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Ask Dave Nova Your Own Question
Dave Nova
Dave Nova, Chevrolet Technician
Category: Chevy
Satisfied Customers: 19450
Experience:  ASE Master Certification. GM World Class Certification
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Random misfire gmc ***** ***** just had it at a gm service

Customer Question

Customer: random misfire gmc ***** ***** just had it at a gm service kenny ross for this they did a compression check leak down test all came back good they then installed a new rotor cap and gear said the gear was worn and cap had some corrosion didnt go about a day engine light back on codes checked by my local mechanic still random misfires same thing name is joe
JA: Thanks. Can you give me any more details about your issue?
Customer: joe not ***** ***** thats the car
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Submitted: 11 months ago.
Category: Chevy
Expert:  Dave Nova replied 11 months ago.

What year and model is your GMC? Engine size?

Customer: replied 11 months ago.
gmc jimmy 2001
Customer: replied 11 months ago.
4.3 vortech
Expert:  Dave Nova replied 11 months ago.

Does the check engine light ever flash? Do you feel a misfire while driving?

Customer: replied 11 months ago.
it flashed yes that is why i took it to a gm garage dont feel a major misfire but under load seems to be a little not as bad tho after the gm garage replaced the above items in my question
Customer: replied 11 months ago.
what do you think
Expert:  Dave Nova replied 11 months ago.

Have the plugs and wires been replaced recently?

Customer: replied 11 months ago.
not recent maybe about 4 to 5 yrs ago but you would think that the gm garage would have done it if they felt it was needed along with the new cap and rotor gear ,they had the plugs out to do the compression test and leak test so they would have seen the condition of plugs this motor is new only has about 20,000 mile on it thats when plugs and wires were put on due to new engine the old engine head cracked new maf to on it
Expert:  Dave Nova replied 11 months ago.

You would think that the GM garage would have done all necessary repairs, but obviously they missed something. Misfires under load are caused by faulty ignition system components. Plugs are likely okay, but I suspect that you may have some bad plug wires.

Customer: replied 11 months ago.
what about coil not puttin enough juice out under load starts it but weak coil i heard could do this the amps have to be a certain range that was never replaced
Expert:  Dave Nova replied 11 months ago.

Yes a failing coil can cause the same symptoms.

Customer: replied 10 months ago.
Can you believe my luck that is a brand new jasper motor with about 30,000 on if that and the cam lobes are wore chevy dealer found it and the 3 yrs is past by about a yr for warranty gonna cost me around 2500 to fix must have got a cam machined a bit wrong they had the valve covers off and seen that the lifters are not in sync
Expert:  Dave Nova replied 10 months ago.

That is an odd one for sure. Not something that would be expected. We did see a lot of camshaft failures in the 1980's on GM V8 engines, but it is not common today. Glad you were able to get it sorted out, sorry that it is going to be an expensive fix.

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