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Old 06-29-2009, 06:48 AM
 
Location: Pennsylvania & New Jersey
1,548 posts, read 4,227,542 times
Reputation: 1768

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My pickup is acting up. At times, when I need power, (climbing, heavy acceleration,) it poops out - it sputters, hesitates and sometimes it even backfires. The problem is sporadic and not consistent, yet it seems to get worse in wet weather.

When in acting-up-mode, the truck struggles trying to get up to speed on a busy highway. It's bad enough to be dangerous. In the old days, I'd say that the choke doesn't seem to be working right.

Part of the problem may be that the truck doesn't appear to downshift quickly enough, but even when I downshift manually, I still have the hesitation problem. I wonder if the engine and transmission are not communicating properly. How computerized is my 15 year-old truck?

Any ideas for curing my problem? I've already changed the fuel filter as well as the cap and rotor and the truck was tuned-up within the past year.

"The Eagle," as I call it, is about to cross 200,000 miles and I'd like to keep it "flying" for another hundred thousand.
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Old 06-29-2009, 07:39 AM
 
Location: I think my user name clarifies that.
8,292 posts, read 26,198,750 times
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I think the tip-off is that it's worse when it's wet. I'd guess it's your ignition coil. If it has even tiny hair-line cracks in the case, it'll misfire when wet.
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Old 06-29-2009, 10:29 AM
 
Location: Del Rio, TN
38,847 posts, read 25,256,819 times
Reputation: 24741
Also check your plug wires, I had a '89 Chevy P/U that did similar things. Rerouting the wires corrected the issue. Can you hear arcing (snapping) at idle with the hood up? Or see it with the hood up at night or in a dark garage? Is it in all gears, or more of an issue in a higher gear?
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Old 06-29-2009, 10:34 AM
 
Location: North Pole Alaska
886 posts, read 5,619,040 times
Reputation: 843
Time for a simple tune-up Plugs wires cap and rotor should get you going in tip top shape. You might also want to look at your EGR valve. There is a good chance it could be sticking.
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Old 06-29-2009, 11:20 AM
 
Location: I think my user name clarifies that.
8,292 posts, read 26,198,750 times
Reputation: 3919
Quote:
Originally Posted by Toyman at Jewel Lake View Post
Also check your plug wires, I had a '89 Chevy P/U that did similar things. Rerouting the wires corrected the issue. Can you hear arcing (snapping) at idle with the hood up? Or see it with the hood up at night or in a dark garage? Is it in all gears, or more of an issue in a higher gear?

That's your best bet for checking your plug wires. Open the hood at night, we no lights around. It's amazing what you might see!

Also, have a Windex-style bottle, filled with water. When the hood is open, in the dark, spray some mist around in the area of the distributor, plug wires and plugs. That might give you some answers.
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Old 06-29-2009, 11:55 AM
 
Location: Eastern Washington
16,875 posts, read 55,555,352 times
Reputation: 17933
How long since you did a comprehensive tune-up? A set of NGK plugs, a fuel filter, and maybe new ignition wires if indicated by the tests already posted up above, has to be your first step - probably will cure what ails it, if not, at least you are starting from a properly tuned engine that you can troubleshoot properly.

Always catch up on deferred maintenence first if a vehicle won't run right.
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Old 06-29-2009, 12:00 PM
 
Location: So. of Rosarito, Baja, Mexico
6,964 posts, read 21,538,868 times
Reputation: 6932
Key words are when it's wet weather. Dampness means a short (arcing) probably with the plug wires. Engine heat down near the exhaust manifold will dry the wires which will crack or oil on them will do the same near the starter side.

Another possibility is the trans modulater valve vac hose connection. Had that problem with my turbo 350 trans.

Back fire could be a cross firing on a cyl when the exhaust valve is open or some gas accumulation in the exhaust system from one cyl not firing.

On a tune up with the cap and rotor being replaced...a good rule of thumb is to replace the plug wires the same time...one less headache later on.

Steve
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Old 06-29-2009, 12:50 PM
 
Location: North Pole Alaska
886 posts, read 5,619,040 times
Reputation: 843
There is no vac modulator valve on the 4L60E trans.
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Old 06-29-2009, 02:25 PM
 
Location: Pennsylvania & New Jersey
1,548 posts, read 4,227,542 times
Reputation: 1768
Default Many thanks!

You've given me a lot more to go on than many local mechanics. Thank you for your replies and feel free to keep them coming. I will check out all of your suggestions.

More so, once I get the truck running correctly again, I'll tell you what we discovered as being the problem(s). That's just it... I suspect it's more than one thing and most local mechanics around me aren't diligent enough to work out a multiple-issue problem.
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Old 06-29-2009, 03:19 PM
 
Location: So. of Rosarito, Baja, Mexico
6,964 posts, read 21,538,868 times
Reputation: 6932
As a mechanic learned many decades ago not to replace just one item as per customers request.

Invariably they would return with a similiar problem and wanted warranty on my work. Problem was another electrical ignition part took a dump.

Look at your hand and fingers. See each finger as a ignition part. Close one finger at a time and see how much strength your hand has left. Close two and three fingers and try to pick up a pail of water.
The results will tell you what is happening to the ignition system. They all have to work together.

I would explain this comparison to some of my customers in order to get my point across.

Steve
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