318i starting mystery

[shankster77]

Hey everybody this is a sweet little forum you got here. hopefully some of you may be able to enlighten me with your wisdom and experience with these wonderful driving machines.

I picked up a 93 318i with 132 xxx on it for 500$, but it does not run. I have tried to pick it apart a little bit so here's what I got:

The car turns over and fires just fine, but nothing catches and keeps burning.

I have fuel pressure and voltage off of the pump.
I have fuel getting to the rail as well

I have spark, a plug on a ground made it happen, but with a timing light it looked a little intermittent to me.

plugs are clean

Noid light on injectors produced flashes that also looked kind of intermittent perhaps

I checked out the DME and it showed no visible signs of water damage, but I bought a different used one anyway- no change

No fault codes due to power failure

the check engine light is on with ignition, shuts off once you start cranking (thats normal right?)

oil smelt like gas

Tried spraying fuel into throttle body while cranking, and we got fire from that... believe me!

The guy i bought it from said it progressively ran worse and worse until.. yeah

thats all I can think of right now. Sorry about the long first post. What else is next to check out with this thing?

Hope you can help, thanks guys

[Big Evil]

You need to know what the pressure at the fuel rail is (35psi ish), You need to know how much fuel the injectors are flowing when activated. Maybe time for a fuel filter, if you don't know when it was done last, do it. Spark getting intermittent....maybe low voltage, weak coil, how's the battery, maybe the harness is getting worn or frayed. Plugs on this SHOULD be standard copper core if I remember right, platinum's and all that other hocus pocus crap is just that, crap. Don't use it, it's a waste of money. Your getting power to the fuel pump but its possible the pump vanes are worn out so it'll push fuel but no where near enough, COULD have caused the problem. If the oil smelt like gas, you could have a ring problem in any of the cylinders.....or it's just really old oil. Compression test it yet? The engine light thing is normal. Hard to say what else without actually being hands on with the car

[shankster77]

Thanks Big Evil

No I have not done a compression test yet. It looks tricky to get at that fuel line off of the rail to splice in my pressure gauge but i'll work it out. How do you know when your coils are going out? I 'll make sure to do that fuel filter. yeah come to think of it one of the cylinders did look a little leaky on the plug, so maybe I have a ring or two that are wearing out. the battery and harness give me my 12 volts or so, and look okay. i'll be back once i check some of that out thanks again G.

And this is a sweet little ride. It has an M3 front bumper, some nicer wheels(17s i think) from a newer bmw, exhaust, short shift 5 speed. i'll post some pics once it will actually get me places haha

[3050rpm]

Not to dampen your enthusiasm, but to me there's something wrong with this picture. 132,000 miles on a '93 isn't very much mileage, and the two statements that "the oil smelled like gas" and "he guy I bought it from said it progressively ran worse and worse until..." are ominous signs, suggesting failures due to abusive treatment and perhaps no maintenance whatsoever. Do you have any hint as to what the service record is on this car? What does the oil look like, or was it changed only the week before you bought it? How about the coolant, does it look as if that's contaminated with oil?

[shankster77]

the coolant looks clean. I still have not gotten a fuel pressure reading close to the rail yet, i'm going to do the fuel filter then also. I am getting different spark from different plug wires when i put the same 'tester' plug on a ground. Could the coils be going out? is there a way to test them for continuity or something? but yeah no doubt this car has been abused.

[Big Evil]

Could be the coils wearing out, could be the drivers in the PCM wearing out, could be worn out plug wires, is your engine coil on plug or does it have a distributor still? You mention plug wires and then coils, not coil. If it's a distributor style it's one coil usually on the fender well, and then a cap and rotor on the front of the head, rotor bolted to the end of the camshaft. Those wear out. New cap and rotor, new wires and yes you NEED the oem style replacement wires that are like a hundie plus because of the connectors (sucks, but those are the breaks). Do the cap and rotor first, then recheck the wires (replace as necessary), if you're getting spark chances are the coil and PCM are fine. If it's been running rich (lack of spark) that could explain the fuel saturated crankcase, also replace the pcv valve if equipped. You may not be in to bad of shape here.

K

[shankster77]

It is a distributerless ignition with the coil packs. I found a chilton's resource that talked about getting an ohms reading of .4 to .8 from the coils. I found a reading of 1.4 on each of them. new fuel filter, I tested and found a good psi reading for fuel pressure right by the fuel rail. after the fuel filter change I noticed a little more firing when turning the car over i believe. I will test the plug wires out. I also thought I might have a bad ground somewhere seeing as that could make my resistance higher. I remember reading a thread about a guy who had a bad ground to his dme, I believe, it prevented him from getting started too so i dunno. any way to check out the pcm?

[Big Evil]

Your resistance is about double what the spec given is, that CAN cause your issue since the amperage running through the pcm drivers is quite low. If you're getting spark your pcm has to be working. Just look around clean up chassis grounds and such if you're really worried about it (never a bad idea anyway). Try a trip to a salvage yard w/your meter and see if you can find a replacement for the coil pack, otherwise it sounds like its time for a new one. Plug wires should read several K ohms per foot, but ohming out wires doesn't always tell you the whole story (not any/enough current to tell you if the wire develops high resistance when it gets hot w/electricity running through it). Basically though based on your tests/info, new coil pack first, then maybe wires (should be cheaper than the dist type) and if none of that solves it, THEN look at the pcm.

[shankster77]

Those plug wires are giving me readings of 5.8 to 8.0 k ohms so they might be on the way out too? Have you heard much about using performance coils? I was looking at some from bavarian auto that claim to boost performance a little bit. With exhuast, intake, and a performance chip, would this help add to all of that do you think? what else completes the performance picture?

