GTA88

88 GTA with 167,000 miles.

This started out of nowhere last week. I start it up, and it idles rough, like a 'lopey cam' but doesn't stall. I get some blue smoke, not a ton, but noticeable. I can rev the rpms and it acts normal, but gets rough when I let it back down to idle.

After about 3 or 4 minutes of rough idle, it smooths out. I can then drive it all day and it runs great as long as I don't let it cool down again. It idles normally after warmed up.

I looked for rodent chewing and don't see any.

Before this happened, I was been driving it once or twice a month this winter to keep it in shape. So it hasn't been sitting a long time.

Clogged injector that only affects cold idle?

PCV valve? I just thought of the PCV right now. I haven't checked it for vacuum yet. Will check that soon.

Coolant Temp Sensor?

Any ideas?


Thanks !

GTA88

I just remembered: the smoking and rough idle started right after I added about a half quart of oil, just to top it up. ANother thing: it has always smoked a bit sometimes on startup, but now it also has the rough idle.

Bow_Tied

iTrader: (1)

Valve guide seals?

BIRD91ZRAG

iTrader: (1)

Which has allowed a spark plug or two to start fouling out maybe. Pull a few plugs and see what they look like, might be time for a set of plugs and valve seals.

88ripper

I agree with you. I had the same problem and it was due to oil fouling and had to change plugs

88ripper

As far as oil issue put in 20w50 oil with a no smoke additive. It will help

GTA88

Thanks for the replies. Yes, I did assume worn valve guides were letting oil drip into the cylinders overnight, and the next day I'd get the blue smoke on startup. The interesting thing about that is that if I let it sit 2 or more days, there is no smoke. I think the oil seeps right on past the rings, and on down in 2 days, or something.
So I could have a dirty, fouled spark plug or two, eh?

88ripper

For me I was dealing with the rough starts for a while but since it cleared up I waited. Eventually it fouled a plug beyond coming back to life so I knew it was time to change them. You can wait and like I said go with a heavier oil and see how that goes. What's in it now ?.

WildCard600

Regarding the smoking, make sure the oil drain back passages in the head are clear. Mine were a bit sludged up and causing excessive oil to pool in the valve train area. Once I cleaned them out the smoke on startup went away almost entirely. My valve seals are still worn out i'm sure, but there is no longer a puff of blue when starting the engine anymore.

GTA88

I have 10W-30 in it now. I was thinking of running a bottle of Techron through the gas tank, hoping it would clean up any deposits on the plugs. I already tried to just take out one spark plug, and it was a minor nightmare. The boot wouldn't even budge. So I gave up on that one, and I was able to get a different plug out to look at it a year ago, and it was OK. Took me a half hour just to get one plug out, and back in.

GTA88

Huh. How'd you clean them out? Remove both valve covers? And use kerosene and push a wire into drain holes? Maybe I need some of that 'high mileage' oil they sell, with stronger detergent package or whatever?

WildCard600

Pull the valve covers and a stiff piece of wire. Kerosene probably won't hurt, just make sure you change the oil before trying to start it again.

88ripper

So change the oil to a 20w50. You should notice a difference. As far as the plugs they are a pain in the ***. I had my mechanic do them. It is better with a lift. I would hold off for now though. Techron probably a good idea.

GTA88

Update: I let it sit for 3 days, then started it up. No smoke and no rough idle! Just a normal startup. OK, I'll take it. I assume if I start it up again within 24 hours, I'll get the blue smoke again, but I hope not the rough idle.

I looked inside the oil fill hole before and after starting the car, and I saw zero oil in there, except for a tiny pool the size of a dime. After it was all the way hot ( 220 degrees F ) I looked again, and still saw the same thing, just that dime sized pool of oil, probably left over from when I added the oil. And some vaporized oil mist. Pretty dry up there at all times, apparently.

Nice day. Drove the GTA on the highway for a while just to get the oil hot and perhaps clean some passages out here and there.

GeneralDisorder

iTrader: (1)

Why don't you replace the valve stem seals? If they are original to 88, then they are COMPLETELY SHOT. Trust me there will be a lot of bits and pieces of the old stem seals floating around in the heads and in the oil pan.

