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Loss of power

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  #1  
Old 05-16-2018, 12:52 AM
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Loss of power

So this past month ive noticed a TREMENDOUS drop in power, i assumed it had jumped time cause timing chain slapped, so replaced that and still the same, i literally have to floor it in the mornings to get up my hill, or up a long stretch of land at like maybe a 15 degree incline and even then it tops out at like 66 , where before it would top out at around 85, it doesnt seem to get enough power to shift, it will just sit at high rpms screaming before it shifts and it sounds really rough inside the exhaust like it rumbles, i have lost over double of the power i used to have and am confused as to why, someone please help

97 f150 4.6
 
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  #2  
Old 05-16-2018, 11:35 PM
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Plugged cats.
 
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Old 05-16-2018, 11:37 PM
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Originally Posted by glc View Post
Plugged cats.
thats exactly what im thinking but im not sure how to check or test it, i dont have an infared thermometer or vaccum guage tester, and the way the pipes are in an elbow and a 45 degree angle on one end, i cant look through the pipe and see if its clogged
 
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Old 05-17-2018, 10:26 AM
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When I had a cat back pressure tested at Midas, they drilled a hole in the exhaust pipe in front of the cat and held a gauge against the hole while the engine was revved. Then they welded up the hole. It didn't cost that much.
 
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Old 05-17-2018, 01:20 PM
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Or you can get a rubber mallet and hit the cats to see if you hear any "loose change in a coffee can" noises.
 
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Old 05-17-2018, 02:46 PM
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Didnt hear any noise but i hear it knock when i drive, right in the cats
 
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Old 05-17-2018, 02:54 PM
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You could have a clogged exhaust that includes the muffler and/or the CATs.

I once owned an '89 E350 chassis that had a motorhome coach on it. It took more than 40 gallons of gas to go downhill from Parker, AZ., to Indio, CA. The few uphill stretches gave me a top speed of about 35, but downhill was strong at about 65. I pulled the exhaust and expected to find a clogged CAT, but the CAT was okay, the muffler had caved in on itself, clogging the exhaust. If your engine cannot push air out, it will not pull air in, and the car won't go above a certain speed.
 
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Old 05-17-2018, 07:01 PM
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You can try doing what JDStrickland said. Try removing the muffler. Yes it will be loud, but see if it gives better performance.

If not, then proceed to the cats.

Another way to find a clogged cat is using a laser/infrared heat meter.
 
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Old 05-18-2018, 10:33 AM
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Bottom line, take it to a muffler shop to be tested.
 
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Old 05-18-2018, 11:46 AM
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I dont have the money to get it tested
 
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Old 05-18-2018, 11:53 AM
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Then you'll either have to rent/buy the tools and DIY. Those monkeys at Midas and such are not geniuses, although they try to be. At this point, from watching/reading, you should be capable of more than then those monkeys.

Use my suggestions:

1. Remove the muffler -- All you need to do is disconnect it, use some wire wrap and move it out of the way since it's not a permanent solution. See if that improves or worsens the performance. If it improves -- stop reading and replace the muffler.
2. Check the temperature of the cats -- Use a cheap Harbor Freight laser temp meter when your truck is at full running temp. Note any large temperature differences between cats. They should be within 100F of each other. If one is much hotter >250F then you've got a restriction.
3. Pressure test the exhaust system -- Use an exhaust pressure tester (rent or buy) to test this. There should be only a small amount of pressure. 8-10 PSI is normal under full load. Any higher, like 15+ PSI you got something wrong.

Good luck.
 
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  #12  
Old 05-18-2018, 12:14 PM
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Will do, is there any negative effects from taking the exhaust pipe off the exhaust manifold and driving it to see how it does
 
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  #13  
Old 05-18-2018, 07:02 PM
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After the cats, no -- just noisy as heck.

Before the cats, a CEL, running poorly, and noisy as all can be.
 
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  #14  
Old 05-18-2018, 07:26 PM
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Well i hit the cat with a mallet and i dont hear any noise except metal being hit, but like when im driving it sputters from the exhaust, and pooor poor power and acceleration, i used to be able to burn rubber now i can bareky pull out kf my driveway, if the cats arent broken and i dont hear any noise, could they just be clogged, and is that fixable
 
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  #15  
Old 05-18-2018, 08:12 PM
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First you have to determine what the problem is and then fix it. Call a muffler shop and ask them what they would charge to determine if the cats are plugged.
 
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