after a long sit my 1.7 blows black smoke

DocWheeler · Post by **DocWheeler** » Thu May 23, 2002 10:43 am

'73 914 1.7 W/d-JET after a long 6-8mo.
sit is now alive in my '67 Porsche 912!

It idles and runs smooth with no obvious
evil noises, but is pumping out some very
stinky exhaust<G>

The engine has a California History..
bought from running car in a quick trade,
but zero history.

Is rich black smoke residual California
gas being bruned off, or is this strong
black smoke indicateing rich mixture with
the D-jet or some critical yet un-connected part?

WWUDO?

Doc

Dave_Darling · Post by **Dave_Darling** » Thu May 23, 2002 12:25 pm

Probably a filthy-stinking-rich mixture.

Step 1: Check the ignition system thoroughly. All of it.

Step 2: Valve adjust and compression check.

Step 3: Verify hose condition and routing. Make sure the wires are all plugged in correctly. Check fuel pressure--should be 29 PSI.

Step 4: Verify part number for the MPS. (I once tried a Type III MPS that caused my 914 to blow black smoke.)

Step 5: Check condition of FI parts. In particular, the MPS may not hold a vacuum. Or the head temp sensor may have very high resistance. Or there could be some other cause.

--DD

------------------
1974 VW-Porsche 914 2.0 (Type IV powered!)

Pelican Parts' 914 Tech Geek http://www.pelicanparts.com

Switchblade · Post by **Switchblade** » Thu May 23, 2002 7:25 pm

Dave,

First off what is a "MPS"?

Second, could you elaborate on how to check the head sensor??

My 1.7 appears to be running a little rich also, idles high at lowest idle setting, black exhaust pipe, etc...

Dave_Darling · Post by **Dave_Darling** » Fri May 24, 2002 6:52 am

As we discussed in our earlier e-mail, the MPS is the Manifold Pressure Sensor.

Two really great D-jet resources--
http://www.914fan.net/djet.html
http://members.rennlist.com/pbanders

--DD

------------------
1974 VW-Porsche 914 2.0 (Type IV powered!)

Pelican Parts' 914 Tech Geek http://www.pelicanparts.com

ray greenwood · Post by **ray greenwood** » Fri May 24, 2002 11:23 pm

If you are idleing too high at lowest screw position...you have a vacume leak. Most probably a hose, injector seals or manifold boots...and very probably the diaphram in the back of the MPS could be cracked. This will cause black smoke most noticably on start-up...and an over rich condition, because loss of vacume in the MPS signals enrichment at the diaphram. Ray

Post by **Piledriver** » Tue May 28, 2002 8:00 am

Propane torch (unlit) is a safe way to find vacuum leaks, the biggest cause of rich running on that EFI system.

DocWheeler · Post by **DocWheeler** » Fri May 31, 2002 8:54 am

*BINGO!

*Problem solved!!

MPS line was burned off and
there was other vacume issues!

Runs great!

Thanks!
Doc

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Piledriver:
Propane torch (unlit) is a safe way to find vacuum leaks, the biggest cause of rich running on that EFI system.<HR></BLOCKQUOTE>

ray greenwood · Post by **ray greenwood** » Fri May 31, 2002 5:18 pm

Burned off?...I thought piledriver said to use an unlit torch! Hee Hee Ray