How does Low Speed Pre Ignition (LSPI) ruin engines? And what are the causes?

[@LubricationExplained]

Looking for more structured lubrication courses? Join LE Pro for $30AUD per month (that's about 20USD). lubrication.expert/product/le-pro/

[@JettaRedIII]

Actually, gasoline ignition happens typically between a few degrees before TDC and up to ~50 degrees before TDC (though this is uncommon) in a spark ignition engine. In a diesel (compression ignition), fuel is usually injected after TDC though it can start being injected before TDC too. LSPI is damaging because it occurs randomly and not "on time".

[@charvakkarpe]

Yes. I'll add the reasoning behind this. When the spark occurs, it begins a flame front that spreads kind of like an expanding ball through the cylinder. Waiting until the piston is at TDC to light the flame front would mean the fuel mixture doesn't burn in time to maximize pressure over the power stroke. If you fire the spark too early, the pressure could rise too high at TDC and spontaneously ignite the fuel-air mixture in a bomb-like detonation instead of a controlled flame front. I wonder if using direct injection instead of the entire intake charge being premixed fuel and air makes detonation impossible.

[@puncht37]

Pre igintion can occur in any engine. LSPI usually in GDI motors. Turbo makes it worse. Use a good SP rated oil and warm up before hammering on your engine.

[@Ezekiel-OffRoad]

I own a 2013 Hyundai Accent with the 1.6 gamma gdi the engine is toast with only 83000 miles. When I bought the car within the first 10000 miles I started noticing lspi symptoms Took my car to Hyundai and they confirmed this and said that there’s nothing they can do i installed a oil catch can and switched to premium fuel immediately which helped a little. The problem is the EPA is putting the squeeze on car manufacturers forcing them to sell inferior products to the consumer not giving them enough time for proper research and development ultimately we the consumer get screwed.

[@eacan12]

I also own a 2012 Hyundai Accent 1.4 gamma engine. I think LSPI is occurring on my engine. I'll try to change my oil from Castrol to Kixx. Any thoughts on these?

[@Ezekiel-OffRoad]

@@eacan12 I’d confirm it’s lspi all you need is a scan tool that’s able to read live data then monitor the ignition timing Under conditions you think you’re getting LSPI to see if the knock sensor is retarding your timing. One cheap and easy option is to buy a cooler thermostat I believe OEM is 200°F I wouldn’t go below 180°F also you can try cooler spark plugs but not too cold to where they foul.

[@Ezekiel-OffRoad]

@@eacan12 look up the specs for your year accent and compare them to the 2016 or newer accent with the same GDI engine I know here in America the 2016 or newer N/A gamma 1.6 are detuned with slightly less peak power ratings that’s because Hyundai knows of this problem and quietly fixed it. If they are rated slightly less it’s possible to somehow Use the upgraded tune with your vehicle not sure exactly how but It’s possible either by swapping the PCM or re-flashing the one you have

[@karlrovey]

There is something they could jave done. They could have honored the 10 year 100,000 mile warranty and replaced the engine.

[@larryssnova76]

My guess would be low quality fuel and higher compression ratios and turbo charger engines with high cylinder pressure

[@tbl8560]

Great vid. Lot's to understand with octane, cetane and volatility of elements in a combustion chamber promoting PI or det. In my experience, oil in the CC has always promoted preignition and detonation with all other variables being equal. I would assume increased fuel octane will reduce LSPI. I would also assume retarding timing would have no effect on PI unless there is a detonation component at low speed/high load which is always a concern on engines until past peak torque. Just some thoughts.

[@grownupgaming]

Great video, so choosing the right oil reduces impact of LSPI. But how do we reduce chances of LSPI itself? 1500-2000 rpms is unavoidable.

[@trevorgauntlett-jx8ub]

A good oil reduces the chances of LSPI. As Rafe explained, substituting magnesium for calcium in the detergents has proved to be an effective solution. Magnesium-based detergents have been around as long as calcium-based ones, but they are more expensive. Calcium and magnesium are one above the other in the Periodic Table, so a lot of similarities in detergency, but also differences in some chemistry. In this case, sufficient difference to impact LSPI.

