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Discussion Starter · #1 ·
Hello Guys,

I am really stumped. I have a 2007 Maserati Quattroporte automatica (ZF transmission) with only 52k miles. I have had misfires on cylinders 1 and 3 since I got the car a month ago. CEL fault codes P0300, P0301, and P0302. I took it to the local Maserati dealership and they have not been able to find a fix. Here is their writeup:

"Had misfire on cyl 1 and cyl 3, disabled injectors on cyl 1 and 3 and could tell a difference in running, swapped coils to cyl 2 and 8. Misfire stayed with cyl 1 and 3. Removed coils and spark plugs, checked plugs, plugs had recently been replaced, antiseize was still wet on the threads. Moved spark plugs to cyl 2 and 8 with coil packs, tested again, misfire was still on cyl 1 and 3. Disabled injectors on 1 and 3 by unplugging, car hesitated when unplugged, unplugged coils on 1 and 3 with running, car also hesitated with unplugged. Checked compression on 1 and 3, was slightly lower than normal but not enough to condemn any other parts. Noticed alternator was new when testing, used throttle plate cleaner and found leak on intake at cyl 3. Removed intake, bolts were way over torqued, taped off all ports, performed leak test, no abnormalities on intake manifold. Found pinched gasket on cyl 3, replaced all gaskets, properly torqued intake and replaced all components, misfire not present, car is running as designed."

That sounded good on paper. However, after driving the car about 15 miles, the CEL came back with the same exact code. Took the car back to the same dealership and this is their second writeup:

" Pulled codes and had codes p0301, 303 and 300. Checked for intake leaks, none found, checked coil an injector connections, all were good. Proceeded to check cam timing with scan tool, reset cam variator timing control. Checked voltage to injectors and used oscilloscope to check injector voltage and firing pattern, checked cylinders 1, 2, 3, 7, 8 and all were firing same pattern and voltage was good. Disconnected battery and performed hard reset, removed coils and plugs from both banks to compare and swap back to original places, used breakout box to check can line going through ecm, all can lines had correct resistance and voltage. After hard reset started vehicle and vehicle ran smooth. Checked misfire counter with scan tool and was reading 0 misfires on cylinders. Checked ground point for injectors and coils, ground point good. If this car had a misfire for an extended period of time and the vacuum leak in the intake that it did, it could overwork the injector driver in the ecm and cause erratic behavior as random misfires. vehicle is running as designed at this time."

After I picked up the car and drove it another 10 miles or so, you guessed it! The same codes came back again, but with one more code that hasn't shown up since: P0430 (catalyst efficiency below threshold bank 2). When I tried to take it back they said it could be the ECM failing.

I had since taken the car to my indy mechanic who has done work on pretty much every import. He swapped parts from another 07 Maserati Automatica I have with 44k miles: mass air flow, spark plugs, coils, etc. He even opened up the valve cover on bank 1 and inspected that side. Checked compression, did a smoke leak test, there are no vacuum leaks. Everything looks good and clean. Car seems a little sluggish when driven. There is no rattling noise coming from the engine.


What else could it be? I am hoping it is not the ECM The maserati dealership don't want to see me anymore, and the other maserati place in town tells me they will not reprogram a used ecm to the car -if that is what ends up to be the problem. They will only reprogram a new ecm, of which there is none in USA or Italy available. Maserati would have to make one to match my specs.

Somebody please help.
 

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Yeah, you have a dumpster fire going on for sure..That does not sound like an ECU issue and you are not gonna be able to program a used one to the best of my knowledge or at least I cannot with my software..I would go back and just forget about all the stuff the dealer did and just start over..Have you checked the catalytic on that side for damage? Hope that helps...Stuff like that is hard to diagnosis over the internet...Jason
 

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Well it seems that the dealer has pretty much confirmed that the ignition coils are okay, and that there are no intake system leaks. I'd look closely at the fuel injectors for #1 and #3 , they may be okay electrically but perhaps there is a mechanical issue....
 

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Discussion Starter · #4 ·
vacuum leak or bad wire?

