I'll start off by saying that I have printed out heaps of information from this board on tuning the 730 and have read through it a couple of times and am starting to get some sense from it. Finally have less school work so ECM tuning is really taken my interest. Have not started to burn a chip yet but trying to get all the information I can before I get stuck into it, which will hopefully be soon because I want to get some tests done.

I do have a couple of questions which are:

I have an AutoXray scanner which can take 28 second snap shots of data in 1 sec intervals. I now know that is not the best for getting data but it will have to do for the time being. I had a look at my readings from a while back and my MAP readings are in VOLTS.

I had a look in my AutoXray booklet and it says MAP (kPa or Volts)

Range : 10 to 105kPa or 0 to 5 volts

I however don't have a function to change from Volts to kPa, or is there one anyone know? I have not been able to find it or any reference to it.

Anyway so will I have to convert the Volts to kPa.

So given the above information

105 -10 = 95 / 5 = 19Kpa per volt, is this correct or someone please correct me.

5v = 105kPa
4v = 86kPa
3v = 67kPa
2v = 48kPa
1v = 29kPa
0v = 10kpa

My second question is

I read a post by Tim I think it was where he was describing how he goes for a drive 2-3min and gets data and then makes changes accordingly to the Block Learn. If you have an auto do you drive the car in D or in OD? Or it does not matter? I drive the car in D mostly as I don't go much on the highway so leave it in D right? Probably a stupid question but just had to ask

Michael

PS.

I have the suspision that my car is running rich but I just has a look at some data I captured a few months back and it shows the opposite. The reason why I say I think I am running rich is that my plugs are black and I have an excessive smell of gas ocming out of the exhaust.

This is a slice of data

Throttle Angle % 8 8 8
Engine RPM 1635 1641 1638
Block Learn 144 146 146
Integrator 135 134 132
MAP Sensor Volts 1.41 1.41 1.41 (26.79kPa) from above formula
Speed MPH 38 37 38


A BLM above 128 means the ECM is adding fuel yet my rich/lean Flag is stating RICH in these data fields.

Am I missing a point here?

 

Question 2-You can do both. If you drive the same speed on the same grade of road, 3rd gear will give you data for one relatively constant load and 4th gear will give you different load data for the same speed. Make sure you record TCC control when you do this because it plays into engine load.

 

On Volts to KPA this is what I do.
See what the volts are before starting the car, most times for me its 4.72 to 4.74 but I have seen it as low as 4.68. It can change do to weather and altitude so you need to get what the voltage is before starting the car.
Now you can get what the voltage is at the rpm's that you want to change and divvied that by what the voltage was before stating the car.


Say I have 3.78 volts at 1500 rpms.
3.78 -:- 4.72 = .80008 this = 80 KPA

 

So it looks like you are running lean, might be the O2 sensor is bad.

 

Z_Ghost , thanks for the conversion idea easily done, just wish it had the kPa read out on the scanner save some time.

Yeah well I got some data again today and BLM is above 128 Lean/Rich flags are both on readouts of above 128. But really if the BLM is above 128 then there should only be the Lean flag displayed yet I do get the Rich flag there too.

My spark plugs are black sooty so maybe the ECM is adding too much fule and is causing the black plugs. Maybe he is just over sparying it a little too much. Has to be something as black plugs and an indication of running lean don't make any sense.

BTW my MAP value before start is 4.9V

Here is what I got

RPM MAP Volts kPa BLM Int Speed
1585 2.29 (47kPa) 145 141 23
1601 2.48 (51kPa) 146 135 24
1820 3.07(63kPa) 130 134 26
1890 3.05 (62kPa) 132 154 28
2052 3.43(70kPa) 132 139 30
2087 3.35(68kPa) 128 160 32
2087 3.19(65kPa) 129 159 35
1813 2.72(55kPa) 133 152 37
1649 2.95(60kPa) 134 142 38
1727 2.8(57kPa) 136 153 40
1793 2.72(55kPa) 137 150 41
1858 2.56(52kPa) 138 144 43
1927 2.5(51kPa) 139 145 44
1977 2.43(49kPa) 139 140 45
2035 2.35(48kPa) 141 138 47
2078 2.31(47kPa) 128 137 48
2118 2.25(46kPa) 130 157 49
2160 2.17(44kPa) 131 158 50
2214 2.11(43kPa) 132 156 51
2254 2.05(41kPa) 133 154 52
2280 1.09(22kPa) 135 154 53
2014 0.43(9kPa) 128 119 50
1700 0.52(11kPa) 128 111 43
1310 0.84(17kPa) 128 128 36
894 1.19(24kPa) 129 129 30
934 1.09(22kPa) 129 126 23
788 1.39(28kPa) 127 117 18
868 1.37(28kPa) 135 117 12
715 1.6(33kPa) 133 116 8

 

Yea I wish Easy showed KPA instead of volts.

My O2 flag goes rich- lean even with the blm above or below 128, the computer is adding and subtracting fuel all the time so it constantly changing.

