Car trouble

[Brad Johnson]

Yeah, and probably need to figure some way to spoof the IAC.  It's trying to idle up to 3k+ RPM sometimes.

Whether faulty IAC, bad gasket, or hole, uncontrollable high idle is an almost 100% certain vacuum leak. (IAC is just a controlled vacuum leak, after all.) Spoofing the IAC will only make the problem worse and likely create more problems.

Brad

[KD5NRH]

Whether faulty IAC, bad gasket, or hole, uncontrollable high idle is an almost 100% certain vacuum leak. (IAC is just a controlled vacuum leak, after all.) Spoofing the IAC will only make the problem worse and likely create more problems.

There are so many spaghetti-size hoses around there that have been cracked, replaced, (without fishing the original one out of the tangle it's in) plugged with screws, etc. that it would almost be easier to rip them all out and start over...if I could get to both ends to see which ones actually do something.

[KD5NRH]

I'll echo what others have said... Start with a compression check.

On the list if I can get some time when any of the places on the way between work and home are available to do it.  Trying to avoid any side trips that aren't completely critical.

That will tell you if the mechanical is, by and large, okay.  Especially after having a "Check oil" light (which I take to mean as GM's version of an oil pressure indicator lamp), you may have something internal going on.

Not overly worried about the light; it was about 1/16" below the "add" line, and went off after adding a quart.  On a car that old, a couple thousand miles to the quart isn't usually an indication of a serious problem...especially considering the valve cover gasket was cracked and split, so some oil was definitely being lost there.

The complete lack of smoke from the exhaust keeps me thinking it's something non-catastrophic that I just need to find and fix, but everything else keeps not fixing it.

On another note, it was chattering under load yesterday, so maybe a slow-closing valve could be the issue.  I didn't see any actually stuck when I had the cover off, oil flow was vigorous, (as in, when it caught, it showered the entire engine compartment with oil) and the cam lobes looked good, so I may have to decide whether it's worth the effort/expense to pull the head and get a good look at the valves themselves.

If I had a spare car, this thing would be a real dilemma; strip and scrap, or refuse to admit defeat, tear it apart piece by piece until I find and fix the problem...then drive it for a while longer until something readily identifiable breaks, and then strip and scrap it.

[Brad Johnson]

There are so many spaghetti-size hoses around there that have been cracked, replaced, (without fishing the original one out of the tangle it's in) plugged with screws, etc. that it would almost be easier to rip them all out and start over...if I could get to both ends to see which ones actually do something.

A spray bottle of soapy water is an easy and inexpensive way to check for both vacuum and current leaks. Start spritzing in a slow, controlled way until you hear the engine change tone.

Also... a failed intake gasket on one runner will cause the engine misfire you describe. If it was previously failing but not failed it could also te the source of your random high idle problem, though a location common to all cylinders is more likely. GM gaskets from late 80s/early 90s are a common problem area.

Brad

[KD5NRH]

A spray bottle of soapy water is an easy and inexpensive way to check for both vacuum and current leaks. Start spritzing in a slow, controlled way until you hear the engine change tone.

As I recall, one of the redneck methods for finding an intake gasket leak on the Saturn was to spray carb cleaner on the intake and listen for a change.  Given the amount of plastic and rubber in that area, I never tried it.

[Brad Johnson]

Carb cleaner works too. I was just never to hip on using an aerosolized flammable liquid as a testing medium.

Brad

[KD5NRH]

I should also note that the high idle doesn't start until it's been running for a minute or so, so it's apparently not just a vacuum port wide open to atmosphere all the time, but something that opens up after starting.

[KD5NRH]

All right, not enough time over lunch to have O'Reilly do the test, so I grabbed a $30 tester.  Also picked up a roll of silicone tape in case I can find that vacuum leak, and a more durable 12V test light.  (Have a feeling I'll be taking things apart again soon, so I can put off replacing any bad lines until then.)

[roo_ster]

I do wonder what heinous offense you have committed rates dropping a 1994 Pontiac Sunbird in your lap?  I do not think I have seen one in a long time.

Good luck fixing it.

[KD5NRH]

I do wonder what heinous offense you have committed rates dropping a 1994 Pontiac Sunbird in your lap?  I do not think I have seen one in a long time.

Well, I was passing right though your neighborhood NYE shortly after picking it up.  Could have stopped by and let you admire its custom crackle-and-fade paint job.

Not sure I'll get the engine back to its former glory performance marginal adequacy, but I do need to rebuild the tool pile anyway.  Compression gauge isn't exactly the sort of thing one use often, but I'll admit it's a good one to have around to rule out certain issues. 

[Brad Johnson]

I should also note that the high idle doesn't start until it's been running for a minute or so, so it's apparently not just a vacuum port wide open to atmosphere all the time, but something that opens up after starting.

Check the EGR valve assembly. Vacuum leaks not manifesting until some consistent time after start would be consistent with a temp-related control function. EGR valves fit in this category and old units are prone to leaks due to corrosion.

Brad

[KD5NRH]

Check the EGR valve assembly. Vacuum leaks not manifesting until some consistent time after start would be consistent with a temp-related control function. EGR valves fit in this category and old units are prone to leaks due to corrosion.

