Missfire

[tim15888]

Just had a really good morning, firstly I get a missfire on start up, which is bad enough to put the engine management light on with a code saying missfire, so I reset it with my code reader... Flying down the m60 to the scrap yard to get a window mech for a friends Megane, all seemed ok apart from my wheels being out of ****ting balance from when I had new tyres fitted a couple of weeks ago... next thing I know engine management light back on, plug in again and code is saying my front Lamba sensor is open circuit, so I shall go get one of those later with a ton of other bits that I am treating it too today... Anyway, the missfire isn't going on for long enough to test the exhaust manifold temps or unplug the coils to see which one it is. Has anyone got a set of coils for sale? The plugs are quite new but I'm going to be changing these aswell and shall inspect them for mixture but as it's only missfiring for a couple of seconds on startup so I don't expect this is going to tell me a right lot. Just posting the thread to share my dissmay at the whole experiance really, I shall post later when I fix it. Has anyone else had this problem? It's a T5 ME7.

[M-R-P]

When mine blew a coil, it wasn't intermittent. It went, ran like a bag of ££££ and threw the code "missfire cylinder 3" I would have thought it would tell you which coil it was but it could depend on your reader. You might want to unplug and clean the coil connections to see if that helps.
Good luck mate.

Martin.

[tim15888]

If it's the coil giving a wrong resistance reading or something then it should really tell me but if it's a duff plug then it won't be able to tell usually. I changed coil pack 1, cos' that's the common one to go apparantly according to a mate that breaks them. I also changed front Lamba sensor however I'm not sure if I got the right one, could do with you havng a look on yours if possible? Mine has 2 sensors, one with a big 6 wire plug and the other with a smaller 4 wire with a red locking clip. Mine has been de-catted and I'm not sure if they was mixed up when the decat was done. It wouldn't really make any difference cos' they will both get the same gasses anyway with no cat in, but my reader was telling me it was the first one, I'm sure that should be the 6 wire one but when I took it off it was the 4 wire if you get what I mean. Basically what I could do with knowing is if the front sensor has 4 or 6 wires? Would be a great help if you knew?

[AndysR]

If the misfire is still there despite the fact you've swapped the coil I'd be tempted to check the plugs for dampness and condition before starting it one morning....

[M-R-P]

Hmmm, at high mileage, the coil packs go randomly, afaik. As fot the lambda sensors go, where abouts are they and I'm happy to go have a look.

[M-R-P]

Just checked the haynes book of lies, the front one has more wires on it than the back one. BUT it looks like the front has 4 and the rear has 2/3.?
If your code reader doesn't give a cylinder number, then as Andy says, check the plugs.

[tim15888]

The missfire seems ok now that was an unrelated fault. If it was a coil that was open circuit/blown then it would tell me which one had gone but I think the faulty one is just weak, as the missfire is only when first started from freezing cold, when the engine is running richer than Bichard Brason. Thanks for having a look at the lamba plug for me. My engine should be the same as yours, it's the ME7 fly by wire like they put in early phase 2 upto about 04 I think. The lamba plugs both plug in on top of the gearbox... if this is right about the big plug being on the front one then they have been swapped as I thought, and therefor I've changed the wrong one! Oh well back to the breakers in the morning before work....

[tim15888]

fixed the lamba fault, twas the one with 6 wires, me just being dumb why I changed the other! It's right up near the turbo flange the first one, could have sworn it was right before the cat, or where the cat should be at least! Going to get a new set of plugs in her later and hopefully should all be well. Missing my noisy exhaust already though

[SteveRuss]

Just had a really good morning, firstly I get a missfire on start up, which is bad enough to put the engine management light on with a code saying missfire, so I reset it with my code reader... Flying down the m60 to the scrap yard to get a window mech for a friends Megane, all seemed ok apart from my wheels being out of ****ting balance from when I had new tyres fitted a couple of weeks ago... next thing I know engine management light back on, plug in again and code is saying my front Lamba sensor is open circuit, so I shall go get one of those later with a ton of other bits that I am treating it too today... Anyway, the missfire isn't going on for long enough to test the exhaust manifold temps or unplug the coils to see which one it is. Has anyone got a set of coils for sale? The plugs are quite new but I'm going to be changing these aswell and shall inspect them for mixture but as it's only missfiring for a couple of seconds on startup so I don't expect this is going to tell me a right lot. Just posting the thread to share my dissmay at the whole experiance really, I shall post later when I fix it. Has anyone else had this problem? It's a T5 ME7.

I've got five coils I took off my C70 T5 1999.. I've been working away from home for centuries (or so it would seem) but i'm back in Bristol from Monday 28th November. My C70 (RIP) had done 117000 miles but the coils worked perfectly. Oil problem killed it. All the bits i've taken from the car I want to sell personally to other Volvo forum owners. I don't want to give them away but i'm happy that the people that have helped me get a nice time out of it..

PM me if you feel we could help each other out..

Regards. SteveRuss

[tim15888]

Thanks for the offer mate much appriciated. I have actually got a set on my back seat from a T5 which was broken at 65k for the same reason... Oil pump faliure. My mate breaks these Volvoids so I'm usually pretty dicked up when it comes to parts. I was after a new ECU last week so the MAPing guy can get the origeonal info out of it to adjust as mine has has been bodged up by the last ££££ who tried to MAP it a couple of years ago. Mine has a rare ecu on it for which the guy I'm using this time can't get a file for, lukily I managed to find one now though. Just hope it's the right one. If not ad you still have it I'll be asking what numbers are on yours!

