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Shelbydo · 09-21-2018, 06:31 PM

Hi all, 04 Itasca Sunova, 03 workhorse chasis. 8.1 vortec.
Getting closer to our maiden voyage with our new to us Sunova. Ever since we picked it up the check engine light has been on. I did take it to Advanced auto and had the code read. I'm afraid enough time has gone by that I don't remember the code id number but it was open circiut O2 sensor bank 1 I believe.
So reading multiple post regarding O2 sensors here I decided to have a look to see what style I have. Believing bank 1 is drivers side I started there. Much to my surprise the sensor backed right out.
I also researched testing methods for O2 sensor, i.e. heater circiut power and resistance. So via a test light I found power (key on no start) also I had resistance through the O2 heater @3.2 on 20 ohm scale. So while I'm under there I opened the other O2 sensor on bank 2 and tested with identical results.
So I did notice that the exhaust pipe connection at the drivers side manifold allowed alot of wiggle. Not wanting to break a stud in my driveway, I didn't attempt to tighten.

So now I'm not sure which way to go from here and am open to suggestions

Thanks
Chris

CJ7365 · 09-21-2018, 07:05 PM

I just had the same issue with mine, lose exhaust pipe at the manifold after reading a few post here it seems that the donut gasket WH used is a little on the thin side, people have ground down the clamps 3 points of contact to make if fit snugger.

I deceided to order a new donut and see if this would fix the problem, because I had a couple of days to wait for the donut gasket to come in, I sprayed kroll oil on the 3 studs and nuts everyday.

When the donut gasket came in I could see it was a thicker one, so I was excited that I should fix the wobbleling exhaust.

I used an impact to take the studs/nuts off, I believe it's a 13mm no breakage.

Below is a picture of the 2 donut gaskets for comparison, I bought 2 of them from rock auto, they were on clearance for under $3.00 plus shipping.

Here is the part# MAHLE F31731 They are still $2.04 shipping to me was about $6

vettenuts · 09-21-2018, 08:11 PM

I had to replace one of mine that was leaking as well, except I hate exhaust work so I took it to someone I trust. He said the nuts came right off with an impact. I also did the Brazel’s modification to tie the two pipes together which they found helps with donut failures.

AKIQPilot · 09-22-2018, 11:28 AM

Quote:

Originally Posted by vettenuts

I had to replace one of mine that was leaking as well, except I hate exhaust work so I took it to someone I trust. He said the nuts came right off with an impact. I also did the Brazel’s modification to tie the two pipes together which they found helps with donut failures.

Can you tell us more about the Brazels mod on your exhaust. A link would be nice if you have one.

vettenuts · 09-22-2018, 02:37 PM

Quote:

Originally Posted by AKIQPilot

Can you tell us more about the Brazels mod on your exhaust. A link would be nice if you have one.

Someone mentioned this to me a few years ago. From what I understand, tying the two pipes together has been found to reduce issues with the manifold donuts. I had mine done when I had the donuts replaced (although he didn't want to do it at the time) but he did do a beautiful job using a stainless exhaust piece and grinding the ends so they fit the tow exhaust pips like a puzzle. He then welded in place.

AKIQPilot · 09-22-2018, 04:11 PM

Quote:

Originally Posted by vettenuts

Someone mentioned this to me a few years ago. From what I understand, tying the two pipes together has been found to reduce issues with the manifold donuts. I had mine done when I had the donuts replaced (although he didn't want to do it at the time) but he did do a beautiful job using a stainless exhaust piece and grinding the ends so they fit the tow exhaust pips like a puzzle. He then welded in place.

OK roger that. I assume the cross pipe just connects to two sides together for support? It's not like an H Pipe that actually lets exhaust gas flow between the two sides?

I have the Banks Exhaust on our Itasca and it has the full diameter H pipe connecting the flow between the two sides. Our Adventurer is still stock with no crossover pipe.

vettenuts · 09-22-2018, 05:14 PM

Correct, no flow. Supposed to help with twisting of the manifold joint.

Arch Hoagland · 09-22-2018, 05:21 PM

I was getting P0150 and P0151 Check Engine Light codes on my Workhorse 8.1 engine. Replaced the O2 sensor...no help.

Going across Nevada on a trip I was getting them on every hill and mountain.

Got to Salt Lake City and went to a really good shop.

They cleaned the MAF and the codes went away forever and I gained a ton of power back.

Shelbydo · 09-22-2018, 05:50 PM

I did spray clean the MAF and changed the filter at the same time. Ive only idled the engine in the driveway since and still have the check engine light on.

Arch Hoagland · 09-22-2018, 06:33 PM

UltraGauge OBDII Scan tool & Information Center

When I started troubleshooting my check engine light problem I bought the UtraGauge to tell me what was going on..I'd suggest you do the same.

It doesn't have to be an Ultragauge, just an OBDii reader will help. It will pay for itself.

My problem lasted a year and was very intermittent at first. You can also use it on all your other vehicles.

hawkeye1995 · 09-22-2018, 11:53 PM

You can turn the light out by two methods. One buy a cheap OBII Scan Tool and turn the light out, or you can disconnect the battery for about 30 minutes, then reconnect. The problem with a long battery disconnect, you have to make the computer learn all over again. This is not a big deal, just have to sit at high idle for a few minutes, then do some driving around town, so the computer can set all the perimeters again.

vettenuts · 09-23-2018, 05:51 AM

Quote:

Originally Posted by Shelbydo

I did spray clean the MAF and changed the filter at the same time. Ive only idled the engine in the driveway since and still have the check engine light on.

If the CEL is on and you correct the issue, the engine has to hit that test again to clear the light. Some require two error free test cycles. So this may be a case that the light will go out on its own if the problem has been corrected. However, if you have an exhaust leak it may not go away and you may be skewing the fuel to one bank that can result in bigger issues later on.

If the doughnut seal is leaking, you need to get that squared away as well.

Arch Hoagland · 09-23-2018, 12:30 PM

I disconnect my W22 2004 8.1 engine battery every time after a trip and the computer does not have to relearn anything. Runs and shifts exactly the same.

I use a knife blade switch right at the battery.

hawkeye1995 · 09-23-2018, 06:03 PM

Quote:

Originally Posted by Arch Hoagland

I disconnect my W22 2004 8.1 engine battery every time after a trip and the computer does not have to relearn anything. Runs and shifts exactly the same.

I use a knife blade switch right at the battery.

Guess I should use the word "may have to"? I have not removed the battery on my 2004 8.1, but my 2000 5.3 GM will not idle once the memory is lost over a period of time. I was told that is normal, and because all the capacitors loose the energy stored. But, things could have changed over the years. When I first start after a long battery disconnect, I have to sit with my foot on the gas pedal for a few minutes, then go for a short ride, and all is back to normal. If, I don't, it will not idle, and die at the first stop. Just saying. my experience with GM computer. Anyway, I hope that if he disconnects, it will turn the light off, it does on mine. If not, after so many starts, and the problem is fixed, it should turn itself off.