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1987 Chevy Suburban runs rough, hesitates
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hixsix
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Apr 11, 2009, 5:48 AM
Post #1 of 7
(5768 views)
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1987 Chevy Suburban runs rough, hesitates
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We have a 1987 Chevy Suburban, 350 V8, automatic transmission (2WD), not sure of mileage, but probably over 200,000. Last time we were officially driving it (4-5 years ago), it gave us an engine code of 44 - oxygen sensor detected lean mixture.
The suburban will start up, run, & drive, but it's very hesitant upon acceleration, and it's very "chuggy"....runs very rough.....back before we parked it, it also stalled a lot. Now's it's smoking out the tailpipe too....whitish/grayish smoke...smokes a little while idling, smokes alot when the gas pedal is pressed. Including before parking it & now, we have replaced the fuel pump (it is definitely working), fuel filter (just checked again & the fuel filter is perfect), fuel injectors (replaced last year), fuel pump relay, spark plugs & wires (4-5 years ago....should those be replaced again?), oxygen sensor, distributor rotor & cap, vacuum hose, gas in tank, throttle position switch, & temperature sensor. But, suburban still has the same symptoms (minus the stalling...yet!), & we are not sure what to try next.
Not sure if it's still giving the same code or not....we'll have to check. Anyway, anything else we can to do get the engine running smooth, and not hesitate upon acceleration? (and hopefully stop the smoking?) We have on our list that it might be:
- needs new plugs & wires
- cracked hoses
- bad gasket
- faulty EGR or PCV valve
- water in fuel (but we doubt it)
- defective thermostat or coolant sensor (but again, doubt it)
- MAP sensor (can't remember if we ever replaced this)
- catalytic converter
- fuel pressure regulator
We really don't want to sink any more money into replacing a part if it's not going to fix the problem. Any help/ideas would be much appreciated!
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 11, 2009, 6:11 AM
Post #2 of 7
(5767 views)
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Re: 1987 Chevy Suburban runs rough, hesitates
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At the 200k area anything is possible that hasn't already been known done and good.
Spark plugs at the age and miles should be an annual event without much regard to how far it went. Take note of each plug at they have a story to tell.
The smoke is an unknown at the moment. Is coolant being consumed? Pressure test cooling system would help to nail down if a head/intake gasket.
Vacuum leaks: You gotta check everywhere - spray carb/throttle body cleaner at any suspect area and if idle changes there's a problem there. These cleaners are flammable so use caution and with engine on cooler side is safer. It can flash if you hit hot items! I think this uses a lot of small plastic vacuum hose that is brittle as pasta with age and can be replaced with rubber hose as needed.
TIMING CHAIN: That's about the end of even real chains most of the time. You gotta think about that and there are ways to test if you know it's likely to still be original - let me/us know. Not actually all the bad a job on the Chev or big bucks if you DIY.
What is your idea on the sludge situation - some, none, lots?
T
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hixsix
User
Apr 13, 2009, 10:33 AM
Post #3 of 7
(5758 views)
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Re: 1987 Chevy Suburban runs rough, hesitates
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We definitely plan on replacing the plugs & wires, just haven't gotten around to it yet.
We don't think coolant is being consumed, but will post again if that info changes. (would coolant in engine cause it to run rough & hesitate?)
Not sure about timing chain, but it's probably the original. We have never changed it since we've had the suburban (and we've had it since 2000).
Besides the fuel injectors, where else would we spray the TB cleaner to check?
Sludge - don't know....our guess would be lots since it's in an old engine & it's been sitting a while.
Does anyone know anything about Marvel Mystery Oil, and does anyone recommend it?
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Loren Champlain Sr
Veteran
/ Moderator
Apr 13, 2009, 1:44 PM
Post #4 of 7
(5755 views)
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Re: 1987 Chevy Suburban runs rough, hesitates
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Marvel Mystery Oil is great lubrication for air tools, but there is no way I'd put it in my engine!
Loren
SW Washington
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 13, 2009, 4:20 PM
Post #5 of 7
(5747 views)
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Re: 1987 Chevy Suburban runs rough, hesitates
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Just a note on sludge: Sitting isn't the problem - it's lack of changing oil, cheap oil with plenty of overheating in the history. Sludge just plain plugs up tiny ports and things don't get oiled that should and if bad enough it's really not correctable.
No real magic tricks in a bottle to remove neglect,
T
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hixsix
User
Apr 17, 2009, 8:29 AM
Post #6 of 7
(5722 views)
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Re: 1987 Chevy Suburban runs rough, hesitates
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When we got the suburban, it was already 13 years old, so there's no telling how much sludge was already in there. During the time we were driving it 2000-2002, we did regular oil changes & it never overheated. In 2002, it started giving us trouble, and in 2003 in got worse. In 2002 & 2003, we replaced & tried several different things (see first post). Then in 2004, we parked it. Now we are trying to get it going again (well, it is running....just runs rough & hesitates on acceleration). But, if the sludge is bad enough, are we wasting our time & money? What does it take to clean out the sludge?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 17, 2009, 12:24 PM
Post #7 of 7
(5713 views)
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Re: 1987 Chevy Suburban runs rough, hesitates
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Sludge: You may not have any! You need to look and most accurate way is to remove a valve cover. Age dosn't = sludge AT ALL! It has to do with heat and worn out oil as in lack of changing it.
I own an engine 62 years old now alread with ZERO sludge!
The reason is when you get a good look that if there's any then how much. If you can dig a flat headed screwdriver into the clots - or fudgy stuff then at some point unseen things plug up - much like throwing a blood clot medically and that item could be a lifter, lube for camshaft and you just don't win. Folks will try to clean them but that just makes clots move along to fast - so if fair now just change oil and it actually will slowly remove sludge with the additives of new oil and keep track and on top of that.
Before wasting too much money find out the real condition now - that, compression and any ticking or knocks and decide how far to go with this engine from there,
T
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