03 fx4 valves rattling and no power
#1
08-19-2018, 10:30 PM
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03 fx4 valves rattling and no power
Hey guys. Im brand new here. I’ve primarily been a Chevy owner over the years but now have a 2003 supercrew fx4. I got it with 170k on it and it ran like a dream. Lately, the valves rattle so bad on the driver side it sounds like my old diesel. Only with 87 octane though. 93 tones it down to where it’s bearable.
Anyway, it’s also weak.. it seems like it doesn’t want to get out of its own way. Almost to the point to where I’ve begun to despise driving it.
It has new timing chain tensioners and chains, new plugs, couple new coil packs and new fuel filter.
Ive tested the maf and egr. Both passed. Checked for vacuum leaks, none found.
Any idea what the deuce could be causing this? Cats plugged up maybe?? There’s no codes being set off so I’m kind of at a loss.
I do have a sound that resembles an exhaust leak on the same side but I know it’s not one. Almost sounds like combustion resonance coming from the pre cat.
Anyway. Help?? Please???
Anyway, it’s also weak.. it seems like it doesn’t want to get out of its own way. Almost to the point to where I’ve begun to despise driving it.
It has new timing chain tensioners and chains, new plugs, couple new coil packs and new fuel filter.
Ive tested the maf and egr. Both passed. Checked for vacuum leaks, none found.
Any idea what the deuce could be causing this? Cats plugged up maybe?? There’s no codes being set off so I’m kind of at a loss.
I do have a sound that resembles an exhaust leak on the same side but I know it’s not one. Almost sounds like combustion resonance coming from the pre cat.
Anyway. Help?? Please???
#3
08-20-2018, 12:01 AM
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My 99 had plugged cats on the driver side and hollowed out cats on the passenger side. I never once got a CEL the rear o2's thought everything was fine.
Anytime someone with a 2V says they hear something that sounds like an exhaust leak but isn't one, makes me think a spark plug is wiggling loose and is about to eject. If it has new plugs, how tight did you torque them?
Anytime someone with a 2V says they hear something that sounds like an exhaust leak but isn't one, makes me think a spark plug is wiggling loose and is about to eject. If it has new plugs, how tight did you torque them?
#4
08-20-2018, 07:43 AM
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The dealer put the plugs in before I purchased it so they only have around 30k miles on them. I had tossed the idea around of replacing them again anyway just to see. The so called exhaust leak type sound I hear is more like what you’d hear at a long tube header collector. If that makes any sense.
The loss of power is extremely noticeable, when you take off from a dead stop it will act fine. Then it shifts into second gear and falls on its face. It acts like it wants to have power, but just doesn’t.
I’ve cleaned the throttle body carbon, and tried my best to run some of that sea foam you spray in the throttle body to help with carbon buildup if there is any. I know sea foam isn’t the best by any means, but that’s all I could get my hands on at the time.
Im just short of dropping the exhaust y pipe or removing the front o2 sensors to see if that helps free up the exhaust if the cats are plugged. That’s the only way I know to check.
The loss of power is extremely noticeable, when you take off from a dead stop it will act fine. Then it shifts into second gear and falls on its face. It acts like it wants to have power, but just doesn’t.
I’ve cleaned the throttle body carbon, and tried my best to run some of that sea foam you spray in the throttle body to help with carbon buildup if there is any. I know sea foam isn’t the best by any means, but that’s all I could get my hands on at the time.
Im just short of dropping the exhaust y pipe or removing the front o2 sensors to see if that helps free up the exhaust if the cats are plugged. That’s the only way I know to check.
#5
08-20-2018, 10:57 AM
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When I had one checked Midas drilled a hole in the exhaust pipe upstream of the cat, placed at pressure gauge with a rubber tip against the hole and measured the pressure with the engine running. Then they welded up the hole. I think they charged $35 but this was close to 20 years ago. Mine was ok.
