My Biturbo isn't feeling very well.
Can you help? Please!

Any owner having a problem with their Maserati can send me details and I will publish these, together with any subsequent advice I receive, on this page.

Just drop me a line at


Even if I don't succeed in helping you with your problems; and I do try, it would help other Maserati owners a great deal if you could let me know how you managed to solve your problems. THANK YOU!


Pat in the USA writes:-


Re: Early Biturbo electrical failure!


The 84, 85 & perhaps some later models, here in the US, frequently have the solder on the circuit board pin for fuse #5 become unsoldered.

The load on this fuse includes the A/C & heater blower, and the A/C compressor clutch. The load appears to be the primary failure cause, and I suspect the double, triple if you include the fuse, exposed connector(s) get a significant amount of damp air condensation producing corrosion and subsequent resistance & heat.

I've heard later cars have two additional relays installed off the Junction box to control the air conditioner blower. I have been unable to find it on my MIE wiring diagram or the accompanying load or line charts. Am I overlooking something?

Is this an addition and is there a diagram of this circuit?



Reply from Andy:-

Re: Early Biturbo electrical failure!

"I have never had problems with this on an older car (i.e. one with the push button control panel). I thought however that the heater blower was on a fuse in the box but that the A/C clutch was run through a relay on the bulkhead anyway. However, it was certainly a problem on later cars with the touch panel climate control and Maserati produced a piece of loom with two extra relays to combat this. It was available under part no 00009468, not sure if it still is. There was a diagram that went with this but it is pretty useless!



Tony in the USA writes:-


Re: Biturbo powerless!


This is Tony, over in VA. Beach, in the USA.

I own a 1986 Maserati Biturbo. The car runs fine for the most part. Here's the problem. When accelerating, and boost builds up, still below yellow on the turbo boost gauge, all of a sudden I lose all power and boost until I let my foot up of the gas. Within 3-5 seconds of running with my foot off the gas, the car will run normal again.

Please help!




Reply from Enrico:-

Re: Biturbo powerless - but only for a short time!

"This could be caused by a number of things.

Presume this is carburettor car 1986? If so, have you checked the fuel pressure - i.e. not only at idle but also that as boost increases, so does the fuel pressure (the fuel pressure regulator is adjustable). It may just be that you are running out of gas! It could be that the regulator is badly adjusted, that it is faulty and needs replacing, that the fuel pump itself is worn out, that you have a split vac pipe to the regulator etc etc.

If this does not help, then you have to consider whether the knock sensor is working properly. If it detects knock in the engine, it will retard the ignition timing and also vent the boost in order to protect the engine. It may be that it is doing this early because it is faulty. However, the knock sensor itself is not usually the problem - more likely the connection to it which is a black plastic block located over the right hand cam cover - cable in is white, cable out is black. Try cleaning this connector.

These are the most likely causes of your problem so see how you get on.



Rene in ? writes:-


Re: Biturbo MABC!

"Hi guys,

My question relates to the MABC on my 84 2.5 Biturbo.

Whether the MABC is connected or unplugged there is little to no difference in performance.

The blue wire from terminal 12 has been disconnected, but when I connected it again, there is a constant click in the turbo actuator (think that's what you call it).

The blue wire from terminal 12 has been connected to another blue wire in the main fuse box, the car has boost from 2300 rpm and goes deep into the yellow on the boost gauge when accelerating. When disconnecting the wires, the boost comes in at about 2800 rpm and does not accelerate as strongly but can also move far into the yellow on the boost gauge. Is this normal?

The knock sensor is not turned very far into the head of the engine, can this cause problems?

Would it be possible to repair the MABC? While the boost was in the yellow zone I heard a rough sound briefly, backed of immediately and have not pushed the car hard since, everything appears fine, any ideas what his was or MABC related?

Thanks for all your valuable info,



Dominic in the USA writes:-


Re: Biturbo boost noise!


Let me start by saying that this site has been an invaluable resource, so thanks!

I have an '84 Biturbo (US). Under boost conditions (above 2000-3000 rpm) I hear a 'whoosh' noise, like air escaping. I haven't noticed a significant loss of power, but the noise is certainly new. Could this be a turbo bearing protesting under use?

I've checked all hoses and plugs for a good clean connection and still no leads. The car does have 100k miles, but still has a kick!

Any ideas?

Thanks a lot,



Jamie in New Zealand writes:-


Re: 1989 Biturbo.


I am writing to you from New Zealand, My brother and I are currently repairing our wonderful 89 BITURBO.

During the past few months we have been inspired by your website. Inspired to repair the car for track day use and targa rally events locally. To do this we would love to upgrade the intercoolers and all related plumbing. Being in New Zealand we have a huge variety of Jap turbo’s. Can any of these intercoolers be used as a way of saving a few bucks?

