Adjusting high idle on 3200 GT (manual)

[Alecci]

Greetings to the board,

Is there any way to adjust the idle beyond making adjustments to the pedal potentiometer?

Car usually sees 1,000-1,100 rpm at idle, which I'd say is a bit high for a V8 (although a small volume one at only 3.2 liters).

The cas already has both the contactless throttle-body as well as the contactless pedal potentiometer. The recommended voltage output at accelerator idle position for the pedal pot is listed as 0.35-0.50 V, but due to it being some "play" at the accelerator idle position I've had to set it at 0.41 V (otherwise if you mistakenly tap - with your toes - the backside of the accelerator towards you it will creep below 0.35 V and throw a CEL).

Also, the car likes to rev a bit when pressing the clutch in order to change gear, to about 2,200 rpm, and it's a bit jerky to drive at lower rpm. Letting it drive on idle in second gear is about 30 km/h, which also seems a bit high, and it's altogether impossible to drive at walking speed - even in first gear - since the idle rpm is so high.

 

[Gecara8183]

Hi from my experience they all fluctuate a bit on idle. To improve mine I changed all the non return valves in the vacum system which improved it significantly

Sent from my SM-G781B using Tapatalk

 

[allandwf]

It should idle at 1000rpm

 

[RichTaps]

If your throttle body and pedal pot are working correctly, I'd say you might have a vacuum leak somewhere. Worth checking all connections into the Intake manifold:

- All vacuum hoses
- Throttle body gasket
- Intake manifold gasket
etc

 

[BennyD]

Just be thankful it’s still running.

 

[urquattrogus]

Boring video but this was mine after lots of work, prior to that It did used to idle higher and hunt more.

There is a thread on it but changed many hoses and sensors, as others have said definitely check vacuum lines, any one way return air valves such as the one before the brake servo etc.

 

[Lozzer]

The Idle cannot be adjusted, the pedal pot voltage is either in range or its not. Mine used to fluctuate on Idle, quite badly for someone with OCD! I spent many an hour or weekend even, trying to trace some sort of Vac leak to no avail. The contactless converted TB's play a big part in this fluctuation I believe, something to do with the conversion interfering with the electronics. Mine had magnet failure so needed replacing, I got a converted Volvo Unit off Dave Shanks @davy83 who reprograms the TB's and the difference was like night and day. This is my 3200 with Davy's unit fitted.
Going out on a limb, if you have no Vac leaks I would be pointing the finger at your TB.

 

[davy83]

Greetings to the board,

Is there any way to adjust the idle beyond making adjustments to the pedal potentiometer?

Car usually sees 1,000-1,100 rpm at idle, which I'd say is a bit high for a V8 (although a small volume one at only 3.2 liters).

The cas already has both the contactless throttle-body as well as the contactless pedal potentiometer. The recommended voltage output at accelerator idle position for the pedal pot is listed as 0.35-0.50 V, but due to it being some "play" at the accelerator idle position I've had to set it at 0.41 V (otherwise if you mistakenly tap - with your toes - the backside of the accelerator towards you it will creep below 0.35 V and throw a CEL).

Also, the car likes to rev a bit when pressing the clutch in order to change gear, to about 2,200 rpm, and it's a bit jerky to drive at lower rpm. Letting it drive on idle in second gear is about 30 km/h, which also seems a bit high, and it's altogether impossible to drive at walking speed - even in first gear - since the idle rpm is so high.

It should idle at 1000 rpm, its a factory setting. It can be adjusted a little by messing around with the throttle body but moving the pedal sensor will just create errors and not affect idle at all. It is a little high but I suspect Maserati were trying to keep the oil pressure up. As has been mentioned vacuum leaks can cause idle problems and also contactless sensor conversion sadly can actually cause this to get worse if not set up right. If its just started doing this then the cause is a fault somewhere, not adjustments.
I am wondering with the revs going up to 2200 when you put your foot on the clutch whether you have friction in the throttle body with the magnet breaking up. There are two very common failures on the throttle bodies, first is the rotary sensors (and the contactless upgrade removes the faults but can cause instability at idle) and the second is friction in the rotor caused by the magnet breaking up. yo ucna try to feel for this problem see this video I stuck on the tinterweb.

Vacuum faults are also a common fault so the comments about hoses and one way valves, the kaiser valve is also prone to failure.

 

[BennyD]

The Idle cannot be adjusted, the pedal pot voltage is either in range or its not. Mine used to fluctuate on Idle, quite badly for someone with OCD! I spent many an hour or weekend even, trying to trace some sort of Vac leak to no avail. The contactless converted TB's play a big part in this fluctuation I believe, something to do with the conversion interfering with the electronics. Mine had magnet failure so needed replacing, I got a converted Volvo Unit off Dave Shanks @davy83 who reprograms the TB's and the difference was like night and day. This is my 3200 with Davy's unit fitted.
Going out on a limb, if you have no Vac leaks I would be pointing the finger at your TB.

Now you can have a go a fixing the speedo.

 

[Alecci]

Thanks for all of the replies. If that high rpm is the factory setting for idling then I guess there's nothing much to be done. At cold start I see 1,000-1,100 rpm idle, with engine warm or hot it's usually about 950 rpm. It just seemed a bit high to me (e.g. my BMW/Alpina B10 V8 would idle at ~700-750 rpm, my Skyline GTRs would idle at ~800-850 rpm), the engine being a V8.

The increase in rpm has improved quite a lot after doing the accelerator reset, and it's now barely noticeable with the engine warm or hot.

As mentioned in the original OP, I've already got the contactless throttle-body and pedal potentiometer.

Anyways, now I guess I'll have to start a new thread about the heater shenanigans instead.

 

[urquattrogus]

When I had my 3200 one woman said I had just sat there revving my car (it was just idling high and low!).

 

[allandwf]

Its not a BMW or Nissan lol

 

[Tamariini]

Hi, My problem is quite opposite. Idle is too small (around 650-750rpm) which tends to bring up OIL and oilpressure light. With AC on, idle is a bit higher and problem is not that big and comes up only with really hot engine. I have modified Volvo throttle and contactless pedal sensor and low idle has been "problem" since i changed to Volvo unit. Any way to rise idle to normal? i have replaced all gaskets and hoses on intake so it shouldbe ok.

 

[davy83]

Hi, My problem is quite opposite. Idle is too small (around 650-750rpm) which tends to bring up OIL and oilpressure light. With AC on, idle is a bit higher and problem is not that big and comes up only with really hot engine. I have modified Volvo throttle and contactless pedal sensor and low idle has been "problem" since i changed to Volvo unit. Any way to rise idle to normal? i have replaced all gaskets and hoses on intake so it shouldbe ok.

Your magnet for the sensor is in the wrong position. Obvious really. Without an SD2 tester or a CAN bus interrogator its pretty hard to make sure the magnet is right. you need to dismantle the position sensor again and loosen the nut that holds the round sensor magnet and rotate it clockwise, tighten it again and try again. And you just need to keep pulling it apart moving it and trying again. With the right tools its possible to work out how far to move it, and indeed when its dead right. But in your case its just trial and error. if you cant get the idle up then it will need modified to get it right, again without the right tools its quite tricky.

 

[Tamariini]

If i remember correctly, this Volvo unit is not with magnets but original sensor since it was low mileage and no need to touch?