Excessive blow by from F4i

[MikeDutsa]

We are running an F4i. it has always had a little bit of blow by, just some smoke now and then. but lately it has just gotten to be ridiculous, tones of smoke and oil all the time. Has any one seen this? Any ideas of what this might be? our back up motor that we run in the old car does not show any signs of any blow by at all, so i'm pretty sure that this isn't typical of all F4is.

Thanks,
Mike D
UTSA

[MikeDutsa]

We are running an F4i. it has always had a little bit of blow by, just some smoke now and then. but lately it has just gotten to be ridiculous, tones of smoke and oil all the time. Has any one seen this? Any ideas of what this might be? our back up motor that we run in the old car does not show any signs of any blow by at all, so i'm pretty sure that this isn't typical of all F4is.

Thanks,
Mike D
UTSA

[TMichaels]

Hi Mike,
we are not running a F4i, but from my experience with our GSX-R's I can say that you might have a bigger problem. I saw an increased amount of gases coming out of the crankcase ventilation twice. The first one was a broken piston ring. The second time it was a damaged connecting rod bearing. The second one is obviously not really increasing the blow-by, but it looks like this as the oil overheats between the bearing shells and the bearings and leaves the crankcase as gas which looks like an increased blow-by. Therefore I would suggest to disassemble the engine and track down the damage causing the increased blow-by before it is too late to fix it by changing bearings, bearing shells or piston rings.

Regards,

Tobi

[Brett Neale]

We saw some excessive crankcase venting from our F4i on one of our dyno runs last year, a few weeks later the #4 big end bearing decided to give up. Keep an eye on it, or even use your backup engine before time gets tight...

[MikeDutsa]

Thanks guys for the ideas, i think we are going to start the analysis by checking the cylender pressure. I'll keep this updated as we find out more.

Thanks,

Mike D
UTSA

[Kirk Feldkamp]

This is smoke/oil out the breather or out the exhaust?

[MikeDutsa]

breather

[Pete M]

Sounds like you've damaged a ring or a piston to me. Compression/leak down test it and see if one of the pistons is very different to the others.

[MikeDutsa]

Also, little diffrent topic, Our two cars have very similar drivetrains, the only major diffrence is the headers and muffler. very similar intake, same throttle body, same ecu, same fuel system. but one car makes about 80hp and the other more like 30. is it possible to build headers that are that bad? the low power ones are 180? 4-2-1 and the others are 360? 4-2-1.

Could excessive back pressure cause a piston ring to crack? or possibly blow out a valve seal?

[Biggy72]

You sure the problem on the car making 30 hp isn't something wrong with the way it is wired or something? Is it actually firing on all 4 cylinders? Last year at comp we were making a healthy 35hp on 3 cylinders or less.

[MikeDutsa]

We ran diagnostics on the injectors and plugs, all are working as they should be. we spent some time retuning to account for the diffrent exausts, and were able to get the air-fuel raito pretty close to where we want it throughout the rpm range. but still slow and narrow power band. it doesn't want to rev up over 11.5 grand ever, while the same motor, in the other chasis had no problem flying to 13,000.

[Pete M]

I second that it's electrical/tuning, it's about the power loss you'd expect from being down a cylinder.

One thing you may need to watch is that you can't trust an AFR reading if a cylinder is missing as the unburned oxygen will bias the sensor lean. You may be running the 35 hp one absolutely pig rich, such that one of the cylinders isn't firing. Have you compared the two fuel maps? Do they look sensibly different (ie, minor differences to account for the different headers)? Does it sound clean?

[Biggy72]

swap engines and see if your results are still the same.

[TMichaels]

I also agree to the previous posts. It is impossible to build such a bad header. There may also be a leak in front of your lambda sensor, if you only use one. This will cause your sensor readings to appear lean. We had this problem two years ago and the engine ran like a bag of nuts.

Regards,

Tobi

[Brian Evans]

A bad tune causing detonation can take out piston rings, erode pistons, take out bearings, basically all of the problems mentioned. A header will only make at most about 10% difference in power and that only at peak. Bad exhaust leaks can burn exhaust valves, though.

[MikeDutsa]

Pete,

That sounds pretty close. When we checked the WOT data from a few passes it appeared that it was not getting near enough fuel. But intuitively, it seamed that if all the injectors were working and it was not burning a cylinder, then it would appear stupid rich due to all the unburned fuel. I'm going to look into this today, thanks for all of ya'lls help. I'll keep yall posted on the findings.

