Alfa GT Jts misfire cylinder 2 - Alfa Romeo Forum
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(Post Link) post #1 of 30 Old 4 Weeks Ago Thread Starter
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Alfa GT Jts misfire cylinder 2

Hello,
I've a 2.0 JTS GT 2004 since beggining of 2018. I've made 25000 Km with it.
I've decided to clean up the head so it was taken off the car, cleaned (admission + valves), valves seals etc. I took off all 4 injectors and the ramp and took it to a specialist for check and refurbishing. Now the head is back on and everything is nice and clean I am facing a problem, I get a Misfire on cylinder 2 on the ODB. I swapped coils, spark plugs and no change.
The funny thing is that when the error comes onthe fuel level goes from 3/4 full to empty with the light on ...
Has anyone any idea where I should look at. All fuses havve been checked and cleaned.
I saw on a post somwhere that it could be electric problems but I don't now how or what to check...

Nicolas
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(Post Link) post #2 of 30 Old 4 Weeks Ago
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I think you are looking for this;
https://www.alfaowner.com/Forum/alfa...lts-fixed.html (Strange electrical faults fixed)
It is in the tech guides, faults etc sticky in the 147, 156 & GT lounge.

Obviously, check the ignition coil multiplug terminals but with the other issues, it does sound to be either an earth or a main positive supply.
An hour with some fine emery cloth or a wire brush and some anti corrosion spray should fix it.
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Hello,
I have done the cleaning of the battery connections and no difference...
Is there a way I could test the connectors of the injectors ?
I detached the 2 big blue and brown connectors on top of intake and sprayed with connector cleaner, let it ervaporate and put back together, but no difference...
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(Post Link) post #4 of 30 Old 4 Weeks Ago
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I'll assume you have cleaned all the related terminals (cylinder head, inner wing,) and also have cleaned up the terminals on the battery positive terminal distribution board and all the engine bay fuses.

I'd also check the terminals of the relay plate in front of the battery. Clean all of the above as necessary. It may be worth swapping the fuel injection (ECU) relay with the fuel pump relay. Sometimes the contacts in the relays can wear/oxidise and not carry sufficient current at a high enough voltage. You can test the high current switched positive output with a multimeter and ensure it is within 0.25 volts of battery voltage (ideally with engine running so it is drawing current).
I expect the fault to lie somewhere in what I described.

Failing that, if you disconnect the multiplug for an injector and the start the engine, you should have the MCSF log a P020*/P120* code pertaining to the relevant injector. You could disconnect the plug for no.2 injector to ensure the fault code is indeed for no.2 injector. That would tell you that the connection is good and the multiplug is fitted to the correct injector. It won't tell you if the spray pattern and delivery volume for the injector is good but it should be as you stated the injectors were serviced. It should verify that the fault lies elsewhere and also verify that the wiring from ECU to all injectors and back to ECU is good.

That then takes you back to my original point of power supply or a defective injector. You could verify the injector is good by disconnecting the ignition coil and running the engine from cold for a few seconds. If the spark plug is removed, it should be wet with fuel but in any case, I'd expect a pre-cat O2 sensor fault to be triggered as the mixture would be so far out.

Another possibility is that there is an issue with a multiplug terminal for no.2 ignition coil. Unfortunately you did not give the fault code so this is only conjecture. If so, I'd expect 2 fault codes; 1 for the misfire and another for a no.2 coil circuit fault. If you have a 4.8mm male spade terminal, you could insert it into each of the no.2 ignition coil terminals to check the female spring terminals are tight enough and give a good connection.

As already stated, the erratic fuel gauge suggests it is a main positive or earth fault though.

Last edited by Fruity; 4 Weeks Ago at 11:03.
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Just a final thought; it may be worth carrying out a compression check and ensuring no.2 cylinder compression is not down. If it is I'd suspect either an issue with the valve face sealing or perhaps careless valve cap installation which damaged a valve spring.

If it is a valve spring, it should be possible to change valve springs without removing the cylinder head again. If so, I can explain how.
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AFAIK, blue and brown connectors on inlet manifold are for camshaft position sensor and knock sensor.
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The tell is the fuel pump going to empty when it happens. You have an problem with the electrical harness/connection going to the injector on cylinder #2.