[@tracylewisperformance1328]

We have a Patented full time vacuum crankcase evac system that constantly flushes and removes the excessive raw fuel, oil vapors and other contaminants from the crankcase, so we have seen over the past 14 years of testing almost eliminates LSPI incidence. I say almost, because there still can be when low octane fuel is used as the owners manuals state. In the US I urge ALL to use 93 with GDI engines.

[@Kodiak727]

Which oil would you recommend for turbocharged di engine?

[@mikescudder4621]

oil with gf-6!

[@bmwlane8834]

Amazing information.Appreciate all the work.

[@hurrican11Bpoint]

Great Video needs more attention it makes me think my car was broken which it not. 2016 bmw 320i

[@karimwibrahim3786]

Thanks for a very, very well explained comprehensive video.

[@RyanEmeryLovesCars]

Can LSPI be a reason for fuel diluting engine oil? Or is that another cause?

[@LubricationExplained]

Generally fuel dilution is going to be the result of blow-by. So the rings aren’t creating a perfect seal against the cylinder wall, either because of liner scoring, ring sticking or ring damage.

[@egeayvala1799]

i owned a mazda mx-5 with fucked up valve stem seals the car on cold starts smoked like mad this ended up degrading my oil alot-when my oil was new my hydralic lifters didnt do any noise but after around 3,000 miles or 5,000km my engine started making weird noises when i change my oil all the noises went away. so yes FUel dillutes oil especially on cold starts no matter how good your engine is-i lived where it was -18C... thats below 0 farenheit

[@krod2162]

What I wanted to know and I've never had answered. Is what does the LSP I feel like when you're driving the car can you feel it hear It? What are the symptoms You hear or feel when you're actually driving?

[@glasser2819]

Brilliantly shared insights. 👏

[@tomasnokechtesledger1786]

Lake Speed Jr, of Joe Gibbs Race Driven also says that LSPI is caused by excess fuel dilution ... (?) That the oil Dilution makes the oil go to the combustion chamber, as having a lower octane rating, causing the preignition.

[@LubricationExplained]

Interesting - I haven't heard that one before. I'm not entirely sure how that works because LSPI is generally pre-ignition of a hot spot, that causes pressure waves which can then combust the fuel. But the engine oil has a lower volatility that the fuel so technically a mix of fuel and oil would be more difficult to ignite? Having said that, Mr Speed is pretty knowledgeable about this stuff having worked at Driven and Mahle, so maybe he knows something I don't.

[@tomasnokechtesledger1786]

@@LubricationExplained Actually, he says just like you put it in the video as one of the possible causes, by the mix of oil diluted by fuel, acumulating at top ring and being shovel up to cc, igniting earlier by the lower octane of this mixture. But to me, is excess ashes from Ca making hot spots. I Took that from the fact that Aviation Oils don't use Ca, because of the detonation problem at very lean hot conditions. Aviation oils as you know, only use Dispersants, not detergents, because of that preignition prone problem. Not that I would know more that Mr. Lake Speed Jr., but this theory of diluted of shovelled up, is a little too much for me. Maybe I'm wrong.

[@LubricationExplained]

@@tomasnokechtesledger1786 Oh right, I understand now - I thought you meant he had another explanation over and above what I had in the video.

[@mikescudder4621]

My car has this problem, but its not a turbo, and it happens at idle under high load conditions, with air con. on, turning the steering wheel to the end of its course, or accelerating hard will cause pre detonation. There is a lot of oil vapor coming through the intake (car has 130,000 kms), also the valve stem seals are no longer doing their job. Without knowing about the GF-6 oil, my last oil change i used a mobil gf6 spec oil, but made no difference. I have to run pure ethanol, which wont pre detonate, while i´m still trying to discover the problem.

[@arthurmario5996]

AFAIK pre-ignition and detonation are two very different things. pre-ignition is one important cause of detonation, and it is the detonation that damages engines. the knock sensor should reduce boost , downshift, enrich mixture, inject ADI etc.to control LSPI induced detonation

[@highrzr]

DI works great in diesel engines, but not so much in gasoline engines. Then there are the carbon build up issues as well.

[@andrekemp5059]

Thanks

[@LubricationExplained]

You’re welcome!

