Several trouble codes, where to start????

[WI_Dave]

I picked up a 2009 crew Silverado z71 with a flex fuel 5.3L and a 6speed, got it cheap because its throwing a lot of trouble codes. Where should I start looking, or do I just swap motor? I will pull the codes myself tomorrow but these are what they gave me. Truck runs and drives, it is hesitant at lower rpms but opens up ok when on throttle hard. No noise at idle, some faint tinging when reving. I am into it cheap enough to put a motor in, but don't want to if I don't have to. Any ideas or suggestions? Best trouble shooting routines?

 

Dave

[Jsdirt]

Usually with this many codes it;s only one or 2 issues causing it. You've got alot of ignition codes, so wiring would be the first thing to check out there. I'd start with the easy stuff first - check both battery connections and cables. Make sure the battery has at least 12.6v at rest. Then get a scan tool hooked up with live data, and start wiggling the harness in a orderly fashion, starting at the ignitor, and going out from there.

 

Swapping engines is a last resort. If you want to rule that out, start with a compression test, followed by a leak down test and see where the engine is at before you do anything - if those tests show the engine is worn out, no point in going through all the wiring troubleshooting. Can be very time consuming.

[WI_Dave]

Thanks, I will start there. Is it possible that many lifters died? I believe it has the LC9 engine with dod afm

[Jsdirt]

These days I don't doubt anything. Stuff that used to never fail, fails spectacularly lately.

 

Probably better to yank a valve cover and watch the rockers move as you rotate the crank. Measuring the valve travel would be a sure way to know - not sure if those specs are out there. Should be, I would think ...

[WI_Dave]

I am at work researching on lunch, am I correct in seeing that it is the 4 corner cylinders tripping misfire codes? 1-2-7-8 that seems odd to me, hopefully it is something stupid. I will not have time to check until Wed. but I am researching what I can.

[Jsdirt]

Yeah, those ignition codes are for those cylinders. With so many similar codes, it's a good chance it's a bad connection, or chaffed wire somewhere. Either that or those 4 coils took a dump - not likely those 4 failed at exactly the same time, but you can't rule that out these days.

[WI_Dave]

Thanks for the help, when i get the truck home tomorrow i will start with investigating wire connections, injectors, coils, plugs, and lifters. Hopefully i find it in one of those areas.

[Jsdirt]

No problem. I would start with wiring, IMO. Whenever I see multi-code problem children like this, 9 times out of 10 it's wiring, or related to it.

 

Just take your time, and use the net - that will keep you from yanking your hair out. Sometimes it can be a real pain in the ass to troubleshoot these things for us common folk who don't have access to good wiring diagrams.

[WI_Dave]

Well I drove it an hour home last night, pretty bad miss/hesitation under low rpm's but ran good enough to get home. My code reader had some trouble trying to communicate with pcm, (maybe my reader needs to be updated, its an older one) so I pulled plug #1 and looks new. Messed with code reader again and after a few fails, I got it to pull 1 code- cylinder 5 misfire. I looked at wires to coil and pulled plug 5, it looked good as well. I put a spark tester on coil wire and was giving good spark. Put plug back in, cleared pcm and drove it around maybe 2 miles. All was perfect, misfire was gone. So I decided to try and find the ticking that only occurs under throttle on drivers side, and very front exhaust manifold bolt is broke. Took it to work today and so far still good with no missing, and no codes. Its too early to jump the gun, but it may not be as bad as I was told, and may have gotten a steal on the truck. It does have an air bag light on as well, but I wanna make sure motor issues are good before I troubleshoot that. Not sure if the dealer pulled the other codes and cleared pcm or not, but cyl 5 was not one of the 10 they gave me.