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GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15201
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2007 suburban 5.3 flex...driving at 70 mph engine suddenly

Customer Question

2007 suburban 5.3 flex...driving at 70 mph engine suddenly began running rough....cylinder 1 misfire code......swaped cyl 1 and 3 coil.....multi mis fire code at idle....swapped back.....code at idle is now 3pooo however if clear the code and get engine up to speed I only get cyl 1 code.....Chevy house out on there scanner and at idle 1 total misfire....cyl 8 minor misfire at idle.....checked cyl 1 for spark good.....listened to injector good....swapped inj with cyl 4 still cyl 1 misfire.....swapped oxy sensors 1&2 from side to side still cyl 1 misfire........fuel pressure idles high at about 55 psi instead of 45.....swapped fuel pump in order tochange regulator....didnt change anything.....sprayed carb cleaner looking for vacuum leak ......nothing.....220000 miles 20,000 since rebuild. smells rich to me....Help.....Im lost.
Submitted: 1 year ago.
Category: Chevy
Expert:  Joe Prestia replied 1 year ago.

Do you have access to a scan tool or a compression tester?

Customer: replied 1 year ago.
I have a basic scan tool but it doesn't tell me much. No compression tester.
Expert:  Joe Prestia replied 1 year ago.

Sorry to be the one to bring bad news but you covered everything you can without a scan tool capable of reading live data, a compression tester, or a smoke machine. The only thing you haven't checked that you haven't already covered is looking at the injectors spray pattern and taking a sample of fuel from the rail and checking for contamination

Customer: replied 1 year ago.
The gas was low in the begining and I have out a couple gallons from different station since changed the pump so pretty sure it isn't that....if it was ink spray pattern that would have kicked a different cyl code when I swapped ejectors. Thanks for trying but I'll need to get a refund from just answer how do I do that.
Expert:  Joe Prestia replied 1 year ago.

Honestly I'm not sure how that works. I'm brand new here. But if you can contact customer service with a link to this conversation I think they'll be able to help you! Good luck!

Expert:  Gary replied 1 year ago.

Hi Joe,

Does your engine has AFM or DOD, becomes a 4cyl under light load cruising?

If so, I would say you have a cam roller lifter that has rotated and now has a permanent disabled cylinder 1.

AFM cylinders are 1,4,6,7.

If this is the case, it now becomes quite expensive to repair.

IF the camshaft has survived, you'll need to replace all the lifters, lifter guides and head gaskets etc.

Hope this helps.


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