Very Weird Misfire

[DeeeeC 0]

Hi all,

 

 

Smaky, are you around please? And people who might be able to help - pls save an Alfa from being scrapped

 

I originally posted this at alfa156.net http://forum.alfa156...2580&PN=1&TPN=1

 

Posted: 10 August 2012 at 02:58 | IP Logged

Hi all' date='

 

please give me some advice on this problem on my 2004 156 2.0 JTS.

 

I had an MOT fail on emissions due to a misfire. The EOBD scan showed cylinder number 3 misfire. I suspected the coilpack was shot, and swapping it from cylinder to cylinder, the fault code would follow the duff coilpack. The misfire was the only fault code. I tested disconnecting the MAF for good measure - made no difference and I would expect that would have affected all cylinders.

 

That pretty much isolated that only the coilpack as being the cause of the misfire. I checked the plugs and at 98k miles they were all dark black and oily so I changed for NGK platinum. I ordered a used coilpack on ebay, and when I put it in - still a misfire. The ebay seller urgently sent me another used coilpack (as an aside I should have just got a new one).

 

OK so here is where it gets weird. If the second replacement coilpack was also duff, then moving it to other cylinders would cause the fault code to follow it to whichever cylinder I put it in - just like before. HOWEVER, now whichever cylinder I put it in the fault code stays at cylinder #3.

 

Yes I did clear the code each time before scanning!

 

Also, I pulled off each coilpack connector with the engine running, and doing so on #3 made no difference.

 

 

So, what could it be? I need to attend the retest on Monday.

 

 

Because the coilpack is eliminated as being good (by swapping) and the plugs are new, I think it is something upstream on the wiring loom causing a lack of spark. The old plugs didn't show a significant difference for #3.

 

If it is a fuelling issue, I'd expect at least some difference from unplugging. Why would that one injector fail all on it's own at the same cylinder I had a duff coilpack on? Unlikely?

 

If the headgasket was leaking I'd not expect a good vaccuum of -22 psi. There is no oil in the water. Also, if there were air leaks would there be such a good vaccuum?

 

 

My other observation is my MAF gives low reading of 5 g/s at idle and 16 g/s at 2000 rpm which seems low.

 

Notes:

 

-I rewired the back black loom connector everyone solders but didn't do the brown/purple one yet.

 

-Also, the MCSF light used to always be on now it comes on under load at over 2k rpm.

 

-Also I've run about 4 bottles of Wynn's injector cleaner with 1/8 tank each time to thoroughly clean the injectors. How come cylinder #3 never threw a code when a good coilpack was in the port before?

 

-The fuel to air ratio is reported as up to 22:1 which is rich AFAIK but does drop down to 18:1 at times.

 

-The idle rpms were always about 1000 but now are consistently around 850.

 

-Throttle and ecu resets have been done umpteen times.

 

Edited by DeeeeC on 10 August 2012 at 03:13

Posted: 10 August 2012 at 17:19 | IP Logged

 

I need some ideas please - before I resort to stripping down the engine and painstakingly checking the wiring loom.

Posted: 13 August 2012 at 00:27 | IP Logged

Ok I have torn apart the wiring loom and will publish the results after I've had some sleep.

 

I don't seem to have any error code for an injector or any other sensors. My hunch is a bad connector on the ECU.

 

I took out the ECU, and the connectors were an unholy mess of rot. Going to take a look under it's hood (er bonnet) soon

 

 

Is this a lonely thread or what?

 

Edited by DeeeeC on 13 August 2012 at 00:28

 

Posted: 13 August 2012 at 17:45 | IP Logged

 

OK it's a sad 301st post.

 

The ecu was a pain to undo - bonded all around the edge. The board connectors were heat damaged - might explain why the misfire kicked in at high revs. I'm looking for a new ecu now with the control box and key so I don't have to reprogram it.

 

If you have one - let me know it's for a 156 JTS 2.0 '04 facelift. Bosch 0261 s01 027. Ebay sellers are saying that Bosch 0261 s01 007 will work - any clue if this is true?

 

This is all taking so long, I'm going to declare SORN, get a road tax refund and cancel my insurance. Will probably sell the car once fixed and then get a trusty old Volvo that can be fixed with paperclips and a hammer again.

 

I'm so

 

 

Since then I took a hammer to the ECU to vent my frustrations! Should've keep running on 3 cyclinders now I have to walk miles to get a pack of cigarettes

 

I'd be really annoyed if it wasn't an ECU problem and I added that step for no reason. I know they don't go bad too often. As I said, I had no sensor errors at all. Have not performed a leakdown test or compression test.

 

I forgot to mention before I went to test the ECU I finished rewiring the brown loom connector and tested the coilpack connectors. I even measured the springs in the coilpacks to make sure they were actually compressed 3mm by the spark plugs so were connecting well.

 

The state of the ecu connectors were as bad as those main loom connectors - very oxidised and gold worn off.

 

I also tested the resistances of the coilpacks terminal by termainal and they were all close to each other. I also tested the voltages with the engine running and they seem to be very much the same as each other.

