Increased max rpm - need to adjust timing?

[BLACKCAT]

In the last few days I installed a modified ECU in my auto 7MGE.

The shift points at WOT have been increased from 6200 to 6700 rpm & the engine pulls to this new redline in 2nd quite well as I am running the BC264 cams & new valve springs.

Would I have to increase the static timing by 1-2 degrees (currently 13) for the extra piston speed & what to look for on the spark plugs if I have incorrect timing?

 

[AJ'S 88NA]

In the last few days I installed a modified ECU in my auto 7MGE.

The shift points at WOT have been increased from 6200 to 6700 rpm & the engine pulls to this new redline in 2nd quite well as I am running the BC264 cams & Comp Cam valve springs.

Would I have to increase the static timing by 1-2 degrees (currently 13) for the extra piston speed & what to look for on the spark plugs if I have incorrect timing?

I have mine at 15 deg, I've always run premium though, I'm sure you are slso.

 

[sarinas_dragons]

Hey AJ, what does changing the static timing do?

I was under the impression the ecu was triggering spark, no?

I know there are alot of mysteries to discover about our cars but I just don't know how to approach this. Does the ecu get tricked into allowing more advance by resetting the static timing?

I'm familiar with what links will say on the subject. I was just wondering is your own experience proof to you that the ecu ignores a stock timing map if you advance the distributor?

Or alters? Help me to understand this.

 

[AJ'S 88NA]

Hey AJ, what does changing the static timing do?

I was under the impression the ecu was triggering spark, no?

I know there are alot of mysteries to discover about our cars but I just don't know how to approach this. Does the ecu get tricked into allowing more advance by resetting the static timing?

I'm familiar with what links will say in the subject. I was just wondering is your own experience proof to you that the ecu ignores a stock timing map if you advance the distributor?

Or alters? Help me to understand this.

From what I understand it's the initial timing, jumper wire, set dist., etc. The Ecu also adds an amount of timing as needed, there's different things that causes the ecu to add timing. I don't understand all of it myself but I have for a long time had my timing set at 15 deg btdc, and like I said I've always run prem. fuel.

I would like to know the total timing, initial plus what the ecu adds, at WOT. I haven't been able to find that info. I can't say if the ecu ignores the map if you advance the timing, I don't think so, I believe it has those maps and doesn't alter them.

JJ would know the picticulars, hint, hint.

 

[amichie]

Have a look at technical article 40 on this page

 

[AJ'S 88NA]

Have a look at technical article 40 on this page

What page are you talking about?

 

[amichie]

What page are you talking about?

Ooops.

This page

http://www.autoshop101.com/

 

[sarinas_dragons]

What I have figured out about the 5M and 6M goes for the 7M.

I've mentioned that the overall ignition event could be described as beng divided into BTDC and ATDC.

It may sound counter-intuitive but it's not, the benefit of the ignition event ends as the piston acceleration increases. This helps us to apply an OHROT, or old-hothodder rule-of-thumb, the esoteric 5/9ths timing event understanding.

If we know the point of peak cylinder pressure ATDC then we consider the entire timing event as nine parts with, 5 parts occurring before top dead center and four parts happening after top dead center.

The point where the piston hauls ass is important. The engine crank and rod geometry is important. The camshaft events are important. But the factory tells us to set the distributor for a reason.

To a known mass of air is added fuel. This injection process is timed to the ignition, too. It is difficult to grasp the inter-relation of all these events. Even more has to be consideed for just a basic education. The inline six has a pattern of engine pulses. in one complete cycle all the cylinders will fire. This creates a wave of pulses all exerting on the crank. The pulses look like a heartbeat-type wave pattern. Up, then down and back up the pulse will go.

Noticing the shape of the pulse is important. All engine designs exhibit power pulses. Different designs have different rates of pulses per cycle. The frequency of the pulses also shapes the wave.

For the 7M the initial pulse is caused by ignition and the development of the deflagration process. At the first instant of spark the piston is so high in the cylinder that it is almost to the top but space remains. The piston is also decellerating.

This moment is one of study for me.

From the air mass a fuel mass is about to be injected. When and how much is subject to analysis by the ecu. But let's say we actually know at full-load the number for the fuel mass in whatever scale we need (molar weight). To the air is the exact fuel requirement injected. On what air mass was the fuel derived?

