Crappy idle and jerky throttle response after new injectors and TPS

[Knockenwelle]

On the note of the AFM, is it better to run the m30 version? When I was researching the injector upgrade it was mentioned several times, but it's not mentioned as being needed on the Mark D site and in many of the thread I read about, it seemed like the m30 AFM was a waste of time. Of course, I am open to changing it out in the interest of better running conditions, just want to be sure it's necessary.

I know I'll get some heat for this, but...
Many guys that upsize injectors and experience 'no poor running conditions' without changing anything else either have a lot of tolerance for poor performance, or have so many other engine control problems that they don't notice it. Enough vacuum leaks will lean the mixture right back out, too...

Motronic is not a very smart system. It is a calibrated system, and the only way it will work properly is if all critical parts are working together and matched to eachother. If there is more fuel being delivered for a given pulsewidth, the computer must know this, because otherwise it sees the same amount of air intake and thinks there's something wrong with the mixture.

The M30 AFM is a popular upgrade on modified cars, because it has about 40% more passage area than the M20 version. Changing it helps relieve intake restriction when the motor is using enough air to need it. It it also a direct replacement (plugs right in) for the Motronic 1.3 cars, and though the measured air volume signal being sent to the computer is smaller, this works well with 19 lb injectors: the increase in injector flow is proportionally almost exactly the same as the 'decrease' in air flow, so the mixture stays correct based on the factory fuel tables.

To check the mixture without the O2 sensor, read the plugs.

Also, have you checked your fuel pressure? Motronic is very sensitive to this, since WOT is completely open-loop.

[E turd]

Update #3: I replaced the two sensors on the thermostat housing as well as the crank position sensor and it changed nothing, but ended up being a good thing because I found out that my CPS wire was showing the metal core through the insulation where the clutch fan had worn it away. I am missing the little cover that holds it close to the engine and out of harm's way. When I put in the new one, I got a little creative with a couple of zip ties so that it wouldn't happen again.


Today I checked the circle plug under the manifold that goes to the injector harness and the connections are clean. I shot some terminal cleaner in there for good measure, let it dry and applied a thin layer of dielectric grease to the terminal pins before reconnecting it. I also cleaned the MAF today with some MAF cleaner and found a ridiculous amount of oil in the TB, intake boot, cold start valve, MAF and airbox. It was so much that it had soaked a good amount of the oil filter and deposited a decent sized puddle in the bottom of the box. I cleaned all the oil out (again, since I just did this when I replaced the injectors and installed the new TPS), replaced the filter and took it for a drive. The bogging is still there, but it is far less prominent than before cleaning the MAF.


I have a hypothesis that the engine may be misfiring due to poor compression in one or two cylinders, but I have yet to test it since I don't have any sort of leak down equipment. Past that, I just don't know how that much oil is back flowing into the intake system. I tried to locate some kind of PCV like I had on my VW, but I couldn't find anything and I'm at a bit of a loss trying to figure out why my mk2 with Digifant II had an oil splash guard above the cam and a PCV atop the valve cover, but my newer technology E30 doesn't have either of those, nor any equivalent components that I can identify.


At this point I think I might just take the chip and injectors out and sell them. I will be picking up an m52 in a few weeks and there is a pretty good sized list of parts I will need to get in addition to the motor, so spending much more on the tired, old m20 with questionable history doesn't seem like a very good idea.


I'm not sure if I mentioned it before, but my m20 uses a good amount of oil. It is seeping some oil from the head gasket too. I can tell that some kind of poop for brains idiot molested the car before I got it by the red RTV that can be seen squishing out of the head gasket perimeter, not to mention the full tube of black RTV that was used in place of an oil pan gasket to re-attach my stripped oil pan. My exhaust tip has a nice black soot ring on the edge of it's opening as well.


So, unless someone has some kind of miraculous fix they want to throw out there, perhaps this is all a lost cause.


Thoughts?