Same thing happens with the 159 Diesels, get a dodgy connection to any of the injectors and you get a misfire and the fuel gauge goes to zero. (And no, I haven't worked out why it does it yet, been to busy, but it's what happens)
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Probably shared driver in ECM.

I thought it would trigger a circuit fault- obviously not.
Great information, thanks.
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(Post Link) post #9 of 30 Old 4 Weeks Ago Thread Starter
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Hi all of you and thanks for advice ...
A compression test is planned on tuesday morning, but I'm also going to have a look to the wiring loom to check the 2 cables from injector 2 to the central wire block on top of admission and check if I don't have a leak on these cables...
I am going round all ground cables and cleaning them with emery cloth and a connection cleaning spray...
I will be telling you about investigation results ...
What a shame, the car is a marvel to drive ...
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Hello again, I seem to have a lead on my problem, looking at the engine bay from underneath, I have a loose connector ... But I have no idea what it si meant to be connected to ...
Any one got an idea from picture ?
Attached Images
File Type: jpg connector small.jpg (63.9 KB, 21 views)
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(Post Link) post #11 of 30 Old 4 Weeks Ago
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TS & JTS engines seem to have that spare plug. I think it was perhaps due to earlier cars and 916 GTV & Spider having an oil temperature sensor so it may have had something to do with commonality of engine wiring looms.
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Hello all of you
I am still stuck with this problem.
Last steps in the investigation are :
went to local garage and got compressions measured : OK between and PSI on each cylinder
The chap at the garage said he could hear a air sucking noise.
I got the whole admission down, cleaned the air intake, swapped injectors from cylinders 2 and 3.
swapped plugs (they where dark) and coils from 2 and 3, bolted the admission and fuel rail to the correct torque.
Well the result is the same :
P0302 Cylinder 2 Misfire Detected
P0300 Random/Multiple Cylinder Misfire Detected

Could this be due to incorrect torque on cylinder head ?
Anyone got an idea ?
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Did you all ready cheqed the connector s on the second coil?
Is the waterlevel stabble? If not take off the coil en take out the spark plug on cylinder 2 start the engine,start the engine if there are small is water drops spitting out off the spark plug hole you have found the problem and tighten the cylinderhead to much and damaged the cylinderhead gasket

Last edited by Afco; 3 Weeks Ago at 11:08.
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Quote:
Originally Posted by Afco View Post
Did you all ready cheqed the connector s on the second coil?
Is the waterlevel stabble? If not take off the coil en take out the spark plug on cylinder 2 start the engine,start the engine if there are small is water drops spitting out off the spark plug hole you have found the problem and tighten the cylinderhead to much and damaged the cylinderhead gasket
a damaged gasket should show up on a compression test though shouldnt it? (not sure if a small leak to a water channel would show easily)

Personally im more inclined to suspect the wiring to injector #2, but given that the JTS is a direct injection engine with precision timing, and the signals are bound to be very short, piggybacking injector 2 and 3 together on 3s signals is out, and you would likely need an oscilloscope to test the signal to #2
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Quote:
Originally Posted by vitorio View Post
a damaged gasket should show up on a compression test though shouldnt it? (not sure if a small leak to a water channel would show easily)

Personally im more inclined to suspect the wiring to injector #2, but given that the JTS is a direct injection engine with precision timing, and the signals are bound to be very short, piggybacking injector 2 and 3 together on 3s signals is out, and you would likely need an oscilloscope to test the signal to #2
You are right did not read everything butt if you have done a copression test and everything is ok than the gasket should be ok. You also did the swich test with the coils. Butt on mine over a periode of +/-1 year i had to change 3 of them. When i had the first problem the test was like yours it was ok, when i did he same test a couple of 300 km later it showed that the fault was no more on the second butt on the third . I still do not understand why the first test was differend from the second

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Hello All,
all 4 coils are new ...
I tested the wiring to injector and it was ok.
I will test the wiring and spark on coil 2 Harness...

