (ish)

Engine running
Pin 3 - battery
Pin 7 - 8.9V
Pin 8 - 0
Pin 9 - 6.6V
Pin 10 - 0
Pin 12 - 0

Those marked as 0v were low values (0-20mV) which are not much more than what I see with my multimeter connected to nothing at all. So there may be info there, or there may not be.

Dunno if this helps or not

If you put a scope on 9 you should see oscillations if the engine is running. If it's not, I don't know what it will show. I can check voltage on mine.

When you say an engine is "sideways" what does this mean? I'm not familiar with this terminolgy?