I just changed the spark plugs in my car. Went to start it and it fired once and then nothing. I tried again but it sounded like there was no compression (and obviously didn’t start). I pulled the plugs back out and tried to see if there were any marks on the pistons. I didn’t see any, but the viewing area is pretty limited. I then drained the oil to see if there was any foreign material. Nothing. I’ve been seeing a lot of ecotec horror stories about the timing chain tensioners. Is there any other reason to lose compression suddenly or could I have gotten lucky that none of the valves were fully open if/when the chain failed?
If your car was fine before you replaced the spark plugs,you messed up somewhere.I would put back the old ones and see if it starts. If still nothing,go over your work to see if you didn’t knock something out. Are the replacement spark plugs the same? are they gapped properly? are the ignition wires or coils installed properly? Let us know
First of all, it’s not my first time changing spark plugs. It’s not even the first time in this car. Second, the engine fired. Only once but it fired. Something happened because there’s no compression. Yes, they’re the right spark plugs. Yes, I set the gaps. Yes, I checked for any stupid accidental mistakes like not plugging in the coils. I may not be a mechanic but I’m not a moron.
Sounds like it’s time to do a compression test.
And we would know that how?
Give us the benefit of the doubt as we get posters with ALL kinds of abilities.
One can pretty much tell when an engine has no compression when trying to start it.
And on a 14 year-old car it’s quite possible the timing chain failed.
Especially when that car has a reputation of timing chain tensioner failures.
how have you verified this?
and know that we aren’t here to bash your skills, but we have to ask questions to figure out what is going on and what you have and have not done. We aren’t there, we didn’t watch you do the job, so we only have the info you tell us. We have to rule out the silly things before progressing to more difficult diagnoses (which is even more difficult without being able to see/hear/touch the car.)
You could describe steps. Ohc motor? Individual cop coils? Unplug coil. Remove coil. Replace plug. Times 4x. Was it this simple?
how do you know you have no compression? I would do a compression test. if you have compression I would check to see if you blew any fuses or relays to rule that out.
When the engine is flooded it can sound like there’s a loss of compression. I had that occur on my truck one time when the carb was leaking gasoline into the intake manifold. I think there actually is a loss of compression, b/c the excess gasoline washes the oil off the piston rings and cylinder walls. So one possibility is something went wrong w/ your plug change-out and some of the plugs aren’t firing, which will cause unburned gasoline to accumulate in the cylinders. Before presuming your symptoms represent a major problem, such as the timing chain, double check that the plug wires are properly connected to the plugs, and that the ignition system’s electrical connectors haven’t become inadvertently disconnected.
Apparently there was enough carbon and other deposits crusted in my cylinders that came loose when the old plugs came out that it held some valves open. With the symptoms it had and this engine’s reputation, I refused to even try to turn it over again before checking the timing chain. Had it happen on a BMW before. It was junk. I took the valve cover off which was a pretty simple job and the chain was still intact however it is rather loose and that will be the next project… If it lasts that long. As for the valves, well, not the best decision but I cranked until it cleared. luckily it worked. Thanks for your help and sorry I backfired on y’all.