1516 replies to this topic

[lookforjoe]

ozzimark, on 20 November 2009 - 01:18 PM, said:

Your AFR spikes rich when you get off the throttle for the shift? I don't have a wideband yet, but I know my car goes into closed loop when the engine is at some RPM higher than idle and my foot comes off the throttle, I always assumed that it reduced flow of fuel into the engine at that time, not tried to flood it

It spikes lean on decel- it may swing full rich for a millisecond, but then it will peg 18+ - look at the timing, too - it goes close to TDC on closed throttle/heavy decel

Shift is only momentary reduction in load, look at the time span & the timing advance during shift

heres a crop from the csv file

[ozzimark]

ozzimark, on 20 November 2009 - 01:18 PM, said:

Your AFR spikes rich when you get off the throttle for the shift? I don't have a wideband yet, but I know my car goes into closed loop when the engine is at some RPM higher than idle and my foot comes off the throttle, I always assumed that it reduced flow of fuel into the engine at that time, not tried to flood it

Er, I meant open loop, not closed

[ozzimark]

lookforjoe, on 20 November 2009 - 02:04 PM, said:

It spikes lean on decel- it may swing full rich for a millisecond, but then it will peg 18+ - look at the timing, too - it goes close to TDC on closed throttle/heavy decel

Shift is only momentary reduction in load, look at the time span & the timing advance during shift

heres a crop from the csv file

I've seen the stock timing map for out engines, 0 and 5% load rows have timing values in the single values or low teens, so that makes sense that the timing retards to almost TDC, I don't see the lean spike you're referring to though, only that it's going down to ~10:1 as soon as you shift, and then comes back up a little less than a second later. I guess that basically is a split second

[lookforjoe]

ozzimark, on 20 November 2009 - 04:47 PM, said:

I've seen the stock timing map for out engines, 0 and 5% load rows have timing values in the single values or low teens, so that makes sense that the timing retards to almost TDC, I don't see the lean spike you're referring to though, only that it's going down to ~10:1 as soon as you shift, and then comes back up a little less than a second later. I guess that basically is a split second

Sorry, lean spike is on decel/off load, not on shift points - you can see the MAF doesn't change there...

yeah - more like half a second on the timing/AFR change

[EricF]

ozzimark, on 20 November 2009 - 04:47 PM, said:

I've seen the stock timing map for out engines, 0 and 5% load rows have timing values in the single values or low teens, so that makes sense that the timing retards to almost TDC, I don't see the lean spike you're referring to though, only that it's going down to ~10:1 as soon as you shift, and then comes back up a little less than a second later. I guess that basically is a split second

Your thoughts on timing are off quite a bit

If you follow a stock map's 25% line, it will start at 15 degrees for the 500 RPM bin, and climb to 37 degrees by the last bin. The 100% line starts at 12 and climbs to 26... The last bin is 6200 RPM btw.

Especially in the higher RPM range as you get further away from the torque peak, you need quite a bit of timing even on small fast burning chambers like these with centered spark plugs.

Here is my current timing map, I think it is a little too conservative in a few places. (I'm running 17-19 psi boost, so at WOT by 4000 I'm in the 200-230 KPA range.


I have a suspicion Hussein's datalogger is lying to him about timing. Or else it's all being pulled for some reason.

[Captain Bondo]

lookforjoe, on 20 November 2009 - 02:04 PM, said:

It spikes lean on decel- it may swing full rich for a millisecond, but then it will peg 18+ - look at the timing, too - it goes close to TDC on closed throttle/heavy decel

Shift is only momentary reduction in load, look at the time span & the timing advance during shift

Ugh. No. Engines go rich on decel. The lean spike is actually a (normal) rich misfire.


Are you sure your analysis of the timing is not backwards, it makes more sense that it's going to 30 when you let off and down to ~5 when you are wot.


Assuming that the numbers look fine to me.

Again, since it is pegging the maf, you really have no actual way of knowing how the ecu is determining required ignition advance past that point.

That advance seems reaosnable based on your boost pressure though. It might take some more up high in the revs, but you won't tune that without a dyno and a programmable system.

Eric your map is way conservative based on my experience. Get to the dyno.

[550]

Is there a way to go with a MAP sensor on the USB TT? Maybe the goofiness is due to the MAF?

Also, yeah my car goes to almost straight O2 on decel.

[lookforjoe]

Captain Bondo, on 20 November 2009 - 11:28 PM, said:

Ugh. No. Engines go rich on decel. The lean spike is actually a (normal) rich misfire.


Are you sure your analysis of the timing is not backwards, it makes more sense that it's going to 30 when you let off and down to ~5 when you are wot.


Assuming that the numbers look fine to me.

Again, since it is pegging the maf, you really have no actual way of knowing how the ecu is determining required ignition advance past that point.

That advance seems reaosnable based on your boost pressure though. It might take some more up high in the revs, but you won't tune that without a dyno and a programmable system.

Sorry, I thought that's what I said - it certainly is that way on the graphs.

Not much I can do with it now, so I'll just record some more & then swap to the TT ECU & go from there....

[lookforjoe]

Bought a Cusco CC, based on searching several websites, they all claimed it was a baffled can - guess what - it's not







The seller has refunded me some of the purchase price, so I cut it open to add my own baffle. I'm going to use this for the cam cover vent & drain back to the block. Vent line will go to the other CC.

[turbotuner]

550, on 20 November 2009 - 11:42 PM, said:

Is there a way to go with a MAP sensor on the USB TT?