[Kingsford G]

Just had a really good morning, firstly I get a missfire on start up, which is bad enough to put the engine management light on with a code saying missfire, so I reset it with my code reader... Flying down the m60 to the scrap yard to get a window mech for a friends Megane, all seemed ok apart from my wheels being out of ****ting balance from when I had new tyres fitted a couple of weeks ago... next thing I know engine management light back on, plug in again and code is saying my front Lamba sensor is open circuit, so I shall go get one of those later with a ton of other bits that I am treating it too today... Anyway, the missfire isn't going on for long enough to test the exhaust manifold temps or unplug the coils to see which one it is. Has anyone got a set of coils for sale? The plugs are quite new but I'm going to be changing these aswell and shall inspect them for mixture but as it's only missfiring for a couple of seconds on startup so I don't expect this is going to tell me a right lot. Just posting the thread to share my dissmay at the whole experiance really, I shall post later when I fix it. Has anyone else had this problem? It's a T5 ME7.

If your car has a coil pack (I assume it is newer than my 850) Whatever cylinder missfires a good diagnostic machine should tell you but not the cheapy ones.If you have OBD 2 socket I have a snap on machine to test it but depends on where you are.They charge £25-30 to plug it in I won`t charge any of our members.

[tim15888]

I know mate, mine would tell me which one it was if it was a diagnosable problem with a coil too. They will only tell you which coil it actually is if the resistance peramiters of that coil are outisde a certain amount which then rings alarm bells in the ECU that there is a problem in that coil. Sometimes you get a random missfire which can mean that the coil is arching out against that spark plug tube, however electronically is functioning the way it should and won't be picked up as a problem by the ECU apart from by the laba picking up unburnt fuel. (Brings me onto another subject about plugging cars in, often you get lamba faults coming up when something else is wrong as it is the last in the chain of sensors and if the engine is running wrong due to a MAF or something that's reading wrong, the ECU won't notice that the MAF is actually reading wrong and will only pick up that the engine isn't running right at the lamba etc). You can get a missfire sometimes when it is just causing a weak spark without the resistance of the coil being to great or low for the ECU to pick it up. They only usually scense problems with a coil when a coil goes open circuit but mine is working most of the time, just not creating a big enough spark to cope with the running rich mix when fist started from freezing cold. This is one theory anyway, the other one being a problem with the software on the ETM, as I have changed this for a 2nd hand one about 7 months ago andit has been fine ever since but I havn't used it in winter coldness with the new one on. I would be surprized if it was an ETM fault though as all it really does is open the throttle, and the missfire is there even if you rev it up. The ETM theory is just something that a Volvo specialist told me it could be, I don't really see how it could be that myself though but the guy who told me seems to be **** hot when it comes to Volvo's, and I am always like listning to people who know more than me about somethng.

[Kingsford G]

Do you get a slight judder or a little choke when you put your foot down?

[tim15888]

Oly when cold

[Kingsford G]

would be a good idea to try new leeds if you can borrow and see what happens,they can be a little missleading b****ds.Also I know you changed the s/plugs but they can cause a lot of nonesence and you do get a bramd new parts faulty.You would be surprised what you come across doing mechanics.Try this if you can before you start spending money.Lambda faults can be caused by the above mentioned bits,MAF and so on.Coil pack can be bad in a cold start up.I have had different cars with similar simptoms effected by what I said.What is your sistem like?One coil pack for all or one for each cylinder

[tim15888]

Unfortunately with the return of the cold weather, the missfire has returned. Thought it had gone when Hamish remapped, and married up the throttle body propperly but unfortunately it was just coincidence that it warmed up a bit after that. The car is fly by wire with a coil for each cylinder. Fortunately my mate breakes Volvo's so I have alot of parts available to try. I've tried, new plugs firstly, then a new set of coils. No change. Yesterday the missfire was really bad, and it was even doing it without leaving it over night, so the next thing I tried was the temp sensor. Big improvement all round on the engine running scince doing that so I thought I'd cured it, but still got a missfire this morning, just not as much as before even though it was snowey and freezing. Too be honest, I think that possibly the new plugs are just foweled up, going to change them for a set of quad electrode Brisk plugs, which are supposed to be really good, but will see when they come and let you know. The temp sensor on these is a really wierd setup. Instead of a sensor for the fanswitch, one for guage and one for ecu, the 1 sensor goes to the ecu which then controlls mixture, fan and guage. Sussed this out when tinkering with it the other night. If you unplug the sensor, the fan will start up, nothing unusual there, but if you plug it back in the fan will carry on going until you reset the ECU. Just though that was interesting so would share it.

[craigshake]

Tim, how did you get on changing the plugs... did it help? Got the same problem with mine, suspect coil or leaky injector.

[tim15888]

It's the Alternator mate, I sold the car with the problem but I'm getting it back tomorrow hopefully. I had a massive stereo and think I damamged the alternator cos' batt voltage was dropping a bit on startup and taking about 20 seconds to come back up