Climbed 6000-10000' in elevation, car is E36 M3ting bricks

He's about 1000 or so miles from home.... and I'm guessing he didn't bring the stock injectors with him.

The place he's going to might have a set, though .

I don't think that would help much without a remap, though, as it's going to be mapped for the higher flowing injectors.

It does... but it's disabled right now because i only have one MAP sensor. From what i understand, the "correct way" to do baro correction on this unit is to use the onboard MAP sensor for baro, and use an external MAP for fueling/ignition requirements.

So... what you're saying is that your engine controller has no way to measure and adapt to barometric pressure changes? And you are somehow surprised/confused that it is running totally berkeleyed up now??

Any stock speed-density fuel injected car has a way to sample ambient pressure to apply a correction factor based on that. On most of my cars, the map signal line goes through a 'baro solenoid' that occasionally shows the map sensor ambient pressure so that it can adapt to changes in altitude while driving.

It really sounds to me like whatever feature is SUPPOSED to be doing that on your standalone, isn't working, or simply isnt hooked up or doesnt exist. THAT is the source of your problems. Your cooling issues may be unrelated, but i would not bother trying to diagnose ANYTHING else until i verified that whatever lets the computer sample ambient pressure, is present and functioning. Doing anything else would be treating the symptoms, not the cause, and would probably just create more problems that you'll have to undo later when you get the pressure-sampling thing fixed.

A stock Miata fuel pump shouldn't have any trouble with that power level, and those injectors should be fine. ARE fine according to the duty cycles, although that goes up with RPM. They can deal with the higher flow levels required. That said, MSMs do run a different fuel pump for some reason and there were more failures of them when new than with most Miatas.

IRRC the haltech can be told to sample baro pressure on startup, before cranking.

whenry wrote: sounds like the larger FI injectors might be stressing the stock system and especially if a component is failing ie fuel pump. I dont have any experience with MSM but I used to make the switch of injectors on 1.6 cars and it made some cars run leaner than others. Can you switch back to stock injectors?

Can't switch back to stock injectors. Don't have 'em, don't have the tools to swap them, and stock injectors will not safely support this car. It made 245whp on FM's dyno 2 years ago, and it's substantially faster now. (when it's running right, that is.)

Vigo wrote:

It does... but it's disabled right now because i only have one MAP sensor. From what i understand, the "correct way" to do baro correction on this unit is to use the onboard MAP sensor for baro, and use an external MAP for fueling/ignition requirements.

So... what you're saying is that your engine controller has no way to measure and adapt to barometric pressure changes? And you are somehow surprised/confused that it is running totally berkeleyed up now?? Any stock speed-density fuel injected car has a way to sample ambient pressure to apply a correction factor based on that. On most of my cars, the map signal line goes through a 'baro solenoid' that occasionally shows the map sensor ambient pressure so that it can adapt to changes in altitude while driving. It really sounds to me like whatever feature is SUPPOSED to be doing that on your standalone, isn't working, or simply isnt hooked up or doesnt exist. THAT is the source of your problems. Your cooling issues may be unrelated, but i would not bother trying to diagnose ANYTHING else until i verified that whatever lets the computer sample ambient pressure, is present and functioning. Doing anything else would be treating the symptoms, not the cause, and would probably just create more problems that you'll have to undo later when you get the pressure-sampling thing fixed.

It's VE tuned. The only thing that SHOULD matter is what the manifold is seeing. If it were an n/a car set up like my Escort is, then i'd use the Haltech map to sample baro.

This is all a little over my head, but because turbo, and because VE, i don't really think barometric correction should be necessary. And even if it was, there's no way it should be this drastic, and i think it'd be rich, not lean.

I could be way off base here, though. There's not much i can do today about it other than to log it while attempting to return my wedding tux and drop off her wedding dress to be shipped back.

A fuel pump going out would be very coincidental, but would make sense in terms of the symptoms.

I HAVE noticed that the longer i drive it in one shot, the worse it gets. Drives halfway decently, but still not perfect for probably about the first 10 minutes. After an hour, if it hasn't overheated by then, it's all pretty much gone to E36 M3.

Hmmm, does it ever feel like its breaking up? This could be the start of a dying cam sensor.

