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My brother in law, who is a master mechanic and who worked for Ford for many years, explained the way he'd prefer to do it. He likes the idea of spraying SeaFoam or other intake valve cleaner *VERY SLOWLY* into the intake. He recommends a rate that would spend the entire can in about 45 minutes, rather than the repeated 30-second burst method. And you'd keep the RPMs up at around 1500 for the duration. He said that if it takes you 10 minutes to empty the can, it will not do any good at all. He has used this (slow) method before and used a snap-on professional grade endoscope, and said that the valves looked like new after doing it. I don't know of a really good way to be able to regulate the flow of the can to a rate that slow, but it might be a good way to do it.

I haven't heard of this super-slow method on the forums before, and since my brother in law is a professional, I thought I'd repeat what he said here. I might still decide to pull off the manifold, though, so I can see what I'm doing.

My issue is that I haven't seen any really good guides on how to remove the manifold. I found a guide, but I didn't think it was very good. Any suggestions?
I like your brothers method. I sprayed mine slow, took me about 20 or so minutes, was not quick and a totaly pain but worth it. I honestly wouldn't use SeaFoam but it might be the same stuff as the CRC stuff, who knows, I was told that the CRC stuff is made for out type of DFI /turbo car.

I think a good method would be to put it on a vac line that would auto feed it from under the hood and drive the car at 2k til the bottle runs out, couldn't do it with the CRC but SeaFoam would work if it is ok for the car. basically let the vac of the car pull in what is needed? idk just thinking up ideas but not sure if it is a good idea or a bomb under the hood :\


Removing manifold:

one of dozen videos on you tube. if that video doesn't help I recommend taking it to a "professional".
 

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Discussion Starter #22
Thanks. That's a great video and much better than the forum post tutorial I saw before.
 

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Discussion Starter #23
I ran the CRC GDI valve cleaner through my intake as I described and it seems to have worked pretty well. It was a long process! I sprayed it as slowly as the can would spray and took a few breaks here and there. The car is running super smooth now.
 

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Hey guys, nice to see the CRC GDI cleaner worked for you. I may be doing that myself. Since it's been a little chilly in MD the past few weeks, my car has thrown many codes. P0300, P0302, and P0316. Also P0299 but that was self inflicted from not putting the stock BPV on correctly - which is now fixed. I have owned my '16 ST3 since December and put about 4k miles on it. When it's below 40 degrees, that's when it seems to misfire. I'll describe what happened today, it's completely insane.

Been misfiring consistantly for a few weeks, MIL on, codes thrown, everything.
Start the car this morning (about 35-40 degrees outside) = heavy misfire - like 400-500 range.
Start the car at lunch (around 45-50 degrees) = mild misfire - like 60 or so. Still have the MIL on.
Start the car at 5PM to head home (59 degrees out) = no misfire. none at all.

Has anything been said on any thread about the temperature? And what our cars do when it's cold? I've read some general things about the fuel mixture being too high, the incoming air being too cold, and it not igniting properly - causing a misfire. I'm not a professional by any means, just an enthusiast that loves this car. I have an appointment at the dealer to have them check things out, even though I know they probably won't find anything and will throw parts at it like what happened to the previous owner. This car had the entire top end, head and all, replaced at 13k miles. I bought it with 15k. Didn't know that prior to the sale, but that's besides the point.

For the record, I didn't have any mods on the car that would cause a misfire - to my knowledge. I had basic mods like the RS airbox (stock filter), Boomba BPV (with 1 set screw out), Cobb RMM, Cobb short shift plate, and shifter bearings and stuff that have no effect on the motor whatsoever.

I also noticed there's a new TSB out that recommends replacing the plugs with Fiesta ST plugs gapped at 0.40, which seems outrageous. I just replaced the plugs in my car with OEM Ford plugs (for the Focus ST) and now the plug in cylinder 2 looks like its been in there for 50k miles.

Anyway, can anyone out there a lot smarter than me explain the cold weather portion of it? And if there's anything we can do to prevent this from happening?
 

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I went through a similar situation last month. Had lots of misfiring on idle and cyl 1 misfire (warm or cold starts). Fixed my gaps, replaced plugs, moved coil packs then plugs. Had good compression on all 4 cyls and removed my tune. Still the misfired continued. Took off my intake manifold and had lots of carbon buildup. Got it all cleaned out last weekend and that did the trick.

I'd check your valves before buying new parts.

Sent from my LG-H872 using Tapatalk

How many miles were you at?
 

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I got the P0300 random and P0302 clyinder 2 misfire. New plugs. No change. New coils no change. The purge valve code pops. Im like what the hell 50 bucks is cheaper than 400 for injectors.did the purge and all misfires went away..10 miles so far.
 
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