Diablo Running hot... Advise please

Hello everyone

 

I've been driving the Diablo a bit, and have had the following issues come up:

 

1) L Engine Light - comes on at stops/low speeds, blinks while accelerating, and goes away at higher speeds... comes back/blinks at lower speeds, etc

 

I tried to get the codes with a scanner, but the light DID NOT come on the two times I drove with a scanner (and charged laptop)... the other 3-4 times, it has done the above, but I have been unable to pull codes as the laptop has had a dead battery!!

 

2) Coolant temp running hot - car shows 95+, OBDII scanner shows 205F (98C-102C) while driving!!

 

Intake air temp sensor shows - 55C-60C

 

Actual outside temp during this drive - 39C

 

Other info noticed in drive (during issue #2)

 

Engine timing advanced 15-20 under normal accelerating/cruising

 

Can anyone point out if I need to be concerned about the car running hot? Should the intake temp be that high (60) when the outside temp is only 39? The coolant temp is also 100 (205F) - is that a cause of concern?

Can anyone explain what the Fuel Trim figures (short term/long term for Bank 1/2) are?

The check engine light flashing is not good. it is telling you that is is running or missing bad enough to do damage to your Catalytic Converter. Long trim fuel numbers is on the high side but I never look for a problem unless they are +10 or -10 (on normal cars) The short trim fuel is used to fine tune the fuel to keep the O2 sensor so they are able to go above and below 450 mill volts. Your car has a problem so the numbers for fuel trim is bound to be off. It sounds like you have a miss. Does the car buck or jerk at all? We really need the codes to see what cylinder is acting up.

The check engine light flashing is not good. it is telling you that is is running or missing bad enough to do damage to your Catalytic Converter. Long trim fuel numbers is on the high side but I never look for a problem unless they are +10 or -10 (on normal cars) The short trim fuel is used to fine tune the fuel to keep the O2 sensor so they are able to go above and below 450 mill volts. Your car has a problem so the numbers for fuel trim is bound to be off. It sounds like you have a miss. Does the car buck or jerk at all? We really need the codes to see what cylinder is acting up.

 

Thanks for the reply. In this instance, the light did not come at all (not once). The pic is at the end of a 30 min drive, during which there was no Engine Light, and the scanner said there are no pending codes/fault codes at all..

 

Also - is the coolant temp a point of concern? Or the intake temp (since the outside temp is only 40, shouldn't the intake be the same, or is it 'normal' for the intake temp to be higher (60 in this case) than the outside air temp)?

 

Thanks!!

Make sure your cooling fans are coming on...easy to overlook. I had a similar problem in my 6.0 and it turned out to be the cooling fan relay. Simple fix. But if that fan isn't coming on, your car will run HOT quick.

205F isn't particularly hot, but I am not sure how cool the Diablos run.

 

the Fuel trims mean the computer is adding or subtracting fuel by that % on the respective bank, in order to achieve the targeted air fuel ratio.

Thanks for the tips guys... will look into the fan next time I take her out for a drive (currently out of country on a trip)..

 

Does the make make an audible noise that can be heard while driving? Or is it something I will need to check when stopped? Also - which fan - drivers side, or pax side?

Thanks!!

The fans do make a noticeable noise when they are on. Either side could be affected since km pretty sure there are relays/fuses for each side.

Can hear fans with window down

first make sure coolant level is full.than let it idle and not drive it to verify fans are working as designed.

Fans will come on at idle? Sorry to sound like such a newbie...

 

Also regarding left vs right fan - I was told one of the fans is for the AC, and the other for the Radiator - is that true/false?

Fans will come on at idle? Sorry to sound like such a newbie...

 

Also regarding left vs right fan - I was told one of the fans is for the AC, and the other for the Radiator - is that true/false?

 

Fans can come on at idle. But it will depend on other factors as well. If its a cold start the fans probably won't kick in for 5-10 minutes. If you've just been driving and the engine is still warm then they will probably come back on as soon as you start up. There are radiators on both sides with a fan for each.

Start car and immediately run A.C. full blast. One fan should kick on immediately. Can't remember which side. Jump each fan with a 12V source and work backwards from there; you'd need a wiring schematic. Of course this assumes, you've found nothing on fluid side (level ok, no leaks etc.)

flashing CEL is usually a misfire.

I believe one fan runs all the time, and the other comes on with the A/C. Can't remember which side is which though.

Flashing CEL usually is a misfire, have you pulled the Thermo Sensor at the radiator for the fans? Any changes?

 

I didn't know one fan was supposed to run all the time?

I just replaced the thermostat on my 6.0. Before the car had a wandering temp gauge. It would go up when at a stop light and back down on the highway. When I took the old thermostat out I put both the old and new in a pot of boiling water. The new Thermostat opened further than the old one. When taken out of the water the old thermostat closed very quickly while the new one took 3X longer to fully close.

 

While letting the car idle to bleed the air out of the coolant I observed the following: The left side fan switches on/off based high side pressure of the AC system. Both fans comes on when the coolant temperature gets to about 85C. They turn off when the temperature drops to about 82C. (Numbers are approximate due to the gauge not being that accurate).

 

The most challenging part of replacing the thermostat as a DIY project is draining the coolant. The drain plugs on the bottom of the radiators are in an awkward location. I've been told usually frozen stuck. I was lucky in that I was able to get the right side plug to turn. You only need to get one plug out to drain the system.