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Daryl, Shop Owner, Certified Mechanic
Category: Car
Satisfied Customers: 12549
Experience:  28 years experience, Master Mechanic
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blazer: code p0340 - running rough-misfire. cam pos sensor A-bank 1

Customer Question

same blazer as last question. code P0340 - running rough-misfire. cam pos sensor A-bank 1-circuit malfunction.lists number of problems.starts easy.misses like dead cyl.
Submitted: 6 years ago.
Category: Car
Expert:  Daryl replied 6 years ago.

With the P0340 the cam sensor is usually the problem but the only way to be sure is with some testing, a lab scope is needed to do this type of testing.

Customer: replied 6 years ago.
installed new CPS no help. now code P0304 #4 cyl missfire. has fire. installed new style MFI injection sys from auto zone. could #4 inj not be working or crimped. wire shorted.miss is getting worse.just checked and rechecked everything. 4 plug looks like only getting slight amt fuel. more I run it - worse it gets.compression good.spark good.
Expert:  Daryl replied 6 years ago.
A cps is a crank position sensor so do you mean you installed that or the cam position sensor? If there is spark it can still be out of time if the cam sensor is bad or the distributor is out of time the timing needs to be set using a scan tool. Or there could be a fuel issue so I would start by getting a fuel pressure reading.
Customer: replied 6 years ago.
put new cam pos sensor. did not help. everything worked fine before I pulled eng and rebuilt it. the only thing new is the new spider updated injectors.#4 cyl is dead. ign sys is locked in place. fuel pressure is fine..I may have crimped line when installing or injector is bad or wire broke.
Expert:  Daryl replied 6 years ago.
If you are still getting the P0340 code the timing is still probably off so that needs to be fixed as well, but if #4 is dead you need to check that injector and wiring.