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Pretty decent day at Summit. Ran 1:20 on old dead tires and low (12-13) boost. I'll put some more details and video up, but I got two hours of sleep and I'm beat.
Nice Peter
That kind of time on shot tires and low boost means some great stuff in the future with sticky rubber and a few more psi
I went out for the first session with a full tank, and immediately smelled gas. Pulled in, and pulled the pump cover, and could see it was wet all over. I recall it was a bitch to get all the screws lined up when I put it in with the new tank, so suspected it wasn't seated right. I pulled it, and raised the fuel pump on the stalk about 1/16", and it seated SO much more smoothly. Problem solved.
Next—It appeared to puke some oil out of the dipstick, despite a large (-10) vent line off the filler neck. It wasn't much, but enough to make a mess. BUT, in the very last session, it appears to have puked a bunch of oil out of the vent filter from the OMP nozzles that I just replaced. I'm wondering if prolonged boost is just too much for the check valves in them? It's quite a mess. I am really at a loss as to what to do about it, and don't know whether they are now compromised again or what.
I'm also seeing some occasional stalling—I noticed a few times on the street it would stall when you throw the clutch in coming to a stop, and a couple times I started it, only for it to run a few seconds, then shut off as the idle settled. I suspect something related to the throttle body isn't right.
On track, the car feels really good. Lots of power, great response. I don't see running more than low boost (12-13 psi). The water temps never got out of the 80s, and the IATs never got out of the 30's. I never ran the tank down below 1/4 indicated on track—somewhere between 1/4 and 3/8 sitting in the pits.
I definitely need to pin this hood. I didn't quite have time to finish that before I left, and it flaps around too much for comfort. The wing is cool—I only ran it basically flat, so not really sure how much its doing. But, it actually improves rear visibility, and it didn't fall off, so I'll call that good.
Here's the video. I'm still rusty and leaving a lot on the table. Even at 1:20. There's a 19 even on old tires. You can year me yell, "yeah ************!" when I see the 1:20.
I'm wondering if prolonged boost is just too much for the check valves in them? It's quite a mess. I am really at a loss as to what to do about it, and don't know whether they are now compromised again or what.
The answer is yes, you have the oil injector nozzles hooked up wrong if they are seeing any boost.
The oil injection metering pump nozzles should see ambient air only (no boost and no vacuum).
No, the oil injector nozzles are vented to a little filter. Which is puking oil after sustained boost, even though both nozzles are brand new (old nozzles did it on the dyno).
So, the "boost" I'm referring to is from inside the engine—i.e.: its pushing past the check valves.
^^^
Your engine will be so much happier if you take a 5 gallon race jug, dump in 1 full quart of premix , fill the rest with 116 octane leaded race gas and add that to each tank of gas when on the track.
There are a couple options for venting the OMP lines. I could add a -4 bulkhead to 1/4" hose barb to the back of my catch can.
Or, I could run them to this unused 1/4" nipple on my filler neck (which is vented by a -10 line to the catch can)
The big question for me though is, are the OMP nozzles injecting oil as they should be when this is occurring, and if not, what changes need to be made? If one would normally not run decel fuel cut without an OMP, does that mean I'd need to do the same?
It's no problem to dump the lines someplace that won't make a mess, but I'm thinking long term engine health.
The other thing did before I changed them out was to install this check valve on the "vent" line. My understanding is that the line is to draw air, not vent it per se, it only vents oil when the check valve fails. So I installed with arrow towards the motor so they could draw air, but not push oil out. That prevents the filter acting as an indicator of nozzle failure, but I can't really tell if that's going to be valid at this point anyway.
The big question for me though is, are the OMP nozzles injecting oil as they should be when this is occurring, and if not, what changes need to be made? If one would normally not run decel fuel cut without an OMP, does that mean I'd need to do the same?
Right, your oil leak through the OMP nozzles is presumably under boost when your engine is getting lubrication from premix (and probably not much from the OMP if the finite volume of oil from the metering pump is leaking out the top instead of into the engine).
