4200 throttle sticking issues getting worse.... Help !

[AlfaMail]

Fellow owners please help !. My 4200 is getting worse ( see below ). I've tried 2nd hand throttle body and pedal potentiometer and the problem is exactly the same. Even tried an air flow meter to no avail, again, exactly the same. Funny thing is I cannot replicate the problem when the car is stationary ?, it only happens when on the move. I have removed my inlet plenumb chamber and checked for air leaks and the removal plate with the o ring gasket, all good. I'm down to thinking that it maybe an ECU problem. If I'm doing 70 on motorway and slip it into neutral the revs will slowly climb to 4500 rpm !, however, if I then let the clutch out and break hard in 6th gear the transmission will pull the revs down to idle in no time. Q: can a second hand ECU be fitted to the car or do you need a 'virgin' unit ?. HELP !, john.




My 2002 4200 manual has a niggling issue. When in normal driving the engine revs will not die off when throttle is released. I find myself using the brake pedal to slow the engine and the car down. If I dip the clutch the revs whip up to 2500 to 3500 RPM and stay there for some time before dying off to idle. If I keep the clutch up and the car in a high gear and use the footbrake to slow the car the revs do die a lot quicker. I have tried a good 2nd hand throttle potentiometer and good 2nd hand throttle body and there is no difference at all to the problem. I have tried to "re-set" the system by
switching battery off via boot switch for 20 minutes / switch back on and re-set alarm / entering car & closing door / switching all systems off / switching on ignition & turning radio off / start car not having touched pedals / let it idle for ten minutes / test drive. Tried this a couple of times and no difference at all.
I'm thinking that there may be an air leak after the throttle body ?, those small bore plastic pipes ( 3 or 4 of them ) that are all over the inlet plenumb chamber ....... could one of those be broken off and causing this issue ?. Is my re-set procedure coorect ?. By the way, I have removed the throttle body from hoses to look at the butterfly valve and left cables on and when pressing the throttle the valve opens and closes immediately like there is no problem ??. HELP

 

[CatmanV2]

I suspect you need to get this plugged into a diagnostic. Where are you?

C

 

[jluis]

Sounds like an air leak.
Check for codes and see if the fuel trims are registering a lean burn condition as that can be a sign of leaks.

 

[Trev Latter]

One way valve on brake servo failed/ failing perhaps? How do the brakes feel?


Sent from my iPhone using Tapatalk

 

[spn]

Have you used the correct reset procedure for the throttle ?

From the manual:

WARNING: Each time the battery master switch is turned to “on”, wait at least 30 seconds with the ignition key turned to position “MAR” before starting the engine. This enables the electronic system managing the motordriven valves to perform the selflearning procedure. During this time it is essential not to activate any device.

Cheers,

Simon

 

[AlfaMail]

I took my Maserati 4200 to a specialist dealer, I was told that this dealer had invested in Maserati diagnostic equipment. After plugging her in I was told that the air flow meter could not be read by the ecu. A new AFM has been ordered and she goes back there to be fitted on 24th of this month. I will let you know if this cures my problems or not. For anybody in the North East the dealer is in Hartlepool and is called CarTech Prestige, john.

 

[StuartW]

Fingers crossed John

 

[CraigWaterman11]

If it was the MAF couldn't you just unplug it and test whether this was causing the problem or not? It will set the CEL but you'd know whether this is the actual issue. Alternatively, check the wiring, to make sure there's not splices or chaffed wiring.

 

[Yeti]

I've been having a bit of a problem myself with my 4200. Throttle seems "sticky" and I seem to have to push through the dead zone. Is this down to the woirn carbion tracks in the throttle body? If so, can anyone remember the name of the guy who makes up a new version?

 

[redsonnylee]

I've been having a bit of a problem myself with my 4200. Throttle seems "sticky" and I seem to have to push through the dead zone. Is this down to the woirn carbion tracks in the throttle body? If so, can anyone remember the name of the guy who makes up a new version?

Mine was rebuilt at the Maserati Shed, he did a very good job.

 

[Yeti]

Mine was rebuilt at the Maserati Shed, he did a very good job.

That's the guy. I'll get in touch, thanks

 

[Ian3200]

Leave him alone, he's working on my car!

 

[redsonnylee]

Three cheers for Mike!

 

[AlfaMail]

Yeti, The guy that rebuilds throttle bodies is The Maserati Shed and he replaces the carbon tracks, however, he only does the 3200 which has an Italian throttle body ( I Think ), where as the 4200 has a Bosch unit. I have a good spare 4200 throttle body and pedal potentiometer if you want to make an offer for them ?.

My throttle problems are now solved !, thanks to CarTechPrestige of Hartlepool. My car had two issues, the first was the air flow meter ( or air mass meter ) also Bosch. The ECU was not reading this device properly. A new meter from Eurospares was fitted, it was around £175. Another issue picked up on their diagnostic equipment was that there was an ECU fault with the ABS. An incorrect tyre size fitted to the rear made the rear rims slightly larger in diameter than the fronts and this was causing problems. I fitted two tyres to the rear with the correct aspect ratio and the problem disappeared. The car is really flying now and it obviously had had a problem with the air flow meter. After fitting the correct size tyres to the rear the throttle is now perfect.