1997 328is only firing on 5 cylinders - BMW Forum

aj328 · 06-24-2007, 03:31 PM

Hi, Any Ideas? I determined the coil pack was OK by swapping. New plug installed. Seemed dry, so changed fuel injector, but still not fixed. Checked wire and terminal continuities. Still only running on 5.Are there known wiring or computer problems with these. Please help, thanks, aj328

Starmavin · 06-24-2007, 07:10 PM

Noid test the injector socket. Then do a compression test.

aj328 · 06-24-2007, 08:31 PM

Thanks for responding Starmavin, Another tool to buy, I'll see about getting a set tomorrow. I can do the compression test, but I don't want to know the outcome. aj

aj328 · 06-25-2007, 09:23 PM

Starmavin, I haven't done a noid test yet, But went straight to the compression test and all cylinders were within 20 lbs. It was a relief, because I was expecting the worst. I suspect no signal to the injector, But don't know yet. Are there any common reasons? Thanks, aj

Starmavin · 06-25-2007, 11:18 PM

Buying a noid light isn't necessary, unplug the injector and use a test light to find the 12V power supply, then attach your test light to 12V and test at the other connector in the socket. It should flash when the engine is cranked. If not unplug your DME and check for corrosion. If there is none do a continuity between the socket and #33 in the DME connector. (the #5 injector wire should be brown with a green tracer)

aj328 · 06-26-2007, 04:58 PM

Thanks Starmavin, I will get to that ASAP, but have other comitments tonight. aj

aj328 · 06-28-2007, 08:55 PM

Starmavin,I did the 12v test on the injector wire (it was the #2 cylinder that isn't firing, brown and red) and it checked OK. Then did the continuity test to the DME connector (#34 or 35 I think for #2?) It was good, and no corrosion was in connector or compartment. I went on line to find what they cost and found a site to install a chip,is this an option over the cost of a new DME?

Starmavin · 06-28-2007, 09:05 PM

No 12V or no ground signal from the DME?

aj328 · 06-28-2007, 09:30 PM

I did get a positive 12v test from the injector connector when the motor was cranked, however the light stayed on while the engine was running (on all cylinders). But also got a light on the red wires to all connectors. Should I have not had the tester attached to common ground? AJ

Starmavin · 06-28-2007, 09:51 PM

The injector circuit works like this: While the key is on there is continuous 12V to one of the injector plugs terminals the other goes to the DME. The DME provides the ground so the circuit is complete, and the injector fires. The noid light is just a 12V light bulb that represents the injector's coil. When it flashes, it indicates that the circuit is operating correctly.

What you do is connect the your test light to a + source or any 12V power supply and hold it to the one of the terminals in the injector plug and have someone crank it, when your injector flashes that circuit is good. Test all of the injector plugs.

P.S. Another way is to go out and buy a pack of #194 light bulbs, bend the wires down. Then insert it so that the wires touch the terminals in the injector plug, then crank.

aj328 · 06-29-2007, 03:18 PM

Sorry Starmavin, I was testing it a**backwards, using ground instead of 12v. I should have read your 6-26 note closer. Will try it the right way tonite. Thanks for spelling out so even I could understand !! Thanks again, aj

aj328 · 06-29-2007, 08:47 PM

Starmavin, Took your advice on the #194 bulbs, tested all injector sockets for the signal from the DME and all flashed ? I sort of thought #2 wouldn't, what do you think? I downloaded some pictures into vbgarage. (which took awhile to resize for this site) One shows a close up of the coil packs and shows a loose brown wire, could this be part of the problem? aj

Starmavin · 06-29-2007, 10:35 PM

If all the injectors are getting a signal then the issue is either in the injector it self, or a spark issue. Change all the plugs, and test each coil.

Starmavin · 07-03-2007, 04:55 PM

I looked at your pics you posted and that is a ground wire, and it should be mounted to the metal plate that the coils bolt to. And yes, that could cause your problem.

aj328 · 07-04-2007, 12:16 PM

This motor is playing games with me. Starmavin, Per your suggestion from 6-29, I went back to square one. I pulled the plug and it was wet. Then, I did a spark test....No spark ! ! Whereas , at the start of this , There was spark and the plug came out dry, So the first thing I did was, put in a new injector. Today, I grounded that loose wire but it didn't help. Swapped coil packs, problem remains at #2 cylinder. Are there intermittent signal problems or is there a history of possessed 328's? Thanks aj