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Discussion Starter #1
My 25th loses power on acceleration in every gear. Once I let off the gas to shift down, up, brake, whatever; the car doesn't die. It backfires and then comes back to life. It happens in every gear, and always comes right back after backfiring.

I am thinking the fuel filter, fuel pump, or maybe even the timing.

Starting with the fuel filter tomorrow. The onto the other stuff. Anyone else have any ideas.

thanks in advance,

Greg

Just wanted to say the new sight looks great
 

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Looses power can be a very ambiguous staement. Are you sure it has an power besides the ability to start & run?

I would fiest check the exhaust gas nembers for CO & HC's. And have a look at the Inside of the Distrib Cap (& clean if necc.) and then with an Inductive Pick-up Tool check all Plug Wires for firing...then get readi to pull & check the plugs. Afyer that you will need to check the Fuel Pressures on both banks. I'll tell you right now, without an Exhaust Analyzer to point you in the right direction it can be a long hard road.
 

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JRV:
What is the best cleaner for a distributer cap? Also, what have you found to be the best method for cleaning the contacts inside of the cap?

Steve
 

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Hi Steve,

You can use either Contact Cleaner or Brake Clean...niether leave a residue. Wipe with a clean cloth. I use a jewlers flat file to gently clean the contacts until the corrosion from arching is removed sufficiently to provide a reasoble contact area.
 

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Discussion Starter #6
I will check those items. About the losing power, it runs fine down the interstate, or through town; as long as I don't try to heavily accelerate. under heavy acceleration between 3500 and 4000RPM, it totally loses power. The gas pedal does nothing, acts like the car is dead. I push in the clutch, the car drops back to around 1500RPM's and backfires. Then it is fine and will accelerate again. This is in every gear. Doesn't seem like a misfiring, as I can take the tach up a lot further, as long as i am gradually getting there. This is why I am thinking the fuel system.

This is basically on mid to high range acceleration.

What should the correct fuel pressure be?

Thanks,

Greg
 

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Hi Greg,

these types problems are hard to second guess over the internet. :(

Make sure the Frequency Valves are working..they Hummmm, and can be easily listened to with a mechanics stethescope.

Fuel Control Pressure should range from 2.6-2.8 bars Cold to 3.2-3.4 bars warm .

You might want to have a look at the Lambda Control Circuit Board in the right rear corner to see if when cold the two led lights blink. This is an indication of whether or not the 02 sensors are on line & working. And make sure the Timing Retard Relay in the front trunk left upper corner is in good condition.
 

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Sometimes the rev limiter goes mad and cuts off the engine, unmount the ignition box and clean all connections between the big box and the two bolt on units.
Mine ran a lot better afterwards, but for real power install an MSD-Unit...

Of course the things that John mentioned have to be checked too!

Raymond
 

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raymond said:
Sometimes the rev limiter goes mad and cuts off the engine, unmount the ignition box and clean all connections between the big box and the two bolt on units.
Mine ran a lot better afterwards, but for real power install an MSD-Unit...

Of course the things that John mentioned have to be checked too!

Raymond
yes the Marrelli Digiplex could certianly be the culprit. I also have seen the rev limiters go haywire and shut off the fuel pumps at wrong RPMs
 

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What do you guys think about a partially clogged fule line filter. Have seen something like this in a Lexus. Also a failing fuel pump will do this. When you accelerate there is an immediate need for fuel. The pump must deliver, the line must be clear.
 

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John,

it could be something like that. Really, not enough info has been provided such as Exhaust Gas numbers or Fuel Pressure numbers to make more of an educated guess. I had a Countach guy lose power suddenly not that long ago, the engine idled perfectly, but when he tried to drive, simply way way down on power. He limped in to the shop.....popped the hood, reconnected left bank throttle rod that had popped off and Wallaaa...instant power gain back to normal....:)
 

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Discussion Starter #12
have checked fuel pressure and exhaust gases, everything appears normal in those areas. I have been checking on the electronics, and have had the car running normal a few times.

I am currently thinking a bad connection or a bad relay for the timing retard relay, but could be one of the other items.

After pulling relay box and re-seating the relays, the car ran fine for a day. This may or may not be related to the real problem. I know we had checked the ignition box as well, and may have slightly shifted it. Not real sure. I will be back on this thing sometime this weekend.

Thanks again for all the help to date.

Greg
 

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How is your car running now?
Mine had some connection problems between the ignition box bottom and the two boxes above screwed on the lower part, one is the rev limiter and the other I suppose a voltage converter.
 

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Discussion Starter #14
Msd

It appears to have been the ignition box. I am planning on changing to an MSD ignition, so do I have to have the 7AL-2 ignition modified for a V-12, or is it acceptable the way it is. I have heard it both ways. Would like to do it right. If it has to be modified, what modification is necessary. Also, which coil would everyone recommend, and any wiring specifics would be helpful.

Thanks
Greg
 
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