No I don't think so, unless you use some sort of MAF to MAP conversion system. But why would you want to anyway?

550, on 20 November 2009 - 11:42 PM, said:

Also, yeah my car goes to almost straight O2 on decel.

That is normal.

[Captain Bondo]

turbotuner, on 21 November 2009 - 02:37 AM, said:

No I don't think so, unless you use some sort of MAF to MAP conversion system. But why would you want to anyway?

Why would you want to be able to tune ans EMS like a normal speed density system? Unless turbo tuner allows access to all of the sensor trims that result in the load calculations, being able to run an actual speed-density system would be very desireable. Of course you would want to.

[turbotuner]

Captain Bondo, on 21 November 2009 - 05:26 AM, said:

Why would you want to be able to tune ans EMS like a normal speed density system? Unless turbo tuner allows access to all of the sensor trims that result in the load calculations, being able to run an actual speed-density system would be very desireable. Of course you would want to.

OK, but I was trying to understand why someone would want to.

[550]

turbotuner, on 21 November 2009 - 02:37 AM, said:

No I don't think so, unless you use some sort of MAF to MAP conversion system. But why would you want to anyway?



That is normal.

I know it's normal ;-)

Map tends to be better for big boost cars from what I have seen.(Only from what I have seen, I have never modified a MAP based car) I mean when you look at supra's you don't see MAF's on them. From what I have gathered MAF's are flakey :-/. Where as a MAP is based on the absolute pressure in the manifold it provides a better way to manage things on the car.


Isn't there a lot of things controlled from the MAF? As in, the MAF can be the reason for things like timing pull, (aside of the knock sensors), and goofy AFR's?

I just seems to me that if you could do away with the MAF and go with MAP, that some of the oddities of these cars would maybe be solved? You can go MAP when you go standalone, right?

[turbotuner]

550, on 21 November 2009 - 01:23 PM, said:

From what I have gathered MAF's are flakey :-/. Where as a MAP is based on the absolute pressure in the manifold it provides a better way to manage things on the car.

If a MAF sensor isn't working correctly, then sure the engine won't run properly. But the same would apply to a faulty MAP sensor too! I'm still curious how a MAP based version would be better to manage things? It's a genuine question BTW - I'm intrigued because if there are significant advanatges then I would look into this for the TT.

550, on 21 November 2009 - 01:23 PM, said:

Isn't there a lot of things controlled from the MAF? As in, the MAF can be the reason for things like timing pull, (aside of the knock sensors), and goofy AFR's?

Yes, but only if the MAF is faulty. Goofy AFR for example can be down to faulty sensors, air leaks, mapping etc. You could get equally goofy AFRs with a MAP based system.

550, on 21 November 2009 - 01:23 PM, said:

I just seems to me that if you could do away with the MAF and go with MAP, that some of the oddities of these cars would maybe be solved?

What sort of oddities?

[550]

When you use a MAF you aren't taking into account the absolute manifold pressure for fuel tuning. When in reality you are only measuring the amount of air comming in. So unless you modify the signals from the MAF (which you are doing with the TT) it is harder to adjust the amount of fuel going into the engine.

With a MAP based system you add fuel based on pressure not on air flow.

[turbotuner]

550, on 21 November 2009 - 04:28 PM, said:

When you use a MAF you aren't taking into account the absolute manifold pressure for fuel tuning. When in reality you are only measuring the amount of air comming in. So unless you modify the signals from the MAF (which you are doing with the TT) it is harder to adjust the amount of fuel going into the engine.

With a MAP based system you add fuel based on pressure not on air flow.

What about the IAT? With a MAP based system, don't you also need IAT sensor to calculate the air density?

[BlackT5]

Yes. I use a combined MAP/IAT sensor in place of the MAF with Nira.

From my understanding, the disadvantages of MAF are that they can be slow to react, sensitive to damage, expensive to replace, and are a restriction in the intake.

Advantages being that it measures the amount of air entering the engine making fuel mapping easy, and good for emissions over the entire life of the engine

[lookforjoe]

^ interesting conversation


worked on my modded breather system today...

Oil cap take II - fitting silver soldered inside late style cap..





modified Cusco can - now has 2.25" baffle sleeve inside, setup like the Volvo breather box

1/2" drain, 3/8"vents






... oil cap will vent to Cusco can, which will vent to old CC, and drain back to factory breather like this...

[Captain Bondo]

A "load" calculation that is generated by a fixed formula based on throttle position, intake air temp, mass flow, and whatever odd values it uses, does not give you the control a MAP based system does. Unless you can actually modify how things like intake air temperature modify the load calculation.

For example - with a map based system, you can exactly define how much fuel trim is added or subracted for any given intake air temperature independent of load.

You can alter the pulsewidth calulation base don each variable independently, rather thanon a calculated mish-mash value that tries to incorporate them all.

[lookforjoe]

Worked on the revised breather system today - pulled the intake & the box - added the extra drain port, replaced the drain hose. Fitted the modified Cusco can, put it all back together.... the formed drain tube is the PCV/flame trap hose from a 740 16V, vent hoses are 740 power steering return lines...

back together


Catch can - added a sleeve to the vent outlet inside the can, to reduce direct oil draw into inlet tract (see sketch below)




drain nipple & hose



new can.. did away with the sight tube, don't need two .



..trying to upload more pics... network connection sucks tonight...


modified box






overview...