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Chevy misfire...need help

Sep 4, 2010
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Keith Miller
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As always, thank you in advance...

Here's the situation:
08 chevy express 2500

It's reading misfire on #7. I have taken it to 4 different places and have none of them are quite sure what's going on.

Some of them think it's got to do with the fuel system others say the heads need to be replaced.

Have any of you had this issue with chevy?

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MikeGaure

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Plug
Wires
Fuel
Vac leak
Coil

Can be any of these, even the threads for spark plug in the head can give you grief
 

jtsunbrite

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Change your rotor, plugs, wires,,, give it a tune up usually that stops those misfire readings.
 

ColoradoCleaner

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I'd pull that spark plug... if it looks like it's been steam cleaned compared to the others then you have coolant leaking into the combustion chamber. If it looks normal compared to other spark plugs, most likely a simple ignition problem like plug wires will fix it.
 
Sep 4, 2010
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Keith Miller
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Sorry, already did all the tune ups stuff spark plugs, wires, etc.

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When we did all the tune up stuff it worked for a couple days and then had the same issue except that now it is a specific piston not just a random misfire like before.
 
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Ken Raddon

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Sounds like a stretch but here goes...

Have someone replace the Crank Shaft Positioning Indicator switch. If that thing is bad then all the other things will be temporary and since you said that the fix you did was fine for a few days I think it is the CSPI switch. It's a cheap fix too, less than $100.
 

Kingdomcome84

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maybe the fuel injector spraying in cylinder 7 is clogged. switch your fuel injectors
 

Mikey34

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Obviously switch the things that can be swapped i.e. Coil, plug, injector etc. And write down which items were swapped and where. I have gotten faulty coils directly out of the box.

If the problem does not move cylinders you now have a mechanical issue or electrical, leak down and compression test are always good.

If those r fine time to find someone who knows how to diagnose electrical issues. Always check ur grounds they can cause stupid problems.
 
Sep 4, 2010
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Keith Miller
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It runs rough pretty much all the time. Sometimes it will run fine when I first started it and then a few minutes later it's ramming really rough again.

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Pinosan

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*running

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have you pulled the OBD2 codes to find out what the problem is? a misfire is often something simple but difficult to pin point.
at tune up I assume you changed the plugs. did you change the wires and coil pack?
that van has individual coils if I'm correct.
Disconnect the battery
replace the plug once more its only 2 bucks
take the coil from number seven and swap it with any other one.
Run the truck until it fails again

Still number #7
take it to a good mechanic the fuel system as well as the electrical will need to be monitored
leak down test if necessary.

The fault moved to the piston number where you installed the coil?
buy an OEM coil and be done with it.

9 out of 10 times it ends up being the coil.
 
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Pinosan

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Also, there was a recall on fuel pumps on those particular vans if I recall correctly, If you bought it new, call the dealer. They should be able to tell you if your van already got the upgrade or you will need to bring it so they can do it for you if you still qualify
 
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Sep 4, 2010
35
3
8
Real Name
Keith Miller
Business Location
United States
have you pulled the OBD2 codes to find out what the problem is? a misfire is often something simple but difficult to pin point.
at tune up I assume you changed the plugs. did you change the wires and coil pack?
that van has individual coils if I'm correct.
Disconnect the battery
replace the plug once more its only 2 bucks
take the coil from number seven and swap it with any other one.
Run the truck until it fails again

Still number #7
take it to a good mechanic the fuel system as well as the electrical will need to be monitored
leak down test if necessary.

The fault moved to the piston number where you installed the coil?
buy an OEM coil and be done with it.

9 out of 10 times it ends up being the coil.
One mechanic did move the coil and it was still missing on #7. They wanted to take that piston to a machine shop. It was going to be $1300.

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I did change the wires but not the coils