Also I would love to change the rims for a more competition look and more traction!!!! But need to have them custom made in Australia. I have seen many Biturbo's online with different rims so there must be a better way?? Change the hub?? Import from Europe??

Any Help would be awesome.

Many thanks,



Richard writes:


I wrote this answer to the common question "my boost guage stops when it gets to ambient pressure/8 O'Clock position on the boost dial". You may want to put it in your "Can You Help?" Pages, as it seems to be a common question there. It's applicable for all Biturbo engines up to the 2.8 18V.

Boost diagnostics 101:

If something catastrophic hasn't happened and you've checked thoroughly for leaks then it's time to check out the three sensors and actuators that the computer talks to. These are the knock sensor, the boost pressure sensor, and the waste gate actuator valve.

Knock sensor.

Check that the connections to the knock sensor are good and that it's actually plugged in. It's a bitch to get it to connect to the sensor at the sensor end without taking the manifold off, but it can be done. If this is disconnected the computer goes into failsafe and kills your boost. Likewise check the three pin connector. If that's ok then move on to...

The boost pressure sensor.

This has a single pipe running into it and two Lucar connectors of different sizes on the top. Once you've checked all the wiring - a broken connection makes the computer go into "safe" mode again - take it off.

Use compressed air at low pressure, a tyre inflator, or if you have strong lungs just blow into the damn thing whilst connecting an Ohm-meter across the two terminals. It should rise up to about 250 Ohms and then stay there no matter how much pressure there is. If it does that, then move on to the...

Waste gate actuator.

This has two connectors on the top and three pipes running into it. Check all the electrics as usual. Then turn the ignition on whilst listening to the valve - it should "click". Now wiggle the connector whilst listening carefully to the valve. It shouldn't 'click' if it does then the solenoid in the valve has a loose conection inside or has burned out and you need a new one - it's a Saab part at a tenth of the cost of what Maserati will charge you. Turn the ignition off, it should click again.

If that's all ok then take the valve off noting the position of the three pipes - the left one (R) goes to the air box, the centre one (C) goes to the turbo on the high pressure (compressor) side, and the right hand one (W) goes to the waste gate actuator.

Blow into the middle union on the valve - you should only be able to get air coming out of the right hand (W) one. Connect up 12V across the two terminals and do it again. You should be able to hear/feel air coming out of the two other pipes. any sluggishness or bleeding through will mean that this is your problem. If it's a bit sticky then you can take the valve apart and clear out any gunk in there.

If that's ok then connect up your airline/compressor/blow down the pipe that was connected to the "W" union. You should be able to hear another clicking noise from both sides of the engine - that's the waste gates actuating. No click, and your waste gates are stuck or the pipes to them are leaking.

Other than that it's lots of electrical and pressure testing of these components under driving conditions - which is fun having wires running everywhere and pressure guages taped to the windscreen!

Alternatively, bring it to my workshop where I have all the test gear...



Cristi in Romania writes:-


Re: 1985 Biturbo.


It's not the first time when I write you. I write you before and the CD that you send me as a gift for my daughter it was very useful for me. Thank's.

But now I have again problems with my Maserati.

It's an electrical problem. When I press the brake pedal the brake lights it doesn't work. Also when I turned on the lights on position one it doesn't work. On position two and three they work.

I've already checked all the cables of the car and the fusebox but everything it's ok. I want to ask you: where they go the cables who they come from the lights of the back of the car? I hope you will understand what I mean.

Please don't ignore my question.

P.S. I've sent you three more pictures with my Maserati. It's a teribille car.



Clay in the USA writes:-


Re: 1985 Biturbo (US specification).

"After 4 plus years I am starting to find time to reconstruct my US market 85 Biturbo.

Heads are back on. Now I am trying to remember how all the wires and hoses run. Factory book shows connections but not routing. If anyone has some good detail pictures of a correct US market 85 Biturbo I'd really appreciate it.



Reply from Enrico:-

Re: Biturbo - plumbing!

"Hi Clay,

I am afraid I don't have any detailed photos but maybe these pages from the parts manual may be of some help.

You can click on the pages for a clearer picture!



Glenn in the USA writes:-


Re: 1984 Biturbo.

"I just bought a 1984 Biturbo with 20,000 miles on it. The altenator isn't charging the battery. I put a new battery in it and had the altenator tested, they said it was fine. When it is on the car it isn't sending any charge to the battery.

With a charged battery it runs fine but quickly pulls it down.

The warning light on the voltmeter only comes on when the reading on the voltmeter starts dropping until it's almost dead!

Any ideas?

