Author Topic: engine starts but doesnt stay on. please help! (Read 4714 times)

issabmw · « **on:** July 06, 2010, 11:52:44 PM »

Hey guys

I picked up an e30 318is

The engine needed work so they swapped it with a working engine from another car. Now the car starts for about 3 seconds then shuts off.

any ideas?

issabmw · « **Reply #1 on:** July 06, 2010, 11:55:04 PM »

I have been told it was wiring

B318M42W · « **Reply #2 on:** July 07, 2010, 12:37:33 AM »

how's the idle when you start it?
can you give more details or post a video?

There are a few things that come in mind: 1) ICV (idle control valve) car won't idle if it's not working. located at the back of the engine

2) massive vacuum leak. won't idle. holding the gas might help the engine not to die.

DesktopDave · « **Reply #3 on:** July 07, 2010, 11:46:24 AM »

Fuel pump priming but not giving enough pressure. Fuel filter plugged. Cam sensor losing sync. Dirty crank sensor. Vac leaks. Fuel leaks.

Check the codes while you're at it. Try the 'stomp test' & let us know what flashes up.

issabmw · « **Reply #4 on:** July 11, 2010, 05:45:33 PM »

Thanks guys.

Heres the issue. I recently purchased a 1991 318is. the vehicles engine needed major work, so the dealership decided to replace it with a running one from a salvage, rear-ended vehicle. The engine in the salvage vehicle ran perfectly until the swap.

Now the engine turns over, starts for about a few seconds then dies down. I was told many things, from the wiring harness to the DME and I need to get this thing running.

The swap was done using a running M42. The engine was running flawlessly, so this negates anything going wrong hypothetically. Everything was swapped over from the donor vehicle, and I'm really starting to think that it is an electrical problem.

I asked the seller to give me the old harness as well as a few miscellaneous parts.

Anything stands out that may give you guys a clue?

issabmw · « **Reply #5 on:** July 11, 2010, 05:48:38 PM »

I downloaded the wiring manual, maybe I can source out an error

DesktopDave · « **Reply #6 on:** July 11, 2010, 06:14:39 PM »

Check the codes with a stomp test. Might be something simple, like a fuel pump or plugged fuel filter.

http://e30world.com/fuel/BMW-E30-DME-Motronic-fault-codes

issabmw · « **Reply #7 on:** November 27, 2010, 04:32:00 PM »

Havent bumped this for a while.

Heres a video of the car for those who don't know the problem exactly.
http://www.youtube.com/watch?v=ntMYFjZcKOY

Its sitting in the shop. Lots of work has been put in.

The storyline:
Hmm, seems like no spark. Cleaned the spark plugs and checked compression while at it (was very good) and check spark w/ the gun looking machine. Was ok.

MAF may have a problem. Tried starting it while maf door was worked on. Nothing. Got another MAF and hooked it up. Nothing.

Coded the radio, as one suggested an anti theft may be it. Still nothing, although the speakers sounded pretty good

Hooked up a friends crank sensor, although its not confirmed to be in working condition. Nothing happenned.

Heres the weird part
Sprayed starter fluid with the intake hose off and the car started for 5 seconds. The exhaust came out, the engine was rumbling just fine. After 5 sec it was off. I couldnt get it to do it again, yet the start was a sign.

It was moved to a shop and the wiring harness was changed and still nothing.

Any ideas?

issabmw · « **Reply #8 on:** November 27, 2010, 04:34:15 PM »

Quote from: B318M42W;94362

how's the idle when you start it?
can you give more details or post a video?

There are a few things that come in mind: 1) ICV (idle control valve) car won't idle if it's not working. located at the back of the engine

2) massive vacuum leak. won't idle. holding the gas might help the engine not to die.

Doesnt idle, as it will not start. Holding gas did nothing.

Here she is.... please help me get her back on the road

DPINEDA · « **Reply #9 on:** November 27, 2010, 07:23:57 PM »

Sucks to hear that it's still not running.

I didn't see you post your results of the stomp test. I'm no expert, but I would start with the basics which are stomp test and maybe see if you are getting fuel. Friend of mine showed a small trick. Disconnect the fuel line from the fuel filter (the line that exits the fuel filter towards the engine). Put a small bucket underneath it to catch the bit of fuel that will spill. Have another person turn the key to the 'ON' position (don't turn the car on all the way) and the fuel pump will try to pump fuel to the engine. You should see a steady stream of fuel flowing into your bucket.

After that I would check for vacuum leaks.

DesktopDave · « **Reply #10 on:** November 27, 2010, 07:28:39 PM »

The starter fluid proves that spark is OK and I'd assume the computer as well. I know the old motor ran OK, but did you test the fuel pump or make sure the fuel hoses aren't swapped? If the return and supply lines are mixed up the car will barely run. Hopefully it's something simple like that.

issabmw · « **Reply #11 on:** November 28, 2010, 03:19:12 PM »

Quote from: DPINEDA;99062

Sucks to hear that it's still not running.

I didn't see you post your results of the stomp test. I'm no expert, but I would start with the basics which are stomp test and maybe see if you are getting fuel. Friend of mine showed a small trick. Disconnect the fuel line from the fuel filter (the line that exits the fuel filter towards the engine). Put a small bucket underneath it to catch the bit of fuel that will spill. Have another person turn the key to the 'ON' position (don't turn the car on all the way) and the fuel pump will try to pump fuel to the engine. You should see a steady stream of fuel flowing into your bucket.

After that I would check for vacuum leaks.

Thanks for your help. The stomp test yielded a blank as the light didn't blink at all. I don't know the reason behind this but the CEL doesnt work.

I will try the bucket thing this week.

issabmw · « **Reply #12 on:** November 28, 2010, 03:26:05 PM »

Quote from: DesktopDave;99063

The starter fluid proves that spark is OK and I'd assume the computer as well. I know the old motor ran OK, but did you test the fuel pump or make sure the fuel hoses aren't swapped? If the return and supply lines are mixed up the car will barely run. Hopefully it's something simple like that.

I thiiiiiiink, we tried that. Im not 100% if my buddy did but we did indeed discuss that exact supply and return issue, thats for sure.

What about the cam and crank? Any ideas about those sensors? I heard they were affected by position, tightness? Any ways to check if they are good?

I also heard could be fuel pump relay? I appreciate the help you guys.

I hope you guys saw the video in the above post.

DPINEDA · « **Reply #13 on:** November 28, 2010, 06:58:36 PM »

Stomp test not giving you any feedback would raise a flag for me right there. Does the 'Check Engine' flash at all when you turn the key to the ON position?

Also did you check if maybe the boot that goes into the throtle body is cracked? Maybe they broke it when the engine got swapped. If that's cracked you will have idle issues. Also check the elec connector that goes to the top of throtle body. If that's loose it will also give you idle issues. From what I've read M42's are super sensitive with vacuum leaks.

Could be a faulty coil too.

Buy a fuse tester at any auto store and check all of your fuses too.

Check spark plug cable order too!!!! Happened to me recently:-)