Weridest Problem ever: A/C or Rear Defog causing engine to bog down.

[T.Dot_E30]

Recently I've been able to narrow down the problem, which baffles me.


If i put the a/c or rear defog on, the engine would bog down badly (if cruising at speed) or if from a stop it would not accelerate, almost as if it wasn't getting fuel or as if water was in the distributor cap.

Now this has me perplexed, no idea where to start. The engine runs perfectly fine with both of these things off, it pulls strong to redline and idles decently.

All i can think of is that i recently installed a markD chip with an m30 afm. Had s50 injectors while running the stock afm and chip and a/c ran fine.

Now i checked the a/c compressor and it spins freely, so it isn't ceasing (even thou this happens when no a/c is on and the rear defog is on)


Anyone has any ideas? I'll be swaping the chip to test, then i think ill try the stock afm and hope it clears.

Engine: Stock m20b25
'88 325i

Recently converted 5spd from Auto.

[uofom3]

Could be a battery problem? Check your charging system and the battery. Sounds like you're system is having a hard time handling that kind of power drain...... but I could be off.

[T.Dot_E30]

Are all cars suppose to idle at 14.4v?

Mine idles at 13.5-13.6v normaly and with the a/c or defog on it it drops alittle to about 13.1-13.2v ?

That seems a little low doesn't it? Car has been driving fine like this for the past 2 weeks, the battery is about a year old (anythou anything is possible)

I feel like when the a/c is on, the car isn't bumping up the idle like it should, i think im going to switch afms and icvs.

I checked the ground straps, althou the engine one seems a little tarnished (open copper wire), which i will look to replace, but it seems to be making good contact.