Anybody done a compression check on an i6? What numbers did you see, wet and dry?

At 150K, thinking of getting it painted but would like to check engine health before investing.

Thinking of jumping the starter solenoid directly with the key out, avoid unwanted fuel, spark, and possible ECU confusion.

Also got a cheap borescope that send video to my phone.

 

Merlin,

I think the the throttle is closed (or nearly closed) with the engine off.

So if you just use the starter then it will likely be that you get really low numbers.

You can disable the fuel pump by removing a fuse by the passengers feet or by disconnecting the connection under the back seat.

If you do the later then look at this thread also https://www.freel2.com/forum/topic36980.html

Good luck

Paul

 

The compression pressure should be checked with the engine at operating temperature.

Checking the compression pressure:

1. Remove the fuel pump relay.
2. Start the engine - the engine will start, run for a few seconds then stop.
3. Remove the spark plugs.
4. Install the compression tester.
5. Install an auxiliary starter switch in the starting circuit. With the ignition switch OFF, using the auxiliary starter switch, crank the engine a minimum of five compression strokes and record the highest reading. Note the approximate number of compression strokes required to obtain the highest reading.
6. Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.
7. Install the removed components in reverse order, observing the specified tightening torques.
8. Clear all DTCs from the ECM.

NOTE: Due to the possibility of loose carbon that has become trapped between the valve face and seat effecting the pressure readings, when carrying out a compression test and cylinders are found to have low pressures, install the spark plugs, road test the vehicle and re-test the suspect cylinders. If the correct pressures are restored, no further action is required.

The indicated compression pressures are considered within specification if the lowest reading cylinder is within 75% of the highest reading.

If the cylinder pressures are found to be low, carry out a leakdown test to determine the location of the fault (if any leakback can be heard through the engine breather system suspect the piston rings, if any leakback can be heard through the inlet system suspect the inlet valve or seat, if any leakback can be heard through the exhaust manifold suspect the exhaust valve or seat. If the measurements for two cylinders next to each other are both too low then it is very likely that the cylinder head gasket between them is burnt through. This can also be recognized by traces of engine oil in the coolant and/or coolant in the engine oil).

 

Thanks. I'm inclined to do it with WOT, maybe just try both open and closed.

 

Remove item 21 and crank he engine and the fuel pressure will drop to zero

 

Followed the directions in the manual, throttle closed. That was not a problem, it quickly exceeded the 300 psi peg on my gauge anyway.

To crank it, I used a remote switch to jump power between the battery Pos and the cold terminal of the R1 (SM) relay socket. The two small sockets are for the ECM, the large ones are for the solenoid. The one you want is the large cold socket (the other is hot 12v). I stuck a small nail into the socket so I had something to clip onto. The wiring diagram led me to that, after I couldn't connect at the solenoid itself. You don't have to get under the car at all, and cannot access the solenoid power terminal anyway (it's on the top of the starter assembly).

Key fob removed. I forgot to pull the fuel pump relay, but probably didn't matter with the ignition off.

For the wet test, I stuck a piece of tube into each cyl and injected three pumps from an oil can, then let it all drain into the cyl before removing the tube. Two or maybe one good pump would have been plenty, it made a LOT of smoke after starting and there's still some oil in the exhaust after a short drive.

1. 245/290
2. 235/280
3. 248/288
4. 255/300
5. 245/290
6. 233/275

So all within 90% (manual spec is 75%)... I'm happy at 150K

The borescope worked for the pistons, but the mirror it came with to look up at the valves didn't really work. The attached image is typical of all cylinders.