Either way, since it looks like everyone is stuck on the barometric thing....

Pressure where car was tuned: 29.84

Pressure at current location where car is eating E36 M3: 30.28

Not enough to worry about. The pressures have been pretty similar the whole time i've been up here.

Leafy wrote: Hmmm, does it ever feel like its breaking up? This could be the start of a dying cam sensor.

Nah, no misfiring at all so far. Would a dying cam sensor cause a lean condition/slow fueling response?

I DID have a massively leaking valve cover that i changed in the hotel parking lot yesterday morning. Was leaking up front. Cam sensor didn't seem real dirty, though i'm pretty sure it's a Hall Effect, anyways.

Yeah, but the 99+ cam sensors kind of just E36 M3 out randomly. It wouldnt cause a loss of spark but a loss of fuel. But if its not cutting out/breaking up form loss of fuel thats not the issue.

The pressures are a bit odd IMHO - you're substantially higher up now than where the car was tuned, right? Shouldn't the pressure not be less instead of more?

I'm about 8000' higher at the moment, was 12000' feet higher yesterday at one point.

Those pressure came directly from weather.com, verified on Wunderground. (it's actually within about 0.1 on Wunderground.)

Worth mentioning that the car didn't freak out in crazy storms in early Kansas or previously in Indiana.

Oh sorry, I thought those were the pressure readings you got from the ECU.

The only thing that SHOULD matter is what the manifold is seeing. If it were an n/a car set up like my Escort is, then i'd use the Haltech map to sample baro.

Excuse me, i forgot you stayed in boost 100% of the time while the issues were occurring!

In general it is true that turbo cars dont suffer as much power loss from altitude as n/a cars. Since boost control is based on pressure in the intake rather than shaft speed on the turbo, the turbo will just spin faster to compress the thinner air until the target pressure is reached. This generally has the net effect of moving you onto a less-efficient part of the compressor map. On turbo cars with a lot of 'compressor headroom' this generally doesnt cause issues. On smaller turbo cars that are operating closer to the 'limits' of the turbo compressor, the change can be fairly drastic as far as added heat. Generally, though, higher altitudes are colder which makes intercoolers more efficient concurrently with intake temps rising.

However, times when the engine is operating out of boost are still just as susceptible to altitude changes as a non turbo engine is. If your car runs off a MAF, some of them arent highly affected by density changes and can still work worth a crap. But if you're running primarily off a MAP sensor, your out of boost tuning will be way off, and if your boost setting is pushing the turbo pretty hard, your in-boost performance could be affected as well.

So what do you mean by VE tuned?

Vigo wrote: So what do you mean by VE tuned?

He means speed density, but with volumetric efficiency numbers in the fuel table rather than injector pulse width. This method is copes much better with changing environmental variables like barometric pressure and temperature.

Shoulda bought an s2000

All kidding aside, that sucks to have problems on your trip. Could it be something simple like a clogged fuel filter (assuming it has a replaceable inline unit) or a failing fuel pump? I would look into testing the fuel pressure once you get to FM.

Vigo wrote:

The only thing that SHOULD matter is what the manifold is seeing. If it were an n/a car set up like my Escort is, then i'd use the Haltech map to sample baro.

Excuse me, i forgot you stayed in boost 100% of the time while the issues were occurring! In general it is true that turbo cars dont suffer as much power loss from altitude as n/a cars. Since boost control is based on pressure in the intake rather than shaft speed on the turbo, the turbo will just spin faster to compress the thinner air until the target pressure is reached. This generally has the net effect of moving you onto a less-efficient part of the compressor map. On turbo cars with a lot of 'compressor headroom' this generally doesnt cause issues. On smaller turbo cars that are operating closer to the 'limits' of the turbo compressor, the change can be fairly drastic as far as added heat. Generally, though, higher altitudes are colder which makes intercoolers more efficient concurrently with intake temps rising. However, times when the engine is operating out of boost are still just as susceptible to altitude changes as a non turbo engine is. If your car runs off a MAF, some of them arent highly affected by density changes and can still work worth a crap. But if you're running primarily off a MAP sensor, your out of boost tuning will be way off, and if your boost setting is pushing the turbo pretty hard, your in-boost performance could be affected as well. So what do you mean by VE tuned?

