Popping/Backfiring hesitation

[richardb]

So I just finished my swap non vanos m50 into 318is. I drove it to the gas station today about a mile from my house and I had to baby the throttle. Giving partial throttle to accelerate would cause hesitation and unbearably loud back firing with open headers.

It has ebay SS replica headers, and no 02 sensor hooked up yet. I know the 02 will cause some problems, but will run in open loop and will be rich.

The backfiring was so loud it sounded like a pistol going off under the car so I had to granny shift my way home (not hard with 4.10 rear end).

SO... any ideas here? I unplugged the MAF to see if that was the problem, but it ran worse and stumbled and almost died when I did so.

My coolant looks milky but there is no sign of water in the oil (very clean after 1.5 hours of total run time). The car is at 666 fabricaiton getting the exhaust done right now so I hope to be able to drive it home this weekend.

Thanks in advance

[richardb]

I should also mention it has new plugs and coil pack boots, and it idles perfectly and the temp gauge sits at 1/2 way idling. I let it idle for about 45 min, the temp never went above 1/2 way and the electric fan never needed to come on... weird for sure

[M-technik-3]

Your gonna get after-fire with open headers and no o2 sensor. You sure it's backfire? Backfire is into your intake not out the exhaust.

[richardb]

Whoops, I thought it was called backfire. It is in fact, after-fire out the exhaust. It would after-fire so loudly that I was afraid to accelerate and do damage. I saw a video of an s50 with open headers flying on youtube without any after-fire...

[e30polak]

Check out your crank and cam sensors. I had my crank sensor cause such symptons, except worse when the wires were frayed from contact with the drive belt.

[richardb]

I will look into that. It sure does look pretty at least. Here are some from today- I may as well ask while I'm at it, why the hell does one smiley have the smiley lit up (passenger side) and the other one isn't? (Yes they're both smiley)

[M-technik-3]

Did you install them or previous owner? Check to see if in fact there is a city bulb wired and working. OOps was talking about city lights. The smiley maybe it's dirty ?

[richardb]

I installed them, they are also smoked. So I had them apart to paint the housing black and put it back together... they are exactly the same and hard to mess that assembly up so... not sure why it winks at ya

[M-technik-3]

You have the cut off's installed the same direction? Different wattage bulbs or ages of bulbs different?

[richardb]

Oh interesting... I never thought of that. I wonder if the cut-off is 180* the other direction in one of them... would that make the smiley light up or not light up? The bulbs are Silverstars, both about a year old.

[M-technik-3]

The housing rotates roughly 18 degree. It's pretty self explantory.