60 pounds of compression on all cylinders

[Yamaharider74]

hello i am having problems starting my 06 apex with mpi supercharger will the supercharger bugger up the rings if there is to much boost ?
I am new to the whole boosted thing got the sled off a freind cheap it ran perfect last ride of the season talked to the guy who did the clutching and tweaking on it he said it ran great to
i have a code 15 on the dash which is the throttle position sensor i think it tries to fire ,could it be flooded so bad that won t start ,changed plugs still same thing no start

 

[nate007]

Do you know if the sled has had low compression pistons or a head shim installed? How much boost are you trying to run?
The service manual shows that a compression test should yield 206psi at cranking rpm (400rpm) at sea level. I would try doing a leak down test. Sounds like you may have some broken ring lands on your pistons. If you have access to a bore scope, you may try looking into the cylinders to see if there is any damage to the tops of the pistons, or possibly even remove the oil pan and inspect from underneath, as well as check for metal.. That sounds way too low for even low compression pistons. You can also try putting a little oil in each cylinder, turning the engine over a little bit, the check compression again. Chances are good that you have some piston or ring damage if the compression comes up after doing that.

You can check/test/adjust your tps with a volt meter as follows:
Locate the harness connector on the tps, and using a volt meter, connect the positive probe to the yellow wire, and the negative probe to the blue wire.
If the voltage across the two wires reads between .63 ~ .73 V, the sensor is adjusted correctly. If not, loosten the two screws holding the sensor on and slowly rotate the sensor to bring it within that range.

To check for a bad sensor, disconnect the harness connector, and using an ohm meter, test the maximum ohms between the Yellow (+) and blue(-) terminals. If it's more than 3.65 ~6.5 ohms, the sensor may be faulty. Slowly open the throttle and watch the ohm meter to be sure the ohm resistanse changes gradually when operating the throttle, and it should read between 0~5 ohms at wot.

You can also do this through the ecu's self diagnostic function as well, and I can pm or email you the instructions on accessing that if you need it. It's a fairly long portion of the manual, with info on checking all the sleds functions, and more to type than feasable.
It's not hard to do, but I'd check the above measurements after making sure that its' not just a bad connection.

 

[Yamaharider74]

hi and thanks not sure exactly on the boost but it has 27 bottom gear and 22 top gear it seems so weird that it ran fine before lol

 

[kviper]

I have posted this before and may be your problem being that it ran fine when put away.
If the sled was run for a short time (not warmed up good) than shut off and stored for the off season the condensation can corrode valves and cause a poor seal.
It would be unusual to have all cyl at exactly 60 psi from mis use but who knows.
As stated above try some oil in the cyl to see if compression comes up. If it don't it's likely a valve problem.
Some of these cases cleared up by just running them if they start.

Good luck!

 

[rxrider]

X2 on what kviper says.

You will not have good ring and valve seal if the engine has not been run for some time, that is normal.

It's not normal to have piston rings go bad and have the exact pressure acroll.

My advice is to run the sled a few miles and redo the compression test.

 

[Yamaharider74]

Thanks for the advice will see what I can figure out and post results

 

[powershot1]

Also try a different gauge.

 

[Yamaharider74]

Good morning ,did air test on my sled that couldn't start
Well the valves are all leaking must be corroded under the valves ,took head off going to get checked at local engine shop for cracks in the head

I don t know the history of the sled figured May as well get checked for cracks and warpage

where do the heads like to crack around the valves ?

 

[kviper]

This is why I like to run my sled every month or so in the off season. The key though is to run it good on the stand and make sure it is good and warm so all condensation is burnt out.
Even during the season if I start the sled I run it till it is fully warmed up, usually hold my hand on the exchanger till I can't hold it there any more.

 

[Yamaharider74]

valve lapping

took head off removed the valve ,it sure seems to take a lot of lapping to get a nice face on the valves
the sled only has 5300kms on it so am puzzled why valves are not sealing properly must be the good fuel now we have these days .
if i dump fluid in the intake and exhaust ports if valves are sealing it should not leak out ?am i right on this