Mis firing on idle HELP!!!!!
Discussion
Hi,
My chimaera 400 HC 1994 misfires on idle! and now its really starting to annoy me!!
I have done a search on it, found some useful information.
These are the symptoms:
Checked plugs and they are quite black! this was after starting the engine for about five minutes then stopping and taking the plugs out. The 2 cylinders at the front of the engine on either side were black and damp from petrol. you could see that they were wet.
The rest were black, checked the bible and it means the car is running rich.
Changed all the plugs and checked they were all gaped correctly. when i started it up it sounded alot smoother for about 2 minutes but then it went back to misfiring!!
I then cleaned the butterfly valve, stepper motor, and changed the leads.
This still hasnt helped. I also eliminated the (cant remember the correct name) plugs in between the spark plugs and the leads by the engine!! I took them off and tried it without them on but it still sounded the same!!
This is really starting to bug me now as driving at 30mph where i have to, is awkward as hell as if i put it in 4th gear it jolts as the engine is misfiring..
Once i get above 1800rpm the engine is totally fine!
I really want to get this sorted so any advice will be greatly appreciated.
Thanks in advance!
Dale
>>> Edited by dalecrx on Monday 13th October 12:59
My chimaera 400 HC 1994 misfires on idle! and now its really starting to annoy me!!
I have done a search on it, found some useful information.
These are the symptoms:
Checked plugs and they are quite black! this was after starting the engine for about five minutes then stopping and taking the plugs out. The 2 cylinders at the front of the engine on either side were black and damp from petrol. you could see that they were wet.
The rest were black, checked the bible and it means the car is running rich.
Changed all the plugs and checked they were all gaped correctly. when i started it up it sounded alot smoother for about 2 minutes but then it went back to misfiring!!
I then cleaned the butterfly valve, stepper motor, and changed the leads.
This still hasnt helped. I also eliminated the (cant remember the correct name) plugs in between the spark plugs and the leads by the engine!! I took them off and tried it without them on but it still sounded the same!!
This is really starting to bug me now as driving at 30mph where i have to, is awkward as hell as if i put it in 4th gear it jolts as the engine is misfiring..
Once i get above 1800rpm the engine is totally fine!
I really want to get this sorted so any advice will be greatly appreciated.
Thanks in advance!
Dale
>>> Edited by dalecrx on Monday 13th October 12:59
I am currently suffering with the same issue so I know how annoying it is. I have been through the same procedure trying to cure it. My next step is to check the fuel temp' sensor. Also, make sure you have setup the trottle pot and fuelflow sensor. I was told that the trottle pot should give a reading of .30-.33 volts when closed and that the flow meter reading should be around .6 volts at idle. (oddly these are different to the information in SH book)
All of these have improved the condition on my car, but not solved it.
All of these have improved the condition on my car, but not solved it.
glynlucas said:
I was told that the trottle pot should give a reading of .30-.33 volts when closed and that the flow meter reading should be around .6 volts at idle. (oddly these are different to the information in SH book)
These are consistent see pages 90-91 in Chapter 5 second edition.
If there is nothing obvious it is time to take the car to the professionals with the appropriate analysis and code reader kit. Otherwise there is a big danger of simply replacing a lot of expensive parts on a trial and error basis.
If the mixture is rich, it is overfuelling either vbecause the ECU is getting duff info from a sensor, the fuel pressure is wrong, the injectors are duff (they are fired as banks) or some other problem or issue. When was the airfilter cleaned? Have the right plugs been fitted? Are the plugs oiling up?
Steve
www.tvrbooks.co.uk
Try changing the plugs.
The car may run rich (was the whole plug black including the ceramic supporting the centre electrode?) or it may just have been running rich as it was warming up (due to extra fuelling whilst warming up). Ideally you need to have run the car fully warmed up for 10-15 mins before letting it cool and checking the plugs.
If two of them are damp they may not be firing correctly. Changing is the only reliable fix for damp plugs (although it won't fix whatever made them damp - but I believe damp plugs in these engines are not unusual due to operating conditions/fuelling etc).
The car may run rich (was the whole plug black including the ceramic supporting the centre electrode?) or it may just have been running rich as it was warming up (due to extra fuelling whilst warming up). Ideally you need to have run the car fully warmed up for 10-15 mins before letting it cool and checking the plugs.
If two of them are damp they may not be firing correctly. Changing is the only reliable fix for damp plugs (although it won't fix whatever made them damp - but I believe damp plugs in these engines are not unusual due to operating conditions/fuelling etc).
I had a sorta similar problem earlier in the year. It started off by manifesting itself as a problem revving over 3200 revs (there is a thread on here somewhere about it) in any gear or even not in a gear at all, just free revving. It ended up being a problem starting, idling or running at low revs, but fine if you booted it or accelerated hard (that's how they are meant to be driven - right??). Anyway, it turned out to be the air flow meter that had died. A replacement one of those (170 quid later) and all was sorted. If you have a friend with a Chim, borrow theirs and try it out. The air flow meter dies because of the heat under the bonnet. If you speak to Mark Adams, he will tell you all about this (including fixing mine!!) If you want any more details, email me.
