Compression check

[Ridefree]

So I have always been one to just lay the plug wires to the side when cranking the engine during a compression check. but I've read once or twice the you ground the plug wire so that the spark has somewhere to go or you could damage the coil or ECU. I will be doing a compression check tomorrow and was wondering how you guys do it, grounding the plug wire or not. and I think I've read on this forum that I should expect about 150 psi from my stock engine, do you guys agree with that?
Thanks in advance, Ridefree

 

[Rocket Scientist]

I would ground the plug to give the spark somewhere to go. Check compression with throttle wide open.

 

[Neville Lush]

150 psi from my stock engine, do you guys agree with that

Check the manual, but i would expect 210psi . If it was 150 it would be very tired...

 

[scot in exile]

Just remove the plug

 

[Rocket Scientist]

So I have always been one to just lay the plug wires to the side when cranking the engine during a compression check. but I've read once or twice the you ground the plug wire so that the spark has somewhere to go or you could damage the coil or ECU. I will be doing a compression check tomorrow and was wondering how you guys do it, grounding the plug wire or not. and I think I've read on this forum that I should expect about 150 psi from my stock engine, do you guys agree with that?
Thanks in advance, Ridefree

Another thing I thought of. Do you still have the secondary "big brother is making sure you don't have to much fun" butterflies installed ? Mine have been out for so long I can't remember if they are full open at start up or not. If they are partially closed at cranking speed it will affect your readings. Good time to toss them

 

[mully95]

Mine have been out for so long I can't remember if they are full open at start up or not. If they are partially closed at cranking speed it will affect your readings. Good time to toss them

I had mine out for awhile but just recently installed them back into the throttle bodies. Using TuneECU I adjusted the secondaries so that they are opened to 30% at idle in 1st and 2nd gears. Then opened them to 80% up to 2400 RPM in 1st and 2nd gears. Otherwise they are opened to 100%.

This keeps up the velocity in this range and helps do away with the off idle and close to off idle "puff" through the throttle bodies. I even noticed a good bit of increased throttle response as well.

On the topic for checking compression and the coils firing I believe I would just unplug the leads to the coils. Grounding all the spark plug wires would kind of PITA. Unless I'm not following correctly on the grounding procedure.

 

[Rocket Scientist]

I had mine out for awhile but just recently installed them back into the throttle bodies. Using TuneECU I adjusted the secondaries so that they are opened to 30% at idle in 1st and 2nd gears. Then opened them to 80% up to 2400 RPM in 1st and 2nd gears. Otherwise they are opened to 100%.

This keeps up the velocity in this range and helps do away with the off idle and close to off idle "puff" through the throttle bodies. I even noticed a good bit of increased throttle response as well.

On the topic for checking compression and the coils firing I believe I would just unplug the leads to the coils. Grounding all the spark plug wires would kind of PITA. Unless I'm not following correctly on the grounding procedure.

I've been happy with mine being gone. Just out of curiosity what did you put on the screws to keep them from getting inhaled ?

 

[Jag]

I've been happy with mine being gone. Just out of curiosity what did you put on the screws to keep them from getting inhaled ?

I tried it, but I did not inhale!

 

[Ridefree]

Another thing I thought of. Do you still have the secondary "big brother is making sure you don't have to much fun" butterflies installed ? Mine have been out for so long I can't remember if they are full open at start up or not. If they are partially closed at cranking speed it will affect your readings. Good time to toss them

I still have the secondaries in but I have the intake plumbing out so I can see if they're closed while cranking. Will be interesting to see

 

[mully95]

I've been happy with mine being gone. Just out of curiosity what did you put on the screws to keep them from getting inhaled ?

Blue Loctite thread locker. Funny thing is that the Triumph didn't have any type of thread locker at all.

I really like the increase throttle response that I have now compared without them.