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George Graham

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Discussion starter · #1 ·
Hi Guys I am experiencing a slight misfire below 2000 rpm on my 4200 above that it clears . I am also getting some vibration around 4000- 4500 rpm which you can drive through. I have already changed the plugs , checked the cats ( seem all clear ) and had the car on the SD analyser. No serious issues were recorded. So any suggestions where I go from here ?? Cam sensors ? Phase variators ? or what else could give this problem . Any ideas would be welcome.
Geo
 
#2 ·
Is it just idling rough or are you getting a discernible misfire and CEL? Are the misfires random across each bank, isolated to the same cylinders every time, isolated to only one bank?These cars idle a bit rough. There are several suspects though, fi you are getting a miss. MAF, crankcase vent valve, ignition coils, injectors, intake vacuum leak, variator control solenoids.
 
#3 ·
An air leak could cause a rough idle. Misfire is a pretty serious term, does it have good gas in it?
 
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#4 ·
I have also heard that sometimes a battery not holding charge can affect timing sometimes. Also I've heard that bad spark plugs (fouled) can cause problems.
 
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#5 ·
Tubber273 said:
I have also heard that sometimes a battery not holding charge can affect timing sometimes. Also I've heard that bad spark plugs (fouled) can cause problems.
Click to expand...
Fouled plugs I can get, but would love to understand the logic how a low battery could affect timing on a running engine.

OTOH this is a Maser we're talking about :)
C
 
Discussion starter · #6 ·
Hi

It does idle a bit rough, but it is when you are driving and try to accelerate smoothly in the 1000-2000 range that you feel a stutter and then when you get above 2000 it goes fine . HOWEVER tonight I had a slow down message as soon as I started and then the CEL came on and it went into what I thought was limp mode .I have checked the OBD codes and they show miss fire on cylinders 4,5,6,7,8. If I switch off and restart it seems to clear. I also have code 1454 Evap system vacuum test malfunction and also 1540Air bypass valve circuit malfunction .
What does this all mean ??
 
#7 ·
Well, if it was me, it would mean taking it to a dealer or independant with the the proper SD kit, as it's well out my knowledge base, I'm afraid :(

C
 
#8 ·
I dont want to scare but i thought i read that the SLOW DOWN meant a failing cat. I may have seen thay im the cars manual. I hope im wrong for ur sake. However theres less expensive alternatives to repairing failed cats.THanks to craig theres a great write up on what he did. Lets hope its not a cat
 
#9 ·
Lorenz, it *can* mean failing cat, indeed. Or overheating cat, I think. Having slept on it I wonder if there's some kind of air leak, and the secondary air system is involved at all.

C
 
#10 ·
Catmanv2 said:
Lorenz, it *can* mean failing cat, indeed. Or overheating cat, I think. Having slept on it I wonder if there's some kind of air leak, and the secondary air system is involved at all.

C
Click to expand...
Cat, the SLOW DOWN message makes me worry. He said he checked the cats but i dont know how he checked them. Josh at ECS even mentioned an vacumm leak and MAF. Those r a couple easy things id check before goin to the dealer. Id certainly be concerend about driving the car. Taking the secondary cats off to scope the primaries frm the bottom and then the top thru the o2 port is the thing to do if he hasent done that already. You probably dont have to remove the secondary cats to scope the bottom of the primaries but i think it would give you a better look at them.Just to be certain on that
 
#12 ·
The Slow Down light kicks on when the cats get hot, which is caused by the misfires. It doesn't necessarily mean they have failed, but continuing to drive the car in this condition will cause them to do so.

The P1454 code correlates with your catalysts over temperature fault. I need to look more to get the proper explanation of the P1540. You need to keep in mind that codes from P0001 to P0999 are standardized through all cars in the US. Codes from P1000+ are manufacturer specific and do not cross reference. Generic code readers often give incorrect descriptions on these codes after P0999
 
#13 ·
ECSofVirginia said:
The Slow Down light kicks on when the cats get hot, which is caused by the misfires. It doesn't necessarily mean they have failed, but continuing to drive the car in this condition will cause them to do so.

The P1454 code correlates with your catalysts over temperature fault. I need to look more to get the proper explanation of the P1540. You need to keep in mind that codes from P0001 to P0999 are standardized through all cars in the US. Codes from P1000+ are manufacturer specific and do not cross reference. Generic code readers often give incorrect descriptions on these codes after P0999
Click to expand...
Josh, thats really great to know. Thanks
 
Discussion starter · #14 ·
Hi Guys

Thank you for all your comments and ideas , I have found part of the problem.
There was a bad electrical connection on one of the cats temperature sensors , Now fixed and no more slow down.
But I still have the 1000-2000 rpm stutter on acceleration. When I looked at the cats ( only 2 on my car no pre cats ) I stripped the whole exhaust off from the back boxes up to the cats and I could clearly see inside on the outlet end of the Cat . Everything looked great from that end no collapsed core or blocked cells , all clean and light grey.
The reason I mention this is because the stutter ( I have been told ) can be caused by partially blocked cats so when I had the slow down I thought I had a cat problem.
I will follow up on the sugestion of checking the front end of the cat through the O2 sensor hole.

For interest my car has on each side a down pipe from the manifold straight to the one and only cat as a one piece unit. The cat cannot be separated from the down pipe , Then the normal silencer and then an X pipe before it splits into the two pipes to the back boxes. Also there are no pancake pipes they are full bore all the way .
Geo
 
#15 ·
The easier way to check your catalysts is with a diagnostic computer. You can watch the sensor voltages and confirm whether or not the cats are working based on their voltage outputs, which change with fuel particle percentage increase/decrease.
 
#16 ·
With a random multiple misfire like that I would want to rule out ignition. It would be good to know how many miles you have, and how often you have changed plugs. It is possible that you have bad coil pacs, but it would run rough for a while before a series of failures. A cat would have to be really melted down to cause mis fires. I would not go there. If you have access to a computer, it would be prudent to check your MAF and make sure your O2s are switching. If not, that evap code is a tell tale that you have a vacuum leak. Most likely in the secondary air valves, lines or actuators. Just my two cents.
 
#18 ·
George,

My 4200 was running a little rough, so I removed the 8 injectors and had them professionally clears and they also provide a report on their efficiency too. The car did run better afterwards.


Gary
 
#19 ·
Hi George, I have the exact same problem as you. I have a P0300, P0301 to P0308. On top, I have a P2177. I also pulled a P1566.
There is an hesitation under 2000 rpm as well. I don't have the lights coming on but I think they've been tempered with by the previous owner so it gets irrelevant ;)

I posted about it here:
http://www.maseratilife.com/forums/coupe-spyder-gs/23009-first-issues-deal-engine-2.html

I have no solution for now but the car is at the official dealership maintenance center and they'll look at it tomorrow. I was also thinking cats, maybe MAF, or a leak someplace in the system…

I'll update you if I have more info about this because that could be the same problem. At least, the symptoms seem to be similar. Cheers
 
#20 ·
mas1 said:
George,

My 4200 was running a little rough, so I removed the 8 injectors and had them professionally clears and they also provide a report on their efficiency too. The car did run better afterwards.


Gary
Click to expand...
Did you have similar symptoms under 2000? If so, that could be a hint. Chinese gas is not often very clean so I was not excluding a fueling issue, including dirty injectors causing the misfires.
 
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