REGARDING COIL PACK AND ENGINE DIAGNOSTIC READING

  • Tiny
  • mechanic12a
  • 2008 Mazda CX7
  • 62,000 miles

Engine light came up, took to autoshop for computer reading, came up as 02, 2nd chamber misfiring, vehicle very jittery. Chnaged spark plugs, oil, and checked coil packs. Switched 2nd chamber coil pack with 4th chamber coil pack, erased computer reading by unhooking battery for 2 minutes. Restarted, still jittery, ran at 35 miles per hour, engine light comes back on, reading states chamber 02 misfiring, even with switched out coil pack. Checked wiring, nothing looks bad on wiring for coil pack. Auto still jittery and when driven has a lurching/hesitating pull, on parked, jitters to a very low idle. Why would it still show 2nd chamber misfiring if all wires look good, spark plugs new, oil changed and coil pack switched out? Thank you kindly.

Tuesday, April 10th, 2012 AT 2:28 PM

12 Answers

  • Tiny
  • hmac300
  • Expert
  • 42,046 posts

You need a scanner to erase codes not disconnecting battery. Check your fuel pressure it should be 60-71 psi and clean throttle plate on both sides. Start there first.

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Tuesday, April 10th, 2012 AT 3:41 PM
  • Tiny
  • KHLow2008
  • Expert
  • 41,938 posts

Check the compression for the cylinder.

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Tuesday, April 10th, 2012 AT 3:54 PM
  • Tiny
  • mechanic12a
  • Member

Thanks guys, did have the scanner erase the computer both times, first time was with battery disconnect. Have taken into Dealership to see if they have a more thorough scanner/computer to diagnose, $45.00 to 98.00 I dont have. Dont know where the throttle plate is located. If code is showing misfiring on cylinder 2, then why would compression be the issue? Sorry newbie to these newer engines, give me an older engine and I can tear it apart and put back together in 1 day.

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Tuesday, April 10th, 2012 AT 4:11 PM
  • Tiny
  • hmac300
  • Expert
  • 42,046 posts

You need compression to fire the mix of fuel air in the cylinder. If it is low like at 85# then it won't fire the mix or not very well. Normally your car wold have 140-160# compression per cylinder. If you want to know where your throttle plate is go to the siet here an dlook under tune up it will show you.

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Tuesday, April 10th, 2012 AT 4:43 PM
  • Tiny
  • mechanic12a
  • Member

Thanks. After paying 45.00 at the dealership, the best they could come up with was the same readout I got when taken to autozone and done for free. One mechanic did try to narrow it down for me and stated it is one of three things, bad spark plug(which I just changed out to new ones before taking it in, no change, so thats not it), then he said possibly bad wiring connection to number two cylinder(looked at it, looks brand new all way down), then he said lastly it may be a fouled up or bad fuel injector(very possible but entails taking alot of the engine apart just to get to them). For a very detailed pinpoint inspection, would run 250.00 from dealership. If is fuel injector, would be an additional 250.00 labor not including fuel injector. If wiring, would be additional 150.00 labor not including new wire harness. Thanks for your advices, I do not have a tool unfortunately to check compression right now. I was told by the Mazda person I should consider trading in the vehicle because they have very bad circumstances with those vehicles engines. Will check the throttle plate as my final option before finding a reliable mechanic that can do whatever work, not going back to dealer, very rude people except for the one mechanic who they all kept staring at to leave.

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Tuesday, April 10th, 2012 AT 9:21 PM
  • Tiny
  • Stace2025
  • Member

Mechanic12a did you find a solution - we have the eact same problem - any help would be greatly apprecaited as we are currently running around in circles with this issue?

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Thursday, September 27th, 2012 AT 5:23 AM
  • Tiny
  • KHLow2008
  • Expert
  • 41,938 posts

What is the EXACT trouble code you are getting?

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Thursday, September 27th, 2012 AT 5:45 AM
  • Tiny
  • hmac300
  • Expert
  • 42,046 posts

Was the fuel pressure checked? I bet not.

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Thursday, September 27th, 2012 AT 1:06 PM
  • Tiny
  • Stace2025
  • Member

Hi all have still had no luck with our mazda its been at machincs for a while. They have replace vvt as it had the loud rattle to it and chain etc still having the miss fire fault. They have checked the coils compression fuel pressure changed spark plug still didnt change anything. So then had injectors cleaned as the to fault codes were in cylender 2and 4 both of those enjectors were running at about 40 percent and other two at 100 percent. They got injectors 2 and 4 back to about 80 percent car stopped sending miss fire fault but was lagging due to running at 80 percent. So now I have to change 2and 4 injectors takes about 4 week from ching chong land to arrive so will see if that fixes it its cost me so far 2300 and another 1100 to do injectors so im pritty pissed about it. Il keep you updated

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Thursday, November 1st, 2012 AT 10:52 AM
  • Tiny
  • KHLow2008
  • Expert
  • 41,938 posts

We requested for the trouble codes and never got any reply to that. Without trouble codes, how do you know the cause is the same?
If you want us to help, you need to provide us requested information to understand the problem.

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Thursday, November 1st, 2012 AT 11:33 AM

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