[@invertedpolarity6890]

Sorry but the reasons you give (oil and deposits) for causing LSPI would be causing detonation at all RPM's. This is a good explanation for what causes detonation in general but nothing here is explaining the specifically LSPI.

[@suggesttwo]

5:49 Not likely. The piston slow down the least at TDC as the crankshaft is not travelling in the same direction as the piston.

[@uniquehandle1]

sn plus, sp engine oil does nothing to prevent lspi in hyundai 1.6gdi engines. I suffered engine oil loss and replaced short block

[@j.g.bloodworth9837]

Is there a magic snake oil out there that can significantly reduce the risk lspi?

[@Kodiak727]

Low calcium based oil or gf6/api sp certified oil.

[@trevorgauntlett-jx8ub]

He said it in the video and Lulu and Kodiak say in the comments

[@leftmorningstar6954]

this is that luge that happens when you have too high gear and too low engine speed?

[@LubricationExplained]

Sorry what do you mean by luge?

[@leftmorningstar6954]

@@LubricationExplained a mean if you have a manual car and if you not good with the clutch and you go below Idile and it starts Saking

[@mytech6779]

No, lugging is a bit different issue. The burn happens from the spark in a normal manner when lugging the engine. Lugging has more to do with being outside of the general design intent of the overall engine.

[@mytech6779]

@@Roundholesinsquarepegs I know. Lugging is not what the video was talking about.

[@johnathanbrown9019]

does LSPI occurs in Fuel injection bike? (150cc- yamaha fz-s)

[@LubricationExplained]

Theoretically it could, but I don't think it's a widespread phenomenon as with passenger vehicles. The lack of turbos in bikes probably helps.

[@johnathanbrown9019]

thanks 👍

[@sanfransoho]

Interesting. If I am not wrong, it's only gasoline engines? Why are not diesel engines (di, turbo charged, common rail...) affected?

[@LubricationExplained]

Good question, and not sure it has been studied in detail. However, the “oil droplet” theory requires a mix of oil and fuel that spontaneously combusts. Diesel is both more viscous and less volatile than gasoline, so the mix of diesel and oil will be less likely to be “thrown” into the combustion chamber, and less likely to self ignite.

[@stefan6410]

Only downsized high compression gasoline engines

[@mytech6779]

Direct injection gasoline is low pressure and happens before the compression stroke. Diesel is very high pressure and injects near maximum compression so there is no fuel in the cylinder to pre-ignite and the normal diesel cycle is spontaneous ignition from the heat of compressed air. The diesel injection behaves more like a flame thrower. LE is somewhat incorrect or misleading in saying that diesel fuel is less volatile. It is true that #2 fuel oil [common diesel fuel] has a lower vapor pressure than gasoline, but that is mostly irrelevant because both fuels are being injected as an aerosol and greatly heated. Meanwhile diesel fuel is formulated for a high cetane rating which is conceptually the inverse of the gasoline anti-knock 'octane' ratings; as such diesel has a much lower thermal stability and low autoignition temperature. This is because the diesel cycle relies on rapid auto-ignition. Diesel engines also tend to use higher viscosity engine oil that stays stuck to the relatively cool cylinder walls where autoignition is a very low probability. The Otto-cycle spark ignition must prevent auto-ignition and pre-ignition during compression so that the flame front can be controlled by a spark. Pre-ignition is not defined by top dead center, it is defined as any sort of ignition before the planned spark. The basic 4-cycle description given in the video is inaccurate for real working engines, spark occurs 5 to 30 degrees before top dead center depending on the specifics of the RPM, power setting and engine design, so the flame has time to propagate and reach peak expansion rate just after TDC to get maximum performance while avoiding detonation. In the Otto cycle there are two knock problems. One is pre-ignition which traditionally occurs from a bit of cinder or other solid hot spot acting in place of and before the spark, detonation can be a form of preignition but is usually viewed as a separate category. In older carburated engines the hot cinder could cause the engine to keep running(poorly) after the power to the spark ignition has been turned off. Detonation is second category of knock which is nearly simultaneous auto-ignition and tends to be caused by fuel with too low of an anti-knock rating for the level of compression heating. (True barometric compression not simple piston displacement.) In detonation the total volume of air-fuel mix reaches auto-ignition temperature at nearly the same time and violently detonates rather than the preferred mild end-to-end style of burn. Detonation can occur before or after the spark, if before the only cure is to increase the quality or quantity of fuel(or in rare cases pre-cool the air or direct water-methanol injection to absorb the heat of compression), increasing the proportion of fuel acts to absorb some heat and slows the rate of burn after the spark. If detonation occurs after the spark you also have the option of retarding the spark timing so as to reduce the peak pressure and delay the peak pressure. Each method has its place. That said the lube oil droplet in the video would likely have a low resistance to autoignition compared to the base gasoline. Generally aromatic compounds have high antiknock ratings and paraffinics have low anti-knock ratings, thus toluene has been a popular hydrocarbon fuel in several motorsports. Meanwhile crankcase lube oils tend to have the aromatics removed and with the fashion for extra super low viscosity lube oils it would be easy to have problems. This is especially likely because while many bits of an automobile are legislated or held to some industry specification, oil consumption has only ever been the will of the manufacturer, so I would guess these problem engines also have high oil consumption so more oil is likely in the combustion chamber and more likely to be a free droplet do to the low viscosity.

