1997 nissan altima missing on #4 cylinder

has anybody used seafoam to clean carbon build up in the intake manifold

How do you know it’s missing on #4? Is that from a “check engine” code? Have you checked the spark plug, wires, coil, etc?

I’ve done an intake cleaning by introducing seafoam through an intake port if that’s what you mean. Its not hard to do. I can’t tell you whether or not it did anything for the car. It certainly does clean carbon - the big cloud of smoke pretty much tells you that.

What do you actually want to know?

It would help if info was provided about this car problem; mileage, any history of overheating, etc. along with who and how it was diagnosed as a cylinder 4 miss and whose suggestion it was to use SeaFoam as a miracle cure.

It’s extremely unlikely that carbon in the intake is going to pick on that one cylinder.

car has 185000 miles on it check engine light came on code read missing on #4 cylinder changed spark plugs,plug wires distriberter cap, roter, #4fuel injecter, engine brain box nothing made a differance car idiles perfict but misses when under a load and at crusing speed. I unhooked the vacume line to the egr valve and pluged it car runs perfect mechanic told me intake manifold is pluged and all exhaust is going to #4 cylinder creating a miss fire. also compression test was good

Well then, just leave the EGR disabled! If you must deal with an emissions test, then you will have to deal with this problem…Why didn’t you mention the EGR valve thing in your FIRST post, since you had already cured your problem…

Cars engines ran fine for 60 years without having EGR valves…So will yours…No chemical “treatment” will cure this problem. The plugged passages will have to be mechanically cleaned or replaced…

excuse me !!

I would first check the compression - unless that has been done already.

I’m not buying the diagnosis. If the intake is so plugged up that all of the exhaust from the EGR is going to cylinder 4 then how are the other cylinders being fed enough air to run?

I’d pull the whole EGR system - valve, tube, etc and make sure it all gets cleaned out and see what happens. The actuating solenoid for the vacuum also needs to be checked.

Other than agreeing with cigroller’s comments I’d like to ask what those compression readings actually are.

People routinely post on this forum with allegedly good comp. readings when in reality they are either not that good or they’re downright rotten.
Some of those bad readings are even claimed to be good by the mechanics who checked the compression.

compression reading was 175 all cylinders were within 2 psi of each other