Individual Cylinder Monitoring

[Mike T]

Had a conversation with a good friend that started by discussing injectors. We were discussing variance in fuel delivery per cylinder...mainly the scenario of a weak or partially clogged injector.

Someone please correct me if I'm wrong but my understanding is wideband will go a long way in tracking A/F as a whole but you could potentially have one or more "lean" cylinders along for the ride and still show good on A/F as an average reading of all cylinders?

Short of reading the plugs every run wouldn't individual cylinder monitoring be the only way to insure all cylinders are seeing equal fuel delivery? Taking it a step farther...if fuel delivery is the same what about intake pulsation changing A/F per cylinder?

 

[~JM~]

Would 6 sparkplug mounted cylinder head temperature gauges provide useful information?

Something like these: http://www.trailtech.net/catalogsearch/result/?q=cht

 

[Mike T]

Yes, basically individual EGT readings from every cylinder like a lot heavy hitters run. Seems like something the average guy should be aware of as well.

 

[Boost231]

Most definitely, even better would be individual 02 sensors in each header port

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[Nick Micale]

For the "average guy" EGT is something to discuss, but very seldom an issue since the engine is not at WOT for very long?

My heat gun is used often to check each cylinder temp as it warms up, and if there is not a drastic difference in one or more cylinders, all should be good?

If it has an aftermarket ECM, it may be possible to "adjust" or calibrate each injector. With 6-700 RWHP race cars, we did not have a concern for exact cylinder balance.

With a 900 HP or so, then dyno testing and EGT monitoring would be a smart choice for dialing in the engine and tune.

 

[The Granny]

along with performance levels Nick mentioned another thing that should I think should be taken into consideration is the plenum/intake/spacer used since they flow differently than one another. this is a thread from Richard Clark where he tested a few different set ups http://www.turbobuick.com/threads/interesting-numbers.363911/


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[dank GN]

I'm going to be running this setup that is for a 6 cylinder plane engine that is FAA approved . And I got it for what someone would pay for 1 K type thermocouple. $80 .

I do have this cool switch that lets you select cylinders 1-6 and you could run it off 1 read out or something if one of your guys wants it .

 

[steve hughes]

From my experience cylinder balance can change somewhat with boost pressure. I never had a problem with my car running an HPQ70. I went to 4 bolt 7675. When i really started leaning on it hard i warped valves on # 1 and 3 . Sent the injectors to Chuck Leaper to be flowed and cleaned. No problem found . Flow was very close before and after cleaning. Middle way thru the next season torched the head between 1 and 3 .Had injectors checked again . No problem. A/F numbers always looked good. Richened 1 and 3 seven % never had another problem. And the A/F numbers never changed after throwing more fuel in two cylinders. If i had individual egts would have saved me alot of guess work.

 

[Jerryl]

From my experience cylinder balance can change somewhat with boost pressure. I never had a problem with my car running an HPQ70. . . . .

What fuel were you running?

 

[Boost231]

From my experience cylinder balance can change somewhat with boost pressure. I never had a problem with my car running an HPQ70. I went to 4 bolt 7675. When i really started leaning on it hard i warped valves on # 1 and 3 . Sent the injectors to Chuck Leaper to be flowed and cleaned. No problem found . Flow was very close before and after cleaning. Middle way thru the next season torched the head between 1 and 3 .Had injectors checked again . No problem. A/F numbers always looked good. Richened 1 and 3 seven % never had another problem. And the A/F numbers never changed after throwing more fuel in two cylinders. If i had individual egts would have saved me alot of guess work.

Individual egts saved me.. was able to see the first signs of a hurt valve in cylinder one . Temps started getting weird in the cylinder. Pulled the head and found a hurt valve. Saved me a lot of money. Without egt probes things could have been bad real bad

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[Ttype6]

From my experience cylinder balance can change somewhat with boost pressure. I never had a problem with my car running an HPQ70. I went to 4 bolt 7675. When i really started leaning on it hard i warped valves on # 1 and 3 . Sent the injectors to Chuck Leaper to be flowed and cleaned. No problem found . Flow was very close before and after cleaning. Middle way thru the next season torched the head between 1 and 3 .Had injectors checked again . No problem. A/F numbers always looked good. Richened 1 and 3 seven % never had another problem. And the A/F numbers never changed after throwing more fuel in two cylinders. If i had individual egts would have saved me alot of guess work.

Were the spark plugs noticeably cleaner in those 2 cylinders?

 

[NY Twin Turbo]

I have the FAST EGT module with 6 probes (and 2 spares) and I'm hooked on XFI individual cylinder tuning. There is no way I would even think of controlling my set-up (true dual exhaust) without it. I swap my O2 from side to side occasionally. But that's not enough for me.

But for the rest of you guys, one could make the argument that it is even more important for you to have it. One cylinder out of 6 that miss fires, is dead, rich, or lean usually doesn't display its self until you feel it. Then the damage may have already been done.

You guys would be surprised to find out how off your cylinders are! Even for those of you who have "flow matched" injectors. 20% from the hottest to the coolest is not uncommon. This could amount to 200 or more degrees depending on load conditions. Thankfully, mine are closer than that. But even so, I correct 5% - 7% north and south of my most common temp cylinders. By the way, that's still a 10% - 14% difference!

