ninjazombiemaster

Recently picked up another car. Sadly she's been stealing all the Zs love, but its been 100+ degrees lately and no A/C just won't cut it. Its a 335xi - all wheel drive twin turbo. Absolutely loving it so far. Unreasonably fast for a four door sedan.

Hrm. Went to lunch today, 90 degrees out. Sat idling at a drive through for a while and the gauge only got up halfway today. No problems. Maybe after putting in the new water pump, the coolant hadn't bled enough, leading too some heat problems with the ignition. Right now things *seem* okay - we'll see.

Possibly. But there's not a lot left I haven't tried. Maybe the coil getting hot..

It's the stock coil. Though maybe it doesn't like the heat. The ballast resistor is a few months old, though . Average temps now are 60s at night, 90s in the day. I could try leaning it out a half turn or so, but I really don't think its the fuel mixture. The best way to describe it is that it seems like when it gets really hot, a few of the cylinders don't fire. The engine is still running, sometimes just barely, but it has little to no power, and sputters, and then if you keep your foot down, *BOOM* huge afterfire. Like gas was just dumped down the exhaust. There's still an exhaust leak from the head pipe to the manifold that may be overheating the carbs, and the engine in general. I'm ordering a new gasket tonight. I don't have an in depth understanding of the system, but if I'm not mistaken, doesn't some of the coolant get distributed to the manifold and carbs to help bring them to operating tempurature more quickly? An excerpt from Hybridz "hot water just below the engine thermostat is run into the left side of the intake manifold, touching the carburetors then out the right side of the manifold to a manifold thermostat then around the back of the motor to the input / low side of the engine water pump. The manifold thermostat is normally open and monitors the temperature. At ~140 degrees a valve inside starts to close and closes completely at ~150 degrees. " What if the manifold thermostat is not closing off? That might overheat the carbs, and the fuel, which then doesn't burn properly, until perhaps it's in the exhaust causing the after fire? I still haven't eliminated vapor lock, but I don't know how I might short of spending $100 on an electric fuel pump. But then again, it doesn't really *feel* like fuel at all. I bought new spark plugs and a fuel filter, even though nothing is really wrong with my current ones that I can see. Edit: Took it for a longer night drive. 65 degrees at the time. Temp gauge stayed dead center the whole time. Never had a problem. I cruised for about 20-30 minutes. I'm 100% convinced this is a heat issue.

Hrm. So I brought it to the shop the other day. Timing looks fine. Points are gapped to like .12 inches or whatever.. I can't remember, but it should be on spec. Turns out my water pump was going bad, replaced that. Threw some aluminum powder into the freshly topped radiator. JB welded an exhaust leak on the manifold. It is running incredible for about 10-15 minutes, then it gets to its peak temperature, a little past halfway on the meter. Then all goes to hell. Still afterfires, and sputters. Vapor Lock Maybe? I've never had issues with that before - but whatever it is, it seems to be heat related. The worst part is its really only under load. Edit: Btw I live at about 4,500 feet altitude or so. Currently the carb mix knobs are at 2.25 turns or so. Air is set so it idles at maybe 900, which is a touch high, but any less and its kind of rough. The fact that it runs so well cool-warm makes me think its got to be a minor ignition or fuel gremlin. Maybe its vapor lock after all, and for some reason the engine is just getting hotter than it ever has before. Edit 2: Took it for a night drive, its currently 75 degrees. Carbs were a bit off, but no real performance issues. Definitely heat related.

I've been told my car sounds like a lawn mower at idle.

I bought it at Napa, it was the only one they had. If the dual points are for the autos, then its probably the wrong one.. ugh. I'll see if it has the rating on it somewhere.

Heh, nope. Just my stubborn car. I bought a condenser, too, but haven't put it on. To be perfectly honest I'm not sure they the right one, it looks different than mine and was listed as "Condenser (w/ Dual Points)" which doesnt make sense, but that was the only thing in the system. Makes me a little hesitant to put it in. Honestly I don't plan on going back to electronic ignition.

Solved. It was the points. They were in horrible shape. They haven't been in there that long. Dropped a new set in today, and its running like a champ. Idles a little high, but probably just needs a re-tune now that the ignition is sorted.

Round tops. Seems to do it no matter where I putt the mix. Choking it has no change. Possible. I won't have a chance to check the timing till Monday at best, but I'll report back when I do. Good idea. Fuel filter is maybe 6 months old, it looks pretty clear. I drove it this morning, outside temperate of 81 degrees. It wouldn't start up without some choke, so maybe a little lean (yet it still afterfires, so not really sure on that one). Like before, in first gear it revved up to about 5k. Shifted into second and it made it to 6.5k or so before having issues. I had a similar problem when I switched to electronic ignition, and putting points back in fixed that. It may be the points after all. The sputtering did not happen. So maybe that only comes into play once the engine has warmed up fully.

Been a while since I posted.. I'm not really sure when the problem developed since I go easy on me car in the winter but since things have warmed up, my '73 has run like crap. It was sputtering, stalling and on occasion, dying. The problem seemed to mostly happen under load. In fact it idles okay - not great, but okay - and revs pretty good too. I noticed it was running a bit hot (I think my aluminum radiator may have sprung a small leak ) so I topped off the oil and coolant. It seemed to help a little. Today, I gave the carbs a scratch tune, and got it running seemingly okay. I set the float levels, I set the throttle stops, I set the mixture -everything. It seemed alright, so I took it for a drive, but It was still happening, although not as bad. I also noticed that when stationary, If I rev, it maxes out at 5K RPM, where it stays. After a few seconds, it will begin to afterfire from the exhaust. Makes me think there's something more than a fuel issue there. Spark plugs look fine. Points were installed maybe 6 months ago, along with a new rotor and dizzy cap and ballast resistor. Any ideas on what it might be?

ATF works horrible for me. I've run 20wt motorcycle oil with best effect.

I noticed this too. Specifically the Blue Book sites now list low book value at $8k, up from $7.6k. Average and high retail made even bigger moves.

I tried ATF but it was much too runny for my setup. I get 20 weight fork oil for free from a local motorcycle shop, and that's worked best of everything I tried. Other weight I've tried have mainly been multi-viscous, and I think that if you play it right, you could be one that would behave like a choke on cold days, however I was not able to find anything else that made my engine happy. Any lighter, and it lean popped like crazy. I could possibly go a bit heavier, especially in the cold, but it runs how it is, so I'm not going to fiddle and break it.

Mine has always read 60 Liters but I can only get 10 gallons in at the pump. I believe my fuel sending unit may have been installed crooked and reads empty early, with several gallons still in the tank. Next time I have it on the lift I'll have to look.