chts discussion, enriching trick?

[crowbar]

For those readers that actually are interested in the modification, it is necessary to understand the impact the cylinder head temperature sensor has on the operation of the car.

The sensor is just a NTC thermistor. Basically it decreases resistance as temperature increases.

The ECU modifies the fuel enrichment and ignition timing based on this sensor. It also changes the mode of injection. From Group injection to Simultaneous injection.

So the general idea is to 'lie' to the ecu about the actual cylinder head temperature. This 'forces' the ecu to run in a richer F/A ratio. It also forces the ecu to use simultaneous injection at a lower RPM then it typically would.

Some interesting points:

1. The ecu will run closed loop (O2 sensor feedback) at a 'ccol' CHTS reading. At a cold reading, it will not. I will dig up the resistance values if anyone is interested.

2. The timing is advanced when 'cold/cool' sensor readings are read by the ecu. The timing must therefore be retarded to take advantage of this. I am working on a way to actually advance retard the timing from the driver's position.

[crowbar]

http://img124.imageshack.us/img124/6537/bgetgj5.png

[Jason84NA2T]

You're still not posting any data on your idea, that's what I was hoping for. Again, it seems your logic comes from the basic information provided in the FSM and not actually working with editing the ECU parameters.

crowbar wrote: For those readers that actually are interested in the modification, it is necessary to understand the impact the cylinder head temperature sensor has on the operation of the car.
Most people on this forum already understand that, there's no reason to go there or post pictures from the FSM to back up your statements if we know them to be true.

crowbar wrote: The sensor is just a NTC thermistor. Basically it decreases resistance as temperature increases.

The ECU modifies the fuel enrichment and ignition timing based on this sensor. It also changes the mode of injection. From Group injection to Simultaneous injection.
yup... There is an enrichment coeficient applied below 80 degrees and it alters the firing method.

crowbar wrote: So the general idea is to 'lie' to the ecu about the actual cylinder head temperature. This 'forces' the ecu to run in a richer F/A ratio. It also forces the ecu to use simultaneous injection at a lower RPM then it typically would.

Correct. But this is and incredibly simple idea and what your entire idea is based on. Why are you going over it again; to patronize us?

crowbar wrote: Some interesting points:

1. The ecu will run closed loop (O2 sensor feedback) at a 'ccol' CHTS reading. At a cold reading, it will not. I will dig up the resistance values if anyone is interested.

No need, those values are in the FSM

crowbar wrote: 2. The timing is retarded when 'cold/cool' sensor readings are read by the ecu. The timing must therefore be advanced to take advantage of this. I am working on a way to actually advance retard the timing from the driver's position.

1. There are three basic forms of timing adjustment in the ECU:
cranking
after start
idle
knock (turbo only)

After cold-start, there is no timing adjustment made based on chts resistance as far as I know. We already have a few ways to adjust timing from the driver's position.

2. There are four basic forms of enrichment, but you would only be focusing on the coolant temperature enrichment variables when the engine is already warm. This provides basic enrichment on top of the map data from 15.6% to 48.4% based on the CHTS resistance (as every other enrichment variable is based on).

The only way I see your TPS method working is by making a very momentary (maybe half a second) adjustment for sudden throttle inputs. I was hoping you had a circuit for it or something based off the standard POT in a similar TPS that could act as a momentary switch.

[crowbar]

For those of you who would like to try this, just splice a 470-500 ohm resistor in series with the CHTS. Next, take a timing light and check the timing. Set timing to 25-28 degrees for a start.

[crowbar]

The only way I see your TPS method working is by making a very momentary (maybe half a second) adjustment for sudden throttle inputs. I was hoping you had a circuit for it or something based off the standard POT in a similar TPS that could act as a momentary switch.

As I said before, G-E cut and paste some old posts. The design uses an op-amp now.

[Jason84NA2T]

crowbar wrote:

The only way I see your TPS method working is by making a very momentary (maybe half a second) adjustment for sudden throttle inputs. I was hoping you had a circuit for it or something based off the standard POT in a similar TPS that could act as a momentary switch.

As I said before, G-E cut and paste some old posts. The design uses an op-amp now.

And I keep asking you to post the new design, that's what I am looking for... I'm sorry but it seems like you keep ignoring the content of my replies and just jumping into other things.

With 500ohms you are bumping the temp the ecu sees pretty far down into the cold start region, that could explain the timing.

[crowbar]

50 C 122 deg F (770-870 ohm)

This is the region, yes.

I am just trying to let everyone that could be reading, not neccessarily just yourself, to follow the logic of this.

I can draw up a block diagram and a circuit also if you would like. It is not that hard to even design oneself. basically the op-amp can source/sink and 'dictate' the actual signal that the ecu sees.

Many people say that their VG30 cars feel 'great' a few minutes after they start them. On colder days, they say this 'effect' can last longer. They express that the car feels 'flat' after fully warming up. What is happening is that they are briefly in this 'cool' chts resistance. They have some warmth in the engine and are actually closed loop but the car is opening and closing the injectors twice per valve opening per cylinder and the car is also running at a richer mode.

But if you add some timing, then it gets even better. Murders the fuel economy of course.

[G-E]

warming up the cat would be the most likely, the aiv and running retarded timing would help some afterburn effect just prior to the cat

honestly I'd love to be able to sit down and disassemble the code and learn the ecu and whatnot but that one upon a time has passed

I learned 4 programming languages and html on my own, it's not my lack of ability, I don't have that much free time or money

[mcx]

i can recommend this mod..simple toggle switch and the resistor wired..with the switch off its fully stock,with it off, the base timing is upped 10 degrees and the mixture richened...the car feels better,revs smoother...try it before you knock it.

[G-E]

like jason said, it may be fine and dandy down low, but once you max your fuel system (as in what the ecu thinks is max) then it will stop enriching... if your timing is still advanced at that point, ping pong

[crowbar]

Perhaps I did not explain it clearly enough.

You do not have 'advanced timing'. You set the car, at idle, for normal timing after turning on the mod.

As an example:

1. Warm up car, Set timing on car to 20.
2. Splice resistor in series with chts harness.
3. Check initial timing. It should have advanced to 30 or so (mcx can verify).
4. Back up timing to 20 degrees or whatever you like to run at.

So if your car already has enough fuel to begin with, then there is no issue about 'running out'.

[Alex86na2t]

You know what is so so so much easier? And doesn't require tricking the ECU and will give you more headway? Crushing your stock regulator to raise fuel pressure. Also you won't have to spend the 5 cents the resister.

[crowbar]

How much do you crush the fuel pressure regulator to get Simultaneous injection?

[G-E]

use a leakdown tester on the fpr as you crush it, watch the psi rise, stop when happy

[crowbar]

G-E. Its that reading comprehension thing again. Look into it.