E30 Zone

I have an E30 323i with the standard 2.3L M20 except for a 2 1/2" mandrel bent exhaust with headers(or extractors/6 Branch/etc.) and straight through mufflers, and I recently got a new standalone engine management system fitted which removed the AFM completely (now using MAP).

I didn't get the sort of gains I had expected from the new computer so I have had it back at the mechanic a couple of times (also had to get it retuned for the colder weather). I just took it in again to day and he said that he has just thought that maybe the fuel injectors aren't big enough now and that might be why he can't seem to get it running perfectly.

I did a calculation myself (got it from a very good performance tuning book) that was current power (with my modifications I was looking for about 120kw over the standard 110kw) divided by the number of cylinders and multiplied by 7cc/min. For my car that is (120/6)*7 = 140cc/min as the required amount of flow. In that same book they also have a list of fuel injectors that includes the Bosch part no. 0280150208 which that book says is for the BMW 323 and a quick Google search seems to confirm that. It says that they flow 133cc/min. Is that correct for the 323 injectors?

If so then it would seem that they are too small for my current power level (even if I only have 115kw)? Why did BMW use such small injectors, even with the standard power output they are at 95-96% of their capacity.

The mechanic said he had some injectors from a Ford Falcon that he will try to see if it makes a difference but what are the 325i injectors rated? Maybe I should get some of those? The book I mentioned before lists the 323E injectors as 188cc/min so maybe they would be ok?

Thanks,

Aston

aston, something you could try before going for bigger injectors is to upgrade the fuel pressure regulator. on our 323i's the fuel pressure is 2.5bar, i swapped mine for a 325i regulator which is 3bar. it doesnt make a huge difference to the flowrates but it might be enough. i have some injectors from a commodore to go into my car, i'm going to wait til i have the intake manifold off (to fit the 325i throttle body) before i install them though

your car was tuned on a dyno right? how were the A/F ratios at high revs?

Ok, thanks. I'll check out the fuel pressure regulator.

I did get it tuned on a dyno and when I first picked it up the mechanic said that the fuel ratios where perfect. Then when I said I didn't think it was performing that much better he looked at it again and said he had left it slightly lean in the top end because of the problems with the high temperatures when it was tuned. He said he fixed that up and now it should be great. Now that I have taken it back again he said about the injectors and that they are probably why he can't get it rich enough, he wants it to have a slight black haze around the exhaust under full acceleration but it currently doesn't. So really he keeps changing his mind and I never saw the A/F ratios so I don't know. I might get it dynoed somewhere else if I get a chance.

Keep us informed on how your upgrades go, I will be very interested.

Thanks,

Aston

i'll definitely post when i get the big TB on, i'm so keen to see how much difference it makes!

i should mention that i did notice an improvement in performance with the extra fueling - i'm only tuning with a narrowband sensor/butt dyno so it can be hard to know exactly waht is happening in the motor... as you know the stock injectors are barely adequate for the standard motor, i was pretty sure they were at their limit so i jacked my fuel maps way up at high revs/full load to see if i could get anything extra but it didnt improve at all. after adding the 3bar regulator there was a noticable improvement at 5k+rpms, the car will pull hard up to the redline whereas before it felt like it was running out of puff.

if you are going to get new injectors it would probably be best to source them from one of the local big sixes, they will have ample flow and should be cheap. maybe hit some wreckers - you should be able to get a set for $50 (just dont mention theyre going on a bmw!).

If it's any help I think that E30 325i injectors flow 149 cc/min.

Ok thanks Boots_Walker & jay528ise1985, everything is helps . The 325i injectors sound like they would be ok for now but maybe not if I continue to upgrade the engine and in another thread someone said they are about GBP110 each .

So I will see about getting some from a local six like you said and discuss the fuel pressure regulator with the mechanic. I didn't get a chance yesterday.

The ones from a big six won't be too big will they? I have read that big injectors can be hard to tune at low rpm on less powerfull engines because they put out too much fuel?

Aston

Well I just picked up the car but the mechanic wasn't there (just his apprentice) so I said I would ring him later. I was told though that the mechanic hadn't done anything with the injectors or the fuel supply because he "changed some setting in th ECU" and now it was "running beautifully".

On the way home I tried full throttle in 2nd gear and at bout 5000rpm the power stopped, I mean it felt like maybe a huge dip in the power band or something so I changed to 3rd. I tried it again and it felt ok so I was starting to wonder if I had imagined it. I tried a few more times and sometimes it would happen and sometimes it wouldn't. When it did it was mostly about 5600rpm to 5800rpm I think. Anyway it is kind of hard to tell on public roads, I can only really use 2nd gear and to run through the whole rev range I need to start at about 20km/h and go to about 80km/h. I don't have a lot of places to do that around here with traffic and stuff.

I am going to ring the mechanic and see what he says, maybe I'll let my father drive it first and see what he thinks. Could this be fuel system related (injectors/pressure regulator/pump/etc)? Or is there some other problem? I am getting sick of it, I'm thinking about taking it somewhere else. The mechanic I am using seems to know what he is talking about and seems interested in it, he was the one that suggested the new computer, but he isn't getting anywhere with it and at the moment it doesn't really seem like he wants to.

Aston

that sounds like an annoying problem, ignition related perhaps? i once had problems with sudden loss of power up around 5.5k, put in a new set of spark plugs and that fixed it.

the injectors i have are from v6/v8 commodore motors - high impedance and flow roughly 190-200cc's @3bar. they should provide ample fuel for any mods as long as the motor is kept naturally aspirated. tuning at low revs/load shouldnt be a problem, i would only expect that to be an issue for guys running turbo setups needing BIG injectors, eg 400cc.

it sounds like from your posts that you are forever taking the car back to teh mechanic but not really getting anywhere. i would try to be present during the tuning so you can see what is happening rather than just leaving it with him - maybe he cant be bothered and hasnt even touched it or just made a few changes based on guesswork? have you considered playing with the tuning software yourself? all you should need is an old laptop...

Yeah I think I might have a look at the tuning. I don't have a laptop but I have tried with my desktop and the software said something about ECU Locked. I'll ask the mechanic about it, the software doesn't come with any instructions about connecting the ECU to the computer and setting up the com port .

I might wait and see how you go and make some decisions from there.

Aston

astondg wrote:Yeah I think I might have a look at the tuning. I don't have a laptop but I have tried with my desktop and the software said something about ECU Locked. I'll ask the mechanic about it, the software doesn't come with any instructions about connecting the ECU to the computer and setting up the com port .

I might wait and see how you go and make some decisions from there.

Aston

That doesn't sound good, he may be preventing other to mess with it?
I say do some research, get yourselt the cheapest working laptop you can find and try yourself.