Daunting as this may seem it is just this understanding we need. We have a knowledge of the air mass. We are going to presume full-load and a resultant 12.5:1 AFR. Then for one power-stroke can we determine what the ecu is doing? Continuing, we now pretend we not only know the air and the fuel that will be injected, to what conditions is the intake charge subject?

As the piston ascends there is only intake air for a certain period of time. This is due to the injection being timed just before the ignition. It is cumbersome to consider the time component but at 6000 RPM the crank-speed in degrees-per-inch is around .000028 seconds per degree. This is fifty power strokes per second.

As the piston moves closer to top dead center the pressure increases and so does the heat. Alot of sciences allows us to figure out the intake charge's reacton to these changes. For a given intake mixture the factory established a look-up table for a variety of inputs. We're still considering full-load. The conditions are repetitious, yet only one of these repetitions we want to fully understand. So, the fuel is finally in the cylinder and being compressed and heated. At a certain pressure and temperature the intake charge will detonate....

For the sake of establishing a contrast remember the above example and also consider idle speed for a second.

The ecu controls this deflagration, too. The engine crank speed are lower. There is no load on the engine.....or is there?

Here is where the knowledge of the shape of the power pulse can effective for our understanding-

The power pulse has a strong positive or upper beat, then it starts to weaken to the point of zero and even below. Where this peak is relates to crank degrees. It is the peak cylinder pressure. It cannot last forever and is described as lasting for a certain number of degrees as affected by the rod and crank geometry.

By plotting the piston position per degree for 720 degrees we can see where this point of peak cylinder pressure occurs. The acceleration is occuring at 18 ATDC. If this is the 4 part of the 9 then what is the 5?

 

[CRE]

I would like to know the total timing, initial plus what the ecu adds, at WOT. I haven't been able to find that info. I can't say if the ecu ignores the map if you advance the timing, I don't think so, I believe it has those maps and doesn't alter them.

JJ would know the picticulars, hint, hint.

I don't know if JJ has any sort of published timing map from Toyota as to the specs of the 7M. Due to the nature of the timing mechanism I myself would rather rely on actual measurements... Which, by the way, you have the tools to measure and log (especially if you wired up your MAFT Pro per my diagrams).

I haven't got the time to go through the rest of this thread right now though.

 

[AJ'S 88NA]

I don't know if JJ has any sort of published timing map from Toyota as to the specs of the 7M. Due to the nature of the timing mechanism I myself would rather rely on actual measurements... Which, by the way, you have the tools to measure and log (especially if you wired up your MAFT Pro per my diagrams).

I haven't got the time to go through the rest of this thread right now though.

Keeping an eyeball on me again CRE is such a great guy to have looking over your shoulder keeps me in line :biglaugh:

Of course I wired the Maft -Pro the way you said to, wouldn't have been able to wire it any other way, wouldn't know were to start anyway.

I did see something related to timing on the laptop, but had put it back somewere in my little brain. I seen while playing back a log a number flash a couple of times, but thought that since I didn't wire it up for timing control that that figure didn't mean anything. And you know how I figure when it comes to computers:1zhelp: What would it be called?

BTW CRE, would you want to see a log with the tracking turned off or on. You remember I lost my logs in cyber space somewere and I will need to make some time to log a couple of runs. You're so lucky to have your's as a DD and you can play all the time with it.

Sarinas, that's a lot for me to deciper, I'm from the old school, you know, readin,rightin,rithmatic, I just try to go with what works. Some of it I do understand, it must be soaking in, CRE's a pretty good teacher. I'm trying my best to understand all this about intakes, headers, ITB's all the other tech stuff as to what works the best and how, but sometimes I get lost.

 

[BLACKCAT]

I put a new plug in #1 & took the car for a quick blast, covering only about 2km.
Two bursts in 1st to 6400 & one to 6700 in second & shut it down within a minute and set at 15 degrees timing.
Let it cool down for half an hour before removing the plug.

Too much timing?

 

[CRE]

I hope you're using something more reliable than the stock tach to monitor your RPM... they're not precise at all.



AJ, the timing monitoring and timing control are two different parts of the MAFT Pro you can run timing monitoring without running timing control... but you need to run timing monitoring to use the timing control feature. My diagram wires everything up for timing monitoring. Just look at the value TM on the MAFT Pro's Sensor Monitor screen to see where you're at at any given point. Unfortunately, the software version you're running you can't correct the base timing to anything over 10ºBTDC, so if you're running 15ºBTDC for base you'll and the MAFT pro thinks base is 10º you'll need to add 5º to all of the readings.