Anyway I feel like this is close to the end hopefully, thanks again Big evil

[Big Evil]

Several K ohms per foot IS a normal expected value. The question is do the numbers jive with each other? same length wires similar resistance? Longer wire, more K ohms. shorter wire, less K ohms? Of course there's the old adage "when in doubt throw it out". Dubious test results = poor performance. As far as an intake is concerned I would clean and make sure the one you have has no leaks and run with it, the cold air intake stuff more often than not reduces performance (undoubtedly SOMEONE out there will will try to say otherwise but I've had firsthand dyno experience with many types, and they sure don't convince me). Chipping is a good way to go, exhaust I'd stick with cat back only (again lose the backpressure, the cylinders can't properly scavenge and the air fuel ratio gets diluted and you lose power). The systems on these cars were so well designed to start with there isn't really a whole lot of room for improvements, not without BIG money anyway. Performance coils? Again I'm not convinced, all you're talking about is maybe a few extra wraps on the secondary side and a minor increase of 5-6 KV on a system that's already shooting 15-20 KV, these cars don't run 12 to 1 compression, 15-20 is more than adequate. Now when you start talking forced induction......that's a COMPLETELY different conversation.

[shankster77]

one of the plug wires read much higher than the others and there appeared to be some signs of wear on the contacts for all of them. so probably couldn't hurt to switch them out. i'll let ya know if i'm rollin after I put some new ignition parts in. Yeah with only 4 cylinders, all the extra space under this hood craves a turbo! but i am a poor college student.

[shankster77]

Well I got some new coils installed today. However the car is still not starting. I do not have a cash for wires yet. The resistance on the new coils is good so it must not a bad ground. I need an adapter to reach down into those cylinders to do a compression test with my gauge. The mystery continues..

[Big Evil]

One other thing, when you crank it. Does the engine light go out while cranking?

[shankster77]

yeah once you start cranking the check engine light goes out. Thats normal right? I also thought the gas had been sitting in there a while so I got most of it out of there, added a can of sea foam and 5 gal of fresh premium.

[Big Evil]

Higher octane number (91 premium) only relates the fuels ability to resist detonation. 87 is actually more volatile (easier to ignite). SHOULDN'T be causing a problem but the sea foam might. Your fuel pressure was good at the rail, your plugs have been replaced w/oem, new coils. You're waiting on wires and need an adapter to compression test the cylinders. I think that's where we're at. Only 3 things are needed to create combustion, air fuel and spark. Unless all the injectors are completely clogged and can't flow anything (unlikely but not impossible) you should have fuel, the light goes out when cranking so the pcm is getting an rpm signal and you are getting spark (you've tested that), that leaves air. You really need to get a comp test together. When you do it, crank it until you get about 5 jumps on the needle and stay consistent across all 4 cylinders. If they all read within 20psi of each other you're down to injectors. If not you'll need to do a CLT to figure out where the engine has gone wrong. To bad I'm halfway across the country otherwise I'd try to swing past for an actual look.

[shankster77]

A compression test showed just under 90 psi for 3 out of 4 cylinders, with the other cylinder at 78 psi. I did not actually buy new plugs to go with the new coils (for some reason) but I think I should be cause they are looking a little blackened. The one on the number 4 cylinder I believe, is a little charred and coated. the threads smell gassy. I'm throwing new plugs in tomorrow.

When I had tried spraying vaporized gas into the throttle body it had exploded back out at me, could that mean my timing is off? I'm starting to think I need to open this bad boy up and take a look.

[Big Evil]

You MAY have to pull the head (little more testing needed yet). I'd get the book double check the timing on the engine (cam/crank). 3 at 90 and one at 78 difference of 12 psi doesn't sound that bad but since 3 were consistent and one wasn't and they were all a bit low (120 is closer to normal usually) I'm thinking a cylinder leak down test is your next step. Have you done one before? It should give you a definite direction as to what needs attention base engine or head wise.

[shankster77]

I have not done such a test before. Yeah I was hoping I would not have to crack the engine open.

[Big Evil]

CLT, or Cylinder Leak Down, Test is preformed with the same basic stuff you use for the compression test. You need to pull the valve cover and crank the engine by hand (with a wrench) until you see both valves are fully closed on the cylinder you will be testing (piston needs to be top dead center, intake valve will open then close, and then go about 1/4 rotation on crank). You then have someone hold the crank in position (it will move so use a big breaker bar on the snout bolt, with a big friend) and you push compressed air into the engine at around 100 psi using compression kit adapter with an air fitting. Then you get listen for where its leaking from. Pull out the oil dipstick, if air is coming out you have bad rings or scored cylinders. Open the throttle plate, if air is leaking out the intake you have a bad intake valve, exhaust - bad exhaust valve. All the plugs should be out while you do this, if air is leaking out of the degas bottle for the cooling system or the adjacent cylinder then you have a bad head gasket. You should then be able to tell if you need head work (valves), base engine (pistons, rings, cylinders), or a head gasket. If you need a head gasket you'll need a straight edge (machined) and some feeler gauges to make sure the block and/or head isn't warped. The test will tell you with a good deal of certainty what, if you want to try a rebuild, or if you want to look for a secondhand running engine and swap 'em out. (Just keep the new ignition stuff and transfer it over as a second hander would most likely need it also). But yes, don't crack it open until you know what and why you would be doing it.

[shankster77]

Cool man, thanks for the detailed post. Looks like I will need to carve out a day or two to get this one done. I think I've got the right friend in mind to help out. Be back later with an update.