I have opened up a '80s carb car with 125k to find the valves coked up with what I seem to recall was about 1/2" of carbon on them. Conclusion: Carbon build up is a real problem.
My first car was a FI Nissan (Q45) that I bought with 178k, and took apart at 246k. A very thin film of carbon on those valves. Conclusion: FI cars do not need their valves cleaned.
That same Nissan, I did test injector volume with a stop watch and a graduated cylinder and every single 1 of the 8 were dead on to within 1 or 2 % (my measurement error, probably). Visually, the spray patterns looked good, with even atomization on all 8. Conclusion: The benefit of injector cleaner on fuel injectors is suspect.
FWIW, I have also soaked valves in injector cleaner for a week, and did not see any difference. The carbon did not dissolve or get soft. It was still as crusty and hard to remove after soaking as it was before. Maybe the heat inside the engine makes the difference? Conclusion: I think it's all snake oil.
I suspect the smoke you see out the tailpipe when you run sea foam in an engine is just the sea foam.
My first car was a FI Nissan (Q45) that I bought with 178k, and took apart at 246k. A very thin film of carbon on those valves. Conclusion: FI cars do not need their valves cleaned.
That same Nissan, I did test injector volume with a stop watch and a graduated cylinder and every single 1 of the 8 were dead on to within 1 or 2 % (my measurement error, probably). Visually, the spray patterns looked good, with even atomization on all 8. Conclusion: The benefit of injector cleaner on fuel injectors is suspect.
FWIW, I have also soaked valves in injector cleaner for a week, and did not see any difference. The carbon did not dissolve or get soft. It was still as crusty and hard to remove after soaking as it was before. Maybe the heat inside the engine makes the difference? Conclusion: I think it's all snake oil.
I suspect the smoke you see out the tailpipe when you run sea foam in an engine is just the sea foam.
