"Poppy" exhaust sound....

is it pingging under a load try a higher grade of gas advance your timming ?

did you shake the tailpipe vigorously to see if it's bumping against anything under load? the usual cure for that is to jam something between the pipe and body and pry it away. all low tech wrench guy stuff.

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tudysm--

So, by inference, does that mean my timing is off? it's got over 100k miles on it, so maybe.... I've only had it for 30,000 of those miles, and I've never had the timing checked, so perhaps that's my problem......?

William, Didn't rattle when I shook it, so I guess nothing's loose....

How many miles, and when was the last time it got a tuneup? Spark breaks down most easily under heavy load.

nate

It's sitting at about 125k, and define "tune up"......

I don't take it in for a whole lot of work, unless it'd be cheaper for the shop to do it, or I don't have the tools for the job.

I change the spark plugs every 3 oil changes (I'm experimenting to find which gives best economy) but I tried switching out the spark plugs from Platinum +4's back to standard plugs when I first noticed the sound, but that dropped performance significantly, and made my engine noisier (I have no idea why, doesn't make sense to me that it should get louder with standard plugs).

I changed the plug wires at the turn of 100k, but I thought they were good for 50k or more....

I change my oil religiously at 3k (It's just my thing, probably don't need to be so anal about it), and I use full synthetic, and a midgrade oil filter (Fram tough duty), the air filter I change less religiously (every 3 oil changes or whenever I think it's getting bad)

I tried a can of Seafoam (1/3 in the oil, 1/3 in the gas, and 1/3 through the PCV) just to see if I could free things up. Did wonders for my injectors, even boosted my mileage, but the noise persists.

Advancing the timing would not improve ping.

Sounds like misfire. I bet one or more of your plugs are shot. Take them out and have a look. When mine was doing this (occasional pop uphill), about 500 miles later one of the plugs had its insulator touching the electrode and no spark. My plugs were burning up due to too far advanced timing because I did not follow the correct procedure to set the timing when I rebuilt my distributor.

Tighten them down good? Right heat range and right gap? I agree that standard plugs should be fine if they are indeed the correct plugs.

They can be. Some are much worse. The rubber insulation dries out with age, cracks, and the wire discharges somewhere where it shouldn't.

Sounds like my own maintenance plan. Except I use Pennzoil for no particular reason.

I can't remember, if you mentioned is the noise accompanied by a noticeable power loss? If so, it could be ping given that your injectors, plugs and wires seem to be in good condition. Try premium gas. If that doesn't change it, check your timing. Timing that has been either retarded or advanced from spec could cause ping.

Something else that is worth mentioning is that if your EGR is not working correctly, the motor will want to ping when it is hot. If it pings when cold then the problem is likely to be somewhere else. You can do a quick visual examination of the valve by having someone rev the motor and seeing if the diaphragm moves freely. However, the valve could be working and yet the exhaust passages or intake manifold passage is clogged with carbon.

You should also be able to reach under the EGR valve and gently push up on the diaphragm with a finger. (If the engine is running it should stall.) It should move smoothly. If not it might need cleaning which you should be able to do yourself. Spraying WD40 on the underside of the valve can free up the stem but you should be able to take the whole thing off and clean out the carbon with solvent (eg paint thinner).

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That, I will try when I get off work.

Not sure where EGR valve is on my Saturn, but I got a repair manual, I'm sure I can find it.

No spark problem, I check them every oil change. Although, I suspect I might have some worn rings, as I notice some oil one the cyl-3 plug from time to time and that might be causing some issues....

If you are using platinums, that may be your problem. Especially Bosch, they do not tolerate oil fouling at all. I forget, are you running regular copper core plugs now?

nate

Could be coming from valve cover or valve stem seals too. Do a wet-dry compression check if you aren't sure what condition things are in.

No distributor on his car. There is no timing adjustment either.

Time for a back to basics approach... Check compression on all cylinders. Might have an exhaust valve starting to burn.

wet-dry compression? what's that mean?

Also, if I want to do a compression chack, does the engine have to be cranked by hand, or can I just stick the guage in and turn the key?

read the compression, then put a teaspoon of oil in each cylinder through the spark plug hole and and read the compression again. if there is much if a difference the rings are worn.

You'd have difficulty cranking the ingine by hand. Use the starter motor as you suggest. Some people use a hand held swith clipped to the starter motor which lets you do it from under the hood. I've done it both ways. It can be tricky trying to see the guage from inside the vehicle while turning the ignition switch with the key.

I'd get a basic car maintenance book from the public library and read how to do a compression test. If you buy a compression guage it should have instructions with it.

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Check compression. Add a few squirts of oil to the cylinders, trying to get it all around the top ring as best you can from the top. Check compression. Compare numbers. Ideally, they should be the same. Differing results indicate worn rings.

Remove spark plugs. Remove coil primary wire. Remove fuel injector(s)/ECM relay or whatever is necessary to prevent fuel delivery. Insert compression gauge into #1. Floor the gas pedal. Crank motor 5-6 times with key or remote starter switch. (Pressure should build up quickly.) Record number on gauge. Relieve pressure. Remove gauge and repeat for all other cylinders. Post your numbers here for analysis.

The numbers should be between 120 and 160psi depending on your motor, and they should be relatively uniform. One cylinder wildly different from the others could be bad rings or a valvetrain problem. Two cylinders right next to each other with the same low compression is usually a blown head gasket.

relay or whatever is necessary to prevent fuel delivery.....

Yeah, that's what I was curious about; whether I shold cut off fuel from entering the cylinder or not.

I do know how to run a compression test, it's just that the term wet/dry isn't familiar to me. I'm used to working on 2 strokes and small 4 strokes anyway....

I'll run the compression test when I have some time, probably tomorrow.