yoeddynz

DIY Fuel injection thread.

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Bosch 4.9 sensor failure....... Mine has been a little erratic recently and now gets up to temperature and reads lean, is that a sure sign its poked?

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Most likely! 

Mine's been going for ages now but seems to be reacting a bit slow... Or maybe I've just noticed how slow it actually is. 

Might preemptively get a new one soon.

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Ideally you should get up to 100,000km from them, but I dunno what conditions that's operating in (OEM constant 14.7:1 from a dulled down engine I guess). 90% of the sensors I replace is because the heater failed.

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its done 5000km +/- and been treated to my experimentation while tuning twin carbs, def not operator error ;) 

I did wonder if it was blocked, gave it a good cook out with gas and found doesn't react moving in and out of the flame, best budget for a new one

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On ‎11‎/‎12‎/‎2018 at 10:21, Roman said:


Just thinking about the setup some more 

So you have an air inlet on the supercharger. Supercharger moves a volume of air thats fixed with RPM. 

But then after that a bypass valve lets some of the volume of air back out, essentially in reaction to throttle position.

To deal with varying throttle positions the pre throttle pressure rises until spring pressure of the bypass valve lets air out (?)

Sooooo you have different high pressure situations pre and post throttle body and they both affect VE of the engine.

Efficiency of the throttle is affected by variables of both pre and post throttle changing a lot so maybe not a stable variable for a load axis

What could be interesting would be to hook up a second map sensor between the throttle body and the supercharger.

Because that effectively represents both your throttle position and how well the bypass valve is working. It's really a combination of these two things that affect your map readings in the plenum not just throttle angle itself. Because a mechanical bypass valve will have some latency that isnt represented by throttle angle alone, but pre throttle pressure will change when this happens.

Otherwise if you fit a type of bypass valve that you can control with PWM then you can play with the curve to a really nice linear throttle response and also use that pwm% as the load axis on a compensation table.

so have been making adjustments every morning and afternoon driving to/from work mucking with idle/coldstart and datalogging. slowly getting better. the intake backfire is definitely from lean conditions not ignition. comes and goes with fuelling changes. have got rid of most of it now by blending in some mapDOT acceleration enrichment and adjusting the fuelling.

still needs the full sequential setup though, there is a dull miss (probably from too rich) even at idle which must be from the uneven air fuel ratios, which would also explain why it seems to need a richer mixture than you would think - e.g mid load cruise 75kPa just over 13:1 when you would think 14:1 would be ok even with the S/C.

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It's weird though I would have thought that an uneven intake manifold would only really pose an issue when you're at full throttle and the engine is trying to consume as much as possible.

When you're at part throttle one cylinder doesnt really have a mass flow advantage over another?

What injectors are in there, is this the car with those single pintle 1000cc?

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33 minutes ago, Roman said:

It's weird though I would have thought that an uneven intake manifold would only really pose an issue when you're at full throttle and the engine is trying to consume as much as possible.

When you're at part throttle one cylinder doesnt really have a mass flow advantage over another?

What injectors are in there, is this the car with those single pintle 1000cc?

These are xSpurt 1000cc/rebranded ID1000s, not the china 1000's

The pressure drop difference occurs at all rpms,  the blower puts 1.6L of air in every rotation of the engine but its easier for that air to get into cylinder 1 and 2 than 3 or especially 4, so even though only 1 inlet valve is open at a time there will still be a difference, more residual pressure in the manifold than reaching the cylinder in a given time. As rpm increases and there is less time for the air to move, the relative difference may change slightly one way or the other (not sure which way). As pressure increases with boost the relative difference will be less.

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Oh so is it more to do with lobe pulses and when you get that burst of air, rather than unequal runners?

 

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35 minutes ago, Roman said:

Oh so is it more to do with lobe pulses and when you get that burst of air, rather than unequal runners?

 

I don't think it's about unequal runners at all? The runners are all equally short and the injectors are near the runner's inlet. I think the issue (in theory) is the log plenum causing a pressure difference between the runners and potentially having the front cylinders stealing fuel from the rear ones. 

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yup, not to do with lobe pulses but the log. as said runners are basically non existent and #1 is directly infront of the S/C and #2 is very close but #3 and #4 are two 90 deg right turns and 75mm and 150mm of  log away at 45mmish diameter, which is about the same as the port and valve sizes.

The lobe pulses may have some other effects, and the bypass valve is between #2 and #3 so that will have some other effects too.

just all about solving problems no one else ever has because of one else has been silly enough to persist with quite the same setup.

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facepalm..

 

"my car hasnt had 02 sensors in.. forever. it roams around in a open loop speed density tune. killing small children and raping helpless mothers at night."

 

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21 hours ago, scooters said:

facepalm..

 

"my car hasnt had 02 sensors in.. forever. it roams around in a open loop speed density tune. killing small children and raping helpless mothers at night."

 

Carburetors are open loop and work just fine

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27 minutes ago, ajg193 said:

Carburetors are open loop and work just fine

Yeah... I'm picking up what your putting down.. 

Was just trawling the net found that and I went into a tail spin laughing.

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2 hours ago, tortron said:

kiwi Holden vn and VP v6s never had O2 sensors or cat converters. 

Run slightly better in Aussie because of it

Did my time at Holden in ozz Caloundra.. 

Use to get told a lot about how the police pack stuff had ECM's that was tuned for more power (loads of shit) all the kids were pining over BT1 chassis codes. (1" lowered suspension" ) 

ohh God love the OBD1 ROM chip days. 

 

 

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3 hours ago, tortron said:

kiwi Holden vn and VP v6s never had O2 sensors or cat converters. 

Run slightly better in Aussie because of it

Same with some NZDM early 90s BMWs. No cats, no O2 sensors.

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I use my wideband only for logging not fuel trim.

It over/undershoots a lot in reaction to itself because of sensor latency (and no fuel film model in ecu) and makes oscillations when otherwise id only have a small % error.

There are some settings I can adjust to make it less sensitive but really need to adjust in real-time which is hard without a 2nd person to drive.

 

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On 28/12/2018 at 22:16, kws said:

Same with some NZDM early 90s BMWs. No cats, no O2 sensors.

Yeah as we had leaded fuel at the time? 

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