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Engine low on power, plus other stuff

R

RCBearings

Full Member
Joined
Dec 17, 2012
Messages
95
Location
Castle Rock, CO
2004 Avalanche 1500 Z71, about 240k on her.

OK, I posted on another thread about my turn signal problems.  Now I noticed that I am way down on power.  It isn't so noticeable running empty, but with my travel trailer hooked up, it is like I am running a small V6. Gas mileage is a little lower towing, from 12 down to 10mpg.  No CEL, no stored codes.  Then, this morning I started her up to hook up the trailer.  Got it lined up and turned off the key. STARTER WAS STILL CRANKING!  Turning off and on key made no difference.  I went under hood and disconnected neg on battery.  Waited a bit and touched it to the terminal and engine started cranking again.  Waited a bit and touched neg to pos.  Everything back to normal.

Truck had been run a few hundred miles with two bad cylinders dumping oil out the exhaust.  I suspect the catalysts are plugged. Any other thoughts on the sluggishness?
 
I'm wondering if it could be the ignition switch.
 
As for starter continuing running there is a thread in this section or maybe PROBLEM: BASIC ELECTRIC.

How were the 2 cylinders dumping oil into exhaust and how was it fixed?

Plugged cat shows up as when you stomp the pedal nothing happens and high reving engine takes a bit longer to dro pback to idle when pedal left off.

Also cat gets REALLY REALLY HOT and will glow red if driven for long miles.

You say you get 12mpg wo towing on a 1500?

THat is crazy low unless all city.... you should be getting 16-18mpg as average
 
  Along with the cat's. When is the last time you changed 02's?
I've experienced low power with out CEL.
I generally change them at around 100k  on my vehicles. Power and mileage came back.
 
Oil came from blown cylinders.  I don't know the exact cause but it was Cyl 7 and Cyl 2.  I got a salvage engine from a 2004 Silverado to replace it.

I did the IR check and the cats seem to be working.
 
JVZL1 said:
  Along with the cat's. When is the last time you changed 02's?
I've experienced low power with out CEL.
I generally change them at around 100k  on my vehicles. Power and mileage came back.
Click to expand...

How much power did you gain back?  Mine seems to be running about 60% power.
 
    The mileage dropped, idle was a little rough, and it just did not have the smooth responsive acceleration it once had.
It?s been sometime I can?t put a percentage on it. When I cleaned the throttle body, MAF, air filter, and changed plugs
and the fuel filter there was no real gain. So being it was at the 100K mark I changed out my O2?s. For me it was a game changer.

I not sure on what you would gain. If they have never been change or over 100k. They are do.
 
I have only changed bank1 lower (after the cat) in the 120k I owned her.  But this came on rather suddenly.  One day I hooked up my trailer and its like towing with a V6.
 
ygmn said:
You say you get 12mpg wo towing on a 1500?

THat is crazy low unless all city.... you should be getting 16-18mpg as average
Click to expand...

Actually I used to get 12mpg while towing.  Now it is 8-10 on level freeway.  Without towing, I am averaging about 16mpg, 18 freeway unless there is uphill.

It is getting so bad that freeway overpasses cause a downshift to get over.  I did another check and O2 bank 1 sensor 1 has high voltage reading.  Not enough to trip a code, though.  Gonna replace that once the thing cools off.
 
Found a $50 off coupon for Advanced Auto so I ordered the Walker full CAT system with Y pipes and all for around $380.  Will pick it up today and install tomorrow morning.
 
RCBearings said:
2004 Avalanche 1500 Z71, about 240k on her.

STARTER WAS STILL CRANKING!  Turning off and on key made no difference.  I went under hood and disconnected neg on battery. 
Click to expand...

This happened to me. I replaced the original, worn out, starter last fall with a Delco. A few months later, in January, the starter stuck on as you describe. The problem was that the solenoid contacts on the starter itself stuck closed. (I told the story of Abigail's demonic possession here.)

You are lucky that you discovered the problem right away. I started the truck and drove off. By the time I noticed the noise, tracked it down to the starter, pulled various relays and then finally disconnected the battery, the starter was burnt out. (Fortunately it was replaced under Delco's warranty).

If your's has stuck once, I strongly recommend you replace the solenoid at your earliest convenience, before it happens again.
 
RCBearings said:
Found a $50 off coupon for Advanced Auto so I ordered the Walker full CAT system with Y pipes and all for around $380. Will pick it up today and install tomorrow morning.
Click to expand...
Did you ever finish the install? How do you like the Walker cats? I need to replace mine.
 
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