Codes U1000,U1016,P1071,P1074,P0300

[Jediguy]

Been getting P1071,P1074,P0300 off and on since I moved to Colorado from Florida 2 years ago. It goes away and comes back, usually when its really cold out. A mechanic told me it was no big deal so I've let it go on, still checking the codes every time I get a check engine light.

2 days ago, the truck is misfiring bad, rattling engine etc. It pulls the codes P1071,P1074,P0300 but with an additional P0200 indicating the injector circuit was not doing good. Paid a shop for a diagnostic, they pinpointed to ignition coil #4 shorting to ground. I installed a new one, the truck seems to run fine again so I clear the codes.

Today I get the check engine light again but it seems to run normally. This time codes pull P1071,P1074,P0300 with the additional U1000 and U1016. "Class 2 communications failure".

Any ideas what I'm dealing with here? Is this worth diving into?

I just want my truck to run right. It already needs so many things for the suspension & steering I've been planning to do. Now the list is growing, its at 225k miles and I'm kind of attached to it. Already put a rebuilt transmission in it and so much more has been put it into maintaining it. I'm starting to wonder if I should part ways with it as its becoming a time, money and energy pit. Would love to hear your thoughts! Thanks

 

[zora]

The P0300 indicates all cylinders are misfiring. Combined with the P1071 and P1074 you should be looking for a vacuum leak, bad hose or gasket.
For the U codes you may want to check the condition of the connections at the ECM for corrosion or other issues.
At 225k it might be advisable to do a compression test to determine the health of the engine.

 

[Jediguy]

Thank you Zora, that gives some direction. I appreciate the help.

 

[Jediguy]

I cleared the codes again and the next day all 5 of them came back. The misfire codes all came back as "intermittent" on the code reader. The truck still seems to run fine.

It does not appear to have a vacuum leak, bad hose or gasket as far as I can tell. I sprayed starting fluid under the hood, around all hoses, etc. but noticed no change in rpms or the sound of the engine. I wonder if there is a better method to locate a leak.

It's been at least 35k miles since I replaced the spark plugs/ wires and I did go with the cheapest option at the time. Considering I'll have to take the plugs out for a compression test I thought it might be worth a shot at replacing.

Could overdue spark plugs and wires be the cause of the misfiring?

I am trying to avoid wasting time and money throwing new parts at it unless it really has a good shot at helping resolve the issue.

 

[zora]

I would only uses AC-Delco plugs especially if you are having codes pop up.
Found this for the P1071/74
Before you going near the O2 sensors and cat.converters, make sure the MASS Air Flow sensor is clean or working properly. (BTW is there a K&N filter installed?)
If MAF sensor is good, I'd do a fuel injector balance test. If the right quantity fuel won't enters the combustion chamber in the correct form (vaporized), lean condition occurs.
The MIL will be on if the long term fuel trim (LTFT) reaches 23%.
Intake leaks are not easy to find without a smoke pump, the slightest leak will push the LTFT out of its limits.
The reaction and condition of the O2 sensor (also the cat.converter efficiency) could be tested without removal, with the correct diagnostic tool.
Don't just start to replace components because someone thinks they are bad, get a diagnostic and confirm.

 

[Jediguy]

Thank you for the suggestion. Just curious, why AC Delco?

Regarding the MAF sensor, I paid for a diagnostic about a year and half ago to pinpoint the cause of the P1071, P1074, P0300. They said it was the MAF sensor, after I had already cleaned it. I replaced it and the code seemed to go away for a few days but eventually came back. It would go away for weeks at a time, even a month some times.

I recently looked maybe 2 months ago. The air filter looks clean and it’s about 2 years old. I changed the fuel filter about the same time. I don’t think I went with a K & N filter. I believe it’s a Fram. Are K & N’s known cause issues?

It looks I may need to suck it up and pay for another diagnostic to get to the bottom of this. I’ve never done a fuel balance test before. Looks like you need a kit, same as the compression test. It would be nice to know if there is a leak I can’t find.

Anything I should be looking for towards the 02 sensors and cat converters?

 

[zora]

The AC-Delco is because that is what the GM engineers used when designing the engine and the correct plug has a specific heat range. I find that going to other plugs, especially Japanese, the heat ranges do not directly correlate to what GM used.
If the K&N filter is oiled, it will cause problems.

 

[Jediguy]

Sadly amidst a pretty gnarly winter storm last week my truck was totalled. Thankfully no one was hurt and it wasn't my fault. It doesn't look like I'll be working on this truck anymore.

Thanks for all your help Zora! I've learned a lot through the few posts I've made and interacting on this forum the last 2 years.

Amazingly it still drives and is still my commuter as the insurance figures everything out. Hopefully I 'll have a rental soon.

Check out the damage:

https://drive.google.com/open?id=16sce6CTzb4QZA8jX1J0dAu8ova6-q_wm

 

[zora]

Really sorry to hear that, see on the news the crazy winter weather across the country. Glad to hear you and hopefully no one else was hurt.