Funny; I'd have assumed they were prone to leaks due to guys like me soaking them in solvent and bashing them with a hammer in an attempt to avoid having to buy an $80 replacement for something that shouldn't even exist.

[Brad Johnson]

Funny; I'd have assumed they were prone to leaks due to guys like me soaking them in solvent and bashing them with a hammer in an attempt to avoid having to buy an $80 replacement for something that shouldn't even exist.

Nah, that's an acceptable and formally recognized repair technique. Has to be something else.

Brad

[KD5NRH]

Nah, that's an acceptable and formally recognized repair technique.

Only when accompanied by significant application of obscene language.

I'm still convinced this is why the missionaries have so much car trouble...I know it's why I never invite them over to help with auto or plumbing repairs no matter how many times they offer.

[cassandra and sara's daddy]

As I recall, one of the redneck methods for finding an intake gasket leak on the Saturn was to spray carb cleaner on the intake and listen for a change.  Given the amount of plastic and rubber in that area, I never tried it.

Ether (starting fluid) works too


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[KD5NRH]

Ether (starting fluid) works too

It does, but it's a bit too volatile for me to want to spray it near hot engine parts while my head is under the same hood.

Using it for a flamethrower to take out a swarm of mosquitoes or a wasp nest, OTOH, is worth the risk.

[charby]

Ether (starting fluid) works too


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Good way to smoke the o2 sensor and then plug up the cat.

[cassandra and sara's daddy]

On the topic of cat converters is there a non kinetic way to unclog one?


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[Boomhauer]

On the topic of cat converters is there a non kinetic way to unclog one?


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Tweaker with a battery powered sawzall.

[Fly320s]

On the topic of cat converters is there a non kinetic way to unclog one?


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Detcord is non-kinetic, right?

[charby]

On the topic of cat converters is there a non kinetic way to unclog one?


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None that I know of, there is website out there with some ideas, but I think it would be just easier to buy a universal and replace it.

[brimic]

On the list if I can get some time when any of the places on the way between work and home are available to do it.  Trying to avoid any side trips that aren't completely critical.

Not overly worried about the light; it was about 1/16" below the "add" line, and went off after adding a quart.  On a car that old, a couple thousand miles to the quart isn't usually an indication of a serious problem...especially considering the valve cover gasket was cracked and split, so some oil was definitely being lost there.

The complete lack of smoke from the exhaust keeps me thinking it's something non-catastrophic that I just need to find and fix, but everything else keeps not fixing it.

On another note, it was chattering under load yesterday, so maybe a slow-closing valve could be the issue.  I didn't see any actually stuck when I had the cover off, oil flow was vigorous, (as in, when it caught, it showered the entire engine compartment with oil) and the cam lobes looked good, so I may have to decide whether it's worth the effort/expense to pull the head and get a good look at the valves themselves.

Stop right there.
Before you run the engine any more, get an oil pressure gauge on your engine. Oil warning light doesn't mean 'low oil' it means low or no pressure from your pump. Oil might notbe getting to your crank journals, your next indication of having a problem might very well be a thrown rod.

[KD5NRH]

Before you run the engine any more, get an oil pressure gauge on your engine. Oil warning light doesn't mean 'low oil' it means low or no pressure from your pump. Oil might notbe getting to your crank journals, your next indication of having a problem might very well be a thrown rod.

Oil was most definitely flowing fine when I cranked it with the valve cover off.  Also, it's not the "every valve" chatter of low oil; more like what I'd expect from one or possibly two cam lobes breaking contact and then a smack as the lobe comes back around and makes contact again.  The oil light hasn't come back on since the few minutes last Thursday, which was just long enough for me to drive to a level parking lot about 3 blocks from where I'd been parked on a hill, and pull up near a good light to check and add oil, except for right after the oil shower incident when it was obviously a bit low again due to a pint or so having been vomited out the open cover.  Since it's staying off with the oil in the "happy" range on the dipstick, that seems to be a good sign that it's working properly.

Did a single piston soak last night, partly just to see if the Sea Foam would stay in the cylinder for 15-20 minutes.  It did, so the rings are at least still that good.  Compression gauge barely moved before that, though, so I think we're back to a slow-closing valve.  Forgot to recheck after.  This morning, while obviously not fully well, it did sound/act a little better, so maybe some of that solvent splashed its way up through the port during the starter spin to clear it, and loosened things up enough to let it catch up a bit.  May try one guy's solution of pulling the exhaust manifold off enough to hose a bunch of PB Blaster onto the valve and then cranking it through to try to get it up the stem.

[Nick1911]

Compression gauge barely moved before that, though, so I think we're back to a slow-closing valve

How was the compresson on the other cylinders?

[KD5NRH]

How was the compresson on the other cylinders?

#2 is going to need a Helicoil if I ever feel the urge to rework the head.  Outer threads beyond the very shallow depth of the compression tester's threading are shot, though the plug seats and snugs up good.  3 and 4 were over 150psi, though I didn't keep spinning enough to solidly say either was giving a true maxed out reading; they're working so I was checking mostly to make sure the gauge would really go up past the 15-20psi from #1.