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| MacGyver |
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I have a misfire problem that is mainly evident at idle on my 4l EF. It is a miss on every stroke which gives the car a baby calming shake. The miss becomes less noticeable on part throttle applications and seems to disappear at 1000rpm.
I have done the following: replaced plugs, leads, compression test (all 180psi), new coolant and radiator flush (not related I know), spray tested for vacuum leaks, replace PCV, disconnect PCV (no difference), reset idle speed to factory spec, clean and test ISC, change LPG mixtures to full rich to see if lean miss, change LPG mixtures to full lean to see if rich miss. By placing a timing light on all leads it seems that cylinders 4 and 5 are missing. This would discount coil pack as they are no on the same coil (it is 1,6-2,5-3,4 isn't it?). Any ideas? cheers Scott
_________________ If it doesn't fit, jam it. If that doesn't work use a hammer. - Engineers Motto Last edited by MacGyver on Sun Jan 21, 2007 1:48 pm, edited 1 time in total. |
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| t66_bt1 |
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exactly the same problem in my ef! just i dont run gas!!! anyone have any ideas???
_________________ R.I.P George.D.Gogas!!!
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| MacGyver |
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I think I have eliminated fuel as the problem as above. Compression is out as it is perfect. That only leaves ignition. I have a spare coil pack here so I will change it when the engine gets cool.
cheers Scott
_________________ If it doesn't fit, jam it. If that doesn't work use a hammer. - Engineers Motto |
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| millard455 |
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there was a thread on how to fix poor idle on the i6 a few weeks back. it was some little things in the computer that needed replacing, cant remember what they were called but it didnt seem like a big job.
_________________ EL XR8 SERIES 2, 5SPD, HOT CHILLI RED, 200 ODD RWKW OF V8 FUN AND GAMES |
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| MacGyver |
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No that would not apply. This is not a rough idle ramping up and down as the ECU tries to control the idle speed, this is a misfire on one maybe two cylinders.
cheers for the input though Scott
_________________ If it doesn't fit, jam it. If that doesn't work use a hammer. - Engineers Motto |
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| haggis |
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Is this only on LGP ?
_________________ I can see through wooden doors. |
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| 4.9 EF Futura |
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Do the crank angle sensor and harmonic balancer ok?
_________________ I promise..... I will never die. |
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| MacGyver |
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Car is LPG only. As I mention it is not fuel related as I have adjusted the mixtures to very rich and very lean with no difference in the misfire.
cheers Scott
_________________ If it doesn't fit, jam it. If that doesn't work use a hammer. - Engineers Motto |
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| MacGyver |
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Just replaced the plugs again, tried a different coil pack and tested all the leads (they were new anyways). Still a miss. Maybe a little bit better.
I guess I should test the cam and crank angle sensors. Also should do a ECU diagnostic. I'll let you know..... cheers Scott
_________________ If it doesn't fit, jam it. If that doesn't work use a hammer. - Engineers Motto |
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| snap0964 |
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Yeah, certainly seems ign related - you'd probably find if you were still running petrol, the condition probably wouldn't be noticeable.
Unfortunately with LPG, any little weakness in the ignition system will show up. I can only suggest to give the coil pack plug terminals a quick wire brush to make sure they are absolutely clean - plug leads are new so nothing needed there. The other thing I'm wondering maybe a couple of plugs are struggling with the plug gaps. IIRC plugs come set at 1.1mm - maybe try 1.0mm. The crank sensor may need a good clean. Since a petrol EF motor will run fine without the cam angle sensor (only needed for injectors), I doubt checking it will have any bearing on LPG operation. The other thing is maybe do a nighttime visual on the plug leads while the engine is running - might notice some crossfire, etc. You wouldn't think so with new components, but wouldn't hurt.
_________________ 96 XH Longreach 'S': LPG, Alarm, 3.23:1 LSD, Cruise, Trip Comp, ABS, Power Windows, Mid Series Dome Lt, Climate Ctrl |
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| MacGyver |
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Update. I have pulled engine codes....111 so no problem. I have tightened intake bolts and rechecked for air leaks and nothing. Next I will try and see if I can isolate to one cylinder only by pulling plugs.
I'm having lots of fun.... 
_________________ If it doesn't fit, jam it. If that doesn't work use a hammer. - Engineers Motto |
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| MacGyver |
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I've done some more troubleshooting lately. All valve springs and rockers are ok. No spark jumping across leads. I hooked a timing light up just to see what the timing was doing (can't adjust because it's an EF) and at idle the timing is all over the place. There are really big movements that coincide with the miss. Like 10 degree jumps. When I raise the revs and the miss goes away the timing smooths out to be rock steady with nice smooth movements.
What could this be? Knock sensor? Cam or crank angle sensor? cheers Scott
_________________ If it doesn't fit, jam it. If that doesn't work use a hammer. - Engineers Motto |
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| t66_bt1 |
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i am interested to find a solution
_________________ R.I.P George.D.Gogas!!!
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| briney |
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i did an efi course recently. during this course matey talked about the ef and au having earthing problems for the tps. he said this would cause a flood miss on idle, as the tps tells the computer that the throttle has been opened. when it hasn't. try providing the tps with its own earth.
_________________ vote for pedro ? f**k pedro, f**k him up his stupid a***hole. |
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| MacGyver |
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Dunno if the tps would have much effect as it is dedicated lpg so no way the tps can cause a flood misfire. Thanks for the input though.
Just did some more messing around and number 6 has a quite regular miss while 4 and 5 are missing as well though irregular. Worked this out by using timing light on all leads and 1,2,3 are nice regular flashes, 4 and 5 are a bit messier and 6 is down right disgraceful. I have tried another coil and the miss felt the same although I only had that coil sitting on top of the tappet cover. It is still running the original coil now. Coil has a condenser bolted to the front right. Didn't think EF's had one. I might change that over and see if it helps. cheers Scott
_________________ If it doesn't fit, jam it. If that doesn't work use a hammer. - Engineers Motto |
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