Any electronics/fuel injection ECU wizards out there?

Post by **pettaw** » 25 Apr 2005 03:55 pm

Any idea how to modify this?

To make it run less rich at first start, so the engine doesn't half choke itself to death, for some reason all the 360 injection engines do it AFAIK, so there must be a design flaw. I don't really want to go to the trouble of rebuilding my engine only to have neat petrol washing down the bores spoiling it.

Post by **5lab** » 25 Apr 2005 04:10 pm

they probably do it so they'll start in extreme conditions (sweeden)

Post by **jtbo** » 25 Apr 2005 05:31 pm

My answer is:

So you can:

Post by **Chris_C** » 25 Apr 2005 06:05 pm

Lol!! Is that the Jettronic board Andy? If someone has the schematic I can give it a run through... but it's going to be a mission I'd have thought. Once it's sussed, it'll only be a resistor or capacitor change.

Post by **huskyracer** » 25 Apr 2005 06:44 pm

I think the real key here is to find someone that can read the eprom, and work out which bits control cold start as it must have some sort of table for coolant temp compensation. Its just a question of finding it!!

Post by **pettaw** » 25 Apr 2005 07:17 pm

I don't think its that clever, Husky. From what I can gather its just a very simple analog EFI system. No error codes and no tables. Apparently its all done with a few resistors and capacitors. I could be wrong though.

I talked to a guy at Bosch who was talking about a similar problem on BMWs, and a fix using a resistor in parallel to the coolant temperature sensor, using a relay of some sort, he said it had something to do with the starter.

So I've rigged up a relay that shorts the input of the ECU to ground through a resistor when triggered by the start signal. I've tried a 470ohm resistor which didn't seem to make much difference, so tomorrow I'll try lower resistances. The guy at Bosch said about 2 ohm, but the original sensor is at 20Kohm at 20c.

The weird thing though is, I reckon all 360s with the B200E engine do it.

Post by **Chris_C** » 25 Apr 2005 08:34 pm

I can't see a programmable chip on there, but whithout a closer look... The few chips that are I think are op-amps, and with that amount of RC stuff going on, it would make sense... Andy... is it replacing the 20k for a 2? thats going to do something surely! Would like to see how it does work.

Post by **huskyracer** » 25 Apr 2005 09:09 pm

sorry, didnt look to hard at the picture to be honest, just assumed it would have a chip.

I havent worked on anything with this type of ecu, can anyone give me any more info? surely if you can modify the warm up you can mod other areas

Post by **pettaw** » 25 Apr 2005 09:33 pm

Chris_C wrote:I can't see a programmable chip on there, but whithout a closer look... The few chips that are I think are op-amps, and with that amount of RC stuff going on, it would make sense... Andy... is it replacing the 20k for a 2? thats going to do something surely! Would like to see how it does work.

Yeah, the Coolant temp sensor is located in the cylinder head, and the resistance goes down with temp, so I reckon by effectively wiring a low resistor in parallel, I can fool the ECU into thinking its a hot start, hoping that the cold start injector which runs independently of the ECU control, will put enough petrol in to make it go. I've only got the relay energized whilst the starter is turning at the moment, and with a 470R it worked OKishly. Tomorrow, I'm going to try it with the 100R which I've already got to hand, and then off to buy some really low resistors.

Trouble is testing like this, you only get one chance and then you have to go away and let the car cool down again.!

Everything is adjustable from max RPM to max time of injector ooening, the shape of the pulses, warm up enrichenment, post start enrichenment, over run richness, the lot. The trouble is you need to know which resistors/capacitors to change and I don't!

Trouble is I wouldn't know where to start getting info on the Bosch LE-Jetronic system.

Post by **Fuse** » 25 Apr 2005 10:10 pm

There's some info about LE-jet.

http://users.exis.net/~audserv/Injection.html

Post by **pettaw** » 25 Apr 2005 10:18 pm

Yeah I saw that, trouble is that the circuit boards look nothing like the ones in my car. To start with, there's no upper and lower board. Just one on mine. And all the pin designations are wrong.

Still, it describes the theory.

Now, let me at those pesky resistors

Post by **grizlyadams** » 26 Apr 2005 09:56 am

im with the fin...coughmegasquirtcough

Griz

Post by **5lab** » 26 Apr 2005 10:05 am

i dont get it..

why at full throttle (presumably the colum down the side) does the amount of fuel not rise thruout - surely the '91' fuel mesurement (i guess thats what it is) would mean there was a big 'flat spot' ioin the torque.. also there is more fuel going in if your foot isnt all teh way down... i'm confused!

Post by **jtbo** » 26 Apr 2005 05:11 pm

Mostly because map is not yet finished, there is odd spots all around. Today I did another 50km driving and adjusting.

Current map is bit better than that in picture, but now I need to tune it manually and then I would need really long trips to make all bins perfect, but I'm not going to make it any better until I get new cam installed, that will be next tuesday.
Currently it has clearly more power than when I had last dyno run.
Final tuning need to wait then as I need to move soon.
Water pipes of this apartment are gone bad, they leak inside of structures and they need to open floors so I think better to get better apartment.

Post by **pettaw** » 26 Apr 2005 05:33 pm

Blimey, sounds as though you've got alot on your plate, good luck with it.