HELP - Engine noise/sluggish - play "Name that Tune" again

HELP - Engine noise/sluggish - play "Name that Tune" again

Postby mmmsheen [OP] » April 30th 2014, 11:53pm

Hi everyone, first post here - awesome forum. I've learned a ton. I have a 1995 GMC Safari van that my dog and I LOVE but my wife hates (keeping this thing forever!). 120K miles, AWD.

I'll start with the symptoms:

1. I've been getting some sluggishness/hesitation
2. There is an engine noise when under load (startup, idle are both great)
3. Uneasy shift - I don't know how to describe this but it feels related to the hesitation, it's shifting later than normal (this could be in my head)

HERE's A LINK TO THE NOISE:
https://soundcloud.com/mmmsheen/sets/1995-gmc-safari-engine-noise

Now I'll tell the story:

It all started about 3 weeks ago after I changed the PS pump, the repair took me about a week (20 min here, an hour there) but turned out ok. Side note: the power steering is GREAT now! During the repair two things come to mind that were potentially harmful.

1. I had the filter box off overnight once (I know :naughty: ) but plugged it up with a clean towel the other 6.5 days.
2. Just before I started the repair I hosed down the underside to remove a metric ton of sand from a trip to Mexico 3 months ago and paid A LOT more attention to the getting the sand off than to not spray sensitive parts( :naughty: :naughty: ). Seriously like a 5-gallon bucket of sand came off the underside. It's safe to assume that everything that can get wet from under the van got wet.

Otherwise it was just your general clean it, take it apart, replace a part, put it back together kind of repair. Took off the fan shroud and the belt, nothing else. Wasn't rough with anything.

And here's what I've done / tried:

1. Replaced the cap, rotor, wires. Have not replaced the plugs (I will if you tell me to, they are 6 months old AC Delco).
2. Cleaned the throttle body (it was DIRTY)
3. Checked for (with very limited knowledge/ability) vac leaks. No obvious squeals/whines. One line was rotted, so it was replaced.
EDIT: 4. Replaced fuel filter

That's it. I know you guys will help me out, because you've helped everyone else out.

Thanks!

Mark
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Re: HELP - Engine noise/sluggish - play "Name that Tune" aga

Postby mmmsheen [OP] » May 11th 2014, 5:33am

Anyone? :poke:
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Re: HELP - Engine noise/sluggish - play "Name that Tune" aga

Postby Sailing_Faith » May 11th 2014, 5:02pm

It is kind of hard to hear the recording, is the sound the "rushing air" sound I hear?

It is possible to install the breather box without getting it in the large intake hose... I suppose you could also get the hose behind the flange for the MAF which would cause drivability issues....

Not sure it helps, maybe you can take the air box off again and check this, and then describe the sound.

Good luck!
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Re: HELP - Engine noise/sluggish - play "Name that Tune" aga

Postby redfury » May 11th 2014, 10:00pm

If you pressure washed it, then I wouldn't worry about the plugs as much as I might worry about the plug wires. You may consider pulling the plug wires off the plugs and blowing them out with compressed air and throw a little dielectric grease in there ( or spray with wd40 ) to get any moisture that may be trapped in them.

I'm guessing it's a secondary ignition system problem by what little sound I could hear. I'm willing to bet that you'd see misfires if you hooked it up to a scan tool. Beyond that, the only thing that could affect the transmission would be the switch on the transmission ( sealed connector-like glued tight sealed ) or the TPS. My best guess is that it isn't either of these. I'm betting on it being something simple. You probably have a couple of cylinders on one bank that are having problems. The harder you push the engine, the more the ignition system is going to try to leak spark out to the easiest path as the load on the engine makes it harder to jump the gap. At idle, there's no load and the gap is easy to jump, so it runs smooth.

Perfect example of this is my Toyota shop truck..It just started having morning sickness when it rains. Takes about a mile before it clears up, but under heavy load, I've got like 1 of 4 cylinders firing properly until I let up on the pedal and it all smooths out until the moisture is burned off.
A temporary fix usually becomes a permanent solution, therefore it does not exist.
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Re: HELP - Engine noise/sluggish - play "Name that Tune" aga

Postby mmmsheen [OP] » May 12th 2014, 1:38am

Thanks for the replies!

I actually made the recording with a professional recorder, that's why the gain is low. It was mounted on a tripod facing the engine from inside the van (doghouse removed). The rushing sound is probably wind.

I have all new wires since the problem started and 4/6 new plugs (still working on the other 2). New cap and rotor too. Hasn't seemed to make a difference so far.

Things to check (according to your posts):
1. Airbox seating
2. MAF flange
3. Dampness in the wires (not likely since they're new, but I'll check anyway)

I'll write back when I've had a go at it. Thanks again!
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Re: HELP - Engine noise/sluggish - play "Name that Tune" aga

Postby mmmsheen [OP] » May 12th 2014, 2:55am

Ok, reseated the airbox after cleaning the MAF, checked all the wires and installed the last 2 plugs. Still runs exactly the same. Here's a list I found on another forum, perhaps I can go 1 by 1 through process of elimination:

Vacuum leak.
Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter. <--cleaned MAF, no effect
Throttle position sensor.
**Crankshaft position sensor <--chevymaher suggests this, will try next...
Knock sensor
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
Fuel contamination.
Foul/defective spark plugs. <--done, no effect
Open spark plug wires. <--done, no effect
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor. <--done, no effect
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Re: HELP - Engine noise/sluggish - play "Name that Tune" aga

Postby kennysmoke » May 12th 2014, 3:25am

I had the same sluggishness with my '03 AWD Astro...it never threw a code..... I had only cleaned the MAF on mine as well... it turned out two months later it finally threw a MAF code the day I was bringing it to the shop to install a new Magnaflow CAT... the bad MAF caused my CAT to plug... I'm not saying that's your problem but it turned to be my issue at the time.. new MAF and CAT and back to running 100%...
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Re: HELP - Engine noise/sluggish - play "Name that Tune" aga

Postby redfury » May 12th 2014, 4:33am

Do you have access to a scanner that can read live data? I'd be interested to see what the O2 sensors were reporting. They should fluctuate positive and negative when you are reading the Short Term Fuel Trim ( STFT ) or you should see the voltages fluctuate between .002v to .900v, the middle is .450 which is what your downstream O2 sensors should be reading. If the numbers are pegged high or low you have a problem. I think short of the simple things you can do that cost little money ( cleaning the MAF ), you should really get a scan tool on in that reads live data, even if it's a relatively cheap scanner. You just want to see what those O2 sensors are doing before replacing them unnecessarily.
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Re: HELP - Engine noise/sluggish - play "Name that Tune" aga

Postby akmo23 » May 19th 2014, 12:07pm

4/6 New plugs, Change them all !

Hand Check - pulley bearings. Noise and friction.

Since you suspect an electrical system issue and have done every thing else. I kind of have a little bell in my head saying alternator. You might be making power but it doesn't seem like clean power - suspect diode. Sometimes testers don't catch all the issues. Especially if its a daily driver and you wouldn't notice a parasitic drain.

20 year van look into the big three.

Is there a small exhaust leak around the header ?

Sorry I couldn't isolate the issue in one sentence,
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Re: HELP - Engine noise/sluggish - play "Name that Tune" aga

Postby Leeann_93 » May 21st 2014, 3:40am

Have you tested your fan clutch? It should give you resistance to turning when cold, but spin when warm. It's a pretty good load on the motor if it's engaged when it's not supposed to be.
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