Potential Air Leak?

mchristyuk

mchristyuk

Junior Member
Messages
668
Hi Guys,

The refurb of my 3200 is going well.. had all the rear brakes apart and the handbrake shoes were actually all ok (shock horror) and just needed adjustment. Ran the computer over the ECU and had the grand sum of ZERO errors reported (picks self up of floor).

However it was also the first time I got to give the car the real beans on a dry road and it seems to be holding back on me.

It starts to accelerate ok, however above 4k rpm it just doesn't seem to keep pulling like my old one did. Even in sport mode it kind of gives up and changes gear around 5.5k rpm. In fact in Sport mode nothing really seems to change at all.. the sport button lights up and the dash lights up as it should.. but it doesn't seem to get any "friskier".

With the window down I'm sure I can hear an occasional "dump whistle" (for want of better wording!) from the right hand side when I lift off the throttle after giving it the beans for a brief moment.

So.. seeing as the ECU is reporting no errors and the engine is idling and running fine my suspicion is some kind of leak in the air pipes on the drivers side turbo.

Going to get in there with the spanners tomorrow.. but before I do does anybody have any handy advice on how to get in there and which pipes I need to be looking at (knowing there's oil and coolant pipes down there too..)?

Thanks one an all in advance!

Mark
 
conaero

conaero

Forum Owner
Messages
34,632
My initial though was turbo, what's the mileage?

The actuator rods can get bent but it's more likely to be the turbo pressure sensors or an air leak.
 
Contigo

Contigo

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18,376
The vent to air is normal especially when backing off the throttle. Check the small pipes which go to the pier burg valve close to the throttle body. If they are split that can cause a drop in boost. There are two pressure sensors one downstream of throttle and one upstream on the bulkhead. I would have a good look at the large vaccum hoses coming off each turbo too whilst there especially the ones near to the radiator top and bottom pipes and oil feeds.
 
mchristyuk

mchristyuk

Junior Member
Messages
668
Hi Guys

I can hear the turbos spooling up ok, it just runs out of steam around 4.5k.. And weird that sport mode isn't letting it rev to the true red line. I would have thought if the turbo was dead it wouldn't stop the engine revving.. Which suggests a sensor, but no error codes are reported.

I saw this thread on here
http://www.sportsmaserati.com/showthread.php/11529-3200-has-no-power-(/page3?highlight=Leak

So will check that too in the morning..

Cheers

Mark
 
Contigo

Contigo

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That valve he refers to is the one I changed on my car and the one I referred to as the Pierburg valve. It is a boost control valve and they do frokm time to time stop working if the electrical 12V connection is intermittent or just not present. Disconnect it and check the connections on it and if necessary fit bullet connectors.
 
zagatoes30

zagatoes30

Member
Messages
20,949
Turbo motors are susceptible to vacuum pipe leaks. Check all the pipes for leaks or cracks even the smallest can cause a significant drop in performance.
 
mchristyuk

mchristyuk

Junior Member
Messages
668
Hi Guys,

Thanks for all your input.. however I "think" I've found the culprit..

I took the valve out (scraped knuckles and blood everywhere..) and the connector looked all ok, a bit corroded but not too bad. So instead of changing the bullets (my bullets were slightly too large in my tool box) I cleaned it all up with switch cleaner and re-crimped the connector to be tighter on the valve housing poles.

With that done I did the throttle reset (again) and went out for a drive. No change.

However.. first pass down the national speed limit section it changed gear early (again) and felt it ran out of steam around 5k as usual. I also noticed that sport mode, or not, it didn't seem to drop down a gear when I gave it the beans... Turned around and came back, and out of frustration buried the pedal good and proper so it felt like it was going to come out of the bulkhead and.... tada!.. We get pretty much to the 6k line and it felt much more alive, plus it stepped down a gear before taking off.

Now it still doesn't seem quite as brisk as my old 3200, but I will allow this seeing as its done 100k miles and needs new plugs, etc.. however it did feel much, much better.

So pulled the carpet up by the throttle pedal pot to take the connector off and give it all a clean and... no connector.. just black insulation tape around whether the connector should be. Ummmhmmmm..

So I think that somewhere down the line a previous owner has taken out the connector to sort a CEL and soldered the two "redundancy" wires together. And now it's basically not seeing full throttle as it should and that's why it seems down on power and changing gear early, without any error codes.

So I'm going to strip it all out later, and IF they have been soldered together, undo the bodge, open up the pedal unit and clean the pot up.. then see if that makes it behave.

Will report back when I have done!

Cheers

Mark
 
mchristyuk

mchristyuk

Junior Member
Messages
668
Success!

I took all the tape off and all the wires were attached as they should be, simply the connector had been removed. Fair enough I know the connectors can give problems.

Next up I plugged the multi meter in to the wiring to find out what the pedal was doing. My range went from 370mV (idle) to 2750mV (full throttle). The expected range I understand to be (350mV/600mV to 2900mV/3700mV). Bingo.

So I took the arm of the pedal pot and rotated it one spline. Measured again as 550mV to 3100mV. Did a throttle reset and went for a blast.

Now she goes like she should! Step down happens and the engine pulls nicely all the way to the correct point.

Who knows when the last time the poor engine saw full blast.. I've given it a proper Italian tune up now.. so hopefully when she gets serviced in the next few weeks a few more of those sleepy Italian horses may be awoken!

Thanks everybody for your input.

Mark
 
mjheathcote

mjheathcote

Centenary Club
Messages
9,038
How many are running at sub-full throttle for the same reason?
Wasn't there talk of a contact-less pedal pot conversion a while ago?
 
mchristyuk

mchristyuk

Junior Member
Messages
668
Hi Mike,

I'd say it's quite noticeable and I doubt there are any running around with this issue if the owner knows how a 3200 should go. What I would say is that I bet a number of owners have been stung a lot of money by garages trying to "fix" the issue with new throttle bodies and pedal pots...etc...

I had a gut feeling it would be something daft.. thankfully it was. I know next time I won't be so lucky :)

Cheers

Mark
 
Contigo

Contigo

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Well done Mark it sounds like you have made the right move and I reckon you should get a new connector from forum member Davy.
 
mjheathcote

mjheathcote

Centenary Club
Messages
9,038
Just looked at Eurospares, a new replacement throttle potentiometer for the 3200 is over £500 plus vat!
In comparison, for the 4200/GS, it's much cheaper, a fifth of the price.
I wonder if there are problems with the 4200/GS not giving a full throttle signal to the ECU, how do you check?
 
Contigo

Contigo

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18,376
All down to voltages as Mark mentioned above. As his were already cut it was easier to measure the voltages at the join rather than at the contacts of the connector. The other way to measure them is using an SD2/3 machine at a specialist or main dealer.

BTW you cannot get the original Bosch PP anymore for the 3200, Maserati don't have stock. The one that the WD car needed was made up specially in a batch of 5 and I think the other 4 are with Mike Roberts.
 
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