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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8426
Experience:  I am ASE Master Truck Certified.
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Mr. Cat Man, I have a c15 NXS engine. Truck runs great until

Customer Question

Mr. Cat Man, I have a c15 NXS engine. Truck runs great until its put under load and then begin to white smoke misfire and pop LOUD. Doesn't do it all the time though. And customer says after engine gets warmed up it will not do act up. We have checked fuel pressure and its good. We installed 6 new injector and still did the same thing. I'd appreciate any insight on this issue. Do you think the problem could be in the ECM?
Submitted: 9 months ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 9 months ago.

Thanks for asking your question. I will try and help you out.

Does the yellow check engine light come on when this happens? Are the any code being logged? Or does it do this with no light or codes?

Customer: replied 9 months ago.

these is a code for iva not responding but the engine has had the code for a while. I have never been able to fix that code. I replaced sensor, engine harness, injector harnesses and looked for oil leaks under the valve cover but have found none.

Expert:  Cat Man replied 9 months ago.

Thanks for the info.

There are two things I have seen cause this.

The first and most common is an Iva sticking or malfunctioning. If you are getting one not responding code. I would suspect that Iva housing. If you could cut out injectors while it's doing this an smoking you could isolate which cylinder it is. Then try swapping the Iva with another to see if the problem follows. If it does, you'll know it's the Iva housing.

Second is a faulty injector. It's rare but I have seen an injector do this as well.

I would suspect an Iva.

Please reply back if you need more help or have more questions. I am happy to assist.

Customer: replied 9 months ago.

Would you suspect a sensor could cause the symptoms im having. I can't find anything wrong with the iva housings?

Customer: replied 9 months ago.

and like i said it only does it under a load and tends not to do it once engine has warmed up.

Expert:  Cat Man replied 9 months ago.

Thanks for the information. Yeah the main reason I suspect an Iva is because they only work when the engine is under load. I see these cause this problem a lot. Many times the Iva looks fine but has an internal problem causing the issue.

It could be a sensor but you would have to monitor them all in ET to try and find one reading wrong.

Expert:  Cat Man replied 9 months ago.

Hey. I just wanted to see how things were going. Please let me know if you need more help. I am happy to assist. If my information was helpful, please leave a good or higher rating so that I receive credit. Thanks.

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