My dealer just told me that I need to do a cleaning at 26K miles. When I asked why it was building up they said it was gas or driving conditions. I don't really buy that given that I have yet to see anyone who needed it this early. They claim it's so bad that it's causing misfirings on three cylinders. They are replacing the intake manifold under warranty.
I've always put 93 octane premium in the car from reputable gas stations. I drive aggressively but don't redline it with regularity. Anyone else have this come up so early? Any other theories (preferably warranty-related) that might cause carbon to build up so quickly? They want $800 to do the cleaning. Is that excessive?
Any input would be much appreciated.
Thanks,
Tom
Have the dealership take pictures of the carbon! I would want to see it for myself. You wrote misfire on three cylinders. What is the link to the carbon build up? Are they implying the carbon build up is so bad that the intake valves no longer seat properly and you are getting backfires? Again, have them take pictures. And what was the deal with the intake manifold? Why are they replacing it under warranty? That is pretty major. Did it crack? Why? And gee, maybe that might cause a misfire too.
As an aside, gasoline has absolutely nothing to do with carbon build up on the topside of the intake valves. If that is the carbon buildup they mean, the dealership is talking out of its ass. Carbon build up on the top of the valves can ONLY be created by contaminants suspended in the “intake” air stream. The gasoline is directly injected into the cylinder. How would that affect anything in the manifold or ports? Most likely the carbon build up is from the PCV valve.
If by chance the carbon build up is genuinely this bad, that is a symptom of another problem. Does this mean you have excessive blow by? Are your rings bad? Are bad rings covered under warranty? Have them run a compression check. This whole thing smells fishy to me, unless of course you are Stage 1 or 2. That would explain excessive blow-by.
And on the subject of catch cans, I have a homemade one that cost a whopping $20 total (can, tubing, connectors, etc.) It works flawlessly. Each month I remove at least 4-5oz. of fluid. To me, that is a lot. I know several people here claim catch-cans do nothing, but common sense tells me that much oily fluid can only be bad for the car. Aside from EGR gas, which is not oily, what else could cause the carbon build up anyway? Cheap insurance.