2.0 JTS low revs misfire - Alfa Romeo Forum
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2.0 JTS low revs misfire

Hi all, newbie here.

I bought a 156 2.0JTS at auction last night. It's a 2003 model with 120k on the clock.

All seemed good till I started the engine up and the display starts flashing "motor control system failure", with the engine warning symbol on the speedo constantly on. As soon as I start driving the symbol starts flashing.

The engine has verly little power and what feels like a misfire until you get above about 2 - 2.5 thousand revs, where it wakes up a bit, and the runs smoothly.

Any help most greatfully recieved, thanks!

Sam.
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Try unpluging the MAF, if you want the faults codes read and can get it to swansea i can hook it upto the computer for you...
What auction did you buy it from?
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(Post Link) post #3 of 25 Old 25-02-11 Thread Starter
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Ok I'll have a look at that this evening after work - thanks for the offer too!

I bought it at leominster, £725, however also sold a Citroen at the same time for £575 so it's really only cost me £150! Bargain or what?

Just thinking, tha brakes are rubbish, there's very little effort, I have to really stand on them. It's like the servo isn't working. Could it be that the vacuum hose has come off and is causing both problems?
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I'm from Hereford, my mate down here/ up here is on this forum aswell has a diagnostic and shouldn't mind plugging it in for you! I can ask if you would like as mines been plugged in now which turned out was a slight missfire!
Hope it's helpful
Cheers
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Could be something as simple as spark plugs or a coil pack. I've replaced both on my misfiring JTS this week.
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yeah hopefully it is something simple.

I'm going to buy a haynes manual on the way home from work (I got a halfords trade card ) and have a good look at it this evening.
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You are not gonna find a Haynes manual.
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Really? Dammit.

If there isn't one specific to the 156 then is there a more generic one available?
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Never mind, just seached haynes online. Virtually no Alfa's at all. Why is that then?
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Ok, just been tinkering with it and I can rule out the MAF meter, plugs and coil packs.

I have however traced the misfire to cylinder 2, by disconnecting the coil packs in turn with it running. Disconnecting cyl 2 made no difference.

So I removed the coil pack and plug, both appear fine. I then swapped the coil packs between cyl 1 and 2 and reassembled. When I restarted it, the misfire remained on cyl 2.

Unplugged the MAF meter, ran even worse and would not rev up.

So now totally confused.

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Quote:
Originally Posted by aerosam View Post
Ok, just been tinkering with it and I can rule out the MAF meter, plugs and coil packs.

I have however traced the misfire to cylinder 2, by disconnecting the coil packs in turn with it running. Disconnecting cyl 2 made no difference.

So I removed the coil pack and plug, both appear fine. I then swapped the coil packs between cyl 1 and 2 and reassembled. When I restarted it, the misfire remained on cyl 2.

Unplugged the MAF meter, ran even worse and would not rev up.

So now totally confused.

Sounds like you have an injector fault, they are about £140 + VAT each and about 4-5 hours labour to change, horrible job

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Ah nuts. Was kinda hoping it wasn't that.

Going to double check for spark tomorrow so I can totally rule it out.
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Quote:
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Ah nuts. Was kinda hoping it wasn't that.

Going to double check for spark tomorrow so I can totally rule it out.
You got try a bottle of good quality injector cleaner too;

Forte Specialist Injector Cleaner
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You could try check the electrical connections at the injector and the large loom connector on the bulk head behind the throttle body. If it is the injector its is a horrible job, i requires quite alot to be removed, i think though that cyl 2 you wont need to remove the inlet manifold just the VIM(the large black bit at the back)...
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Well I just drove it to work and it's barely making it up hills, it has so little power.

Good call on the injector cleaner - there's a motor factors round the corner, I'll pick some up on the way home. Hopefully that might do it.

When i picked it up on Thursday it was VERY low on fuel. I'm wondering if it's picked up a bit of debris from the bottom of the tank that's made it past the fuel filter and clogged the injector.

Otherwise I'll dig round for the injectors, I had a look yesterday and I couldn't even see them!
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put 2 bottles of injector cleaner in it, the misifiring has already gotten quite a bit better, and after only about 7 miles. Will drive it some more and see how it goes.

Made an interesting find in the spare wheel well, a 3/4 used bottle of ordinary redex - the carburettor version - the type that CLOGS INJECTORS!!!