Thanks again,

Mike D

[Pete M]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MikeDutsa:
But intuitively, it seamed that if all the injectors were working and it was not burning a cylinder, then it would appear stupid rich due to all the unburned fuel. </div></BLOCKQUOTE>

Nope, lambda sensors sense oxygen, not unburned fuel. If a cylinder isn't properly igniting its charge for whatever reason, then the exhaust coming out of that cylinder will theoretically have an infinite AFR (according to the sensor). When mixed with the normal exhaust from the other cylinders, it averages out to just being "lean". A bit oversimplified, but whatever. This is one of the major flaws of using oxygen sensors to determine AFR.

[MikeDutsa]

So today we did some testing....

First I checked all the coil packs with the spare spark plug, then I checked each of the spark plugs that was installed in the motor, then I checked all of the fuel injectors to make sure they are opening,

Everything appeared to be working just fine. So I uploaded the map from the old race car that runs oh so very well. Took the car out, and... notta, a whopping seventeen HP. We reviewed the data, and the AFR appears to be right about where we want it. But also to be noted the car seams to get a lot hotter than it used to. 210 used to be about the max it would get to, but now 210 is its cool, easily getting as high as 250, not good. Another thing we noted today was that the inside of the muffler is glowing bright orange.

So, there the info, here is the latest thought process...
Tomorrow we will check the compression (we had to have a fitting machined). What I think is happening is that over time the increased back pressure combined with a very aggressive tune off the old car (20? to 40? advance) is causing detonation at high rpms, thus causing the piston rings to become worse and worse. Eventually they wore out (we think, we will know for sure after tomorrows compression test).

Any thoughts on anything else it might be are welcome, or any other suggestions on things to try, lemme hear it.

Thanks guys,

Mike D

[Pete M]

Hmm... what do the two ignition maps look like? It sounds to me like you may be running extremely retarded timing. Most people around here wouldn't call 40 degrees aggressively advanced, but it's not stupidly retarded either. Have you verified your timing is correct, ie that you're actually achieving the advance that's in the table? If you wire the crank sensor backwards, this sort of thing can happen.

If it's a motec, you're looking to make sure the edge polarities of the ref and sync sensors are configured correctly and that you've set CRIP properly. If it's not a motec, it'll be called something similar or it may not be adjustable in software and you just have to get the wiring right.

EDIT: Wait, sorry, the engine that is down on power is the same engine that's got heaps of blow by? In that case, forget everything else and just compression test it. You've most likely lost a cylinder (piston, rings).

[Michael Hart]

I would definitely say compression test it. I'd be surprised if detonation was causing your problems because if it was detonating so much that your power was down 50%, you would know it (your engine will sound like sh*t).

Are you running two separate blocks that are making these different hp's?

If so, have you double checked your cam timing in the low hp engine? If its off even a degree or two, that could kill your power, especially in the top end (which would prevent you from running above 11500)

hope that helps

[MikeDutsa]

Both engines have been in both cars, both made tons of power in the old car.

We are going to throw the new headers on the old car and see how it does. I'm thinking if it makes a ton of power still then... we'll figure that out when we get there. I'm kind of hoping it sucks, that way we can just make new headers. I'm not sure what to hope for ion the compression test, if it is messed up, then it's an easy solution, fix it. if it is fine it is still a total mystery as to why the engine sucks in the new car.

Thanks again for the ideas,

Mike D

[VFR750R]

She's blow'd up.
No amount of tuning-exhaust, air/fuel, or black magic will save that one.

[exFSAE]

210 cool / at idle.. thats an accomplishment

When you can't even rely on black magic anymore youre really sunk.

I heard thats what they got in them hendrick engines

[TMichaels]

I again agree to the previous posts. Disassemble the engine and you will find, what you are searching for.

Regards,

Tobi

[FD2R]

Hi MikeDusta,

Probably something else to look out for is the clutch assembly. We had a problem last year with our dyno engine where the clutch mechanism wasnt fully disengaged when we pull the clutch lever and not fully engaged when we released it! The clutch was just slipping all the time and it cooked up the oil and caused alot of blowby trough the breather. Just remove the side cover and check if your clutch assembly is brown/black.

With regards to the fuel problem, we had quite a similar problem last year right before the competition. When we opened the throttle slowly, the engine just leans out very badly, not even showing on the lambda meter. Then we hooked up a Exhaust Gas Analyser and found out that hydrocarbons were going up when AFR was increasing, which means one of the cyllinders were not firing. The problem dosent seem to happen all the time as well, it comes and goes!We traced it down to a faulty motec connector. Normally with a quick wiggle on the connector, the problem just disappears !

I dont know how relevant this is but i hope it helps!

