Hello Guys,

I'm looking for a bit of info / suggestions to pass to a garage / diagnostics company so they can make some progress with my problem.

The car : 1997 registered VT (although manufactured in 1995).

Symptoms (which have been on-going for a year now) :

* When driving slowly with low throttle pressure car hesitates and jerks.
* Upon startup car runs at appx. 2000 RPM - Stays at 2000 RPM for around 8 minutes and then slowly lowers to 1300 RPM
* Lots of popping and banging from exhaust on over-run
* When starting from cold only one pipe emits white fumes, after 10 seconds other pipe joins-in an emits white fumes too. When hot (3 mins) there is no colour to the fumes.

Points to note :

There are no current error messages on the dash.
Car performs 100% perfectly when 'aggressively' driven - ie. pressing throttle further down.

What's been changed :

* New distributor cap + rotor arm
* New plugs
* 2 x New O2 sensors on exhaust
* 2 x New timing / speed sensors

What's been tested :

A local (respected) diagnostics company tested the car whilst driving and whilst stationary. He ruled the electrics out and said it was a fuel related problem. As it stood a couple of weeks ago he advised initially I run some injector cleaner through it - done this - no change. I'm therefore in search of ideas to throw at them on my next visit.

I've spent a good couple of hours searching this forum today for fuel related Diablo issues, all the posts that show similar symptoms refer to the following collection of parts / problems :

* Fuel pressure regulator
* Idle valve
* Throtle valve
* Fuel filters
* Map Sensor
* TPS
* Mis-Synced throttle bodies
* Vacuum Leak
* Fuel Pump

Without ordering this lot from Lamborghini (a scary thought !) - Has anyone experienced a similar problem and can advise on their resolution ?

Any replies much appreciated

Dave

I would check the throttle bodies are working together first. If they're out, it can cause the symptoms you describe, ie hesitation, but not so bad when you drive aggressively. It would also cause the surging.

Just seen you're in the UK, have you thought about sending it down to Carrera Sport ? They know these cars better than most.

Hi Mike,

Cheers for the tip, i'll mention that to the garage. Carrera Sport - Mine was serviced there in the past (previous owner) but it's so damn far away from me. Last time it had the gearbox repaired it went to a place beginning with 'V' in London (i'm sure some of the UK lot know where i mean) ... took them 2 months to sort so I try to use local places now so i can keep an eye on progress.

Dave

I am not sure if this will help because you are experiencing this problem for a while now, I had this problem once and it was traced to moisture in the distributor cap.
You changed the plugs did this happen after changing the plugs? The reason I ask if the plug gap is not accurate it might cause what you have mentioned.
Regarding the fumes I believe it is related to the TPS maybe it needs to be set again .

Hope this might give you some pointers .

With the cost of parts, and mistakes, on one of these cars, I wouldn't mess about with someone that does not have good experience.

Just my opinion, but I would put it on a transporter down to Carrera Sport and look forwards to the drive back, with it running properly.

Whatever, hope you can get it sorted soon.

Dear Lamborghinisti,

If it a MY97 or even a manufactured 95, it shouldn't have a distributer cap. It should have 3 coil units on each side of the engine bay.

What do you see?


Shamile

__________________
Freeze....Miami Vice !

97.5 Lamborghini Diablo VT Roadster
91 Ferrari Testarossa

A Diablo is like a hot tall thin blonde. Sooo seductive, you just keep putting up with her crap. Buying her high-heels or headers, you know she costs you a fortune. But riding her....oh soooo good!

In your cars VIN, what is the digit that preceeds the sequence LA12?

In a general sense, these two symptoms are normal. The "white fumes" are probably condensation - normal to do exactly what you say. The starting at 2000 revs and going to 1300 is sort of normal since the car runs a start sequence along these lines. Although the 8 mins should be much shorter and the revs should not be quiet that high. The fact that the car ends up idling high (should be around 1050) is an indication that all parts of the FI system are not adjusted properly - at the very least.

As you wrote, the TPS is but one suspect for your "low throttle pressure car hesitates and jerks" symptom. Turning the car off and unplugging its connector will allow you to use a meter to measure its resistance as it moves. The resistance should change PERFECTLY smoothly in unison with movement and without any flat spots paying close attention to the idle end. The problem is that changing this and other parts really needs access to the LDAS software to get things re-adjusted properly.

-mick

Guys,

Thank you for all you're replies, much appreciated. I've pointed this thread towards the diagnostics company and am awaiting a reply on how they think I should proceed.

Regards
Dave

Guys,

What should the fuel pressure be on my car ?

I've read my workshop manual (for a 1994 VT) - it states :

Depression applied = 200mmHg > Pressure (BAR) = 2.3 (+/- 0.2)
Depression applied = 400mmHg > Pressure (BAR) = 2.0 (+/- 0.2)
Depression applied = 600mmHg > Pressure (BAR) = 1.8 (+/- 0.2)

I've read another post on this forum - it mentions :

Fuel Control Pressure should range from 2.6-2.8 bars cold to 3.2-3.4 bars warm
25th Ann loses power

I'm therefore confused as figures do not tally - If anyone knows what the correct fuel pressure for my car should be please advise.

Also, I can't for the life of me see a 'carter motor' on my car, perhaps mine didn't have one fitted - Can anyone verify that a 1995 manufactured VT didn't have a carter motor ?

In reply to a previous post my VIN is : Z49DEO7AOSLA12347 - Full details of discovering my car is 2 years older than 1st registered in the UK are shown in this thread :
http://www.lambopower.com/forum/inde...howtopic=26231

Dave

The S for the year digit in the VIN makes your car a MY95. This is very important as MY96 saw major changes. Things like registration dates are irrelevant from a servicing point of view. What is the actual manufacture/build date? Some changes occured during the later part of MY95.

The carter motor is under the fuel rail nearer the firewall end of the engine. It is the device that runs the cars revs through the start sequence by operating the throttle linkages. Its movement is controlled by the LIEs. Since your description of the start sequence is correct, the carter motor sounds fine.

-mick