problem while running on high RPM's

[SKYR]

Hi honda sifus especially on V-tec technical expert..

My car is showing a lot smoke when running on high RPM's , roughly is about 7-8k rpm,Is it a valve seal problem ?? or anything else that I must looking for it ?? help me out bro, because I need to troubleshoot by mysef first..TQ in advance

 

[2nd2none]

Bro,

Please tell us whether is white smoke / black smoke. If black smoke at high RPM means your engine is running rich and u need to tune da fueling. If white smoke then it could be worn piston rings or other related problem.

 

[SKYR]

actually, it has white smoke...wow, then I must spent $$$$$ to fix it, tq

 

[shiroitenshi]

white/bluish smoke is usually a sign of unburned fuel, either from too rich a fuelling (unlikely if you aren't running higher fuel pressures or had the car tuned by someone incompetent)

It can also mean valve leakage. You can do a compression test to verify which piston's vavle is the source.

Valve leaks means that during compression stroke, the unburned fuel is pumped out the exhaust valve or into the intake tract via the intake valve instead of being properly ignited by the plug at BTDC. on the next stroke, the engine runs too rich, and unburned fuel exits through the exhaust.

The O2 sensor detects that the engine is running lean (O2 sensors detect unburned fuel as air, so it inteprets the engine as running lean, and increases fuelling, so when you take out your plugs, you'll see that it's all black/fouled, a sign of too rich a fuelling.)

Piston ring seal can be gauged by looking at black smoke emitted through the exhaust, and listening to air escaping through the oil cap when manually rotating the crank. (but only if your valves are not the source of the leak)

The amount of oil burned/the amount you need to top up between oil changes is also a sign of piston ring leakage. due to the stock setup of piping engine oil gases in the head to the intake pipe, vtec engines consume a nominal amount of oil even at peak condition, so note the amount of oil you need to top up, if it increases substantially, there's a possible piston ring leak that a leakdown/compression test can confirm.

However this is unlikelier than valve leaks, because unless your engine ingests something, the bore should not be too affected, and we have 2 compression rings and an oil ring to boot on the stock piston! so that's it, unless you're using single ring racing pistons.. (O_o)

Then again, I'd start with the valves, then check the rings. Due to the way they are related, you have to ensure that the valves aren't the source of the leak, then only troubleshoot the piston rings.

Annealed rings are also a possible cause of piston ring leaks, but that's also a sign of trouble elsewhere, so if you have annealed piston rings when you stripdown, look for possible sources of engine overheating to the point the rings are annealed.

There's also the method of removing each plug cable one by one to find out the problematic piston/valve leak, but due to the inherent dangers of dealing with high voltage, leave it to the professionals.

These are all mechanic stuff, so if you mechanic knows what to look for, he should be able to decide the best course of action.

 

[darkemperor]

white/bluish smoke is usually a sign of unburned fuel, either from too rich a fuelling (unlikely if you aren't running higher fuel pressures or had the car tuned by someone incompetent)

It can also mean valve leakage. You can do a compression test to verify which piston's vavle is the source.

Valve leaks means that during compression stroke, the unburned fuel is pumped out the exhaust valve or into the intake tract via the intake valve instead of being properly ignited by the plug at BTDC. on the next stroke, the engine runs too rich, and unburned fuel exits through the exhaust.

The O2 sensor detects that the engine is running lean (O2 sensors detect unburned fuel as air, so it inteprets the engine as running lean, and increases fuelling, so when you take out your plugs, you'll see that it's all black/fouled, a sign of too rich a fuelling.)

Piston ring seal can be gauged by looking at black smoke emitted through the exhaust, and listening to air escaping through the oil cap when manually rotating the crank. (but only if your valves are not the source of the leak)

The amount of oil burned/the amount you need to top up between oil changes is also a sign of piston ring leakage. due to the stock setup of piping engine oil gases in the head to the intake pipe, vtec engines consume a nominal amount of oil even at peak condition, so note the amount of oil you need to top up, if it increases substantially, there's a possible piston ring leak that a leakdown/compression test can confirm.

However this is unlikelier than valve leaks, because unless your engine ingests something, the bore should not be too affected, and we have 2 compression rings and an oil ring to boot on the stock piston! so that's it, unless you're using single ring racing pistons.. (O_o)

Then again, I'd start with the valves, then check the rings. Due to the way they are related, you have to ensure that the valves aren't the source of the leak, then only troubleshoot the piston rings.

Annealed rings are also a possible cause of piston ring leaks, but that's also a sign of trouble elsewhere, so if you have annealed piston rings when you stripdown, look for possible sources of engine overheating to the point the rings are annealed.

There's also the method of removing each plug cable one by one to find out the problematic piston/valve leak, but due to the inherent dangers of dealing with high voltage, leave it to the professionals.

