325i running on 5 cylinders.

Post Sun Jun 23, 2013 6:49 pm

Trying to diagnose why my engine is down a cylinder. I fitted an engine that had been stood for a little while. The cylinder nearest the firewall is not firing.

- checked for spark with the lead and several plugs. Spark is good. It hurt. No drop in revs when the plug is pulled.

- checked compression. Over 150psi.

- pulled the electrical connector for the injector, no change in note.

I'm assuming that because I have spark and compression, it's more than likely to be a sticky injector? I gave it a good tap with a spanner, but no luck.

I still have the injectors from my m20b20, which I've pulled ready to test. Are they a higher rate on a b25 engine?

Post Sun Jun 23, 2013 7:09 pm

B20 injectors are smaller than the b25 ones, also meant to run at 2.5 bar fuel pressure and b25 should be 3 bar. With the injector plugged in engine running get a big screw driver and put the tip on the injector and the handle on your ear may be able to hear if its opening or not. Up have 5 others to com pair sound to.

Post Mon Jun 24, 2013 1:19 pm

Are you certain it's just one cylinder down, and not three? One cylinder down is hardly noticeable, and three down is only one less than most cars have at best.

Post Mon Jun 24, 2013 3:08 pm

The engine revs drop noticeably when I remove all the other leads from the plugs. The last lead produces no change at all.

Post Mon Jun 24, 2013 10:30 pm

Screwdriver test reported no audible click, so i pulled the injectors. The orange buildup around the top of it, and the black sludge at the bottom of the injector definitely suggests to me it's time for a refresh!

Post Tue Jun 25, 2013 12:10 pm

Why not try this method:

Post Tue Jun 25, 2013 1:06 pm

Speedtouch wrote:Why not try this method:

Because it doesn't replace worn bits, it doesn't check the flow rate and it doesn't check the flow pattern.
At just £10 a time, leave it to the professionals.

Post Tue Jun 25, 2013 1:45 pm

not quite injector cleaner but additives just the same

Post Tue Jun 25, 2013 3:41 pm

have you double checked the wiring as well make sure you are getting a 12v feed to all the injectors? also the check the switching side wiring as well, injectors 1,3,5 should be connected and 2,4,6 on the other wire can't remember the colour off the top of my head brown with a white stripe and brown with a yellow maybe?

Post Tue Jun 25, 2013 9:42 pm

You can test the injectors by running a wire from the battery to each of the injectors . I made up a test loom with an old injector wire. Just removed the locking wire from it and test each one. Should hear a click .

I also have a set of 325 injectors if you want them just pay the postage?

Post Wed Jun 26, 2013 7:36 am

Wow, hongkongfuey, that's a very generous request. I'd love to take you up on that please? Could you PM me some details?

I'll set up a test wire to try, but I think it's quite likely to have stuck, which no amount of testing or cleaning will sort out. Also, now that I've got them all off, it would be a shame not to do something about it!!

Post Sun Jun 30, 2013 1:47 pm

Just to follow this up - was a dead injector. Replaced one, and put it back in a different place putting a known good injector in the cylinder that wasn't firing. All good now, although it has shown up I have further running issues.

Post Thu Jul 04, 2013 4:22 pm

Hello mate did you get them ok. Did they help?

Post Fri Jul 05, 2013 7:38 am

Hey mate. Yes thanks, turned up the following day after you sent. I picked the best of the ones you sent and my ones, and put them in the car. It was clearly the problem and the car runs nicely all the way up to the redline now

I've got some throttle response issues still around the low end, but I'm thinking that's a sensor I need to clean up. I'm going to see if I can send a set of injectors off to injectortune too, to improve that further!

Thanks again for sending them though, that was a very kind gesture.