New Grancabrio owner in Herts has 2 big problems

Chenders

New Member
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11
Hi new member here with 2 problems - all suggestions gratefully received thank you.
Purchased a 2011 Grancabrio here in the UK with very low mileage - 11,000 miles. One previous lady owner who in some years did less than 500 miles in total and in one year did no mileage at all - so a lot of standing around being unused for extended periods and a patchy service record. The car was delivered to me on a trailer with an almost empty fuel tank.
The problems:
1. An occasional and very dangerous issue whilst the car is being driven - occasionally it fails to respond to the accelerator pedal. This normally happens when driving around town at speeds of less than 30 mph. I respond by pressing down ******* the accelerator but there is no response. The revs drop right down but the engine does not stall and no warning lights appear on the dashboard. I have to pull over to the side of the road. Then when I floor the accelerator aggressively whilst in neutral I do get a response and can then drive off normally It has happened 3 times on an 8 mile journey and has been an intermittent fault since. The car has of course had a PPI and a full service following purchase.

I suggested to my Maserati service centre that given the age of the car, coupled with its very low mileage /standing around being unused for extended periods, there might be a problem with deposits in the fuel tank. The car has never had E10 fuel put into it. On filling the fuel tank and adding Redex petrol system cleaner to clean the injectors the issue went away for a while but reappeared when the tank was just under a quarter full. Coincidence? My Maserati garage contact cast doubt over this suggestion but I wanted to put it to this forum. If readers of the forum agree it may well be a problem from old petrol standing in the tank for extended periods throwing a deposit what is the remedy please? Does the tank require cleaning out and how is this best achieved please?

2. The second problem is that my boot is leaking really badly and I end up with several litres of water underneath the boot and in the spare wheel well in the boot. My Maserati garage have said this is not an uncommon problem. But the boot seals look to be in excellent condition so I wonder how the water is getting in? The garage drained it but it's back. Is this indeed a common problem and if so what is the remedy please?

Many thanks!

Chenders
 

Zep

Moderator
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9,110
Hi Chenders,

Welcome to the forum. For my pennies worth I would say:

1. did your specialist plug into a diagnostic machine and check for both active and pending fault codes? It does seem like an odd fault. I tend to agree it seems unlikely to be related to the fuel supply, unless the air admittance valve is faulty causing a vacuum a la Redbull in Bahrain. Which seems unlikely. As the car has been standing, also check for wiring damage from little critters. This has been known to throw up odd faults.

2. if the boot seal is good and the alignment is ok, the next culprit is the cable conduit from the body to the bootlid. These can leak water Into the boot.

Before anyone else says it, pictures or it didn’t happen! :D
 

safrane

Member
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16,748
Suspect you may have water in the tank and also poor electrical supply due to the damp in the boot
 

Gazcw

Member
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7,699
If just purchased and from a dealer they should be repairing. Sounds dangerous and needs sorting.
 

CatmanV2

Member
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48,547
Given it does not stall and no warnings I'd be more inclined to think of an electrical fault affecting the pedal position sensors. But as @Zep says it needs scanning and as @Gazcw says: Dealer purchase: Up to them....

C
 

Zep

Moderator
Messages
9,110
Suspect you may have water in the tank and also poor electrical supply due to the damp in the boot

I don’t think it could be water. If that was being drawn into the system it would just stop and not restart.
 

Chenders

New Member
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11
Hi Zep first sorry for late response - firefighting.
Yes my Maserati garage stated on their post purchase inspection report in the context of losing response to the accelerator when driving about town: “There we’re no faults recorded on the engine ECU.”
It happened again yesterday I was doing about 25mph. Again the petrol in the tank was below a quarter. After about 4miles of gentle driving on 30 mph speed limit roads the car suddenly did not respond to the accelerator so I had to immediately pull over and put it into neutral and rev it up. I did not switch the engine off. No dashboard lights came on, then after revving it was ok for the rest of the journey - about another 3 miles.
I purchased the car from a dealer last year but they have refused to deal with the issues and I shall be taking them to court (they have terrible reviews which at the time they attributed to a disgruntled sacked employee!). There was a potentially fatal steering issue too which I have paid to have resolved.
Thanks for the heads up on the air admittance valve Zep which I shall pass onto McGraths. Also the thoughts about water in the petrol Safrane and pedal position sensors Catman V2 however it should be noted the problem hasn’t occurred so far when the petrol has been above quarter tank.
I spoke to McGraths about cleaning out the petrol tank and they said:
It is involved
It will be expensive
I wondered instead whether I should consider using Fuel Fixer Wrong Fuel Rescue. This is marketed for where you wrongly put diesel in your petrol engine or vice versa and they come and pump it out then flush out your tank. They agreed it would work if long standing petrol had thrown down a sediment/ or else water in the tank and quoted me £450 to carry out, which is a tidy sum. Any thoughts on this please? Worth trying?