With the plugs looking black and sooty you are running way rich and the blms should be below 128. If the car is stock and in good running order it should not be that rich.

When was the last time you changed the O2 sensor? If the blms are above 128 then the computer is adding fuel and from what you say the plugs look like it is going to far or not getting the right info from the O2.

It seems like you have a problem that needs to be fixed before you start burring chips.
Have you removed the screen from the maf?
Do you have bigger injectors on the car?

 

Z_Ghost,

That makes sense that the ECM is always adding and subtracting fuel, mine also keeps on toggling between Rich and Lean.

As with the car it is not stock, well it is and it is not. I have an 86 IROC TPI 4spd. It has been converted to MAP, I rewired it myself the conversion was done by a mechanic who did it 5 yrs ago. I have had the car for 1.5 yrs and fixed up the wirring. because they did not swap ECM, Memcal, Knock sensor etc. I did all that and that alone got me 60mph more out of a full tank!

I also made a cold air intake for it and other than that it is stock. Well from what I know it is stock. The engine that is in there is not the original. There is a new reconditioned engine in there with about 20,000 miles on it. I looked at the prefix number and going by the number it is a 305. So I am pretty sure it is a 305 as I also ordered a 305 Memcal for the car also, so if it was a 350 I should get a SES code.

The O2 sensor is pretty new replaced it when I got the car so it is about 1.5 yrs old too and only about 10,000km on it max! As I don't drive the car a great deal I ave another car for a daily driver.

Injectors on the car should be the stock ones. When the reco engine was put in I think the engine was made to stock standards. It goes pretty well and oil pressure tops out at 60 psi when cruising and at lights it will drop to about 40-45 all at operating temperature.

That's about all the info on my so you don't think I sould try and play around with the VE tables and try to get them around the 128 mark yet?

BTW today was a warm day and when I opend the fuel tank cap air rushed out. Had air build up in the gas tank what causes that? I think I might need a ventilated cap as I have also read on this board that having pressure in the tank is not good for the fuel pump.

Mike

 

I do not think that adjusting the ve will help, because if most of the blms are over 128 then you need to add to the ve to get them to drop and the plugs are showing rich you said. You might have a vacuum leak, I know that an exhaust leak will mess up the O2 readings.

When I first started scanning my car the blms were running around 118 to 120 and I raised the injector constants to get the Blms up to were they run 126 to 128. My plugs have always looked clean with a hint of tan on them. You sure that the plugs are not oiled fouled or that they might be to cold of a plug.

Did you change the computer, the maf computer is not the same one as the SD computer (730). I do not know if a 305 Memcal would work on a 350.
Hopefully some of the guys that know a lot more than me will help out.

 

Then I might have to add to the VE to get them down to around 128 or is it not worth it.

Yes teh computer I changed too. Back to the plugs yes they might be oil fouled as there is usually oil on the thread. But also when you smell the plug they have a strong gas smell.

Too cold of a plug? Maybe damn I am not sure what heat range these are BTW anyone know the heat range of plugs for our cars? I will check with the store where I got them from and double check they are the correct heat range.

Also one point you made about the exhaust leak stuffing up the O2 readings. Well I might have an exhaust leak somewhere but if it is one it must be small. I remember once a mechanic said you have an exhaust leak I said do I? He said yeah but did not take it any further. Might post in the general tech section and ask what is the best way to find an exhaust leak.

I did when I got the car seal one pin hole in the exhaust near the muffler so maybe there are more somewhere. Would a small exhaust leak mess up the O2 readings by a lot or just a fraction??

Mike

 

I do not know how much an exhaust leak it would effect the O2, but I remember some having a problem like this and he had a exhaust leak at the donut gasket. He replied back that he replaced it and that fixed it.

 

I will check for an exhaust leak but I have some news. I pulled 2 plugs out today to check if they are still black and fouled like they were always and guess what. They were not fouled they were a greyish bronish color so they looked like they should. But on all I still have oil on the threads. I don't get any smoke on start-up though so don't know what is going on there.

The only explanation I can think of that the plugs are not fouled is that I ran some injector cleaner through the car last tank. Maybe the injectors were dirty and stopped them from operating properly or something? I also cleaned the IAC and idle is smooth as well since them. So those are the only 2 things I done to the car to stop the fouling of the plugs.

So I am running a little lean, do you suggest I adjust the BLM's a little higher to get a little more fuel going?

I am thinking about getting a Cam and Headers put in so maybe I might leave it for now and adjust the BLM's once the Cam is in.

Mike

 

That sounds better and yes I would adjust the VE # a little higher.
Do it like Traxion said to in here:
https://www.thirdgen.org/techbb2/sho...threadid=39254

I know you have read that. You might want to raise the fuel pressure first if you do not have it to high and have an adjustable fuel pressure regulator. That will richen it up some and might get you a lot closer to 128.

I have an conversion table that I made up, it shows the BLM and the # you need to multiply to the ve at that RPM Vs KPA to get the new VE #, so if you want I will send it to you. It's a microsoft word doc and it helps to make it a little easer to change the ve.