#6
08-20-2018, 02:30 PM
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I've been having a hard time getting it anywhere to have it checked out, been working a ton of overtime. Having to work on it myself after work and what few extra minutes I can scrounge up. I guess I'll take the front o2 sensors out and see if that helps.
I will mention that lately it has a very slight "shimmy" feel to it when its idling.
What other ways are there to clean the combustion chambers on it besides taking it to the dealer or a shop?
Ive checked everything I can think of except the cats. And I figured they'd give different symptpms than just low power/spark knock.
:shrug: I'm terrified of these engines.... I don't know enough about them. I can fix most anything on a LS engine without worry.
I will mention that lately it has a very slight "shimmy" feel to it when its idling.
What other ways are there to clean the combustion chambers on it besides taking it to the dealer or a shop?
Ive checked everything I can think of except the cats. And I figured they'd give different symptpms than just low power/spark knock.
:shrug: I'm terrified of these engines.... I don't know enough about them. I can fix most anything on a LS engine without worry.
#7
08-20-2018, 03:30 PM
Senior Member
Put a couple of bottles of Chevron Techron or Gumout with PEA in the gas and that will help clean up the combustion chamber, injectors, and the intake valves. I periodically put a bottle of gumout in my vehicles to keep things clean. It works great on my old motorcycle's carbureators too helping them to stay clean. And all of my lawn tools.
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#8
08-20-2018, 04:45 PM
#9
08-20-2018, 04:53 PM
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I do have one. I've tested the temps to see what they say. One side is close to even, output may be a little hotter than the intake..
other side, intake is over 700*.. outlet is well well below that. say 200* lower. I was pretty sure that one was plugged.
My cousin told me he has his scan tool from work at his house and I'm going to try using it this afternoon and see what readings I can get on the o2 sensors etc that may lean towards a plugged cat.
other side, intake is over 700*.. outlet is well well below that. say 200* lower. I was pretty sure that one was plugged.
My cousin told me he has his scan tool from work at his house and I'm going to try using it this afternoon and see what readings I can get on the o2 sensors etc that may lean towards a plugged cat.
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08-21-2018, 08:51 PM
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#12
08-22-2018, 03:09 PM
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So, now I'm confused. I thought the one with the low voltage was the faulty one, but under load it seems to be the one operating normally. The one staying rich however, is concerning.
I had a few codes stored as well. The misfire code did not come back when we cleared them and tested again. However, both the lean and rich codes returned
P0171 System too lean Bank 1
P0175 System too rich Bank 2
P0306 Misfire cylinder 6
I had a few codes stored as well. The misfire code did not come back when we cleared them and tested again. However, both the lean and rich codes returned
P0171 System too lean Bank 1
P0175 System too rich Bank 2
P0306 Misfire cylinder 6
#13
09-02-2018, 01:14 PM
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So. I had the truck torn down and timing checked again. Mechanic said it was fine. Found that #8 wasn’t firing at all so replaced a coil pack and all 8 spark plugs. Checked for vac leaks w vac pump and smoke test. None found.
NOw I’m getting P0175, valves still rattle with anything lower then 93 octane and there is still a huge lack of power. I dropped the y pipe yesterday and it didn’t affect anything so I’m guessing the cats are not clogged.
Long term fuel trim on bank 2 is constantly in the negative, in fact it’s the exact opposite of the other bank. It almost mirrors the exact opposite of the fuel trims on bank 1.
Im out of options and ideas and I guess I’m going to have to take it to the dealer or a really good shop.
Any other ideas before I take it somewhere?
NOw I’m getting P0175, valves still rattle with anything lower then 93 octane and there is still a huge lack of power. I dropped the y pipe yesterday and it didn’t affect anything so I’m guessing the cats are not clogged.
Long term fuel trim on bank 2 is constantly in the negative, in fact it’s the exact opposite of the other bank. It almost mirrors the exact opposite of the fuel trims on bank 1.
Im out of options and ideas and I guess I’m going to have to take it to the dealer or a really good shop.
Any other ideas before I take it somewhere?