E30 injector problem/ cold start misfiring

[Murachanian21]

Hey I have a 87 325e swapped to a 325i stroker, when I first did the swap I got a used “i” head with everything else you need for the swap. The only thing that was weird is that I had m30 injectors installed on it. So I was running it like that and it seemed to be running really rich! It was blowing smoke shooting flames and 2 stepping. So I recently just got the stock 325I injectors and install them. Now the car runs way better no more flames or after fire that sounds like gunshots but the only thing is is when I first start the car it seems like it’s only running on three cylinders until it’s warmed up. The idol searches and if I try to give it gas to help it warm up the RPMs drop so I basically have to just sit there until it clears itself out it takes about 5 to 10 minutes so I’m not sure if maybe I have the injector plugs hooked up wrong or if it’s a fuel pressure issue any help will be highly appreciated ! It didn’t have any cold start problems before I switch the injectors

[bmwdirtracer]

Hi, and welcome to the forum.

As you seem to have discovered, it's not generally a good idea to swap injectors without research. During this M20/M30 era, there were high impedance and low impedance injectors, and injectors which varied in volume by massive amounts, I used to have a chart, now long gone.

However, if you'll allow me, let's cut to the chase. You have a somewhat unknown engine and set-up. It misfires like mad, cold, but seems to clear up when it's warm? You don't know the condition of your recently installed injectors, to don't know whether they're all firing, or how much fuel they're injecting, if they are firing. It won't take throttle until warm.

Please, bear with me - I'm not trying to be rude at all, I'm just being a technician....we do this to each other, I promise. You did an engine swap, I'm just going to have to treat you like a tech, or maybe a racer.

Have you investigated your engine coolant temp sensor (the one that connects to the DME, not the gauge sensor). You're running a stock AFM?

Does the "e" motor run the same AFM as the "i" motor? I don't think so. Are you running the correct computer, for the sensors involved?

Did you do your research carefully, for this very respected swap?

You need to make sure that the injectors match the computer. You need to just go ahead and replace the DME's coolant temp sensor, because it's like fifteen bucks.. I do not remember whether this is the blue or the brown one. To know this, unplug one of these two when engine is warm, and ignition is on (doesn't have to be running.) Unplug one of those 2....if the gauge goes to bottom, that's the gauge sensor....it's the other one you need to think about.

Or maybe you really just need a smoke test of the intake system? That would truly be my first step.

When was the last time the distributor cap, rotor, plugs, and wires and plugs were replaced with stock OEM parts?

You see, we don't have much computer support in those days.

Just so you know, if you send your stock injectors to RC Engineering, they'll give you "before and after" computerized resuls, ultrasonic cleaning, and injectors which flow and appear much better than new OEM units ever will .

Was the TPS dismounted during this swap? Because TPS has adjustability. Still, I'd want a smoke test, make sure all wiring diagrams and components match respected swap combinations.

All the best.

[Murachanian21]

[QUOTE=Murachanian21;30002055]Hey I have a 87 325e swapped to a 325i stroker, when I first did the swap I got a used “i” head with everything else you need for the swap. The only thing that was weird is that I had m30 injectors installed on it. So I was running it like that and it seemed to be running really rich! It was blowing smoke shooting flames and 2 stepping. So I recently just got the stock 325I injectors and install them. Now the car runs way better no more flames or after fire that sounds like gunshots but the only thing is is when I first start the car it seems like it’s only running on three cylinders until it’s warmed up. The idol searches and if I try to give it gas to help it warm up the RPMs drop so I basically have to just sit there until it clears itself out it takes about 5 to 10 minutes so I’m not sure if maybe I have the injector plugs hooked up wrong or if it’s a fuel pressure issue any help will be highly appreciated ! It didn’t have any cold start problems before I switch the injectors[/QUOTE

swapped the block!,pistons rings were shot causing the smoke, ended up being a bad o2 sensor causing the misfire when cold car runs like brand new again you can really feel power difference too with the compression gain