Tannhauser Posted November 26, 2004 Share Posted November 26, 2004 I posted a while back about my car misfiring following its single/fuel system/emanage upgrade. I now have some coil packs on loan to swap when I get some free time. However, in the mean time, the car has started running quite unevenly and at idle it is sometimes doing something very odd. The revs 'bounce' in a regular rhythm from about 300 to 600 rpm. It sounds exactly like I'm putting my foot on the accelerator very gently and then lifting it off, once a second. It seems to go on indefinitely. It sounds like it surely must stall, but just recovers itself....I can foresee in a week or so, if it continues to deteriorate, it will be cutting out. Does this sound like it could also be plug/coil pack related or could it be something more sinister? Cliff Link to comment Share on other sites More sharing options...
Alex Posted November 26, 2004 Share Posted November 26, 2004 I'd do a check on the voltages the O2 sensor is getting...via a multimeter at the o2 port in the diagnostics pod under the bonnet. Link to comment Share on other sites More sharing options...
tbourner Posted November 26, 2004 Share Posted November 26, 2004 Mine's similar but not as bad. O2 sensor did nothing. Does yours smell strongly of fuel as well? Dude had this about a year ago, dunno what happened though. Link to comment Share on other sites More sharing options...
Ian C Posted November 26, 2004 Share Posted November 26, 2004 Can you check with the E-01 to make sure you've still got a map loaded? If it's running uber-rich it might behave like that. Can you describe the symptoms under cold start, warm idle, and normal driving? You say "sometimes", how often is this? I get a noticeable "hunt" idle on mine, the cams and the big injectors cause that, but it's there all the time, and certainly isn't down to 300rpm! If you rev it up a bit and lift off, does that cause the near-stall condition? -Ian Link to comment Share on other sites More sharing options...
Tannhauser Posted November 26, 2004 Author Share Posted November 26, 2004 1) The odd idle has only happened over the past couple of days and I've noticed it two or three times. I thought I'd noticed fuel smells and increase in petrol consumption too, but those might be my imagination. 2) I'll check the map via the E01; thanks Ian 3) Cold start is now worse than it used to be - often needs a touch on the accelerator to 4) Over the last couple of days, when running at lower throttle the rhythm of the engine is not so smooth as it normally is. 5) I'll try the rev-up-a-bit test. 6) I don't have a multimeter and I don't know where the diagnostics port is, so I can't check that out at present. OK, thanks for help. Link to comment Share on other sites More sharing options...
baojun Posted November 26, 2004 Share Posted November 26, 2004 I have encounter this problem few days ago. And while in the MOT test, the CO increased up to as high as 2.9% EVEN AT IDLE. That was becouse of misfire at idle. And the reason for that should be fuel too running too rich. One of the possible problem maybe caused by faulty fuel sensor. That's what I think. Link to comment Share on other sites More sharing options...
CJ Posted November 26, 2004 Share Posted November 26, 2004 Mine was doing the exact same thing but only after a cold start. Once it warmed up sufficiently, the problem went. Link to comment Share on other sites More sharing options...
tbourner Posted November 26, 2004 Share Posted November 26, 2004 Will the Walbro probably fix this if the O2 sensor didn't? I'm decated with NGK BCPR7ES plugs. (sorry - hijack). Link to comment Share on other sites More sharing options...
Tannhauser Posted November 26, 2004 Author Share Posted November 26, 2004 The map still seems to be still installed. I've just removed the coil packs, my first ever foray into the mysterious underbonnet world. I must say it wasn't pleasant and my sensitive guitarist's hands are all dirty. I am hampered by having an inside leg measurement of 14", which makes everything hard to reach. Link to comment Share on other sites More sharing options...
CJ Posted November 26, 2004 Share Posted November 26, 2004 Quote Originally posted by tbourner Will the Walbro probably fix this if the O2 sensor didn't? Very doubtful as I have 2 x Walbro pumps! Link to comment Share on other sites More sharing options...
absz Posted November 26, 2004 Share Posted November 26, 2004 the problem with idle faults is it could be anything . the way i will tackle it is by starting from basics which is vaccum leaks check around the sensors first .ie turbo pressure sensor/fuel pressure sensor any splits around these sensors will give u uneven idle. to make things easy for your self buy a can of carb cleaner or easy start and gently spray around the pipes with the engine running if you have a split pipe this will cause the engine revs to increase. secondly if you remove your spark plugs that will give you a good indication on your car running rich or lean by the condition of the plug it self . Link to comment Share on other sites More sharing options...
b_have Posted November 26, 2004 Share Posted November 26, 2004 Sounds lean to me, I would clean the o2 sensor and check for air leaks. Link to comment Share on other sites More sharing options...
