once again..engine problems

[JRodsm]

So this time its a little more complicated. I was driving down the interstate and any time I was over 100 mph and pressed the gas it felt like it bogged down and the exhaust was popping. Then my check engine light came on. So I pulled over and at idle the car was shaking and any time i started off it felt like it was in a high gear. Well we checked spark plugs and wires, everything was alright except #2 spark plug had tons of carbon build up and the top of the piston was solid black. So we ran a compression test and the 2nd cylinder had absolutly no compression. All the cam lobes were fine and there weren't any bent valves, no smoking from anywhere. So we started breaking down the head to check it out a little more, maybe piston ring broke, hole in the piston. We're going to do another compression test to see where the compression is going but any ideas of whats wrong/ how to fix it before we get too into it??

 

[Talesin]

Do a leakdown test before you pull the head. That'll tell you what blew.
Difficult to tell when a valve is bent, sometimes they only bend just enough to lose the seal... but you'd usually have at least a little compression with a 'sneaky bend' like that.

My money'd be on detonation and either a toasted piston ring, or a dead piston.

 

[JRodsm]

well we went ahead and took the head off and all the valves in that cylinder were crap. One had a hole burnt through about the size of a pencil and all the others were corroded and were about to burn through. So if i replace all of my valves should this fix the problem?

 

[95 gsx]

Sorry about the bad luck. I would say you had an injector fail and toast that cylinder. Now would be the time to upgrade.

 

[redeclipse7782]

What do the pistons look like, especially the one that corresponds to the best valves? What were the compression numbers on the other cylinders?

 

[JRodsm]

The other pistons weren't that bad but that one the whole top was black. The ones we checked were about 180 and when we got to that one it didn't even move. I'm ordering all stainless steel valves and taking it to a machine shop to get it machined, cleaned and get the valves put in this week. hopefully this will solve the problem

 

[redeclipse7782]

Might as well get bigger valves, and upgrade the head parts to improve performance while the engine is apart. New springs, new retainers, and upgrade to 3g lifters

I'd go 1mm over and get these valves:
http://www.slowboyracing.com/estore/product.php?productid=2314&cat=2404&page=1
http://www.slowboyracing.com/estore/product.php?productid=2254&cat=2404&page=1

Atleast get these to fix that annoying lifter tick
http://www.slowboyracing.com/estore/product.php?productid=1142&cat=77&page=1

Don't forget new valve seals, I'm not sure if they come with the valves.

 

[JRodsm]

Thanks for the info. Right now I'm just trying to get this thing running again but I am going to keep ugrading here and there. New cams and gears, lifters, springs, all the good stuff. just trying to get it back on the road!

 

[Talesin]

Wouldn't bother with the oversized valves, they don't really help much until you start putting out some REALLY big numbers, are a bit of a pain to get installed, and are a bit costly.

Upgrading the lifters is a good one to do though, and upgraded springs are handy to have for peace of mind if nothing else.

 

[JRodsm]

So after about 3 long weeks of working on this thing its just about done. I got all new SS valves put in and everything cleaned. Even a little porting and polishing while I was at it so we got everything on and went to start her up. Didn't start up to easy and was still running rough and kept cutting off. Checked everything and found that my cam position sensor was completely broken. I'm getting one tomorrow afternoon and was told by 2 different people that this was really something serious and was keeping it from running right. Any opinions or facts on this thing and will it help?

 

[Spoolin4Ever]

Cam Angle Sensor? Yes I believe it can do what you were saying it's doing.

You could try swapping it with a known-good used one before spending on the new one, just in case, or just buy a new one.

 

[JRodsm]

Ok sorry its been so long to post what was wrong. After replacing the CAS it ran fine! Ran a little rough for about a day or two..i guess for sitting so long but it smoothed out and ran like a dream. HOWEVER, im having more trouble i believe with a different sensor or possibly having a bad CAS. I've posted on a new thread with the story on it now so if and any advice will help. Thanks for the help!