Now I've got them as perfect as anyone could ever expect with RPM based correction. Most times, mine are dead on. The lines will lay over each nearly perfectly on the data log.
But a load based correction software would work better. I'm cool with the set up though. You just may have to sacrifice a little accuracy on the low boost RPMs to be sure your corrections are good at those same RPMs when your filled with boost.

But when they are this close.........even if a single plug miss-fires for portion of a second, I don't miss it!

 

[steve hughes]

I run C16 race gas.
Didn't see any difference in the plugs.

 

[NY Twin Turbo]

I run C16 race gas.
Didn't see any difference in the plugs.

When do you check them?

Do you shut it down just after you lift off the throttle and have you car towed back to the pits? But even then...........

Don't get me wrong, there's nothing wrong with good old plug analysis. We should all start with this. But this is not like that. Recording your EGTs catches a lot more than just average rich or lean conditions. Every blip on the recorded line means something. I mentioned earlier the 200 degree difference. But I have found that strangely this difference can be lean and then rich on a single cylinder in the same run at different load points! This is impossible to see in a plug reading. Fuel Correction can then be made in the positive and negative for this cylinder at different RPMs.

Sometimes it's a little more predictable. For example, my #4 cylinder is the leanest across the board. I don't know why. Intake? Injector? Who cares? I'm done trying to figure it out. I know by now there's nothing mechanically wrong. So I have positive correction in all places for this one. But even then, it's not the same number in all places.

But for those of you who do not have the ability to trim fuel for individual cylinders, DO NOT GET 6 EGT PROBES!! It will drive you absolutely manic to see these things you can't do anything about. Your better off reading plugs and using a single EGT and the O2. There's nothing wrong with this method. It's worked for most everyone to keep their motors together and running strong for a very long time.

 

[steve hughes]

I regularly check plugs after every few passes unless i make timing and fueling changes then it's after every run for awhile. I kill the engine after then finish line to check plugs.

 

[NY Twin Turbo]

Check this out.

I like these types of threads. I wanted to show you guys some recordings.

The first photo is from about 2 summers ago. I had just started to work on the individual correction and had it almost good. But not perfect, there is an average 56 degree difference from the hottest to the leanest. I wish I had an even earlier data log to show. Because then you would have seen how far I had already come.

But anyway, In this recording you can clearly see that even though the EGT equality is a bit off, the signs of a bad plug wire are clearly being seen by cylinder 5's trace line! At the time, I thought it was a data stream anomaly or something. But later it became dead obvious when the car started to stumble under boost and cylinder 5 went dead. I made up a new set of plug wires.

I learned a cheap lesson. Don't ignore even the little things. Because they mean something.

Now take a look at when things are tuned and correct. Notice how close the temps are. Notice how crazy they get when you lift. There is no correction at 0 TPS in the XFI software. Also you may notice how much lower the EGTs are. This is a street run and it's a little too rich. But safe for tuning purposes.

This one below is crazy close! 16-24 degrees apart for most of the run!!! This is the current correction I have in my tune. I'm going to leave it alone now.

 

[Mike T]

Having data and knowing how to use it is much better than wrenching.

 

[NY Twin Turbo]

Having data and knowing how to use it is much better than wrenching.

Well it turns out sometimes that the data will lead to wrenching.

 

[troyk]

Most definitely, even better would be individual 02 sensors in each header port

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I thought it is not recommended to use O2 in a pressurized environment? I remember at Mega Squirt's Megameet, that I was at, Bruce Bowling was saying how temperature & pressure can scew the readings a decent amount. Unforcanantly, I can't find the video of that tech session.

I found the following, that seems to indicate the WB o2 sensors could take some pressurized environments(2.5bar). Also, you have to watch out that you don't exceed the WB o2s max temperature ratting, in this sensors case it is 1866F, your closer to the port so its going to be hotter than the DP position.
http://www.bosch-motorsport.com/med...nsor_LSU_49_Datasheet_51_en_2779147659pdf.pdf

 

[NY Twin Turbo]

I thought it is not recommended to use O2 in a pressurized environment? I remember at Mega Squirt's Megameet, that I was at, Bruce Bowling was saying how temperature & pressure can scew the readings a decent amount. Unforcanantly, I can't find the video of that tech session.

I found the following, that seems to indicate the WB o2 sensors could take some pressurized environments(2.5bar). Also, you have to watch out that you don't exceed the WB o2s max temperature ratting, in this sensors case it is 1866F, your closer to the port so its going to be hotter than the DP position.
http://www.bosch-motorsport.com/med...nsor_LSU_49_Datasheet_51_en_2779147659pdf.pdf

This is correct. Individual O2 sensors theoretically wouldn't work in our application. At least not anything that any of us unsponsored sportsman / hobbyist would be willing to pay for or even can afford. There may be some OE grade equipment or something that is available for engineers to use. But beyond shade tree mechanic stuff.

Most of us seem quite content reading plugs. Some, (like myself) need a little more. But even I can't figure out what the hell I would do with six O2 sensors! Like a said eirlier, I have a TRUE dual exhaust. So I can only read O2 on three cylinders at a time. Nothing beats this system for me. Just look at the recordings! It plain works.