Can the big injection Box have a leak on one Cylinder ?
The chap I did compressions with told me he heard a slight air sucking sound from the injection ???
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Does the fuel gauge still drop to zero when the misfire occurs?
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Originally Posted by bazzbazz View Post
Does the fuel gauge still drop to zero when the misfire occurs?
No I have just checked, this issue seems to have disappeared ...
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Originally Posted by bigjack23 View Post
Hello All,
all 4 coils are new ...
I tested the wiring to injector and it was ok.
I will test the wiring and spark on coil 2 Harness...

Can the big injection Box have a leak on one Cylinder ?
The chap I did compressions with told me he heard a slight air sucking sound from the injection ???
If air is being sucked in through the injectorport, that would make the engine run lean, which would cause knocking, but im not sure if that is being detected as a missfire. Also, if the leak is substantial enough to let enough air in to throw off the mixture, i would expect a compression test to show lower compression. Unless the leak has some weird one-way structure.
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A leak at injector would not make the JTS run lean (direct injection). It make allow combustion gas to leak out though.
Use a solution of soapy water and spray around injectors to ensure combustion gas is not leaking past an injector which is not sealing properly.

Similarly, use an ether based starting aid or even brake cleaner sprayed around the inlet manifold to detect if a seal or gasket is allowing air to be sucked into the inlet manifold on one of the cylinders. I'm not sure that would significantly affect the JTS though as it is direct injection.

This highlights the importance of careful assembly and it only rewards those who are meticulous. Using silicone spray and/or a heat gun for fitting rubber and plastic parts (including some multi plug seals) is necessary to prevent this sort of really difficult and frustrating type of thing from happening as the JTS is a bit more fussy that way than the TS.
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Moaning

Thanks for you encouragements. When I put the injectors in, I added copper grease to seal it tight, I have not seen any of it been pushed out.
I have taken off the big blck air intake box and opened it. It is full of oil for a reason I do not understand. Furthermore, the seal all round the box was cut in some places and so I don't think the box was perfectly sealed. I'm going to wash it down nad change seal and I 'ill see what ...

It seems I have a spark, I have petrol but it is misfiring ... making me go mad ...
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Hope you resolve it this time.
As far as I remember, the injectors protrude into the combustion chamber so hopefully it is not copper grease fouling. In any case, the fuel pressure reaches 75bar (1100psi) so it should instantly clean off excess.

The oil in inlet manifold is what has come through the breather. It is normal. I think that enthusiastic use may help it to get blown through and be burnt in the combustion chamber.

The JTS is a bit awkward and the fact you have managed it suggests you are quite handy so hopefully a bit of extra care should see it all good.
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Hope you resolve it this time.
As far as I remember, the injectors protrude into the combustion chamber so hopefully it is not copper grease fouling. In any case, the fuel pressure reaches 75bar (1100psi) so it should instantly clean off excess.

The oil in inlet manifold is what has come through the breather. It is normal. I think that enthusiastic use may help it to get blown through and be burnt in the combustion chamber.

The JTS is a bit awkward and the fact you have managed it suggests you are quite handy so hopefully a bit of extra care should see it all good.
I hope you now are at the end of your troublles butt !How much KM/miles had the car as an airbox mayby oily butt certenly not full of oil not even after a 150000 km
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I can't remember, do you have Alfa specific diagnostic software you can hook up to see which cylinder is misfiring or is it generic software?

The original post said software showed cylinder #2, and the coils are all new, have you changed the plugs. moved the plugs/coils to see if the fault moves to another cylinder?
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Quote:
Originally Posted by bazzbazz View Post
I can't remember, do you have Alfa specific diagnostic software you can hook up to see which cylinder is misfiring or is it generic software?

The original post said software showed cylinder #2, and the coils are all new, have you changed the plugs. moved the plugs/coils to see if the fault moves to another cylinder?
Yes I use multi Ecu Scan for diagnose.
I checked the coil by taking a spare plug and checking the spark --> OK
I the undid the original plug and it smells petrol, so I conclude that I have a spark and I have petrol, so I don't get why the cylinder is misfiring ???

Errors on diag are : P0300 and P0302
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