1986 951, sat for 3 mo. Starts FINE, new plugs and vacuum lines. BLOWS BLACK SMOKE when you step on gas. PLugs where carbon fouled, black and dry. Any clue?

 

I am new to the 951 as I recently bought one. The people hear were nice enough to point me in the direction of blink codes, also mentioning the TPS, AFS, and the O2 sensors. It ran great but black smoke under hard accel.

Also mentioned was a large vacuum leak or fuel pressure, but my car was pulling good vacuum and the fuel pressure was correct.

Turned out it was the TPS found via the blink codes. After I got the old one off, I opened it up and one track was completely gone.

 

Car starts but then gets rough idle and BLACK SMOKE as it idels and on STOP! (Stomp The OLd Pedel) sorry a little punchy today!

 

P.S. WHAT BLINK CODE?

 

The KLR stores blink codes only while the engine is running. You can pull the codes via the diagnostic connector with an LED.

Since the idle is rich as well, try "back probing" the O2 sensor with a Digital Volt Meter (DVM). Just insert the positive meter probe into the back of the sensor connector at the black wire. Connect the negative meter lead to a good ground, set the meter to read the 2 Volt DC scale, and start the engine. At idle you should see the DVM display cycle across 0.50 volts. Higher is lean, lower is rich.

If the meter reading does not cycle, disconnect the sensor. With the sensor disconnected you should see between 0.6 and 0.7 volts DC. Blip the throttle a couple of times. The reading should go lean and then rich. If the reading is too high, too low, or does not cycle, change the O2 sensor.

 

The search feature is great for newbies trying to find a lot of information that has been re-hashed many many times.

But since you didn't use that, let me give you the 10 cent tour. The black smoke is unburned gas. That's GOOD! With turbo cars there is a split second that the injectors will pour on a lot of gas, before the turbo is spooled up to meet the air requirement for clean burning. You'll even get black smoke in non-turbocharged cars for the same reason. Another reason that you want a rich mixture is that it helps cool the combustion chamber and exhaust, and it prevents pinging or detonation which is a killer (it can burn a hole through the pistons in no time).

Basically, your car is working normally. Depending on which chips you have installed it may be running rich, but it's still in the acceptable range.

Dal.

 

Thats exactly what my car did. Rough start, black smoke under accel and sometimes on start, black dry plugs, 11 mpg, just basically running way too rich. The blink codes gave me a TPS error. It was totally shot. Replaced it and the car is running perfect. No more rough start and no more black smoke or carbon fouled plugs and i am getting normal gas milage.

Just go to Radio Shack and pick up a $1.50 LED and a couple of leads.

Here is the link that was passed on to me.

On the left go to DME fault codes.

http://members.rennlist.com/951_racerx/

 

TPS in this case means throttle position sensor?

 

Yes, one of the resistance tracks was completely gone.

 

Looking at the Vac lines now, some do not look like they go to the correct location. I have secured a diagram and trying to purchase the last volume of the shop manuals

 

I think your car just selected a Pope.

 

No that is WHITE SMOKE

 

True enough...Which means either a new pope or a bad HG...LOL