Technical support request!!

"Mattbob" (mattbob) 04/13/2015 at 09:26 • Filed to: None

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Oppo, so I've been fighting with his issue with my car for a few weeks, but I got more information yesterday. The car is an e36 325i. It will not start. I am getting both fuel and spark. The plugs are wet with gas, and I am getting spark (I saw spark with my own eyes), and no codes. When I first took the plugs out to check them, they were pretty filthy black. I cleaned them up and put them back in to try again. No luck. I had the crazy idea that it was flooded, so I took out the fuel pump relay, and cranked it. It cranked for a while, then began to start, and ran for a second, then died. When I put the relay back in, I get nothing. This was all after fully charging the battery. My wild ass guess is that the Cam position sensor is stuck in the on position. If that were the case, and the car was injecting twice as much fuel as it needed, could I possibly get flooded and no codes? Anyone have similar experience.

*edit* I should clarify, that when I say I get nothing, I mean I get no ignition. It turns over quick enough, just no bang.

Any suggestions given are greatly appreciated.

RiceOwl > Mattbob 04/13/2015 at 09:33

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The cam position sensor is a reasonable guess. I'm not sure about the e36 specifically, but it's possible albeit unlikely that the sensor could fail or get stuck without tripping a code.

It could be a failure of the O2 sensor causing it to run super rich, but again I think that's unlikely without throwing a code.

Twingo Tamer - About to descend into project car hell. > Mattbob 04/13/2015 at 09:35

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Maybe try some new plugs, cleaning up the old ones doesn't always work. If the old ones are shot it'll struggle to run when fuel is pumping in, but will light a small amount of fuel to run well enough for a little while. Sometimes once plugs have been fouled they're done for.

Had this deal with an old moped with a ruined piston ring. Changed the ring and cleaned the plug that'd been fouled with oil, it'd run for a few seconds then die, wouldn't start unless you let the fuel evaporate first. New plug and it ran pretty well.

Tinfoil Hat in a thunderstorm, now with added diecast > Mattbob 04/13/2015 at 09:35

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Auto? In park? Don't laugh and I'm not being a smartarse. I've seen a friend struggle with similar symptoms only to discover the shifter wasn't all the way in park so the engine won't fire. If you have a manual disregard. Good luck

Mattbob > Tinfoil Hat in a thunderstorm, now with added diecast 04/13/2015 at 09:38

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This is oppo, of course it's a manual, and it's in neutral. I would think that if it was a gear position sensor it wouldn't even try to start. This is turning over, just not firing.

Leon711 > Mattbob 04/13/2015 at 09:39

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Fudged.

Replace and try again. It might do it, it might not, but you need new ones.

505Turbeaux > Mattbob 04/13/2015 at 09:40

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and why would you be pulling the fuel pump relay to try and get it to fire off? It certainly wont run with it out. For fuel: find the test port, put out your cigarette, crank it over a few times and stick something in the valve and see if gas sprays out. If so you have pressure. If not pop the cover off the relay and see if the contacts close when you crank it over. If it does, fuel pump is suspect or wiring

did you pull a few plugs, ground them to the block while connected, and watch for spark?

Mattbob > Twingo Tamer - About to descend into project car hell. 04/13/2015 at 09:40

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I was going to get new plugs yesterday, but I just put these in last year. I will do some more testing. Maybe hook a scope to the Cam sensor. If that doesnt work out, I will try new plugs.

Tinfoil Hat in a thunderstorm, now with added diecast > Mattbob 04/13/2015 at 09:42

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Ha Ha! Just checking. My mates one just cranked over but wouldn't fire, just like if a kill switch is off. So there is definitely visable spark?

Twingo Tamer - About to descend into project car hell. > Mattbob 04/13/2015 at 09:43

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Okay, good luck with it. Hopefully it's an easy fix.

Mattbob > 505Turbeaux 04/13/2015 at 09:44

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I pulled the relay, because the plugs were soaked with gas, and I wanted to turn it over without gas to try to clear it out. (hoping for a recreation of that flight of the phoenix scene I guess) It did have some ignition with the relay out though.

To test the plugs, first I used a spark checker thing that plugs into the coils, made sure that there was a spark with that, then I did what you described (after cleaning the gas off) and saw that there was spark on the plug.

505Turbeaux > Mattbob 04/13/2015 at 09:48

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you try something simple like - clean the gas off the plugs, install, pull the relay and see if she will fire on starting fluid? If so, put relay back in and see if you can get it fired off on starter fluid.

It sounds like you have a metering issue. Check the run of hose between your MAF sensor and the throttle body, and all large connections off of there. Also I would check the throttle butterfly front and back for cleanliness, maybe it isnt closing all the way and causing an overmetering of fuel

Mattbob > Tinfoil Hat in a thunderstorm, now with added diecast 04/13/2015 at 09:49

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yeah, definitely a visible spark.

Mattbob > 505Turbeaux 04/13/2015 at 09:51

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do you thing an air leak between the MAF and the intake could cause this? Because the rubber hose there is pretty sketchy. Its fairly old and cracked.

Also, I have heard that gas on the plugs is a bad thing, as in it will not start. Once gas is on the plugs, it pretty much wont's start till I clean them off, right?

Tinfoil Hat in a thunderstorm, now with added diecast > Mattbob 04/13/2015 at 09:54

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Strange, and the timing is right?

505Turbeaux > Mattbob 04/13/2015 at 09:55

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that would be my first thought right there if it is sketchball. If you have a leak in there you aint getting that thing started, and it will just pour fuel in thinking it is wanting to start. Drawing on my experience with Vanagon boots being all banged out, go get your self some shoe goo and go to town haha

Mattbob > 505Turbeaux 04/13/2015 at 09:56

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will do.

