jonnyoutram

hi, i have a 1984 500sec, just wondering what causes black smoke when u rev the engine hard??

i am assuming its over fueling... (££££$$$$$)

are there any sensors that can cause problems like this??

if so how do i diagnose them and where are they??

thanks for any input


cheers

Untertürkheim

We need more information, like the service history of the car or any other symptoms. Also, does this happen when the engine is hot and driving, a load factor, or above a certain RPM? The more information the better.

Could be injectors, and air filter, CO adjustment (rare) O2 sensor, or carbon burnoff.

jonnyoutram

thanks for helping out, the car has had:


new:

injectors
plugs
ht leads
dizzy cap
rotor arm
air filter
oil&filter

the car has done about 130,000 miles

i have had the co adjustment done


it uses too much fuel we think

it only makes the black smoke when revved hard both under load and when in neutral

no differance when its hot or cold!

the throttle body has been cleaned out with lots of carb spray

could it be a problem with the fuel distributor thing??

it does only seem to make the puff of black smoke at hi rpm

i hope its an easy fix .... spent too much on this car already

thank you

Untertürkheim

The cheapest and easiest solution would be an old O2 sensor that is not responsing fast enough.

nsmith17044

I would start with the O2 sensor since they are cheap but sometimes a real bugger to loosen and change out.

The 84/85 SEC uses the M117 with a warm up compensator that also performs acceleration enrichment at lower temperatures. If the compensator or temp sensor is faulty it could lead to this type of symptom. I would recommend having someone with a Bosch fuel pressure gauge set hook up and run through the diagnostics. I would also recommend checking the vacuum systems temperature sensors if you have not done so already. Since the whole system works on pressure and pressure changes you can end up throwing a lot of money at the problem and not solve it. Sometimes the fixes are cheap but notoriously difficult to find.

Good luck.

Untertürkheim

Of course, the temperature compensator, I should know, mine was bad too (along with my fuel distributor and EHA due to ethanol in CA fuel). Although, would the warm-up regulator only cause black smoke at high rpm, would the engine not always run rich?

jonnyoutram

anyone? any more ideas what i should check and how i find the o2 sensor or temp sensor etc? its getting embarising covering the road behind me with a black cloud when i put my foot down ha ha

i have just read up on peoples past threads and found that
these can be a problem, the cold start injector, EHA and KE control unit (FI systems brain)...


how do i test them and where can i find them?

thanks

this car makes me feel like this...