[Spike283]

Hi there guys, I realise this is a common fault but I'm going nuts trying to trawl through other posts.

I have a 156 JTS and when cold she runs fine, however once warm (especially in the summer) almost every time I put my foot down she misfires. Yet in the winter pretty much perfect, only misfired occasionally between 2'000-4'000rpm. I have changed the MAF but then it didn't Idle properly and ecu gave MAF error (even after an ecu reset) so popped the original in. So I'm not sure if the ECU is faulty or if the replacement MAF was faulty. I have also replaced the coils, spark plugs, post lambda sensors and checked the pre lambda sensors. I read on another thread maybe the Crank Sensor is faulty? I'm not sure. The exhaust is blowing slightly, I know this won't help power until it's replaced but I shouldn't think it would cause a misfire. Need to get misfire sorted before I do anymore work. Oh also ECU reports the misfire on Cylinder 4

Any help and ideas would be greatly appreciated. I love my Alfa. Brought as a restoration project for almost nothing, but worse than I realised

 

[Tommywho156]

Could be a wiring fault to the coil pack on Cyl-4 or, more likely a dirty injector, the JTS is renowned for them, hence why many of us run a bottle of Reddex or similar through the fuel system every 3 tanks or so. If it's too dirty/worn it'll need replacing.

 

[Spike283]

Ahh yeah cheers for that. I have put a couple of bottles through in the past 6 months to no effect really. However I have just re-checked the faults and we do have a fuel pressure fault as well as cylinder 4 misfire. Do you know if it's possible/how hard to take the injector apart and clean or should I just fit a new one?

 

[Tommywho156]

Ahh yeah cheers for that. I have put a couple of bottles through in the past 6 months to no effect really. However I have just re-checked the faults and we do have a fuel pressure fault as well as cylinder 4 misfire. Do you know if it's possible/how hard to take the injector apart and clean or should I just fit a new one?

Companies like Autolusso can clean/recondition fuel injectors, it's not something a novice can really do effectively as you'll need ultrasonic cleaners and various other bits of kit to do it. You'll also need to do all 4, whether cleaning or replacing I'm afraid. Thats the worse case scenarion, best to get them checked first as it could still be a wiring/coil pack fault.

Give the guys at Autolusso a call, they're the only people I trust with my car...

Autolusso - Alfa Romeo Specialist | Petrol Injector Cleaning & Testing

 

[Spike283]

Well all 4 injectors are out. Gave Autolusso Bournemouth a call going to get some reconditioned injectors so fingers crossed it sorts it all out. I'll post back when it's all back together.

 

[Tommywho156]

Well all 4 injectors are out. Gave Autolusso Bournemouth a call going to get some reconditioned injectors so fingers crossed it sorts it all out. I'll post back when it's all back together.

Did you have them tested before buying a new set? If not that's a pretty big leap of faith!

 

[piedthepiper]

This may sound stupid but how do you know its misfiring? Is there a massive pop and bang or something? or is it the ECU the only thing thats giving it away?

 

[Spike283]

The ecu does give it away with a flashing sign and a failure code. But the the biggest sound is the lack of power and it sounding like a bag o ****e lol. Well it's either the injectors or the cat. They are the only things left to change. I'm thinking about taking the bed off at the same time and getting it all cleaned up then getting the new cam belt and water pump fitted while its all I bits might as well.

 

[piedthepiper]

Ahhh right, thanks for clarification for me, as I know the JTS has a pretty lumpy idle in general. i was wondering how you'd differentiate between the two!

 

[Spike283]

The idle can be sorted out quite easy with a throttle learn. But if the car drives fine then you are alright

 

[NZOLIVER]

Hi,
Did you replace the #4 coil pack?

I have had 2 that did the same. A read by the specialist I use tells me which coil pack it is. Just replace it and all is well.

Oliver

 

[Spike283]

Yes I have, that's the first thing I checked, then the spark plugs (and yes I checked to see if I was getting a spark ) After taking the head off I found that the Inlet Port for Cylinder 4 is almost fully gunked up and the valves can barley open and close properly so I've decided to do a semi-strip down.

 

[TSpark-driver]

I have the missfire on idele issue on my TS. I have misfire on cylinders 1 and 4. What means: gunked up? Have you solved the problem yet.

Cheers