Mattbob > Tinfoil Hat in a thunderstorm, now with added diecast 04/13/2015 at 09:57

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it's a timing chain, and nothing major happened since last time it was started and running well., so I'm thinking the timing is fine.

505Turbeaux > Mattbob 04/13/2015 at 09:57

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oh and it wont throw codes either if that is the case, so #2 reason to check it out

JGrabowMSt > Mattbob 04/13/2015 at 09:58

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Bad Ground. Ask me how I know.

Seriously, double check all of your grounds. I recently helped fix an E36 motor no start issue that sounded exactly like this. They do take a while to start though.

Tinfoil Hat in a thunderstorm, now with added diecast > Mattbob 04/13/2015 at 09:59

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Yeah I'm out of my depth sorry. Hope you can sort it out

jariten1781 > Mattbob 04/13/2015 at 10:02

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I've had cracks in that region cause stalling/stumbling but not a non-start condition, but I suppose it's possible. I also know from experience that if you tape it up really tightly with duct tape you can drive from SC to WA before replacing the hose, haha.

Mattbob > JGrabowMSt 04/13/2015 at 10:48

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where was the bad ground? I am getting spark and fuel. I checked all the grounds at the coils. I don't know where else I would check.

Mattbob > jariten1781 04/13/2015 at 10:49

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I think I am going to try the goop and tape route before I spend any money on it.

JGrabowMSt > Mattbob 04/13/2015 at 11:04

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Bad ground was the chassis ground for the ECU(?) in the engine bay. The one that was supposed to go to the strut tower. Car cranked and cranked and cranked and had fuel and spark and just never started.

Once that ground was sorted out, started up pretty quickly.

That said, check all chassis grounds and battery connections.

Mattbob > JGrabowMSt 04/13/2015 at 11:08

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Thank you! I didn't think to check that one. Now that you mention it, when I got that car, that ground connection was extremely sketchy. I remember making a note of it, and just making sure it was okay at the time. I will double check this today. Fingers crossed. The one thing though, is that my ECU does work. I can read the no faults stored code from the dash. Did the one you were working on do this as well?

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > Mattbob 04/13/2015 at 11:12

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I like 505's suggestions too, but based on your description of the problem I'd check your fuel-rail pressure, not just that you HAVE pressure, but that it's correct. I've had bad fuel presure regulators lead to symptoms like this. The 90's vintage Motronic systems prevalent in many European cars of that era are quite sensitive to correct pressure and even a few PSI one way or the other can screw up fuel metering significantly (note, BMW used two systems that were designed to run at either 19 or 24 PSI, I don't know the exact cut offs for each system, but injectors designed for one pressure will NOT work correctly in the other, thats only a difference of 5psi, and a bad or sketchy pressure regulator will easily cause deviations greater than 5psi.) Low pressure leads to poor atomization and slow-closing of the injectors, this results in hard starting, rich running and poor idle. High pressure can, depending on the wear and age of the injectors result in either rich OR lean running, but usually without the hard starting issue. Check that fuel-rail pressure!

Also of note: Many systems do NOT throw a code for fuel pressure, only the results. I got "random multiple misfire", but the root cause was incorrect fuel rail pressure.

Mattbob > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t 04/13/2015 at 11:20

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it's an OBD1 car, so I'm guessing it probably wouldn't trow a code for that. Once I try a couple other things, I will test for fuel pressure. I didn't see a fitting when I was looking at the fuel rail. Any experience with not having a fuel rail fitting?

Devlin Munion > Mattbob 04/13/2015 at 11:23

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Not sure how many miles are on your car but E46 fuel pumps have a habit of crapping out any where from 90k-150k miles so I would check that even though you are getting fuel maybe it isn't enough.......

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > Mattbob 04/13/2015 at 11:29

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I had to cut a few-inch piece of fuel-line and splice in a T-fitting for the pressure gauge on mine.

(Not my pictures, but this pretty well illustrates what I did)

Also, some BOSCH regulators have the test port *ON* the regulator...

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > Devlin Munion 04/13/2015 at 11:42

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Yeah my bet is on either fuel pump or regulator, this is classic 90's Motronic low-fuel-rail-pressure symptoms.

JGrabowMSt > Mattbob 04/13/2015 at 11:44

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Yes, the ECU worked totally fine. We tried a second ECU thinking the first one was fried, but there was no change whatsoever until the ground had a better connection. Ended up having to connect it directly to the battery terminal, the chassis ground just had a terrible connection.

Mattbob > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t 04/13/2015 at 11:52

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I will see if that is the case before cutting into fuel line for sure. I am goign to try a few fee and easy things first, like grounds. Then its off to the store to rent a fuel pressure tester.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > Mattbob 04/13/2015 at 12:04

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oh, no no no! You don't CUT the factory fuel line! You go buy some line at the auto-parts store and spice it in. In the above image the fuel filter is used as an inexpensive way to go from the factory quick-release coupling on the incoming fuel line to the necessary clamps for the T-fitting... Mine actually had a screw-on fitting so had to buy one of these along with my short lengths of fuel line and hose clamps.

Mattbob > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t 04/13/2015 at 12:08

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yeah... good point.

Mattbob > jariten1781 05/06/2015 at 10:09

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oh hey, I got it running a little while ago. Turned out to be the ECU got water in it. I opened it up, cleaned it and touched up some solder joints, and it fired up. Repairing the MAF to Throttle body hose did make a big difference in how it runs though. When I started it up after fixing that, it bogged down for like 30 seconds while the computer was trying to figure out what the hell changed.