E36 M3 Iinjectors into an E30 M3

[BlackbirdM3]

I haven't pulled my warmer plugs yet but for a while it seemed that nothing had really changed, then one day the car seemed to run better. No changes. I haven't taken any long trips to see what the mileage was but the car seems to feel a bit brighter. Also, I just installed a new alternator and again, the car seems happier. I'm thinking about a 600 mile road trip toward the end of hte month. That should say a lot.

Will

[E30_Dave]

Will,

Interesting. The only thing I can think of that might change with replacement of the alternator would be the engine earthing. Now I think if it, I don't actually know where the earth strap between the engine and the body is. Mine seems fairly happy at the minute, but like you, I haven't yet had the new plugs out. Let me know what yours are like after the road trip.

Cheers,

Dave.

[BlackbirdM3]

There are a few places it grounds. None of which I messed with. The alternator grounds to the dipstick support, and I also ran a separate ground to the block. The block grounds to the body off the transmission bolts, but I also added a ground that comes off the back of the head and goes to the shelf where the coolant tank is. (Because you can never have too much grounding.)

I had a couple of weird issues yesterday. I went to start the car and it would crank but not fire. I turned it off, waited a second, then tried it again with the same results, then stopped, and tried it a third time where it fired up and ran fine. It did this twice yesterday. It was very odd. I wonder if my flywheel triggers are starting to go bad? This morning it fired up instantly. Drove great on my way to work.

Will

[mavrikno13764]

Will,

Are you still using the 028020155715 Injectors with the hotter spark plugs?
Or did you switch to the 0280156048 Injector?

Hope you get your car sorted out.

B.Jay

[BlackbirdM3]

I'm still running the 0 280 155 715 injectors. I think my biggest issue is that the engine is tired, and needs a rebuild.

I will say the car starts (usually) far faster than with the stock injectors. Usually it lights off in one or two revolutions of the crank (the way a modern car should)

Will

[BlackbirdM3]

So after doing 800 miles with dismal fuel economy, I think I'm going to install my stock injectors and see what happens. I like the way the car starts on the modern ones, but it just runs too fat on the freeway. 23 mpg is not cool, especially when I know it used to pull 27.5-28 at 70 mph.

Will

[E30_Dave]

Will, that's fair enough, and many thanks for giving this a try, it's been an interesting exercise.

I'm still playing around with different injectors, although I had a problem with the fuel pump refusing to work last week, which left me trying to get to work - I have a replacement pump on order. I changed from the Bosch X5DTC sparkplugs to the slightly hotter Y6DC plugs used in the E34 M5, but the car quickly began to protest, and I have since removed the 155715 injectors. I replaced them with 0280156048, which did improve matters, but I still wasn't happy with it, so I decided to try to find a split flow injector. I had looked at 0280155865, which uses a USCAR connector (which may still be a possibility), but I soon found 0280156211, which is used in turbocharged Rovers. Interestingly, the operating pressure of these injectors is 3 bar, but the pressure regulator on the Rover gives a maximum pressure of 3.5 bar. I installed these injectors at the weekend, and my car once again drives as it should. BTW, whilst I was at it, I got the sparkplugs out and they looked so much better. How have you found the hotter plugs ? I also wonder how great an effect fitting a fresh fuel pump will have on things.

One final thing, is the vacuum pipe on your fuel pressure regulator in good condition ?... I replaced mine at the weekend, as it was looking a bit ropey !... I had a major air leak develop suddenly on that pipe a number of years ago, and it was a disaster for the fuel consumption.

[BlackbirdM3]

I didn't pull the plugs to have a look. Based on the mileage I figured they would be sooty. I might pull them next week and have a look-see after I get some miles on the stock injectors. The regulator hose looks ok, but I should replace it. I also replaced my fuel pump back in early December. (It began working intermittently one night and I had a new one on hand.)

I think the injectors I pulled last night could work really well if the engine were tuned for them. The other possibility is that they might be fantastic with my Evo2 intake cam installed. With my IIGO SS91 chip its thought that the chip would be a little lean for the cam, but with the injectors as rich as they are, with the cam, it might be a very good combo. I might investigate this in the future.

At this point I'm going to monitor my fuel economy and see if it improves. If not I'll guess that my motor is very tired and leave it at that. I'm not done with the injector experiment, but at this point I'm putting it on hold.

Will

[BlackbirdM3]

I've had the stock injectors in the car for the past week. The fuel economy has gone way up. I got 30.5 mpg on my way home from where I keep the race car yesterday (about 25 miles) Much less soot on the exhaust pipe tips as well. Its not as snappy with these injectors, but the mixture seems to be much better. I think they will be worth a try with the bigger intake cam.

Will