E28 Injectors?

[e28power]

Does anyone know the LB. rating of stock 3.5 M30 injectors from and e28? I think they're 16s but i'm not sure and I can't find a spec anywhere. Now, are there any good inexpensive upgrades to increase fuel pressure? Thanks.

Ian

[thejlevie]

The only reason I know of to fiddle with injectors or fuel pressure (assuming the injectors are working and the fuel pressure is with spec) would be if you've done something that seriously increases the mass flow through the engine. Like a supercharger, turbocharger, or high-flow NoX system. Is that the reason for the question?

[e28power]

The reason I asked was because when it was on the dyno it was running too lean and robbed me of about 20hp, but fuel pressure is in spec, and my stock injectors are fine.

[Mr Project]

The late E28 motronic system is very similar to the E34 535i system, IIRC. On the E34, you can use a 3.5 bar FPR from a Porsche 944 as an upgrade from the stock 3.0 bar unit, and 19# Bosch Mustang injectors are a direct fit (though stock E34 is already around 19#). I've got 19# Bosch Design III mustang take-off injectors in my car. It runs better than ever, and they seem to have helped my fuel economy a little as well.

[e28power]

Great! thanks for the help, I'll try that out soon.

[thejlevie]

A lean run might be as a result of a bad MAF if the fuel pressure is within specs. Or it could be partially clogged injectors. The ECU needs to know how much air the engine is ingesting to set the correct mixture and the injectors must deliver the fuel pulses correctly. With all of the sensors that feed the ECU operating properly and good (stock) injectors the engine shouldn't run lean. So I'd figure out why it is running lean and treat the disease rather than trying to treat the symptoms.

[e28power]

it's not the MAF, I tried two different ones with the same results, but a good guess nonetheless.