Intake Valve Coking on Direct Injected Gas Engines: Fact or Myth?

[harringtondav]

If my new boat ever arrives it will have a VP240SX. 4.3 GM V6 With direct fuel injection.
I also belong to a G5 Ford Ranger forum. Rangers and other Fords also have direct injection. A recent thread on that forum had a lot of discussion and hand wringing about intake valve 'coking'. The theory is the stem side of the valves never contact gasoline with its detergent additives, so the valves coke up.

...any knowledge based opinions on this issue. ... Thanks, Dave

 

[matt167]

Yup, it's a major problem. Ford redesigned most of their Ecoboost engines with partial indirect injection to combat the issue

 

[Bondo]

Ayuh,...... Yer in luck though,.... Yer boat is Chevy powered,....

 

[dingbat]

Ayuh,...... Yer in luck though,.... Yer boat is Chevy powered,....

“With Ford, the problem is there, but it’s not destroying the engine like it is with GM,” he says. “That might be because Ford ran the V6 EcoBoost engines through the Baja 1000 and they essentially beat the crap out of them and I think they put a little bit more engineering into the engine, so it’s able to shrug off these issues a little bit easier than GM engines.”



https://www.enginebuildermag.com/20...e-direct-injection-issues-facts-fictions-gdi/

 

[Bondo]

“With Ford, the problem is there, but it’s not destroying the engine like it is with GM,” he says. “That might be because Ford ran the V6 EcoBoost engines through the Baja 1000 and they essentially beat the crap out of them and I think they put a little bit more engineering into the engine, so it’s able to shrug off these issues a little bit easier than GM engines.”



https://www.enginebuildermag.com/20...e-direct-injection-issues-facts-fictions-gdi/

Ayuh,.... I'm not familiar with the Ford motors, but the Chevys in our boats are direct injected into the intake manifold, 'n not the head, so the valves are still bathed in gasoline,....

 

[harringtondav]

Ayuh,.... I'm not familiar with the Ford motors, but the Chevys in our boats are direct injected into the intake manifold, 'n not the head, so the valves are still bathed in gasoline,....

Thanks @Bondo. Below is GM's info page on the engine in my new boat. Reading this I got the notion it is high pressure direct injected into the cyls.
I believe previous SBC engines were multiport injection into the intake manifold at the intake valves. What's your read?

Doesn't matter now. I chose the 4.3 VP over the Merc 4.5 because it is a GM/Chevy 4.3. ...bullet proof in my experience. Plus it gives me 240 hp and closed cooling. Time will tell....

Site Maintenance

media.gm.com

 

[harringtondav]

“With Ford, the problem is there, but it’s not destroying the engine like it is with GM,” he says. “That might be because Ford ran the V6 EcoBoost engines through the Baja 1000 and they essentially beat the crap out of them and I think they put a little bit more engineering into the engine, so it’s able to shrug off these issues a little bit easier than GM engines.”



https://www.enginebuildermag.com/20...e-direct-injection-issues-facts-fictions-gdi/

Thanks @dingbat. Good read. My take: Change oil sooner than later with spec oil. .....also give the engine a good "cobweb cleaning" occasionally. ....probably more important with my Ranger. Boat engines.....happens naturally.

 

[Lou C]

Interesting article, think I'll stick with my Quadrajet lol.

 

[dingbat]

Thanks @dingbat. Good read. My take: Change oil sooner than later with spec oil. .....also give the engine a good "cobweb cleaning" occasionally. ....probably more important with my Ranger. Boat engines.....happens naturally.

I know have 3 years on Ford 3.5 EB in my truck.

My only complaint, if I have one, is spark plug life. Started getting the slightest idle “tick” @ 40k. Changed plugs and all is good again.
Awesome towing motor. The low end torque is impressive.