Cheers,
C.Kuay
MUR Motorsports 2007

[Pete M]

I'll confirm the clutch theory too. We've slipped clutches many a time (turbo, heh) and if you do it badly for a few seconds, you get a fair bit of smoke out the breather from the oil frying in the clutch. You'll also lose a fair bit of power to it (clutch can't transmit the full torque, ergo less power).

Not sure if it really explains all the symptoms, i'd still tip it as being a blown engine, but it's worth considering. Make sure the clutch lever has slight free play with the clutch engaged to make sure the cable isn't pulling it partly disengaged.

[MikeDutsa]

so yesterday we checked the compression of each cylender. They were all pretty even at around 160 psi.

Then we bolted the new headder to the old car, and it ran like crap. It acted exactly like the new car was. Rough idle, poor reving, low max rpm, the whole bit. So this week we are going to make new headers and see how the new car does.

As for the blow by, that's still a bit of a mystery that we will continue to investigate.

Thanks guys,

Mike D

[Drew Price]

How different from the old headers were this years? Can we see?

Best,
Drew

[MikeDutsa]

I'll post some pictures up here of them later. We took the old car out and drove it with the new headers, it wasn't as fast as it used to be, but it wasn't nearly as slow as the new one was with the same setup. Who ever said ten percent at max power difference from headers was as much as you would get seemed about right, the new headers were still able to wreck the idle and kill the low end torque though. I think next we are going to begin swapping the engine systems a part at a time until we figure out what the difference between the two cars is. I'm kind of leaning toward the clogged injector theory; that would explain the initial super lean reading that we were getting. It just doesn't make much since; the whole thing is so few parts.

As always, ideas are welcome.

Thanks,
Mike D

[TMichaels]

Hey Mike,
what you can do is just unplug ignition coils and/or injection valves at a time when the engine is running. In that way you can easily determine if one of this parts does not work as it should be as nothing should change in the behaviour of your engine when deplugging a defective ignition coil for example. We tracked down some errors over the years with that method http://fsae.com/groupee_common/emoticons/icon_smile.gif Complicated sentence...unplug a coil while the engine idles and see, if anything changes (for example the engine stalls), if not, it does not work like it should, the same with the injectors.

Regards,

Tobi

[Wesley]

Trigger wheel installed a tooth retarded?

From your symptoms I also suspect retarded timing - but if the map hasn't changed, I'd venture to say it's cause of the trigger wheel.

Glowing muffler, down on power, O2 reading lean, all symptoms of retarded timing resulting in continued burn in the exhaust tract.

[MikeDutsa]

I understand how that sounds like it could be it, but what doesn't make since is that we have switched the engines between cars with out changing anything else.

I am leaning tword the bad/weak coil theroy. We are having new headers made now, but when we get it back we shall continue the trouble shooting.

[Kirk Feldkamp]

I understand you put the 'bad headers' on the old car, but have you tried the 'good headers' on the new car?

This close to comp I'd be inclined to just swap all the hardware from the old car into the new car and get more real (driving) testing in). Figure out the cause of the problem later!

-Kirk

[MikeDutsa]

that was the first thing we tried, chasis changed a little to much and they don't fit.

Its okay though, we'll have the new ones back middle of next week. it'll give us some time to finish that design report that i'm sure every one is looking to wrap up. when we get the car back the plan is to spend a few hours swapping everything save the motor from the old car to the new one. hopefully that will uncover what the deal is.

-Mike D

[TMichaels]

I am unhappy to disappoint you but the new header will never ever solve your problems. Better focus on anything else.

Regards,

Tobi

[MikeDutsa]

We know from experimentation the header will help. But by this point we certainly know that something more is causing the power loss.

-mike D

[MikeDutsa]

so we had the injectors flow checked and cleaned and flow checked again. After cleaning they were at 220 202 168 and 112 cc/min. Pretty rough. I think we found our problem. Thanks for all the ideas, we will have to see if all the other problems persist.

Mike D

[Kirk Feldkamp]

Swap the old car's injectors onto the new car and let us know how it goes.

-Kirk

[Ian M]

If you want to check the coils, just hook up you multimeter to them.

For Honda 600RR you should see 11-13 ohms across the two coils wires. If the resistance is lower than 11 ohms than your coils are shot. I don't remember what kind of engine you said this was (Suzuki?) but I would assume that the coils would be close to the same.

We ran into this problem and our engine ran like crap and we went through a couple sets of spark plugs before we found the problem.

We believe we fried them by using a large battery charger to jump the car. Turned the charge time down just a shade just in case.

[MikeDutsa]

GOT IT!!! so we swapped the injectors with the old car, and bolted in the new headers on. freaking crazy fast. this is amazing. thanks for all the pointers. also i'll let yall know how the mazda miatia injector experiment goes tomorrow.