P300, P455, P128 Codes after head gasket replacement.

Tiny
DEJONG23
  • MEMBER
  • 2005 CHEVROLET IMPALA
  • 3.4L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
I took my car to a shop to have the head gasket replaced. Afterwards they gave it back to me saying it's not right yet and they think the fuel injectors are bad. It's misfiring terribly. They wanted me to drive it with some cleaner in the tank. The changed the plugs, wires and made sure the coil packs are good and checked the vacuum pressure (I think). Could having the injectors our of the engine without putting a bag around them cause them to dry and clog if any particulates are inside? Any thoughts to the problem?
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Tuesday, April 21st, 2015 AT 1:07 PM

8 Replies

Tiny
HMAC300
  • EXPERT
I guess it depends where they were set it might but they can runa pro cleaner through them that works a heck of a lot better than the intank stuff. It may not be the injectiors giving the problem anyhow with a misfire. All sensors have to be checked.128 is a coolant temp problem and 455 is evap large leak so there may be a line off or broken leading to canister take it back and have them fix it right
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Tuesday, April 21st, 2015 AT 1:12 PM
Tiny
DEJONG23
  • MEMBER
They seem pretty keen on replacing the injectors. I didn't have a problem before the head gasket change so I'm wondering what went wrong and who should be responsible to fix/ pay for it. I know they don't have a pro cleaner system for the injectors. Every shop I go to seems to guess and check vs. Problem solve. I understand that sometimes that can work but it's frustrating when they're wrong..
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Tuesday, April 21st, 2015 AT 1:23 PM
Tiny
HMAC300
  • EXPERT
Don't know what to tell you on that but I understand.
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Tuesday, April 21st, 2015 AT 3:12 PM
Tiny
DEJONG23
  • MEMBER
Does it seem abnormal to have this problem after a head gasket change?
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Tuesday, April 21st, 2015 AT 3:15 PM
Tiny
HMAC300
  • EXPERT
I would think so unless it had them prior to teardown which it may have had the p300 code. But the others I'd check for a line off on the 455 code and the temp sensor cold have failed or they pinched a wire going to it. Check to see if temp sensor is plugged in and look by back of engine for lines off or pinched together. I still think they should correct the problems, I know I would not let it leave with those codes until I was sure what the problem was. Especially the 455 and 128 codes.
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Tuesday, April 21st, 2015 AT 3:41 PM
Tiny
DEJONG23
  • MEMBER
Thanks for your help! The codes have been cleared and came on again. I haven't settled up with them yet. I know they're frustrated trying to figure it out. Cylinders 2, 4, 6 are dead I just discovered doing a cylinder balance test. They're all in line at the front I think. I've checked the lines briefly before. It just became gusty and rainy so I'll have to look more later. Thanks again!
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Tuesday, April 21st, 2015 AT 4:12 PM
Tiny
DEJONG23
  • MEMBER
It couldn't be a timing issue could it?
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Tuesday, April 21st, 2015 AT 5:03 PM
Tiny
HMAC300
  • EXPERT
Not really a timing issue one of the sensors is misreading as well as any air leak like duct work and or grommets leaking. That would only be for the misfire code the other two are either a bad gas cap or a evap canister purge problem which really should be smoke tested to find the leak. I don't' know how much you can do but these clowns that worked on it should fix this. To eliminate engine problem do a compression test on the cylinders that aren't firing. It could be low on compression as well. If it were a timing issue like a timing chain all your compression would be very low like all cylinders. And I'm sure it's not that. The ect shold be checked for apoor connection but you need a scanner to erase the codes first to see what comes back anyhow. If you have access to a tech 2 or a balance tester for injectors you can find out if your injectors need replacing g or not. That would end the debate on that. Also if you have tech 2 you can close the evap solenoid and see if that is the problem.
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Wednesday, April 22nd, 2015 AT 7:49 AM

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