Yeah, you have a dumpster fire going on for sure..That does not sound like an ECU issue and you are not gonna be able to program a used one to the best of my knowledge or at least I cannot with my software..I would go back and just forget about all the stuff the dealer did and just start over..Have you checked the catalytic on that side for damage? Hope that helps...Stuff like that is hard to diagnosis over the internet...Jason
Thanks Jason,

A friend of mine asked me to monitor the car first thing in the morning with a fresh start to rule out a bad catalytic converter. He said if the car runs a lot better in the morning, the cause would be a bad cat. So here is what I did yesterday morning:

- reset the check engine light, and drove it from Apex to Raleigh - about 12 miles. The car felt more sluggish than the day before when I ran it with the engine hot. It also felt like it had surges of power: with slow and fast periods even though the throttle was at constant pressure.
- As I was driving, I noticed the car wouldn't downshift so it felt like it was driving in a higher gear than usual. For example, it had about 2300RPM at 75MPH. I remember it running at a lower RPM at that speed before. Sort of like it was in Sport mode, except I made sure that it wasn't switched to sport.
- CEL did not turn on for the entire trip, but it did turn on as soon as I stopped the car when I got to the destination, and restarted the engine.
- I was standing next to the car while it was running with an indy mechanic I have worked with for years. He thought the car seems to misfire at idle on and off. It would run smooth for a little while, and then sounded a little rough, followed again by a smooth period.
- we then drove the car for a mile or two. There is plenty of power in the car and it performed great. He thinks it probably has a vacuum leak. At idle it is noticeable but at highway speeds it isn't noticeable since the car needs as much air as it can get. So even if it gets more air than it needs at high speed, the ECU won't even notice it because the car needs as much as it can get.

He concluded it's either a vacuum leak somewhere or a bad wire on an injector.
 
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A bad wire on an injector is gonna give you a fault right away for open circuit...A vacuum leak is gonna give you a P0171 and P0174 fault code...The check engine light came on the second key start because you had a pending code and it takes two starts to flag the fault..What was the fault code? Jason
 

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Discussion Starter · #6 ·
A bad wire on an injector is gonna give you a fault right away for open circuit...A vacuum leak is gonna give you a P0171 and P0174 fault code...The check engine light came on the second key start because you had a pending code and it takes two starts to flag the fault..What was the fault code? Jason
Same exact code as always: P0300, P0301, and P0303 (multiple cylinder misfire, cylinder 1 misfire and cylinder 3 misfire).

Valentin
 
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A vacuum leak is most likely gonna affect all cylinders unless its right at the intake port..Use some carb cleaner around those ports with the engine running and see if the idle changes...Do you feel the car misfire or get a flashing check engine light? Jason
 

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What do your fuel trims look like and have you replaced the upstream O2 sensor on that side yet? Fuel trims (short and long term) usually can get you pointed in the right direction if you understand them.


Sounds like they've pretty much verified fuel, compression and ignition so that would lead me to suspect cam timing is the most likely place to focus on if it's running rich or a clogged catalytic converter if it's running lean.
 

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Checked compression on 1 and 3, was slightly lower than normal but not enough to condemn any other parts.
That leads me to suspect even more that you may have some type of valve timing (variator) issue on that side.

You could also have an issue with the EGR on that side as well but usually it would affect all cylinders on that bank.


If you're close to Jacksonville FL let me know, you can bring it by and it may take a while but I'm sure we can figure it out.
 

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Discussion Starter · #10 ·
A vacuum leak is most likely gonna affect all cylinders unless its right at the intake port..Use some carb cleaner around those ports with the engine running and see if the idle changes...Do you feel the car misfire or get a flashing check engine light? Jason
The check engine light flashes a few times, and then it stays on constantly. And then it flashes a few more times and then it stays on constantly again. I sense that it misfires when the CEL flashes and it sounds fine when the CEL is solid.

This is how they found a leak at the intake before (see the initial write up I reproduced). They found a vacuum leak at cylinder 3 caused by a pinched gasket at cylinder 3 and so they opened the intake and replaced all 8 gaskets. Unfortunately the misfire has not gone away yet. They are saying there is no vacuum leak. I dropped the car off at a different Maserati dealer in town on Friday. I will ask them to do a smoke test to rule out any more vacuum leak. I understand the intake is plastic. Maybe the plastic intake cracked since apparently someone over torqued it and pinched the gasket on cylinder 3?
 

