Shock and Awe - 3200 Throttle Issues.

[urquattrogus]

I have been having some throttle issues with my car.

When I bought it an Autoshield report said "shows early signs of wear" and at 55,000 miles on the original TB and pedal pot, I thought I best change both.

The car ran fine apart from a mildly wavering throttle when you back off in traffic (its an auto btw)

So trying to grab things with both hands and prevent future issues I sent my TB off to Maserati Shed to refurbished/made contactless, and also ordered a contactless pedal pot from davy.

The issue I am having is when I start the car, sometimes it revs to just over 2000rpm constantly. It also still wavers a bit when backing off at low speed.

This happens both with my original pedal pot, and the Davey one - so I think can probably rule out the Davey pedal pot.

My car was at Grimaldi having the geometry set, and Aux tensioners and belts changed etc, general check over, replace brake pedal switch etc.

They did a smoke test and no leaks found, also no visible issues with vacuum or boost hoses that I can see.

The car had all o rings to the plenum replaced just under 2 years ago and less than 3,000 miles ago by Autoshield when it was prepped for sale by Richard Grace.

So, a bit mystified really.

My best bet it that the throttle body is actually sticking - when I tap it with the handle of a screwdriver it seems to go back to a normal idle.

I can try speaking to Maserati shed, but suspect he will be suspicious and presume my car has other issues.

Any ideas guys???

 

[allandwf]

He may not be suspicious, especially when you tell him it will return to normal with a gentle tap. You should be able to check butterfly easily yourself it should move freely.

 

[urquattrogus]

To be honest it's more of a hit than a tap

 

[redsonnylee]

Give him a call and have chat, just had a big overhaul with Mike including pedal pot & throttle body, he was very thorough and diagnosed some problems than were very difficult to find.

 

[Contigo]

Had this issue and the pedal pot is out of calibration. You need to wind the voltage down to 350-700mv at idle. There is a Allen screw on the top which allows the rotor arm to be adjusted.

 

[boomerang]

Allready back in 2009 (first introduction contactless throttlebodies at the dutch Maserati forum), i experienced three faults in the 3200 TB.
1 worn angle sensors
2 sticky valve due to deterioration magnetic rotor
3 electronic module faillure

If yours is sticky, you have the risk of ruining the electronic module, while it has to deliver more current, trying to get that sticky valve in its position.

We do not do just a contactless conversion, but a complete rebuilt/overhaul, so the sticky magnet rotor will not be an issue anymore and the electronic module will not overheat.

Autoshield can also deliver the rebuilt and completely overhauled units.

 

[RW3200]

Had this issue and the pedal pot is out of calibration. You need to wind the voltage down to 350-700mv at idle. There is a Allen screw on the top which allows the rotor arm to be adjusted.

Exactly what I was thinking after remembering the Wheeler Dealers 3200gt episode (around 20mins in to it, after a quick check).

 

[urquattrogus]

Had this issue and the pedal pot is out of calibration. You need to wind the voltage down to 350-700mv at idle. There is a Allen screw on the top which allows the rotor arm to be adjusted.

I presume you mean the Davey pot, not the factory one? Yes I adjusted that and measured voltage.

At the moment I have the standard one on...

I will call Mike Roberts at some stage.

I'm not sure which bits he replaces, might just be the sensors.

 

[boomerang]

You sayd; "when I tap it with the handle of a screwdriver it seems to go back to a normal idle."

To do the basic diagnose for a sticky TB, you could easily take the intake hose off the TB and feel if the butterfly moves freely and returns immediately to its rest position, if you open it by hand.
( Ignition off)

 

[Contigo]

I presume you mean the Davey pot, not the factory one? Yes I adjusted that and measured voltage.

At the moment I have the standard one on...

I will call Mike Roberts at some stage.

I'm not sure which bits he replaces, might just be the sensors.

Both of them are adjustable (Davys certainly is as I have done it recently), the instructions should be with it. The other thing which springs to mind was when a forum member had something similar where the pedal pot and TB got out of calibration and needed to be hooked up to an SD2 machine to fix. I spoke to Emblem about it and they told me that once the car had been recalibrated it drove so much better.

 

[davy83]

i presume you are able to run the pedal sensor calibration ok, since you are swapping pedal sensors? they are not that interchangeable!
it is always a good idea after making adjustments to the pedal sensor and/or calibrations to clear any pending errors too.

however i suspect tapping the TB making the idle return is a fairly good clue as to where the problem is likely to lie. I think mike just replaces the position sensors but i could be wrong, so if you have a sticking butterfly or a problem with the motor you may well have residual issues. I had my whole TB stripped and refurbished, including contact-less upgrade.

 

[urquattrogus]

Yes I have run calibration procedure or 2 Mins idle and then 5 secs WOT.

The standard throttle pot shows an idle reading of 0.378-0.385 Volts, so that seems to be in order.

The throttle body butterfly seems ok to me, moves freely with no binding and evenly against the spring.

Today I got the CEL light and code P1226 which is the pedal pot? However, this was after me testing voltages at the pot and playing with the TB butterfly (with ignition off)

I've cleared it.

