I chose this title as this is a big issue with many modern day cars. Though it's more prevalent with high performance vehicles like the 392 Challenger that I sold before buying my Tucson, it's an issue for every modern cars, especially turbos, and becomes a huge problem for cars that only have direct injection (DI). For example older Tucsons had only direct injection and Hyundai paid dearly to learn that lesson, as did many other manufacturers. DI makes for some great improvements in horsepower and gas mileage, but causes big problems with deposits on intake valves and combustion chambers. That's why I was so glad that my 2.5 Tucson has both DI and port injection. It's well known that port injectors are very effective at keeping intake valves clean. I would not have bought it if this were not the case. However, every modern car has a PCV system where the vapors from the crankcase are vented back into the intake manifold to be returned in the cylinders rather than vented to the atmosphere as they were before 1965 or so. In my Challenger, for example, there was a huge amount of oil in both the intake manifold and on the back side of my intake valves, even as soon as 16k miles. I installed a catch can to prevent this. I decided this week to take a look at the intake tract on my new Tucson to see how it was doing.
Oil in the intake?
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Below, I've removed the 3 lines attached to the "S-shaped" intake tube that connects the air cleaner (blue arrow), and the throttle body (white arrow).. In doing so, I checked carefully around the hole inside this black tube in my hand... right where the PCV vent hose enters from the side. Happy to say that though it had a little oil film on it, there was no dripping oil or excess amount. I checked the inside of the PCV hose (red arrow) and found the same results. Note: my engine only has 600 miles on it. I'll check this again once I get a few more miles.
Then I checked the throttle body itself. Oil from the PCV system likes to collect near the bottom of this assembly right next to the throttle plate (red arrow). Happy to say it was completely dry with little or no oil film detected. This is certainly a good sign. Some cars cough up a lot of oil back into the intake system, and some don't. It's likely too soon to be sure, but early signs here are good.
2022 Tucson SEL FWD Amazon Grey Convenience/Premium/Cargo Pkgs
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This is where I added CRC injector cleaner on the Soul. There was oil there, not dripping but easily felt and seen.Then I checked the throttle body itself. Oil from the PCV system likes to collect near the bottom of this assembly right next to the throttle plate (red arrow). Happy to say it was completely dry with little or no oil film detected. This is certainly a good sign. Some cars cough up a lot of oil back into the intake system, and some don't. It's likely too soon to be sure, but early signs here are good.
If you found it there, you should have seen your intake manifold and the tracts leading up to the valves. You can't have it in one place and not the other. Just a brief warning: not for you Tampa, but for others reading: be careful with additives. Follow directions carefully because too much "of a good thing" is NOT GOOD. Catalytic converters are very expensive and can be damaged by over zealous concentrations of auto store additives. To quote one researcher that I trust, most do little or nothing for your engine, but some do help. For me, when the need arises, Techron gets the call. Have you read in the online manual that Hyundai recommends a bottle of fuel additive every oil change for those who don't use top tier gasoline?
I'm guessing there's quite a bit more overlap in your 392 cam than the 2.5. That would create an intake carbon build up condition without a fuel wash. I think the port injection serves two purposes on the 2.5, washes the intake valve, and cools it (13:1 compression on the 2.5, right?) to help avoid detonation.
Wow, looks like I'm talking to a gear head. Seems that guys who know engines are getting rare these days, especially on forums like this one. Feel like I'm preaching to the wind sometimes. Hey but that's OK, I'm happy to try to share what I'm learning about this new engine. In studying some technical data about the engine, I discovered that though the static compression ratio (measures stroke vs combustion chamber volume), it is indeed 13 to 1. But because of valve timing, the dynamic compression ratio is actually closer to 11 to 1, I forget the exact numbers. But during the power stroke, the torque curve benefits from the longer 13 to 1 static ratio. Best of both worlds.