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Discussion Starter · #11 ·
That leads me to suspect even more that you may have some type of valve timing (variator) issue on that side.

You could also have an issue with the EGR on that side as well but usually it would affect all cylinders on that bank.


If you're close to Jacksonville FL let me know, you can bring it by and it may take a while but I'm sure we can figure it out.

Thank you for the offer ltmax! I am in Central North Carolina so that rules out stopping by with the car. I pray to God it's not the camshaft variator because I would be pretty much up a creek without a paddle if that is the case.

I have another 07 QP with 44k miles that sounds like a tractor. Maserati dealer quoted me about $8k to fix the camshaft variators. This is another problem for another thread, but if that is the case, I would much rather just replace the engine with a used one. I would most likely have to get the ECM that came with the used engine otherwise it wouldn't work....
 
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There is no EGR...If you had a valve timing issue, you would have a cam reference fault and it would be across that entire bank and not just the those two cylinders...I can beat that price on the variators easily if you can get me the car...If you install a used engine, you do not need to swap the ECM and a used engine will most likely have the older style variators so not much to gain there..PM if you are interested...Jason
 

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have they replaced spark plug wires?

It's a good thought but unfortunately no plug wires as it's individual coil on plug ignition and I believe that was one of the first things they did was to swap coils from good cylinders on the other bank of the engine but the misfire stayed on cylinders 1 and 3.

Curious to hear what the next Maserati expert that he dropped it off at on Friday comes up with since the other Maserati dealer couldn't figure it out.
 

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Discussion Starter · #17 ·
Quick update on the misfire situation. The other specialist Maserati place in town thinks it is a variator solenoid that is acting up. Just quoted me $1700 to replace the solenoid. Does that make sense?
 
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No, It would have misfires for that entire bank...Unplug the variator solenoid and drive the car and see if you still have misfires..It is going to set a cam timing fault in the ECM when you do this..Honestly, who ever is looking at the car is in a better position than me to determine what is wrong with it..Jason
 

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Let me start by saying that I'm no expert on these particular engines but I've been handed many basket cases that other so called mechanics had given up on over the years with perplexing misfires. Yours sounds very similar to a 2010 Honda V6 that would only set misfire faults for the first two minutes after starting up cold and turned out to be the last person to service the timing belt was just one tooth off on one of the cam gears and that few degrees made all the difference, no trouble codes, and the car ran perfect other than the short misfire on start. Another one was a V8 BMW with misfires that turned out to be caused by the previous mechanic who replaced the timing chain tensioners getting one of the variators (vanos) a few degrees off when he tightened it back up (probably from not following the correct procedures or not having the proper timing tools) and it gave all sorts of odd timing codes that didn't make any sense. Both of these instances sound very similar to what your experiencing.

From what I've understood about your problem it seems like this car has had several different people trying to sort it out with no luck. Having found vacuum leaks from improperly installed intake manifold gaskets leads me to believe that it's most likely that the manifold has been off a few times trying to fix the misfires with no success with whoever doing it last getting frustrated or sloppy.

Can they tell if the front timing chain cover has ever been off before? If it has, I'm thinking that someone did one or both variators somewhere in the past and got something just a little bit off on reassembly, not enough for the computer sensors to pick up an obvious problem with cam timing but enough to cause your cylinder 1 and 3 misfires. If the cover has never been removed since new than I'd suspect the variator on the passenger side is starting to fail internally. The variator solenoids just allow oil to flow in two directions to advance or retard the intake timing and if they weren't working properly they would affect all cylinders on that bank and the computer would sense that timing wasn't advancing and retarding when commanded and set a fault code.
$1700 is a lot of money to shell out for cam cover removal and solenoid replacement, are they guaranteeing that will fix it or is this just the first payment you'll make to them as they try and guess what might be wrong?
 

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Discussion Starter · #20 ·
Quick Update! Problem is solved, thank God! ltmax is right! intake and exhaust timing were a weeee bit off. They also replaced the solenoid for the same bank 1 and now everything is running well! Feel a difference in power too.
 
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