Still have the same intermittent issues though. A couple of other times its been as if it's not revving high enough on startup.

 

[boomerang]

Not revving enough at start up, has nothing to do with the pedalpot.
The engine ecu sends a signal to the TB in order to obtain pre=programmed minimum idle rpm. (950-1050)
If that does not happen, something is wrong with the TB i am afraid.

 

[urquattrogus]

Thanks, ok, it's only for about a second that it bogs down a bit, and again, that was intermittent...

No codes logged when at Grimaldi.

You feel like a right dick at the petrol station or supermarket when you start your very loud car and it revs up to 2000+rpm straight away !

Maybe the best thing is to try another TB?

 

[allandwf]

Thanks, ok, it's only for about a second that it bogs down a bit, and again, that was intermittent...

No codes logged when at Grimaldi.

You feel like a right dick at the petrol station or supermarket when you start your very loud car and it revs up to 2000+rpm straight away !

Maybe the best thing is to try another TB?

That would be my first thing to do, even if just to discount it.

 

[Contigo]

Correct you can disconnect the pedal pot and the ECU will regulate the rpm. Try it next time the revs drop. It will throw a CEL but will clear once the pedal pot is reconnected.

 

[davy83]

I generally add 10 seconds to the 2 minutes and also hold WOT for 10 seconds as i found with the timings in the manual it does not always work. there is no way to know it has worked either which is a pest.

But yes as the guys say the ECU regulates the revs at first start up, which is why you don't ever touch the pedal during starting.

Yes I have run calibration procedure or 2 Mins idle and then 5 secs WOT.

The standard throttle pot shows an idle reading of 0.378-0.385 Volts, so that seems to be in order.

The throttle body butterfly seems ok to me, moves freely with no binding and evenly against the spring.

Today I got the CEL light and code P1226 which is the pedal pot? However, this was after me testing voltages at the pot and playing with the TB butterfly (with ignition off)

I've cleared it.

Still have the same intermittent issues though. A couple of other times its been as if it's not revving high enough on startup.

 

[Roberts Aerospace]

Chaps,

Much as I'm enjoying the speculation about what I do or don't do when I rebuild a throttle body, or what I would or wouldn't do when someone is having trouble with their car that may be a throttle body that I have rebuilt, it might be easier to explain.

1. I don't just slap on an unmodified Volvo sensor, send it back to the owner, and hope for the best as some ETB rebuilders' do. As Boomerang says, to do it properly, you have to address the servo motor and many other issues that affect these devices. The worn sensor is only a very small part of the problem that are these ETBs.

2. I have a full gamut of specialist test equipment that means I can test a throttle body on the bench before it ever gets put on a car, or is even fully assembled. This means that all the settings can be put into the acceptable ranges before the throttle body even sees a car. Obviously, I also road test every throttle body for a good distance just to confirm that the bench settings are as correct in practice as they look in theory.

3. Because of the above, I have an extremely low failure rate (<2%) of ETBs that don't have fundamental problems that render them irreparable. The tiny number I have had to fix under warranty have come back to me with different settings than when they went out and I can only assume that they received a rough time when being shipped and something moved. So, it does happen. I have had to fix many, many, more ETBs that have suffered attempted repairs by others, than I have ever had to revisit my own.

4. In a small number of cases the ETB needs to be set up on the car it's going to be fitted to with a SD2 diagnostic machine. I am always happy to do this at no cost if you've bought an ETB from me. There is no magic bodge to get around this - so no unplugging the battery, no turning the ignition on and staring at the throttle pedal for 90 seconds, and no sacrificing a chicken, nothing else will work. It needs to be a SD2. There is no substitute for the real thing.

5. If someone does have a problem with their car, I am always happy to try and solve the problem and often go to huge lengths to do so. As far as I know, I am the only ETB rebuilder who also fixes Maserati 3200GTs for a living, so I see a huge number of problems. Many of which manifest themselves as DBW issues, but are not. You would not believe what I have seen, or some of the surreal problems and solutions. However, because of my tiny failure rate, Occam's razor says that it is likely to be something else and I'd like to make sure that absolutely every other avenue has been explored before I waste a lot of time and money testing a perfectly good ETB. Although, I am ultimately always happy to test an ETB - particularly if that ETB is attached to the car it's going to live on. Sometimes, these problems can only be resolved when all the parts of the system are available for testing.

Mike Roberts
The Maserati Shed

 

[Contigo]

And don't send Mike someone else's TB (ie one which has previously been worked on ) as 9 times out of 10 he won't repair it.

 

[boomerang]

Units, worked on by other people, very often seem to be non repairable, mostly because the internal electronic module suffered from "the work".
In the last month, we received three units with OPENED MODULES!
One of them, even had new transistors mounted on the circuitboard...i have never seen something like this before.
The unit was worthless.

Have to agree with Mike; there are plenty of faults that seem to piont at the TB, but in some cases, something totally different is wrong.
We also test the units on the bench, checking throttle response and opening angles, adding simulated hot conditions by heating the unit during the testcycles lately.
We had a few units in the past year, that went down in hot conditions, due to a faulty electronic module when hot.