These are all mechanic stuff, so if you mechanic knows what to look for, he should be able to decide the best course of action.

shiro...

confused on the smoke color ler....black means rich fuel and white/blueish means consume engine oil rite???

 

[shiroitenshi]

shiro...

confused on the smoke color ler....black means rich fuel and white/blueish means consume engine oil rite???

Well, you are right in a way. But burning oil do produce black smoke as well, due to carbon buildup in the pistons. Kind of depends on what amount of smoke though.. too rich a fuelling alone cannot cause a lot of black smoke, unless you're looking at turbos.

Unburned fuel mist leaked through the exhaust port also does not usually become black smoke, because it was not burnt. Well, another way to know is the smell..

I can show you a car that has zero black smoke, and no white smoke, but fuel smell is overpowering that it's obvious is running rich, it's just the fuel isn't burned, hence not registered on the AFR meter.

I think you can use smell as a hint as well.

 

[SKYR]

THANKS dude...another one thing , what about if fuel consuming is greater and less running mileage..let say, full tank of ek estimated around , rm60.00, but the mileage can only reach at 200km, normally can goes up to 450km ( correct me if I'm wrong )..what happened to my ride ? yes,FYI, my car is running with clutch slip a bit, but still can run & I've seen NOTHING abnormal ...Could YOU give me advise on this part ?? Or need to re tune of my ECU ???please help me out ??:hmmmm::hmmmm:

 

[hattech-v]

normally if got smoke (white smoke) during high rpm, it cause by the valve seal worn out aredi..
if piston ring all the time got white smoke...
black smoke during revving coz of the fuel too rich...
the smoke is visible to ur eyes.. unless u got another way to catch the smoke and send the specimen to lab to determine what color.. haha

 

[hattech-v]

THANKS dude...another one thing , what about if fuel consuming is greater and less running mileage..let say, full tank of ek estimated around , rm60.00, but the mileage can only reach at 200km, normally can goes up to 450km ( correct me if I'm wrong )..what happened to my ride ? yes,FYI, my car is running with clutch slip a bit, but still can run & I've seen NOTHING abnormal ...Could YOU give me advise on this part ?? Or need to re tune of my ECU ???please help me out ??:hmmmm::hmmmm:

send ur car for AFR checking... dyno will normally show the figure for WOT AFR... not during cruising / part throtle...
or get a wideband to check it...
i can help u for that... pm me for details... tq

 

[10KRPM]

Yeah as per everyone has said. High revs, oil rings. Get your fren to drive ya car and u can see the smoke colour. White smoke as everyone says again is valve stem problem

 

[SKYR]

okay , thanks ..let me check it out..

 

[darkemperor]

I can show you a car that has zero black smoke, and no white smoke, but fuel smell is overpowering that it's obvious is running rich, it's just the fuel isn't burned, hence not registered on the AFR meter.

I think you can use smell as a hint as well.

mine having this prob. but consumption seems to be very good and no white or black smoke...:hmmmm: a few friends says can light fire from my exhaust kekekek...unless having AFR meter as u said.

 

[shiroitenshi]

I just reread and noticed one thing, if it only happens at 7-8K, then I doubt it's a seal problem.

If you lose valve seal, it will show up on idle, and not 'just' higher rpm. Even a minor leak will be apparent at idle. So is piston ring seal.

If you're emitting smoke, and it only happens at that rpm, I suggest checking everything over.. if you have tuned ecu, plug in original one and see.

WOT and part throttle runs are different, because part throttle runs are ECU corrected, it's damn hard to gauge the AFR, because it changes depending on the 02 sensor readout. So does it happen at WOT only?

If you suspect it's a valve leak, then check with a mechanic. He can try the methods I wrote above to at least pin point the problem.

If you suspect it's fuelling, then the ori ecu should show if that is so, provided you run at the right amount of fuel pressure at the rails, not 1-2bar more than standard.

Darkemperor, heh, just say you're not the only one with that problem.
I'm going to pull out the engine and replace the rings and do a valve grind.
In any case, it saves on labour, because once the head is off, can just tap the pistons out later.

Anyway, mileage is already high, so it's time.. Wondering should bother getting some new crank bearings without looking at the engine yet.. My mech says no need, but I hate do do a teardown, fix it moderately, only to tear it apart again one year down the road for a crank bearing change.

Well, it's going to be worked on sometime at the end of this month after raya though, so slow slow le.

One curious subject I discussed though..
It seems that for high compression engine, even oil leaks will not result in smoke, but get burned completely, depending on how much compression loss.. Anyway the colour for burned oil seems to vary depending on how well it is combusted, so we can assume that although the smoke colour gives hints, but it's not 100% accurate either.