[@chippyjohn1]

Because of the vacuum within cylinders in a petrol engine. A diesel engine is for argument sake atmospheric pressure within a cylinder even at idle. With a petrol engine you have a throttle valve and now with variable valve lift the vacuum is increased even more. this vacuum at idle/low speed draws oil into the combustion cylinder. In the transition from low load to increased load (especially with boost) the oil vapour ignites as with direct injection it is just air that is being compressed instead of air fuel like port injection where the fuel reduces compression temperatures. Once the engine has built a positive pressure in the cylinder from boost and load the oil that passes by the rings is forced downwards instead of being sucked into the cylinder. Hope that helps.

[@tomasnokechtesledger1786]

With Ethanol they don't have LSPI, only on 87 octane gasoline.

[@suggesttwo]

Pre Ignition detonation is caused by sharp metal parts close to TDC when pressures are highest. This is the design basis for the auto start stop system.

[@trevorgauntlett-jx8ub]

If LSPI had been an engineering issue, the auto OEMs would have sorted it by themselves in subtle changes to engine components back in 2010/11, when this issue first began to appear. They didn't because it wasn't.

[@suggesttwo]

@@trevorgauntlett-jx8ub I have a textbook AUTOMOTIVE TECHNOLOGY A SYSTEMS APPROACH 3rd Edition published in 1999 that talks about pre-ignition. In the HAYNES manuals it's called lugging.

[@trevorgauntlett-jx8ub]

@@suggesttwo Rafe mentions lugging elsewhere. Search for Left Morningstar to see that discussion. Pre-ignition has been an issue for probably as long as the internal combustion engine has existed. LSPI was something new and unexpected. Your textbook dates from the year after I joined lubricants at one of the majors. I've been in Lubes ever since. Prior to that I did a lot of analytical work for our fuels guys, many of whom are still friends and still active in making the ICE a better thing.

[@suggesttwo]

​@@trevorgauntlett-jx8ub knocking us usually caused by end gasses not oils. End gasses are what the Catalytic converter burns off. There's no such thing as emissions only end gasses. It's the turbo not the DI. Improving atomization/vaporization cools the charge.

[@larryssnova76]

And the direct injection causes a lot of build up in the cylinder and the combustion chamber causing higher cylinder pressures

[@egeayvala1799]

it does more damage to the intake valves since the stupid PCV returns blow by from the rings. its just a complete mess... multi point injection is way better but its not as fuel saving as GDI

[@Unknown-jl7mg]

funny how Ca increases, Mg neutral, Mo decreases lspi risk. is true, Mg sucks at cleaning job?

[@LubricationExplained]

Unfortunately it isn't so simple. Detergents generally consist of a polar head (metal plus functional group) and a non-polar tail (generally a polymer). The "cleaning" performance of the additive will be a combination of the metal cation (Mg, Ca, B, Mo) and the functional group (sulphonate, phenate, carboxylate etc). So there are a few different combinations.