Ian C Posted November 26, 2004 Share Posted November 26, 2004 The J-spec has a MAP sensor on the intake plenum, that means while idling, any air leaks before the throttle plate are irrelevant, and any air leaks past the throttle plate actually increases the idle speed, as air drawn in by the engine vac is still actually measured. that leaves you with a leak around the hose that connects the MAP sensor to the intake, and that's dead easy to check for. Plus, on a stock system at least, a leak to atmo on that line usually kills the engine, either because it upsets the FPR or because the MAP sensor seeing atmo pressure causes the engine to run mega rich suddenly. The misfire thing is interesting, especially as you've been at the coil packs. But I'd check the O2 sensor first. Multimeters can be gotten for -Ian Link to comment Share on other sites More sharing options...
Tannhauser Posted November 27, 2004 Author Share Posted November 27, 2004 I haven't been at the coil packs yet, Ian, only removed them. I've removed the spark plugs and they are very heavily coated in what I take to be carbon. So it looks as though the car is running mad rich? I have some BCPR7ES to go in - I presume they don't need regapping? From the gauge doohickey that I bought, they seem to be 0.8. Ta Cliff Link to comment Share on other sites More sharing options...
absz Posted November 28, 2004 Share Posted November 28, 2004 as plugs are coated heavily it seems to be running rich? misfire on one cyclinder will cause only one plug to foul up, as all plugs are fouled it seems the fault my be map sensor/02 sensor related as ian has pointed out. please make sure you have no exhaust leakage around the manifold/downpipe as that will lead the 02 sensor into thinking the engine is running lean and will richin the ratio of fuel. Link to comment Share on other sites More sharing options...
Tannhauser Posted November 28, 2004 Author Share Posted November 28, 2004 Took the car out for a run today following replacement of spark plugs. Although initially not too bad, it's now running very rough indeed. Later I noticed black smoke on start up, so took the car down the road and back and it's still spewing it out. I tried to multimeter whilst it was doing its oscillating trick on warm idle, but the diagnostic lid is right under the strut brace, such that I can only reach the top right pin. I can't lift the lid far enough to see what pin this is.None of my tools will get the strut brace off. Of course. Anyway, the big question is: how far can I safely drive it like this? I was going to take it to Matt to get a wbo2 sensor, but I'm concerned about the consequences for the engine - if it will make it that far.... Any views? Edited to add: thanks, Absxxxxxxx, I'll take a look( though I'm not convinced I know what I'm looking for). Link to comment Share on other sites More sharing options...
absz Posted November 28, 2004 Share Posted November 28, 2004 i dont think you will do any damage . if it has a constant misfire there is a chance of damaging the cat with all the unburnt fuel entring into it. Link to comment Share on other sites More sharing options...
Tannhauser Posted November 28, 2004 Author Share Posted November 28, 2004 Cats have long gone, so at least there's one thing not to worry about. I've heard mention of 'bore wash' as a consequence of overfuelling and was fretting about that. Link to comment Share on other sites More sharing options...
absz Posted November 28, 2004 Share Posted November 28, 2004 you will only get bore wash if there is a fault with injector stuck open or plug not firing but thats using car in that state for long periods at a time. Link to comment Share on other sites More sharing options...
baojun Posted November 28, 2004 Share Posted November 28, 2004 hrm... must be faulty O2 sensor. very high possibility.. Link to comment Share on other sites More sharing options...
afennell Posted November 29, 2004 Share Posted November 29, 2004 sorry to be dim but what does theo2 sensor look like and where will you find it Link to comment Share on other sites More sharing options...
tbourner Posted November 29, 2004 Share Posted November 29, 2004 Look under the bonnet, on the driver side, down the side of the turbo near the bulkhead. It's bolted into the downpipe, just a few inches past the manifold. There'll be a black lead coming out that goes to the front of the engine block somewhere. Link to comment Share on other sites More sharing options...
afennell Posted November 29, 2004 Share Posted November 29, 2004 nice one, thanks Link to comment Share on other sites More sharing options...
Chris Wilson Posted November 29, 2004 Share Posted November 29, 2004 Quote Originally posted by Tannhauser Cats have long gone, so at least there's one thing not to worry about. I've heard mention of 'bore wash' as a consequence of overfuelling and was fretting about that. If it's belching black smoke under load it's already suffered *some* bore wash, running it like that will *very* quickly knacker the rings. Find out what's up with it before it needs a rebuild! Link to comment Share on other sites More sharing options...
absz Posted November 29, 2004 Share Posted November 29, 2004 Quote Originally posted by Chris Wilson If it's belching black smoke under load it's already suffered *some* bore wash, running it like that will *very* quickly knacker the rings. Find out what's up with it before it needs a rebuild! black smoke can be caused by even a blocked air filter it does not mean he has already suffered bore wash just cus it smokes:D Link to comment Share on other sites More sharing options...
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