Hope you get it sorted as I know how frustrating this can be!!
Hope you get it sorted as I know how frustrating this can be!!
I had something similar and tried changing the plug leads to Magnicor leads. It still didn't fix it and in fact got worse. It turned out to be the base idle setting which was way off. However, resetting this alone wasn't the answer as it turned out that the new coil-distributor lead was faulty. Replacing the lead + the base idle reset seems to have cured things nicely.....though there is always that nagging doubt at the back of your mind that it will come back....
Excess fuel pressure would cause those symptoms. The fuel pressure regulator is supposed to drop the pressure as the manifold pressure drops when you back off the throttle. If the vac line to it is missing/leaking, it won't get the vac signaL and won't drop the pressure. Or the unit itself could be faulty. These faults would make it run massively rich at part throttle, but have less impact as you open the throttle. I suggest you check the vac lines are all connected at both ends and intact, check the spark strength, and if nothing jumps out at you have a professional look at it. This sort of thing is bread and butter for good mechanic but amateurs are likely to do more harm than good while they investigate it.
I'm gonna keep my eye on this thread as my Chimaera is doing exactly the same.
Interestingly, it seems to have started since it was serviced...great eh!
You're right about the 30mph bounce thing...well annoying and I don't expect the transmission enjoys it too much either!
Been to a land rover repair place today (to get a land rover part) and they agreed that it was running badly and wonder whether they could hook it up to their diagnostics machine - the TVR garage that serviced my car didn't seem too eager to do that for me - 500+ pounds well spent...NOT.
Matt
Interestingly, it seems to have started since it was serviced...great eh!
You're right about the 30mph bounce thing...well annoying and I don't expect the transmission enjoys it too much either!
Been to a land rover repair place today (to get a land rover part) and they agreed that it was running badly and wonder whether they could hook it up to their diagnostics machine - the TVR garage that serviced my car didn't seem too eager to do that for me - 500+ pounds well spent...NOT.
Matt
Im planning on getting my Chimaera hooked up to the diagnostic machine,hopefully today or tommorow as i have a friend that works at a TVR garage, but we hooked it up a while ago when it waws doing it then and it didnt show up any codes!!
I have got to get this fixed as it takes out all fun of driving the tvr.
I will let everyone know what i find out when i have had my chimaera checked out.
I have got to get this fixed as it takes out all fun of driving the tvr.
I will let everyone know what i find out when i have had my chimaera checked out.
Dale,
I'm not replying specifically regarding Chims - this is more a general thing.
From your description it does sound like the engine is running very heavily on the rich side. Bearing in mind that the fuel injection system "listens" to what the lambda sensors tell it and adjusts the fuelling to match, it could be something as simple as a faulty lambda sensor.
I would imagine there is a way to test this, but i have a feeling it would involve something with a multimeter and knowing what values to expect.
HTH
VS
BTW in case you want to know what a lambda sensor looks like, have a quick peek at the exhausts. As they come forward from the manifolds on the sides of the engine you'll see something screwed in to the manifold, about the size of a fat pen. Will have 2, 3 or 4 wires coming out of it. That is a lambda sensor.
I'm not replying specifically regarding Chims - this is more a general thing.
From your description it does sound like the engine is running very heavily on the rich side. Bearing in mind that the fuel injection system "listens" to what the lambda sensors tell it and adjusts the fuelling to match, it could be something as simple as a faulty lambda sensor.
I would imagine there is a way to test this, but i have a feeling it would involve something with a multimeter and knowing what values to expect.
HTH
VS
BTW in case you want to know what a lambda sensor looks like, have a quick peek at the exhausts. As they come forward from the manifolds on the sides of the engine you'll see something screwed in to the manifold, about the size of a fat pen. Will have 2, 3 or 4 wires coming out of it. That is a lambda sensor.
I know how to test a lambder sensor, thats quite easy to do, Using a multimeter set to volts. You measure what the voltage that is being given off from the multimeter by linking in to one of the wires coming from the lambder sensor and ground.
Ill check the bible in a mo to see what the limits are on the lambder sensors.
I have just spoke to my mate at the tvr garage and im taking my chimaera down tommorow lunch time so he can havea look at it and put it on his diagnostic machine to test for faults. Hopefully something shows up faulty as if nothing comes up its going to make it hard to track down the fault.
Cheers
Dale
Ill check the bible in a mo to see what the limits are on the lambder sensors.
I have just spoke to my mate at the tvr garage and im taking my chimaera down tommorow lunch time so he can havea look at it and put it on his diagnostic machine to test for faults. Hopefully something shows up faulty as if nothing comes up its going to make it hard to track down the fault.
Cheers
Dale
I think you'll find that it is actually very hard to test lambda sensors. When the engine is in closed loop mode they normally don't put out a constant voltage but continually 'hunt' just either side of Lambda=1. In open loop mode the sensor will just signal 'rich' continually. You really need a scope to show they are working, and probably an external lambda sensor to confirm that the reading they're giving you tallies with the actual oxygen content. These things do fail, and I've had quite a few go over the years on the V8S, but another possible complication is that any leak in the exhaust upstream of the sensor will throw the Lambda reading way, way out leading to overfuelling at part throttle.
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