Thank you,



Reply from Enrico:-

Re: Biturbo - alternator not charging.

"Hi Glen,

Does the warning light illuminate when you turn on the ignition and when the alternator isn't charging?




Another reply from Enrico:-

Re: Biturbo - alternator not charging.

"Hi, The reason that I asked if the warning light on the alternator lights up is because this bulb forms an integral part on the charging circuit. If that bulb is faulty, the battery will NOT receive and charge from the alternator.



Another reply from Jarle:-

Re: Biturbo - alternator not charging.


1. Is the warning light lit at first, before starting the car? If so, this is working as is. If this light isn't working the alternator won't charge.

Meaning that even if only the bulb is broken the alternator might not work. The alternator has two ports you see, when the alternator isn't charging the power from the battery goes through this port, directly to the bulb in your car. When charging, the charge works as a signal to a relay sort of thingie and the power is directed to the battery, and the power to the bulb goes away. Long explanation, but sort of explains why some alternators won't charge if the light don't work...

2. The alternator is grounded to the engine, and the engine sometimes loses ground. So all Biturbo owners should pull a good quality cable from the - on the battery to the engine. This is the most common reason for bad or non charging. Happend to both of my cars.

3. Erratic charging can also be a result of a worn diode bridge. My former alternator would seemingly work well, but then suddenly start to play around. If both of the above checks out, I would consider overhauling the alternator.



Rene in South Africa writes:-


Re: Biturbo E.

"Hi there !

I recently replaced a fuel filter and some old vacuum hoses on my 1984 2.5 Biturbo. The problem I now have is that the car just will not start ! After repeated attempts, I briefly got the car started ,only by flooring the gas pedal.

As soon as I take my foot of the gas pedal the car dies. For the brief period it starts ( 6 sec ) the engine sounds like it runs on three cylinders and sounds very tinny . Is there a specific procedure when replacing the fuel filter ?

I have been wondering if the cambelt has slipped a tooth or a valve has become stuck, can this cause the symptoms ?

The car did not sound odd or run poorly, nor smoke before I replaced the above mentioned parts. The car has only done 56000 km.

Thanking you,



Another reply from Andy:-

Re: Biturbo problem.

"There is no specific procedure when renewing the filters - there are two under the rear of the car. It is possible that you disturbed the fuel pump wiring when you changed the filter. Have you listened to see if the fuel pump is running now because it does sound as though it is not getting fuel through? It should run for 10 seconds when you put the ignition on - then it will automatically go off. Otherwise, the pipework is fairly straightforward between the filters but are you sure you got it right? It is also possible though rare that the new filter you have is blocked. Take it off again and blow through it. Seems very unlikely and a hugely coincidental that your cam belt has jumped.



HP in Switzerland writes:-


Re: Biturbo E.


my name is HP and I am from Switzerland. Since 2 years I am a proud owener of a Biturbo E 1986 with now 75 000KM on the clock. It seems to be a modified one, it has a 222E frontspolier with added aircoolers and a popoff walve. Goes well, no mecanical problemes at all over the last 12 000KM. Just some minor electrical failures easy to handle.

The only thing that I am not full satisfied with is the brutal and not easy to handle understeer/oversteer behavoir in corners when you have to lift your right food. I avoid to do that but sometimes you just have to.

I wrote letters to the Maserati Owners Club in Switzerland as well to the Biturbo Club Germany but got no answer. Now I found on the page a offer for a Strut Tower Brace for Biturbos 1987 and later and am wondering if this device could help to cure that problem. So I have some questions:

- do you know if this would help?

- do you know of any change in dimensions in the strut tower area beween 1986 and 1987? ( or why should that brace not fit in a 86 Bitrubo if it fits in a 87?

- do you know of any other thing that can be done to reduce or cure this problem?

Look forward with big interst to your answer. Thank you in advance.

Very best regards



Another reply from Andy:-

Re: Biturbo E handling.

"The strut brace will not really help a great deal on its own. This would be something to consider further down the line (and no, I don't think there is any difference between an 87 and an 86 in this respect and therefore it should still fit your car). What I would suggest is to go to and find out about their handling kit. This is a kit of springs, shock absorbers and anti roll bars which makes the car lower, harder - but still with a reasonable ride quality and significantly improves the handling in all conditions. This kit is not cheap but worth it! After that, consider getting some slightly wider wheels. If your wheels are original then they will be 6J. A 425 or Spyder of the same age will have 6.5J and a Biturbo Si will have 7J. All would fit straight on and then you could get wider tyres as well. Only after this would I say it was worth fitting a strut brace.



Roberto in Chile writes:-


Re: Biturbo 2.5-litre.


Does anyone know what the adapter on the side of the plenum chamber is for?

I appreciate the help.




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