Edited August 16, 2012 by DeeeeC

[Smaky 73]

It sounds like it originally was a coil pack, hammers and ECUs don't mix well, but also this problem has also been caused by loose connectors to the coil packs, but if swapping the pack around moved the fault then it's almost 100% the pack, but also there may be a second pack on the way out and insuch cases I'd be temted to go for all 4 packs to be replaced to be on the safe side, and if that one pack has been gone for a while then it may have fried the cat in the manifold.

[DeeeeC 0]

Thanks for such a quick reply Smaky!

 

I guess the next step for me is to then get 4 coilpacks and an ECU so I can start the car again to test it. Cats are so expensive - is it practical to clean it?

[Smaky 73]

Aswell as the ecu you'll need the code box and key chips.

[DeeeeC 0]

Sage advice Smaky, one complete set is being sent out to me tomorrow - but it's ECU ending with 017 rather than 027 that I need (at £50 it was a punt). Just couldn't find the same part number except for $400 from the states or 1800 SEK from a Swedish page I don't understand.

 

If it doesn't work I guess I could try reflashing the software because AFAICT the hardware is MED 7.1.1 on ECUs ending in 007, 010, 017 and 027 so probably only the firmware and maps are different. I have no idea how I'd do that but crossing my fingers.

 

If I can't get it on the road I'll revert to the Jeep with the fscking 12 MPG economy until I get the right parts. That or sell it for the metal.

 

If I want to search for firmwares, what should I use as a keyword. Are they even called firmware or images or roms or what please? Edit: Since I own the original hardware I also own the license to the software already.

Edited August 22, 2012 by DeeeeC

[DeeeeC 0]

Ok I got the ECU, key and control box.

 

Fit the ECU - check - easy.

 

Lock barrel is too long - will just use the transponder in old key - the lock barrel just turns a switch, I think only the transponder matters.

 

Now I'm stuck on the control box. I can't find the location behind the dash on my facelift 2004 JTS 2.0. I took off six bolts holding on the fusebox and secondary fuesebox. The fusebox is loose, but the upper fuses just won't get out of the way. I can't see the original control box anywhere!

 

So I followed the wire from the transponder aerial and it goes to the left of the steering wheel and down along the steering column. I can't see very well, and I took off the fuse cover and side panel already. Do I have to take off the whole dash? Where is the control box? The replacement one is yellow, but I could not see any brightly coloured box anywhere the same size. I saw part of a blue box but thought it might be a relay.

 

Hope this isn't a steering wheel off job, because I've never taken one off with a airbag in it.

Edited August 22, 2012 by DeeeeC

[DeeeeC 0]

PARTIAL VICTORY!!!!!!!!!!!!!!!!

 

I'm happy to say that my punt worked, partially. I couldn't source the correct ECU part number in the UK to replace my broken one ending on 027. Everyone was selling ECUs ending 007 or 010. I got a good price on a unit ending 017, along with the code block and key.

 

Well the ECU worked just fine! So now we know there is some compatibility / interoperability between Bosch ECUs. I googled looking for these terms, and didn't find anything so I guess here we are with the first data point. I think the heat damage and corrosion to my old ECU (at what I think were the injector pulse chips) was causing part of the problem.

 

Now I still have the misfire - but greatly reduced. Now it kicks in at close to 5k rpm.

 

I switched to using MultiECUScan instead of Torque, it's much better and has free code reset now.

 

I have these error codes:

 

P0443 - Evaporation control valve

P0300 - Misfires detected (generic)

P0303 - Cylinder 3 ignition failures

 

Now what/where is this canister thingy? On the facelift JTS? I saw a black cylindrical thing near the driver's side wing at the back of the engine bay. Is that it?

 

The software says "The reason for this fault is that ECU did not receive signal from the sensor. I need to identify the valve to figure it out. Also, wouldn't this cause problems on all cylinders?

 

For my cylinder 3 misfire - I'm not understanding what exact sensor is telling the ECU that there is a misfire? If it was an O2 or lambda or cat problem, then why don't I have a code for that?

 

Something gives me a hunch it's a broken exhaust valve spring or guide causing it to run rich? How can I check that without taking off the top of the engine?

 

 

Thinking about this a step further, I think that the canister is causing the rich fuel air mix, and maybe cylinder 3 is misfiring because it's mechanically weakest, perhaps burning a little oil. Also I started using 10w40 oil (just 2 litres) to top off the oil and a litre of 10w60. I think I should do an oil change too.

Edited August 23, 2012 by DeeeeC

[DeeeeC 0]

MY MISFIRE IS NOW GONE ALL THE WAY!!!!

 

 

All I have to fix now is the connection to this canister purge valve that I can't find o_0

[Smaky 73]

MY MISFIRE IS NOW GONE ALL THE WAY!!!!

 

 

All I have to fix now is the connection to this canister purge valve that I can't find o_0

 

It's under the throttle body.

[DeeeeC 0]

Thanks, I got it