2001 Chevy Malibu PO304 #4 cly. Misfire

Tiny
HJ72
  • MEMBER
  • 2001 CHEVROLET MALIBU
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 138,690 MILES
Hi I have a check engine light on, hook up to sanner cly.4 misfire po304.I check for spark(ok)and check for compresstion(125lbs.)I can not check for injectors pluse because it is under pltam. Could it be a bad moduel?Or injector?What do I from here?
PS I cleared the code and it did not come back on intill the motor was hot then it came back on #4 cly. Misfire!How about a bad coil pack?Help
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Tuesday, March 9th, 2010 AT 7:58 AM

20 Replies

Tiny
LEGITIMATE007
  • EXPERT
Do the cylinders have their own coil(coil over)?
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Tuesday, March 9th, 2010 AT 12:28 PM
Tiny
HJ72
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It has seprate coils.
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Tuesday, March 9th, 2010 AT 12:50 PM
Tiny
LEGITIMATE007
  • EXPERT
I would first start by checking the coil for that cylinder and the plug and wire of course
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Tuesday, March 9th, 2010 AT 1:13 PM
Tiny
HJ72
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I have spark down to the plug could it be a bad coil any way?
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Tuesday, March 9th, 2010 AT 1:21 PM
Tiny
LEGITIMATE007
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Yes it can
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Tuesday, March 9th, 2010 AT 1:23 PM
Tiny
HJ72
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I put a new coil in and still have the same thing!When it frist start up cold it is fine hot light come on po304 come back!I have good spark going down to spak plug, so wire is good coil is good. Could it be the module not giving injector pluse or bad injector?
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Tuesday, March 9th, 2010 AT 2:09 PM
Tiny
LEGITIMATE007
  • EXPERT
Could be injector, try checking the plug see if it is discolored, or has gas on it, or you can get a noid light and plug it into the injector harnass to see if we have pulse, another thing could be a burnt valve. There are so many possibilities, the computer can be faulty too. But not likely
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Tuesday, March 9th, 2010 AT 2:21 PM
Tiny
HJ72
  • MEMBER
There is no gas around injector I can not get a node light in the pltum cover everything. But a brunt vaule sound like that could be it has a lot of tapping on the top end how would I check for that?
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Tuesday, March 9th, 2010 AT 2:36 PM
Tiny
LEGITIMATE007
  • EXPERT
A compression check will help you determine that, I 'll send the info
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Tuesday, March 9th, 2010 AT 2:38 PM
Tiny
LEGITIMATE007
  • EXPERT
http://www.2carpros.com/dia/how_to_check_compression.htm
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Tuesday, March 9th, 2010 AT 2:40 PM
Tiny
HJ72
  • MEMBER
I did a compresstion test I have 125lbs at cly.#4
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Tuesday, March 9th, 2010 AT 3:19 PM
Tiny
LEGITIMATE007
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Ok then we need to do the pulse width on that injector
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Tuesday, March 9th, 2010 AT 8:15 PM
Tiny
HJ72
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Sorry I had to run out!That means I have to pull the top plaum off to get to the injector wires, there is no other way to do that. Could it be a bad rocker arm or push rod, the top end has a lot of tapping going on?
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Wednesday, March 10th, 2010 AT 7:11 AM
Tiny
LEGITIMATE007
  • EXPERT
I suppose there could be a bad lifter for that cylinder, and its not pushing the rod hard enough to make the rocker arm open the valves, but you said compression is normal, and the only way to get to the injector wires is to do what you said remove the plenum
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Wednesday, March 10th, 2010 AT 10:44 AM
Tiny
HJ72
  • MEMBER
I took off the platum I have hot at one side with key off and with key on both sides are hot, I crank it over and had my noed light flash(would not do that again)so I am going to change #4 injector also the spark plug looks like it is white so do not think it is fireing?
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Wednesday, March 10th, 2010 AT 10:56 AM
Tiny
LEGITIMATE007
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No I think its firing but no fuel.
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Wednesday, March 10th, 2010 AT 10:59 AM
Tiny
LEGITIMATE007
  • EXPERT
How do you have such quick access to all the stuff you need?
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Wednesday, March 10th, 2010 AT 10:59 AM
Tiny
HJ72
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I have been a shop owner and a tech for 35 years and I have a sacnner and every thing I need logic prob noed light kit.
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Wednesday, March 10th, 2010 AT 11:18 AM
Tiny
HJ72
  • MEMBER
OK put new injector in #4 cly clear codes runs GREAT!But light came back on at idel give it gas light goes out code says PO304#4 misfire $10 1/1 car runs great only at idel after 3 munites dose light come back on give it gas goes out!What dose the dollars sign$10 HELP!
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Wednesday, March 10th, 2010 AT 4:41 PM
Tiny
LEGITIMATE007
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Wow, I am not familiar with that, let me ask the other mods.
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Wednesday, March 10th, 2010 AT 10:59 PM

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