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2008 Impala engine sputters


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2wonder
User

Feb 28, 2013, 1:14 PM

Post #1 of 7 (8775 views)
2008 Impala engine sputters Sign In

UnsureMy 2008 Impala 3.5L Flexible Fuel V6 with 80,000 miles has developed a rough running problem. I first noticed it on restarting the engine, that it seem to run as if flooded. Now it starts fine but it often feels as if the engine is missing between 45 and 55 mph as it is shifting into a higher gear usually when driving up a grade. It seems to run fine otherwise except for an occasional miss once in a while. The check engine light has not come on, no visable damage to wires or vacume hosses, and I have installed a can of fuel injection system cleaning fluid into a new tank of gas. Any ideas of what the cause is and a fix? Thanks....


Discretesignals
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Feb 28, 2013, 5:07 PM

Post #2 of 7 (8730 views)
Re: 2008 Impala engine sputters Sign In

You going to need to take it to a shop that has a high end scanner that can look at current and history misfire counts in the engine data stream. If you do have a misfire, it is important to figure out which cylinder(s) is skipping.





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2wonder
User

Mar 5, 2013, 12:40 PM

Post #3 of 7 (8656 views)
Re: 2008 Impala engine sputters Sign In

CrazyI had the car checked as suggested and they found a cracked spark plug.

Did you suspect a bad plug?


Discretesignals
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Mar 5, 2013, 1:10 PM

Post #4 of 7 (8648 views)
Re: 2008 Impala engine sputters Sign In

I suspect everything that is concerned with the firing of a cylinder that is missing. The reason you want to find out which cylinder is causing the misfire is so you have a place to start. If it was on one cylinder, then a check out of the ignition system would have probably been the first thing then the fuel system, and so on. Eventually would have found the problem after isolating which component in the ignition system was the culprit. That is how troubleshooting works, process of elimination.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Mar 5, 2013, 1:11 PM)


2wonder
User

Mar 5, 2013, 2:30 PM

Post #5 of 7 (8638 views)
Re: 2008 Impala engine sputters Sign In

If I had suspected a plug I could have changed them myself. But with the newer electronic & fuel systems, (post points, carburetor & mechanical fuel pumps, etc), I'm less sure of what is causing the problem(s), electronic, fuel, vac, or trans. If it is a simple repair, I like to do it myself.

Thanks for the replies.
Brian


Hammer Time
Ultimate Carjunky / Moderator
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Mar 5, 2013, 4:19 PM

Post #6 of 7 (8630 views)
Re: 2008 Impala engine sputters Sign In

Hence, the reason you pay for diagnostics.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



2wonder
User

Apr 10, 2013, 8:52 PM

Post #7 of 7 (8517 views)
Re: 2008 Impala engine sputters Sign In

Here is an update.

The sputters returned after the spark plugs were replaced.

I took it back to the same shop and after the car sat for a day before it was checked neither the test equipment nor the mechanic could find any misfiring but he did take my word that it had.

So he sprayed the plug wires with water and still no misfire. He sprayed the wires again and let the car set for a while when he returned and started the car it was misfiring from two cylinders. He had an assistant put the car in gear, hold the brake and put strain on the engine and then he could actually see sparking between two of the wires that rested across the top of the engine. We did have a lot of rain that month.

He replaced all the spark plug wires and put some protective tubing around the wires that rest on the engine. Now all seems well.

I hope others will gain from this info.






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