I'm not pushing the turbo any harder really, due to the style of boost control. I don't have an EBC with a kpa target, it's just a fairly mediocre manual boost controller, and the car is only hitting about 6.5psi on the onboard MAP at the moment, 10psi on gauge. (i know, PSI is silly, but it's easily for my little pea brain to understand.) We tuned it to 14psi @ sea level, and will push it harder once the stuff for my Flex Fuel/EBC setup comes in.

It's not REALLY a turbo vs. non turbo kind of deal here.... the ECU is spitting fuel/firing plugs based on absolute pressure in the manifold. The same kpa @ sea level will yield the same results as hitting that same kpa @ 10000'.

In theory, that is.

Anyways, i just took about 20 minutes of logs. I'm suspicious of my TPS sensor now, so internets to whomever mentioned that. All was fine and dandy for the first 10 minutes, then i did a long hard 4th gear pull at WOT. TPS wouldn't return to anything less than 1.1-1.2% after that, which made it rich on decel.

On top of that, it seems like that's about when the AFRs got dangerously lean under part throttle conditions. AND, it's also when the coolant temps starting spiking out of control. I was able to keep them 190 and below until then. Then in the last 10 minutes to the hotel, it went from about 183F to 218F by the time i pulled in. I'm not 100% convinced the cooling system is inadequate for the job, but Keith sold me on the Stage 1 kit and water only, anyways.

Sooo... maybe a test of the TPS is in order tomorrow.

Worth mentioning that through none of the 20 minutes did it behave as badly as it has so far, and that this was using my quick 'n' dirty +15% overal fuel trim tune. Will log original tune after about an hour of driving tomorrow if i can keep the car cooled enough to drive that long consecutively. I imagine it'll be way scarier.

Spoolpigeon wrote: Shoulda bought an s2000 All kidding aside, that sucks to have problems on your trip. Could it be something simple like a clogged fuel filter (assuming it has a replaceable inline unit) or a failing fuel pump? I would look into testing the fuel pressure once you get to FM.

It could be any of those things... i just don't really have a way to test it myself since i've just got minimal tools at the moment. (It was a super adventure replacing the valve cover gasket and running new vacuum line to the Haltech in the hotel parking lot. YAY removing undertrays!)

And yes... i should have bought an S2000. Or an RX8. (There's a really nice one in Orem right now that i'm contemplating trading the MSM in on... seriously.) Or pretty much anything else. Really frustrating to battle the car for 2 years in every possible way, then finally get it running right by swapping out the entire engine management system less than a month before the trip.

Then have it all go sour.

C'est la vie. Or some other French E36 M3.

Do we have an update?

Does it make a difference how full your fuel tank is? Fueling issues when your tank gets lower (and has less gas to cool the pump), can be a sign of a fuel pump going bad.

It's done it through about... 4 tanks now.

As for an update, Keith Tanner is the man. Great to talk to, and just a genuinely nice guy.

We tested fuel pressure with the car HOT, and it's dead on, so pressure and pump are good.

TPS sensor being suspect, we swapped it out. So far, so good, but i've only put about 15 miles on it, and prior, it took longer than that to surface. I'll know more tomorrow.

As for the overheating aspect.... the setup works better with BOTH fans working. Motor on one of them is getting sketchy. Probably hadn't been working for days, had to hit it with a hammer to turn on. Didn't overheat for about 4 hours straight today after the first incident which made me hit it with the hammer. However, it means i should probably replace the fan/shroud setup anyways, so tomorrow i'm bringing the car back over to FM.

Stage 1 fan/shroud setup
22psi rad cap
Water and Water Wetter ONLY
180F Tstat.

If that doesn't keep this berkeleyer cool, i don't know what will.

The fun part? Due to lean-ness, i got 32.5mpg out of the last tank.

Fingers crossed that the TPS sensor change fixes the problem.

Sounds like you're making progress - hope the rest of the trip goes smoothly!

Were you able to test the fuel pressure under full load (boost) and rpm conditions? Im assuming yes given that you were at FM and they're very familiar with boosted vehicles.