4200 CC with "Slight" misfire

Contigo

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Could be what happened to Phil's car then. Seems the 4200 does have it's achilles heel too.
 

BennyD

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I understand that there is a very serious issue with 4200 engines which initially manifests itself as a slight misfire and a then a CEL indicating the a cam timing issue on the left bank. It is related to the oil cooler failing and reduicing oil pressure. By the time the missfire becomes very prominent, serious damage is done and the remedy is an engine swap. I got this information when I was looking for a car from a very highly regarded Indy.

However, before you go changing engines because of a 'left bank variator' problem check the connection under the little cover with 'Maserati' cast onto it. Oil can contaminate the connector and that brings on the CEL. Trust me, I know. To sort it, flush out both sides of the connector with brake cleaner and reassemble. The CEL will still be on but can be cleared with an OBD reader or even the 'Torque' app. Take out and thrash to see if it stays off. If so, it's good to go and you've saved yourself an engine swap!
 

StuartW

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And if that doesn't work, you could swap it with a decent twin turbo unit from a 3200, no problems there:)
 

BennyD

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No thanks, I've got enough strife in my life without introducing any more.
 

gd13

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Reliably informed, by reputable indy specialist, that the cats are wrecked and debris sucked up into engine...compression in all cylinders circa 125-130 instead of 180! New engine needed plus cats and full exhaust. Exhaust has been divert/welded. Not sure what else this dealer has hidden..he has had it a year and did sell it in June 1015 this time with an 'electrical problem'. It was inspected by Indy and brought back after diagnostics. So it may be mis-firing but it's not timing or problems with 7 and 8!
 

mjheathcote

Centenary Club
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The cat breakup issue has been reported before. When it has, it appears to be with US specified combined cat/exhaust manifolds. The EU specified primary cats are after the exhaust manifolds.
Personally I still find it strange, the otto engine cycle does not draw in exhaust gases!
 

drewf

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7,159
The cat breakup issue has been reported before. When it has, it appears to be with US specified combined cat/exhaust manifolds. The EU specified primary cats are after the exhaust manifolds.
Personally I still find it strange, the otto engine cycle does not draw in exhaust gases!

That's an easy one to explain Mike - put a teaspoon of flour into an empty bottle, and blow into it hard. Close your eyes first...

That's what happens when the cat breaks down and partially blocks the exhaust - all the bits end up in the engine :(
 

mjheathcote

Centenary Club
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9,033
That's an easy one to explain Mike - put a teaspoon of flour into an empty bottle, and blow into it hard. Close your eyes first...

That's what happens when the cat breaks down and partially blocks the exhaust - all the bits end up in the engine :(

I can see that, but would still imagine the force of exhaust gases exiting would not allow anything coming back at the same time!
 

drewf

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7,159
The shock wave coming back will drag the debris with it. I agree it seems counterintuitive!
 

Contigo

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Yep when I contacted the dealer something didn't seem right. I just wish they would sell it at a price that reflected the work needed, ie a new engine it seems. It's on Ebay now, maybe a few cheeky 3k offers might give the the message that is well overpriced!
 

gd13

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Guy's exactly my thoughts when the indy specialist (IS) told me the that it gets sucked back into the engine and writes it off. i then looked on cat sites and apparently this is quite common...the IS said he's seen it before on these and hence his conclusions...he also measured the compressions on each of the pots. Rather naughty to weld a diversion bypassing the cats though...not sure how it passed the emissions test on the MOT1
 

Contigo

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A friendly MOT tester that's how. They just hold the measuring device a foot away from the tail pipe.
 

gd13

New Member
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4
Maserati 4.2 Cambiocorsa 2 dr SLIGHT MIS FIRE. TRADE BARGAIN
update:
Spoke to reputable indy man today and as expected all confirmed re this car. The cats are wrecked and the debris has found its way back into the engine...seen before...the special lining of the cylinders is therefore wrecked and hence very low compression. Asked if re lining an option...no too costly and virtually impossible to sort. The cats had been cut open and some other 'junk' replaced and then welded up.
Bottomline:
New engine (second hand) if a good one can be found, new cats, labour to fit etc, oil consumables and, if required, whilst engine out new clutch. Cost allow i'm told to complete this work correctly £10,000-£12,000
not sure it's a trade bargain then!!

Any thoughts
 

jayblue

Member
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452
How do we prevent this from happening to our cars?

If you have euro spec manifolds (4 bolt flange) replace the pipe containing both the primary and secondary cats with a custom made or off the shelf solution with sports cats in the secondary cat position. Relocate lambda sensors, job done.

If you have the US spec manifolds (2 bolt flange) with the primary cats in the headers things become more complicated. You have a few options though:

1) Replace the US spec manifolds with euro spec ones and then do as you would for the euro spec above. Very expensive but the euro manifolds flow better so at least a small performance gain to go with your peace of mind.

2) Cut open the bottom of the US spec manifolds, gut the cats and weld them up again. Not ideal for the flow of gas in the exhaust but does deal with the problem effectively. Cut off the secondary cats and replace them with sports cats. There are no off the shelf options available for this (unlike the euro spec one) so you will either need to cut the original pipe or have an new one custom made. Then relocate the lambda sensors to the secondary cats.

3) The most common way of removing some of the worry is to simply replace the secondary cats and squish pipes with decat pipes, leaving the primary cats in the headers untouched. Not as full proof as the first two options but better than nothing.

All three options will free up the engine and may also add a little extra power, not to mention a whole lot of noise is you decide to mod the rear boxes or add a straight through X pipe.