Logging WOT values should be pretty easy. I would do it using AFR tracking for consistency and log runs with the desired AFR set at 11, then a log with it at 11.5, then at 12 and so on up to 13 or 13.5. Keep a close eye on your temps and give the car time to cool on the leaner runs.... although for just one or two runs you'll be just fine.

 

[amichie]

I put a new plug in #1 & took the car for a quick blast, covering only about 2km.
Two bursts in 1st to 6400 & one to 6700 in second & shut it down within a minute and set at 15 degrees timing.
Let it cool down for half an hour before removing the plug.

Too much timing?

6700rpm in second sounds exciting. What speed is it doing then??

 

[BLACKCAT]

6700rpm = 125 km/h.

 

[BLACKCAT]

6700rpm = 125 km/h (78mph).

 

[AJ'S 88NA]

I hope you're using something more reliable than the stock tach to monitor your RPM... they're not precise at all.



AJ, the timing monitoring and timing control are two different parts of the MAFT Pro you can run timing monitoring without running timing control... but you need to run timing monitoring to use the timing control feature. My diagram wires everything up for timing monitoring. Just look at the value TM on the MAFT Pro's Sensor Monitor screen to see where you're at at any given point. Unfortunately, the software version you're running you can't correct the base timing to anything over 10ºBTDC, so if you're running 15ºBTDC for base you'll and the MAFT pro thinks base is 10º you'll need to add 5º to all of the readings.

Logging WOT values should be pretty easy. I would do it using AFR tracking for consistency and log runs with the desired AFR set at 11, then a log with it at 11.5, then at 12 and so on up to 13 or 13.5. Keep a close eye on your temps and give the car time to cool on the leaner runs.... although for just one or two runs you'll be just fine.

Thanks CRE. I don't see a TM on the Tuner pro, I remember seeing one on the Maft-Pro I think, I'll check.

 

[CRE]

Thanks CRE. I don't see a TM on the Tuner pro, I remember seeing one on the Maft-Pro I think, I'll check.

Just look at the value TM on the MAFT Pro's Sensor Monitor

It is in Tuner Pro as well, just can't remember what it's named in the graphs.

 

[AJ'S 88NA]

It is in Tuner Pro as well, just can't remember what it's named in the graphs.

I think it's timing Monitor in the Tuner-Pro.
I'm not getting any readings on either, I once in a while I see something register.

 

[CRE]

I think it's timing Monitor in the Tuner-Pro.
I'm not getting any readings on either, I once in a while I see something register.

If the signal's intermittent then either the wiring has a break, the harness pin has spread and the connection at the MAFT Pro is sporadic (this happened to me with a couple pins, by the way, the fix is easy), or you have it monitoring the wrong line.

 

[sarinas_dragons]

Part of the study was the timing of the ignition flamefront.

The best information says the flamefront speed will vary with pressure and temperature. Since the pressure and temperature are changing every moment it is by moment one decides to analyze this part of the engine operation. I use the crank degrees to time the events.

The seconds-per-crank-degree is rpm dependent. Making a decision to what rpm you are considering a change is the best way to begin. Your cams are what will determine your engine operating range. Cam and intake performance analysis requires the specifics on what lift, duration, intake installed centerline, lobe separation angle.

This chart shows the relationship of the torque peak, horsepower peak, and redline to the intake charge speed. Notice the values for the stock performance- if a cam change is desired the analysis of the upgrade in comparison to stock allows one to 'see' the improvement valve lift has on intake charge speed.

What will happen is the rpm that the charge speeds occur will shift up in rpm. All of the timing of the intake charge speed to the piston speed that determines the changes one needs performed in porting modifications to the head for increases in rpm are based on this specific knowledge. How to get that knowledge is a routine of filling in the blanks.

Knowing the engine rpm range then can enable the study at what rpm to consider for ignition timing changes. I use 92 ft/sec for the flamespread during the ignition event. Being wlling to go throught the extra rigor of figuring out at the flamefront at plus or minus five percent would provide a range but it is alot of effort.

So at 92 ft/sec the time it takes the flamefront to move from the sparkplug roughly in the combustion chamber's center to the margins of the piston is ________? This combined with the rpm dependent number of the seconds per crank degree, the event can be timed accurately. And there are the options of the LSA and its effects to consider.