Low compression help!
 

I searched and had some ideas but I would like to hear it from an experience person. I got my motor rebuilt with RA seals and put about 500 miles breaking in. After that I went with a single turbo and did some self tunning with a datalogit. Just 1 cold day I decided to give it another tune so in 4th gear at 30mph I slightly when WOT to 7000rpm. After I let off the engine idle like crap and sometimes die at idle. I looked at the A/F map on my laptop at 10psi it reads around 12-12.5afr. I was running rich at idle for awhile, so my question is since the seal is RA and it only has about 700 miles on a rebuilt, could it be side seal or apex seal got stuck because of running rich? Could somebody shine some light.

Thanks

The compression on the rear rotor read low.

Sounds like a blown motor. It doesn't sound like you were following a proper engine break-in procedure, either. What are the before/after compression numbers?

Dave

no matter what it is.......low compression means to take it apart anyways. sorry for your luck.

Newly rebuilt motors often don't have full compression until they break in some. How soon, how big of a difference, I don't have experience with. I know if (when?) I rebuild mine I'll do a compression test first thing, as well as after a few hundred miles and a thousand miles.
If we know his exact numbers, someone will be better able to judge if it's normal.

Now the inability to idle suggests a blown motor. Aside from checking the MAP line, I think the low compression and bad idle mean it went ker-poop.

Dave

12-12.5:1 at 10psi. . . id say you may be pushing it with that kind of tuning. . . IIRC the common area is 11-11.5:1 for high boost runs. you may have gotten a little lean on that run. . . and unfortunately, burned up some seals. take your plugs out and check for the pulses.

Since you motor has so little miles on it, it'd be hard to say that it has carbon build-up and the side seals are getting stuck because of that, and or either of the apex seals have let go so soon.

Have you tried reving the motor few times to redline after you experienced the above symptoms? It does seem to help in some cases when side seals stick, either from carbon buil-up or especialy from to much fuel.

Another safe way and best in my opinion to find out and clean up if ur side seals are sicking is to steam clean the motor by hold the idle at 4k rpm and feeding it with some clean water, a liter per rotor I supose the most, there are many posts and how to's about that, best way to do that would be doing one rotor at the time, that's how I do it, when your motor is fully warmed up.

Sorry forgot to mention that I was running 101 octane.

The only reason I think it might be carbon buildup because it toke me almost 6 month to put 700 miles after rebuilt. I'm going to try the MMO first and if it doesn't work than steam clean.

BTW: I have not rev it hard after it idle like crap but to assure that is what I'm going to doing before claiming a blown motor;)

Thanks alot for your input.

How much vacuum is it pulling at idle?

jamespond24
You are welcome,
MMO or even ATF will do the trick, just make sure you pour a little bit a te time and turn over the motor to spread it on all rotor faces and leave it over night.

I prefer steam cleanning, you get the results instantly.


BlueTII
That's one hell of a signature picture,,, Iiii'll be dayyamn, it looks amazing... :eek:

James,

Did you use the RA corner seals and corner seal springs?

Thanks, that is the engine and turbo I am currently running in my FD