I have priced up an injector though and it's only £70 from my local motor factors, so not too bad if I do end up replacing it.
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Quote:
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When i picked it up on Thursday it was VERY low on fuel. I'm wondering if it's picked up a bit of debris from the bottom of the tank that's made it past the fuel filter and clogged the injector.


What fuel filter?

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What fuel filter?

Ned
It doesn't have a fuel filter? you gotta be kidding right?


Been flicking through the service history and found that 5 years ago it had a new cat and 2 new lamda sensors fitted - at a cost of over £1000! Really hoping I don't have to do that to it.

Am I right in thinking it has 2 cats, in the exhaust manifold - meaning you have to replace the whole shebang if one of the cats has had it?

I can see it has 4 lamda sensors - and hope that a diagnostic can specify which of them (if any) are faulty?
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Ok it's not improving - now booked in to a local garage on Wednesday to have the duff injector changed.

I have a theory that the misfiring cylinder is just pumping air through the engine as there is little or no fuel being injected. This in turn is making the lamda sensors read out of limits, which may be the cause of the motor control warning.

I have ordered a fault code reader which will hopefully arrive in a couple of days, so after the injector is swapped out, I can get to the bottom of it.
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Quote:
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Ok it's not improving - now booked in to a local garage on Wednesday to have the duff injector changed.

I have a theory that the misfiring cylinder is just pumping air through the engine as there is little or no fuel being injected. This in turn is making the lamda sensors read out of limits, which may be the cause of the motor control warning.

I have ordered a fault code reader which will hopefully arrive in a couple of days, so after the injector is swapped out, I can get to the bottom of it.
Whilst you have the inlet manifold and VIM off have a good look at the inlet valves to check how clean they are this may also be a cause of you power issues...
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FINALLY got it back yesterday. Turns out the injector was quite seriously dmaaged, burned and melted at the tip. new one now fitted and it's running like a dream.

Plugged in my fault code reader and cleared all the codes - no more warning lights or messages!

Inside the inlet fanimold looked nice and clean too. they didn't take it off, instead they undid the engine mints and rocked it forwards in the bay to get access to the back of the head.

Well happy with it now.
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Thanks for updating your progress on this aerosam, I've been having the same problems with mine, not quite as bad as yours (its also a 2003 JTS 128,000 miles...). Very lumpy at idle. Fault code says lambda failures all round and misfiring on cylinder 3.

Had the problem for 6 months now, been dragging my heels with it a bit, hoping it would go away!

Well actually so far I've checked the connections at the back of the engine bay, cleaned them up, same for the lambda connections at the front. (No change) Stuck some injector cleaner in the tank (no change) also sprayed a can of direct injection inlet valve cleaner into the air intake (noticed a slight improvement). Also changed the spark plugs and swapped around pre cat lambda sensors with 2 other used ones i got hold of...And reset the ECU... But I'm still getting same messages, lumpy at idle, engine light on, misfiring on 3 etc, and i dont think i'm getting the full 165 BHP and also getting very crappy economy (around 25mpg at best)

Guess the next stage is to think about changing out injector 3 as its always this one on the error message.

Out of interest what did they charge you for this - how many hours labour was it...?
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(Post Link) post #23 of 25 Old 10-06-11 Thread Starter
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Hi Waddam,

have you tried swapping the coil packs around to see if the problem moves to another cylinder? Could just be a dicky coil pack.

the injector cost around £170 from alfa and yapps garage in Cardiff, the work was done by a small local garage who charged me about £150 labour, but I also had new rear discs and calipers fitted at the same time, so obviously some of the labour was doing that.

It's been much much better since I had it done, in fact, I took it on a track day with some of the guys from this forum last Thursday and thrashed the living hell out of it.

Hope you get it fixed dude.
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A footnote to that, checked again, the message says cylinder 4 misfiring, thought it was 3 before, but i could be wrong, but will keep checking to see if its consistently on 4 or not...i 'spose coil packs could be the next stage before changing the injector....
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I think my last message posted the exact same time as yours!

I havent yet tried moving the coil packs round, i guess that's the next stage then... £170 for the injector (gulp!). I also have a cheap local garage in mind i will try and use if it comes to it to keep the labour cost down...

Cheers for the info anyway
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