1998 eclipse gsx problem.

[AK-49GSX]

hey guys, here is whats happening. about a week ago my GSX would start up and then die. so, i looked up on some forums on what to do. for some reason i was only getting 50 psi through 3 cylinders and 1 cylinder was running 150 psi. so i changed the spark plugs and threw some oil down in the valves. and sure enough the compression came back up and was running just like it use to. then today, about 8 days later it started idling funny like was idleing at 1500 RPM and then when i would shift into neutral, the RPM's would bounce really low and then come back up to 1500 RPM again. and now it wont even start again. i just checked the plugs and there extremely black like they were last week when i changed them. anyone got any idea whats going on?

 

[U2_slow]

Is your CEL on?

Mines use to idle like that and threw a code P0505... i swapped in a new ISC, and adjusted the screw and now it idles somewhere between 900-1100.

 

[AK-49GSX]

its not throwing any codes. the check engine light is not on. i just talked to some guy who is familiar with dsm's and he said i might need a rebuild because my rings might be sticking in my engine from the seafoam that i put in it. or there may be a leak somewhere. any insight?

 

[sschambers]

How many miles are on the car? As far as rings, it's almost never a ring problem (not to rule it out, though). So before you get too worried, let's look at more basic troubledhooting.

First - On a piston, there's 2 compression rings (upper), 2 oil control rings (lower) that sandwiches an oil expander ring. Also, our pistons are dish pistons, so if you're running low compression on a cylinder, throwing oil down there won't help too much since the oil will sit in the 'dish' and not fully get around the rings.
Low compression can signal a bad head gasket, as well. Is your car smoking at all? What kind of odor does the exhaust have?

As far as Seafoam, I don't think it would have caused this problem. I've used Seafoam a few times with great results.

50psi is super low compression for these motors. Are you 100% sure the compression test was done correctly? The best way I've found to do it is:
1. Take the car for a good beating, and make sure the motor is up to normal operating temp.
2. Pop the hood. Pull the main engine fuse. Pull off the wires and plugs.
3. Hook up the tester in a cylinder (make sure you tighten it as much as you can).
4. Have someone in the car, holding the throttle at WOT and start cranking for a few revolutions.
5. As the engine is cranking, the compression gauge will bounce up, up, up.
6. When it seems like the needle won't budge anymore, there's your reading.

How does the compression *sound*? Like when cranking the motor. Also, how does it drive? Any major loss in performance?

A good way to check and see if your oil rings are shot:
Take the car for a drive. Find a steep hill, and go to the top. Roll down the hill IN LOW GEAR, not touching the throttle. Once at the bottom, mash the gas. See a cloud of smoke? If so, rings could be bad.

Hope some of this helps.

Steve

EDIT> As far as the extreme loss in RPM's when throwing it in neutral - both of my DSM's have always done this. For instance, when boosting (say, in 3rd), if I let off the throttle and throw it in neutral, the RPM's drop so low the engine almost dies, then comes back up to normal idle. A lightened flywheel usually causes this. But in my Spyder, I had a stock flywheel. My explanation in the Spyder was that maybe my BOV wasn't completely closing fast enough after relieving boost, causing a leak for a second.

 

[AK-49GSX]

Well i took it to a mechanic, and he changed the spark plugs. i just took them out to look at them and they are black. DOes this mean he gapped them wrong? or does this lead to any other steps?

 

[AK-49GSX]

I would love to do those tests however it just won't idle. I am waiting for my friend to get home right now, he has a compression tester however i am beginning to think that the mechanic gapped my spark plugs wrong or maybe used the wrong ones.

 

[sschambers]

Spark Plug Diagnosis

That will give you a better idea bout your plugs. Over-gapping the plugs would cause an idle problem. The stock gap on these are .028-.031. It's recommended to stay around the .028 range, though.

You should stay with the stock NGK plugs, they seem to perform the best (for me at least).