I would keep the oil injection system for lubrication on decel (engine vacuum should be pulling oil into engine just fine on decel).
Or
I would ditch the oil injection system (but it may limit what classes you can race in if you decide to race) and turn the decel fuel cut off for lubrication on decel.
So, I broke out my mityvac and tested the old (but pretty new) nozzles I took out of the car before.
When I push air through in the correct direction, one works correctly, and the other will not push through (builds pressure). If I pull vac back through them, the good one builds vacuum, the bad one doesn't.
SO, I don't think we can necessarily assume it will pull in oil under vacuum. I'm not sure what's going on here. Even an external check valve may not necessarily help.
I've got two brand new nozzles sitting in my parts bin, but I hate like hell to do that job again. I have to think that this is a QC issue with new Mazda parts. They had maybe 50-100 miles on them, and should be WAY more reliable given how important it is.
What are the implications of turning off decel fuel cut? flames? fuel/Oil contamination?
In my experience with decel fuel cut off you will see a bit of smoke on decel from high rpm (assuming you have your high rpm low load cells very rich for engine protection while hooning - lower egts) and if you keep track of gas mileage you might see a 1-2mpg dip.
If you normally get flames (usually from an exhaust leak in my experience) your flames will linger off throttle. Make sure your exhaust tip extends past the end of your bumper or turns down (a good tip for any rotary that gets driven hard).
Decel fueling is just injecting as much fuel as the engine needs for low/no load operation (very little) plus whatever safety factor you have for fatter afrs above your lean cruising rpm.
I ran decel fuel cut off for years when I ran aftermarket seals (and 50:1 premix plus OMP).
I'm running aftermarket (rxparts) seals, but the more I've lookied into it, I'd rather not disable that system. Seems like it will require some retuning, which I can't do.
I really need to understand why these nozzles are failing. New ones hold well over 25 psi from a mityvac. There's really no reason that 15 psi should kill them.
....I really need to understand why these nozzles are failing. New ones hold well over 25 psi from a mityvac. There's really no reason that 15 psi should kill them.
A few years ago, I experienced exactly the same problem with a failed oil injector as you have described in your posts above. I initially tried the check valve solution and it caused a well secured vent line to pop off of the injector and puke oil everywhere on top of the motor. The pressure that popped the hose off, IIRC, seemed to be from the omp pump and not necessarily boost--as a result of the injector's mode of failure.
I also noticed that it occurred on a 'newer' production oil injector and the old, original '93 style on the rear with a million miles on it was still functioning just fine. I rummaged through my parts bin and found another early (93?) style oil injector and put it on, problem solved--for now.
My own impression was that the later production oil injectors may have a flaw or durability issue. I am certain that it was not caused by pilot error, so to speak.
Yup. It does seem like maybe its partially design (smaller holes creating higher pressure), and perhaps a quality or quality control issue (I've noted some new OEM parts don't seem to be as nice as they used to be). My car runs the '99 Mikuni OMP that pumps more oil, AND the settings are upped in the PFC, so there's a lot of flow. May have source for good '93 nozzles to try.
I'm tearing it down now, and will take a look at the orifices in the housings as well. The only bitch to this job is, you have to remove the primary fuel rail. I'm so over jobs involving fuel right now.
So, I pulled the oil jets, and BOTH are toast. Lots of oil welled up in the threads. I can see the rubber grommets in there with my handy dental mirror, and since it's both I doubt its some sort of clog or something, or a QC defect. It may be a case of just too much oil tryng to go through a tiny hole. However, I don't get why it would suddenly be happening now, since the OMP, OMP settings, and the original set of jets weren't new.
I've got a set of good/used 93 style jets coming, but I think that in the long terms solution may be taking a 3mm drill bit to the new jets and opening them up from .8mm. Really wouldn't be too tough with a drill press. I might also need to turn down the oil feed given its also a mikuni pump.
I'm wondering if the old style nozzles will be OK to install with the rubber grommet in the housing?
04-15-17, 11:54 AM
