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Matt, Engineer
Category: Cadillac
Satisfied Customers: 20361
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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I have a 2013 xts FWD and at 1500 rpm it vibrates badly. The

Customer Question

I have a 2013 xts FWD and at 1500 rpm it vibrates badly. The Cadillac dealer says it normal. I can't agree with that answer. if an engine vibrates it will cause pre-mature engine failure. Now at the same rpm the car is starting to hesitate between 1/2 shift. what could this be?
Submitted: 2 months ago.
Category: Cadillac
Expert:  Matt replied 2 months ago.


it sounds like the engine is misfiring to me and your're right to stick to your guns as this isn't normal

replace the spark plugs if any of them fail this checklist:

You can also try spraying some water on the coil pack with the engine running. It is possible the coil is faulty and causing the misfire. If you see sparks arcing with the water, then replace the coil.

I'd check the condition of the injector plugs / connections as this could be a lean misfire if an injector isn't firing properly - the best way to check this is with a 'noid' light

Then check all the connections to the engine sensors one at a time, remove each one and examine for signs of corrosion or damage and a squirt of contact cleaner ( not WD40) will also help.

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and leans the engine out causing rough running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas around each joint in turn. If the engine rev's up you've found your leak.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Expert:  Matt replied 2 months ago.


do you still need help?

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