On my Challenger, it indeed had valve overlap, and would have never gotten over 25 (or so) mpg had it not been for the cylinder deactivation. It ran on 4 cylinders up to about 70 if I was easy on the gas. And in doing so got much better mileage at highway speeds. The build up (of oil IN the intake manifold, on the valves and in the combustion chambers) had to do with the serious amount of fuel and PVC fumes pumping through when I was on the throttle: it had some huge ports. That HEMI was a beast.
Concerning the dual injectors on our 2.5 engines, you are right. But there are other things at play. The direct injector is great for gas mileage, emissions, and horsepower. ALMOST the best of all worlds. But it doesn't do real well at high RPMs and it doesn't keep the backside of the intake valve clean. So our injectors activate at different RPMs. One downside there is that if ya don't wind up the engine (a little bit) often enough, the port injectors won't have much to do.
Wish I had more "data" to provide. Only have 650 miles on the car thus far. I just wanted to make a preliminary check to evaluate any oil residue that might be accumulating in the intake tract. Obviously, I didn't look into the intake manifold. I don't plan to do so in the future either. This is not some high performance HEMI. But it was easy enough to check and satisfied my curiosity: at least for now.
One interesting note about our PVC system. This is the hose that travels from the top of the valve cover directly over to the intake manifold. Every engine is mandated to have at least one. It carries with it both fumes and oil vapor, which is sucked by vacuum into the intake tract and on to the combustion chambers. Trouble is all of it doesn't get burned. It never does. As I said, some engines are worse than others, and I'm hoping ours is not on the list. I'll be watching it.
But one thing that concerns me is the sheer size of the PVC hose, and a really short one at that. This is a REALLY big hose. It measures about 9/16 of an inch on the inside diameter. Even my 392 Dodge Challenger only had a 1/2 hose. It's a monster. So I'm wondering, why so big? I never shared this, but that's what got me concerned about just how much oil it might be generating.
Here's my thoughts: on an engine this small (2.5 liters in my case or 152 cubic inches), why would they have such a large PVC hose? Suppose I'll never know, unless we've got an engineer out there somewhere on this forum??
But one thing that concerns me is the sheer size of the PVC hose, and a really short one at that. This is a REALLY big hose. It measures about 9/16 of an inch on the inside diameter. Even my 392 Dodge Challenger only had a 1/2 hose. It's a monster. So I'm wondering, why so big? I never shared this, but that's what got me concerned about just how much oil it might be generating.
Here's my thoughts: on an engine this small (2.5 liters in my case or 152 cubic inches), why would they have such a large PVC hose? Suppose I'll never know, unless we've got an engineer out there somewhere on this forum??
Yep that's what I read, not just the online one but it also says it in my manual that came with car. Getting a service next month at dealer and they were mentioning I should do a fuel line service too for 100 bux CDN. Think they actually do more then just putting Techron in, but I will get a bottle anyhow for my own use, as I cant get top tear fuel here.
Can't get top tier? I'd have a fit. Don't suppose you could contact the various suppliers to see if any are providing the same level of additives voluntarily?
Out in the country here on shores of Lake Erie. As far as I know Shell and Chevron are only major gas stations carrying top tier. No Chevron here and we used to have Shell 20 minutes away, but most Shell's here changed to Esso. So mostly fuel Esso.
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The answer for that is to use Techron additive every few thousand miles. Manual I think says 8,000 miles? I add it at oil change even using top tier. These kinds of additives are among the very few of any additives that clearly make a difference and won't harm the car, and car manufacturers (some) will actually recommend.
Sad that Shell is doing this. They sold off 5 stations in my local area to Circle K, another garbage gas outlet. Now I'm seeing Shell selling a bunch of stations, and not just in my neighborhood.
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They added here, taking over some of the former Sunoco stations and Citgo. I'd say there are some 15 along or near adjacent to Rt19. Sunoco is down to maybe 6 in the general area from 15 or so. And Citgo has just a few left from all they had.
So still many top tier to choose from.
I do have a few that sell non ethanol that I use in the MX5.
Just the luck of the draw, I guess. I've been enjoying a discount at Shell so it's been my fav, but times are a changing in the Spring Hill area.
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