GD

GTA88

GD,

Thanks. Yeah, maybe I should replace them.

My first instinct is to 'dont fix it if it aint broke' meaning smoke on startup doesn't equal broken.

But hey I wouldn't want a piece of valve seal to block off some passage, would I? And no smoke would be nice.

I actually did have the valve stem seals replaced by a mechanic on my 1977 Ford Granada which completely solved a blue smoke problem.

GTA88

GeneralDisorder

iTrader: (1)

I would go with a silicone umbrella style seal.

GD

88ripper

Glad to hear you had no smoke but it will eventually creep up on you again more consistent, especially when hotter out. When that does happen go with the heavier oil I mentioned. Good luck !

Cottong

General disorder, can you give me any part numbers for silicone umbrella seals, without any machining? Any brand will do i guess. 1988 formula lo3, 5.0 tbi.... thanks, Gary.

sofakingdom

iTrader: (1)

I would NOT use umbrella seals. They are not much better than the O-rings in the retainer. They are exactly what they sound like: a sort of "umbrella" that goes on the valve stem and rides along with it, just sort of providing a cover to keep the oil droplets from raining down on top of the valve guide.

The best type are the "positive" ones, They clamp to the guide and fit tight around the stem, preventing ANY OIL WHATSOEVER from getting to the guide where it can then get sucked into the motor.

Problem with any/all of this is, there's more than one cause of blue smoke at startup. The guide is CERTAINLY one of them, but not the ONLY one. A key here may be your "rough idle" description.

One of the other causes of blue smoke is excess fuel in the cylinders, to the point that it washes down the rings. When that happens the rings can't seal, and it gets oil into it that way.

Since your problem occurs only when cold, AND involves rough idle, I'd be strongly inclined to suspect the fuel situation as your issue.

Might want to take a look at your cold-start injector (if your particular year has it; can't remember what year it was discontinued) and make sure its temp switch is working right. Easy way to test it is simply disconnect it. If the blue smoke issue goes away, then it's a likely culprit. Be aware that it probably won't run "right" without it; after all, it's there for a reason; but as a troubleshooting tool, if you can eliminate the symptom that way, it gives a direction to look.

Another possible issue, ESPECIALLY if the car gets terrible gas mileage all the time, is your coolant temp sensor. If the ECM thinks the engine is at -40° or something at startup and never thinks it gets above 150° or whatever, it will ALWAYS be dumping in too much fuel. Might be somewhat OK enough to drive, but not right. Since it's very cheeeeeeep and very eeeeeeezzzy to change, you can just launch a pre-emptive first strike on it, and see what happens.

Note that I am NOT saying "your problem isn't the valve guides"; I am NOT saying "don't change your valve guide seals"; I am NOT saying "your valve guide seals are fine"; NOT NOT NOT NOT NOT NOT NOT NOT. In fact I highly recommend changing them out REGARDLESS, as they are a likely failure point, inevitable even. Always a good idea to refresh them in an old neglected motor. Good opportunity to put in new valve springs as well; the combination of those things might even make it run noticeably better. I think you need these https://www.summitracing.com/parts/fel-ss72527 which you can buy 2 sets and use on both intake and exhaust. For springs you can use anything from "Z28" springs such as from Howard's, Comp 981, other basic entry-level stock-dia springs from Crane, Lunati, etc., LS6 springs w/ Comp 787 retainers, and so on.

I would NOT UNDER ANY CIRCUMSTANCES recommend thicker oil. Of all the proposed "fixes" for your problem, that one is the worst suggestion of all. Use what your engine requires, which is, 10W-30.

calidude

@sofakingdom I'm trying to troubleshoot a similar issue... I'm getting a large cloud of smoke after the car sits for probably about 20 minutes however it does not smoke at cold startup. Already replaced the Coolant Temp Sensor and was wondering if this is fuel and related?

My 1985 TPI has been having warm idle issues where it will rev up to 1500rpm even when at operating temp like it's cold. Would a bad MAT (Manifold Air Temp) sensor also create the same condition and does the computer use this to set initial idle cycle on start?

I would expect it to start at a close of base idle around 800rpm and then sit down around 500rpm..

I've unplugged the cold start injector sensor and didn't see any change.