[@mookieblaylock2589]

LSPI is myth from nowhere. Preignition issue is totally resolved by installing detonation sensors from late 70th and now these are magnificently correct and accurately save engine from LSPI predicting possible LSPI. The problem comes from mapping Transmission unit that tuned for fuel economy by shifting higher speed too early and maintain low RPM. Combined with small capacity hot operating turbo engines their pistons too small and light for this load. Engine oil is not corresponding with this issue. Engineers are abused by environment hysteria.

[@LubricationExplained]

Agree that LSPI is a self-inflicted wound that never used to be a problem until the latest generation engines came along with the focus on fuel economy. Engine oil definitely isn't the cause - we were just trying to highlight that there are minor changes to formulations coming that can help reduce the severity of LSPI.

[@tillivanilli6481]

Yes, too tiny, too high pressures too. But i´ve a 2006 Dodge Charger R/T Daytona with the 5.7L HEMI. This Engines has 2 Spark Plugs per Cyl. and i´m not sure yet but there is the possibility of LSPI problems, possible?! What do you think about? even the reccomendet Oil for these engines are 5W20, ILSAC GF-5 API SN, Chrysler MS-6395. My problem is, that this Oil Visc. is thinning out with increasing oil temp. and especially at roundabout 100°C the Oil is so thin that you can listen that in the Cam/Valvetrain. Ok, the engine has 136.000mls/224.000km but it´s in a really nice condition. But even the thinning out oil visc. is a problem in my eyes, especially with this thin Oils. And now i´m changing this oil into an Mobil 1 FS 0W40, even because i´ll see if then the oil wouldn´t thin out that much with increasing oil temperatures, so that the valve train wouldn´t listen like it does with the 5W20 at roundabout 100°C Oil Temp. I also installed an 15-Row Oil Radiator with Oil Thermostat (opens at 80°C) and the Oil Temp was between 105-115°C at cruising before and is at roundabout 80-95°C now in same driving conditions what is a lot better in my eyes. But i can listen sometimes in low rpm + high loads that there would be too early ignitions. Or even is this really happen?! Because even this listens like... & i bought this car with the premission to optimize it so that it would be a long lasting car, and all modifications are for prevent wear. That´s also wh i wouldn´t use that 5W20 oil visc.,too.. Best regards rom Bayern (germany) Cheers Till

[@mytech6779]

Not all pre-ignition is detonation, and not all of either type of knock can be solved by changing the spark timing. It seems very likely related to the low viscosity oils and high oil consumption relative to engine size. Maybe the calcium just acts as an additional catalyst for the issue either chemically or through hot mineral deposits.

[@andyh8239]

I don't know what good a knock sensor is going to do for PRE IGNITION meaning ignition before the spark; this spark timing is out the window in that event. Knock sensors instead solve issues of knock from post ignition flame propogation occuring too rapidly.

[@robertweinmann9408]

@@andyh8239 Not sure about this , but in the small turbo engines being discussed here, maybe the knock sensor plays a role in determining the boost levels, so that would impact lspi.

[@suggesttwo]

Carbon deposits increase CR.

[@K69g-m7n]

Toyotas daihatsus...move off with 2nd gear always..

[@kummarek9760]

Что за позор ты рассказываешь? Поршень вниз уходит от воспламенения смеси... Какое давление у тебя растёт?

[@mikman7219]

Калильное зажигание возникает при движении поршня вверх.

[@egeayvala1799]

no !!! what the guy means is in a 4 cylinder engine the power stroke accurs AFTER the engine REACHES TDC the power stroke is supposed to GO DOWN a moment 0.00002 seconds after the spark. what happens in low speed pre ignition is that almost like a diesel engine The mixtures ignite before the spark but the pistons dont wanna go down,since two are going down two are going up so they are gonna fight againts each other.. but the forces of the wheels increase the pressure in the cylinder that causes massive blow by for sure usually this LSPI sounds so terrible it can almost spun a bearing by the way it is explained

[@andyh8239]

Catch cans - waste of money?

[@robertweinmann9408]

Most modern engines a designed well enough to keep the majority of the oil out of the crankcase ventilation system.