Hi everyone, I'm having a problem at the moment where it feels like i'm running on 5.5 cylinders. At idle the car is a little too lumpy and there is a bit to much vibration. If you pull the coil pack connector the rpm drops slightly, but not as much as if you pull one of the others. Of course it's number 6 that is giving me problems. I have JECS 550CC injectors installed. I have confirmed signal from the ecu by connecting an efi bulb to the injector connector, injector connector connection appears fine (brand new), swapped coil packs and changed spark plugs. when i'm driving it feels almost fine. I put some injector cleaner through it and took it for a decent drive, but it still has the same issue. I'm starting to suspect that perhaps the injector is partially blocked or something is wrong with the spray pattern. If i'm driving and I shut down #6 using my nProbe software it gets quite lumpy, turn it back on and it drives better, but still feels like it's missing slightly, especially at idle. Anything I might have forgotten to check? I'm at the stage where i'm going to have to pull the rail and test the spray pattern and flow. If it looks bad i'll send the injector back under warranty, but they'll need to rebuild it so that will probably take weeks. I've created a wanted ad in the off chance someone has a spare lying around www.aus300zx.com/forum/showthread.php?t=325980 I'd prefer not to go back to stock injectors because that would mean needing to change connectors and also ECU ROM. Thanks guys, Simon
When you did your plugs did you manually set the gap? They can cause a bit of a stumble from a weak spark if not handled properly.
Hey Jordz, The spark plugs are were changed 4,000kms ago. And just to be sure I bought a brand new one and replace the #6 plug on the weekend with no luck. Cheers, Simon
Also forgot to mention, checked the injectors with a multimeter and #6 came back the same as the other injectors.
Compression test? Might be a little low on one cylinder? What heat range plugs u buy? Disconnected the battery when changing your injector connectors over? If not, might have partially fried one injector circuit? Tried another ecu yet? The ECU rom you have, was it for those particular injectors? Or just a generic tune? Any idea of the latency settings on the injectors? Ohm checked them? When you pull the plugs, is it more sooty on one particular plug versus the rest? Or maybe m ore white-ish? This would indicate lean/rich conditions for the cylinder in question. Series 2 ptu?
I've got the NGK BKR6EIX Iridium spark plugs Yep I replace the whole wiring loom with a new one so the battery etc was out. I haven't tried an new ECU yet. It's a tune for 555 injectors. Not 100% of the latency settings. I've Ohm checked them and they were reporting the same number. 11.6 from memory. #6 is probably a little more sooty, I think it is running a little rich in general, but i'd have expected a new plug to have sorted that? http://www.flickr.com/photos/59348042@N00/9439005177/ It's not as pink as it looks in this photo. Yep series 2 PTU.
Let me know how u go with your problem raZorTT cause ive goth the exact problem as you but mine is on cylinder #2 mines been getting better thoe ive been putting tons of fuel injector cleaner in it.
Did you install the injectors recently? Did you do it yourself? Might have pinched an o-ring and its not sealing perfectly. Beavis
Hi Beavis, Yep installed the injectors myself. It had been working fine for the past 4000kms. I had to do a plenum pull and after everything was re-assembled the issue presented itself. We didn't touch the fuel rail as part of the plenum pull. Cheers, Simon
Only other thing I can suggest is the all the connectors to the coil packs are clean and seating properly. I had on cylinder that was a bit temperamental and there was a little bit of plastic stuck in the coilpack connector and wasn't allowing it to properly click into place. Good luck! Beavis
Thanks Beavis, It's frustrating.. I've even pulled the pins out of the connector and connected them directly to the injector pins and still had the issue :-\ Will see how I go this weekend. Thanks for the help!
Quick update on my issue.. We pulled the fuel rail out on the weekend and hooked the injectors up to test the spray pattern. All of the injectors appeared to be fine. We gave them all a clean and then swapped the #6 and the #2 injectors. The thinking being that if it's the injector, the problem should move to #2. After we got it all back together the problem was still @ #6 I swapped the ECU with a spare and also tried a brand new S2 PTU, again with no luck I guess the last things to try are a compression test, and to try and test the wiring. Cheers, Simon
Finally got around to doing a compression test and all 6 cylinders were withing 5-10 of each other, so I don't think its compression. I did a vacuum leak test with a smoke machine and found a very small leak, but nothing that i'd expect to cause such an issue. Any thoughts?
I also had a multimeter, pulled the ECU out and checked the resistance of each injector and they were all the same.
If you have a Z buddy... Ask to borrow his CAS for about 5 minutes. It is pretty amazing how many different weird issues a flaky CAS can cause.
Hey MaxxAction Ok i've got a friend who has just pulled his CAS off the engine, so i'll give it a crack. Cheers, Simon
Check all plenum/body earths Not sure if your operating o2 sensors, however try disconnecting them and seeing if any changes are made Switch the injector connector from a known good cylinder to the cylinder that isn't firing as good and see if any change is made to the idle drop when you pull the connector
Thanks jamersss I actually tried disconnecting the O2 sensors on the weekend and it didn't seem to make a difference. I had datascan connected and while accelerating I could see the A/R ratio changing from rich to lean. I'll double check the earths.. How many are there.. I can visualise the two at the back of the plenum Cheers, Simon
Two earth points at rear top of plenum, and one body earth near the large fuse box on the passengers side of the engine bay. This was my cylinder not firing thread, give it a read if you got a minute. Quite a lot of things I checked that may be of value to you http://www.aus300zx.com/forum/showthread.php?t=326404
