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George H.
George H., ASE Certified Technician
Category: Cadillac
Satisfied Customers: 18759
Experience:  ASE Master Tech 15+ Years
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I've had a multitude of issues with my 2002 northstar engine

Customer Question

I've had a multitude of issues with my 2002 northstar engine and resolved them all in spite of a half dozen shops telling me to do a complete rebuild. My last issue is this; The engire does purr like a kitten most of the time. But once the engine has reached its normal operating heat, it starts to misfire. When at a stop it feels as though it is going to stall but does not. At one point I sprayed some brakefluid directly onto the throttle box and when I did this, felt as though it was sucking it in thus causing more delay. Again, cold its fine. No smoke just the misfiring. I have a mechaninc who is almost as bald as I am now and he started dwith a full head of hair. Any ideas what to look for?
Submitted: 1 year ago.
Category: Cadillac
Expert:  George H. replied 1 year ago.

Hello I will help you with your question,

These have a problem where the bottom of the boot that connects the throttle body to the intake manifold cracks and unmetered air is dran in.

When you sprayed the brake clean you added fuel to the air being sucked in and it smoothed out.

Not an expensive part ($35) but you have to pull the manifold (1.5 hours) to replace it.

If your mechanic has a scantool that will show fuel trims or O2 sensor voltages they can be monitored when the spray is applied to the bottom of the boot. If the trims/voltages change the boot is leaking.

Please let me know how I can help you with this

Thank you