As far as the water into the boot issue is concerned McGraths say this is not an uncommon issue and it needs to come back in for evaluation. The cable conduit from the body to the boot lid could be a good call and I shall pass it on. It’s driving me mad.
Many thanks!
 

Oneball

Member
Messages
11,075
I can’t see it being fuel contamination, it wouldn’t just happen in the circumstances you mention and it’s unlikely it’d maintain an idle.

I’d be looking for a throttle body or pedal issue even if it’s got no error codes.
 

Chenders

New Member
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11
Ok CatmanV2 many thanks. That would of course save me £450 - strange though it hasn’t happened on a tank above a quarter full?
 

Zep

Moderator
Messages
9,110
The more I think about this, the less convinced I am about the fuel idea.

edit: @Oneball beat me to it

The way I read your description, the car fails to respond to throttle input. It doesn’t stutter or misfire, is that right? If it was fuel, it would run badly, even at idle and you would see a misfire code as the throttle would open when you press the pedal and there wouldn’t be enough fuel to maintain the mixture and it would misfire. This would be especially so when you rev it to clear it. Corelation with the fuel level doesn’t mean causality to my eyes anyway.

The throttle pot on the other hand, if it was randomly stopping giving a signal, wouldn’t give a code because the ECU would think the throttle wasn’t being pressed.

I’d want to log the throttle position using a diagnostic to see what the ECU is seeing from the pedal.
 
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Chenders

New Member
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Yes Zep the car just suddenly ‘loses it’ when I’m pottering around below 30 mph. There is absolutely no stutter or misfire. Simply all response to the accelerator pedal ceases and I have to idle to the side of the road, floor the pedal and it comes back. Yesterday the pedal response returned immediately but on another occasion I pumped the accelerator several times for up to 8 seconds with no pedal response and then at the 8th second the engine roared back and I could continue.
It could be very nasty indeed if it happened while I was entering a junction/ roundabout.
 

Scaf

Member
Messages
6,512
For the leak in the boot, take off the plastic trim either side of the boot where it meets the lights (of that makes sense) and remove any crud from behind, water needs to flow under to drain or it will back up to the conduit and leak into the boot.
 
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Chenders

New Member
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I am certainly going to ask the garage to run that throttle position check with the diagnostic. Thank you very much - and all.
Prob is I have been told it will be May at the earliest before they can book the car in.
I shall of course report back here on whether this fixes the problem.
Any other comments please. I am going to submit everything in this thread to the garage.
Thanks again
Chenders
 

Le Unu

Junior Member
Messages
73
Not sure what long standing sediment this fuel fix people are referring to but I'll bet my annual salary there's nothing in your fuel tank of an unwelcome nature.
 

outrun

Member
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5,017
I am certainly going to ask the garage to run that throttle position check with the diagnostic. Thank you very much - and all.
Prob is I have been told it will be May at the earliest before they can book the car in.
I shall of course report back here on whether this fixes the problem.
Any other comments please. I am going to submit everything in this thread to the garage.
Thanks again
Chenders

Where are you based? The esteemed owner of this forum @conaero also owns a very respected garage, and there are others that we know are good as well. I'd be taking to a specialist as they are far more experienced than most.
 

philw696

Member
Messages
25,114
The first thing you need to do is have diagnostic gear hooked up and record live data whilst driving to see what happens when it misbehaves.
Regards getting the tank out not a overly complicated job but really don't think that's the issue.
Start simply first.
 

rs48635

Member
Messages
3,181
Issue one - throttle pot reset ? Or equivalent procedure which is mandatory on the 3200. Does the modern car get hyper sensitive throttle pot range? Could be such small throttle opening the voltage is effectively zero?

Issue two - drill holes in the boot floor