Fine tuning

Blaise · Post by **Blaise** » Wed Jun 06, 2012 6:55 pm

As many of you know, my 1977 E12 has undergone many improvements and the work continues.

Most recently, I installed a 3.5L M30 and a 5 speed transmission. As you might have imagined, it has transformed the car from the tired car that it was, to a sweet machine that is a joy to drive.

While I am still messing with the suspension and wheels, I found that the motor is still not running as it should.

Under hard acceleration, it will ping. If I back off to about 80% throttle, all seems well.

I wanted to learn more about what was going on, so I took the car for a base dyno run.
 Here is the result:

<table><tr><td><a href="https://picasaweb.google.com/lh/photo/g ... site"><img src="https://lh5.googleusercontent.com/-0S3N ... 1%2529.jpg" height="494" width="640"></a></td></tr><tr><td>From <a href="https://picasaweb.google.com/1030509870 ... e">5080004 base dyno-5-21-12</a></td></tr></table>

As you can see, something happens around 4,700 rpms that leads to a huge drop in air fuel ratio (gets rich) and a resulting drop in torque and horse power.

Assuming a 17% drop in crank to rear wheel power, the torque result is within the motors specifications. Horse power should be getting up to 178 RWHP, but is not even close.

Jeff Dennis · Post by **Jeff Dennis** » Thu Jun 07, 2012 11:11 am

Blaise, What fuel do you use?

Blaise · Post by **Blaise** » Thu Jun 07, 2012 11:39 am

Jeff Dennis wrote:Blaise, What fuel do you use?

91 octane is the highest available in my area. That's what I use.

I tried an autoparts store octane booster, with no difference in the pinging.

Eric Q · Post by **Eric Q** » Thu Jun 07, 2012 12:31 pm

Does your chart say the air/fuel ratio is 14.17 @ 4300 rpms? If so that seems really lean to me, I would think you should be 13 or less under full throttle.

I have trouble with heat...when the intake air temperature approaches 120 degrees, I have detonation problems then.

Blaise · Post by **Blaise** » Thu Jun 07, 2012 1:26 pm

Eric Q wrote:Does your chart say the air/fuel ratio is 14.17 @ 4300 rpms? If so that seems really lean to me, I would think you should be 13 or less under full throttle.

I have trouble with heat...when the intake air temperature approaches 120 degrees, I have detonation problems then.

Yes, that is correct. I am not sure how it is supposed to be.

Eric Q · Post by **Eric Q** » Thu Jun 07, 2012 4:57 pm

Here is a link to some dyno sheets from the E28 board. Most are turbos (which like slightly richer mixtures) but there are a few normally aspirated with air/fuel graphs.

http://www.mye28.com/viewtopic.php?t=62 ... sc&start=0

Yours looks strange as the car leans out between 3000 and 4500 rpm before the mixture turns around and gets extremely rich. The graph should be much flatter.

Blaise · Post by **Blaise** » Thu Jun 07, 2012 6:07 pm

Thanks Eric.

That was helpful.

anthony · Post by **anthony** » Thu Jun 14, 2012 1:03 am

I am running motronic 1.3 with the 179 ECU and the m30b35 head and pistons.

My general understanding is BMW squeezed everything it could out of the big straight six with this setup but it all worked together. So the cam and the bigger valves go together.

Your setup is different but I cannot explain your problem. Maybe the intake valve is not able to allow enought air through with the cam trimming? Then at the higher rpm, 5500, the air flow speed increases. High Volume through a bigger opening vs faster airflow through a smaller opening. I don't know but this may be the are to focus on.

Unlike a sensor, it is a lot of work to put on a different head just to see.

My first swap was a US m30b34 I never liked it so I swapped in the b35.

johnsugameli · Post by **johnsugameli** » Sun Jun 17, 2012 8:20 pm

Hey Blaise,

What headers are you using as well? In my cars' setup, when they added the chip and cam, they also added headers, larger injectors and a higher output fuel pressure regulator. I was also running 93 octane for a while, and I don't know if it was the octane or the corn, but the engine didn't like it as much as the 100 octane at the track. Very hard to find 93 with no ethanol around here to find out if that was it.

Good luck with it, I'm sure you'll get it sorted.

Jack

Blaise · Post by **Blaise** » Mon Jul 02, 2012 1:21 pm

Thanks

Blaise · Post by **Blaise** » Tue Jul 03, 2012 12:54 am

I tested the TPS harness and could not find any problems. I had previously noted a TPS plug voltage with the ignition off, whereas it should have been on. The voltage is still not per the article that I found. This coming straight from the ECU.

I am starting to wonder if motronic 1.3 is supposed to get battery voltage at the TPS.

wkohler · Post by **wkohler** » Tue Jul 03, 2012 1:39 am

Several things that work one way with Motronic 1.0 work the opposite with 1.3, so you can't use that hiperformancestore writeup for everything.

Unfortunately, that's all I have for you since I don't know much about Motronic 1.3, having zero interest in it or it's "benefits."

Blaise · Post by **Blaise** » Tue Jul 03, 2012 2:04 am

wkohler wrote:Several things that work one way with Motronic 1.0 work the opposite with 1.3, so you can't use that hiperformancestore writeup for everything.

Unfortunately, that's all I have for you since I don't know much about Motronic 1.3, having zero interest in it or it's "benefits."

Thanks Chris, I have a suspicion that this may be the case here. I need to find out definitively if it is a 12volt or 5 volt system.

Would any of you running motronic 1.3 be willing to check your voltage between the TPS plug center pin and either outside pin? With ignition on, plug removed from TPS.

Thanks,

Blaise

wkohler · Post by **wkohler** » Tue Jul 03, 2012 2:14 am

Here's a great write up on the 1.3 manual TPS

http://www.bimmerboard.com/members/deme ... %20TPS.pdf

Falkenberg · Post by **Falkenberg** » Tue Jul 03, 2012 3:41 am

According to this:
http://forum.bmwland.ru/index.php?act=a ... st&id=6521
it should be 5V.
The 5V should be coming from the ECU, so if you have 12V there, either there is a terrible mistake in your wiring, or the ECU is defect / not the right one.

If your WOT is not working, than that might explain why the mixture leans out..

LE: according to this site: the 35-pinmotronic (1.0?) also used 5V signals to the TPS.

LLE: another link with connector pin-outs:
http://84.45.115.78/e30zonewiki/index.p ... tronic_1.0