Cold Start Issue - Video - Page 2

safe · safe's Garage

Btw, WUR modification can be a DIY-job, it's been covered here in the forum before.

Paulporsche · 08-14-2007, 06:31 AM

That's what I meant, 1/16th of a turn each time, since 1 complete turn represents somewhere between 8 and 12% CO.

BTW if you check back you will see that I first recommended using a gauge to check the WUR by getting a cold cp reading.

In place of that, you might get lucky and by merely increasing your CO solve your problem, since these engines can run well within a fairly broad CO range, something like about .5 to 4%.

By trying this mca can tell us if he has any other problems, such as a hunting idle when warm, which would tell us the mix is now too rich.

He can also try a slight tap on the WUR plug to lower the control pressure, but that may not be recommended for someone w/ limited CIS experience.

emac · emac's Garage

Paul

I owe you one-- these 57 yr old eyes are not what they once were !!

fireant911 · 08-14-2007, 06:43 AM

I think that this thread has veered off from the original direction. Mca was experiencing some roughness / dying issues upon starting. Maybe it is related to the WUR, the associated fuel pressures, the fuel mixture, or it could be caused by many other things. There has to be a strategy in attacking this problem rather than haphazardly looking at various potential culprits. There is a thread below that will put you in the right direction for the fuel mixture (read sjeeps procedure - I think that I have also seen this procedure in one of the Bosch Fuel Injection manuals).

Where's my dwell?

Jim Williams · 07:13 PM

Magnus asked a question about what happens when you open the throttle, and you replied that the engine seems to start up and settle into an idle. To me this is a possible clue that there is a problem with the AAV and/or the AAR, both of which should be open as the car is started cold. Opening the throttle has exactly the same effect as the open AAV and AAR, and as a matter of fact, this is the way the pre-'76 cars were started.

Changing out the WUR could end up only costing you money if it's not the problem. The only way to know this is to use a pressure gauge (a lot cheaper than a new WUR).

IMO, a check of the AAV and AAR would be the first order of business. The operation of both of these is explained on my website: http://members.rennlist.com/jimwms/CIS/CIShome.html.

safe · safe's Garage

Quote:

Originally Posted by Jim Williams

Magnus asked a question about what happens when you open the throttle, and you replied that the engine seems to start up and settle into an idle. To me this is a possible clue that there is a problem with the AAV and/or the AAR, both of which should be open as the car is started cold. Opening the throttle has exactly the same effect as the open AAV and AAR, and as a matter of fact, this is the way the pre-'76 cars were started.

My thought too, that is why I asked.

Quote:

Originally Posted by Jim Williams

Changing out the WUR could end up only costing you money if it's not the problem. The only way to know this is to use a pressure gauge (a lot cheaper than a new WUR).

IMO, a check of the AAV and AAR would be the first order of business. The operation of both of these is explained on my website: http://members.rennlist.com/jimwms/CIS/CIShome.html.

I think that trouble shooting injection problems should always start with a fuel pressure check.

Jim Williams · 08-15-2007, 04:39 AM

Quote:

Originally Posted by safe

My thought too, that is why I asked.

I think that trouble shooting injection problems should always start with a fuel pressure check.

Just as a footnote to my earlier post --

I should have added that the systematic approach to troubleshooting any unknown CIS problem should start with a pressure check, as the system functions based on fuel pressures. An even more basic check is to check the delivery from the fuel pump -- As called out on my website ("Troubleshooting" page), and per the factory manual.

Given the symptoms of mca's problem, I had the impression that the warm engine operation seems to be normal, and a likely suspect might be the AAV and/or the AAR. However, I suppose that this is as much a stab-in-the dark as suggesting that the WUR might be the culprit. However, both the AAV and the AAR can be checked without a pressure gauge.

Doing a proper analysis of a CIS problem without a pressure gauge is somewhat like attempting an analysis of an electrical problem without a voltmeter.........

safe · safe's Garage

BTW Jim, your website rocks! I had a lot of help figuring out my CIS problems and identifying the components.

Unfortunately I still have problems that I think come from the fuel distributor (the car floods sometimes on cold starts), but I have a "workaround" that works.

Paulporsche · 05:38 AM

mca,

Let us know what yopu are doing on this.

As Jim W says, the AAR and AAV are possible likely causes. The AAV gives the system a gulp of air right @ startup, and the AAR keeps the revs high during warmup. You can check his site or do a search. There is a lot of info on these components.

BTW please realize that I have no argument against a systematic approach to solving your problem, or any problem for that manner. I'm trying to get things moving for you by suggesting some likely areas to check.

mca · 08-26-2007, 06:54 AM

Thanks for all of the info fellas.

I am trying to obtain a fuel pressure guage as this would be the logical first step and a good tool to have for future issues.

Reading through Bentley, it says to bypass the fuel pump relay with jumper wires. It specifies that the jumper wire should have a 25 amp inline fuse ... is it necessary to have the inline fuse?

rootmatt · 08-26-2007, 05:14 PM

No fuse is "necessary" until something goes wrong. Then you'll be glad it's there. How brave do you feel?

Matt

mca · 08-26-2007, 05:45 PM

Quote:

Originally Posted by rootmatt

How brave do you feel?

very unbrave

safe · safe's Garage

If you have a fuseon the shelf, use it, otherwise there's no need IMHO.
You're only running the pump a maximum of 30 seconds.

mca · 09-09-2007, 02:48 PM

UPDATE:

I finally got a fuel pressure gauge specifically for CIS systems (from JC Whitney as suggested by another Pelican) and a jumper wire with a 25 amp inline fuse.

I attempted to run some cold pressure tests today but I had MAJOR fuel leakage at the distributor line. For the life of me I couldn't eliminate the leak no matter what fittings I used.

The Bentley manual specifically says NOT to wrench tighten the connection to the distributor line ... yet this is where the leak occurs ... am I missing something?

Jim Williams · 09-09-2007, 06:24 PM

mca,

I'm not sure what connection you are referring to as the distributor line. Is this the line from the gauge to the fuel distributor where you have disconnected the line normally connecting the WUR to the center connection of the FD?

I don't have a Bentley manual, but I can't imagine what line they say don't wrench tighten. I don't believe there are any lines in the CIS connecting anything to anything else that could be expected to hold fuel pressure by hand tightening.

Could you be more specific about the connection in case I am just not understanding, and exactly what the Bentley says?

Something is definitely not right here........

safe · safe's Garage

I agree, you need a wrench to tighten it. A fuel leak in the engine bay is scary...

mca · 09-10-2007, 05:35 AM

Correction ... the hand tighten warning comes with the instructions for the gauge.

WARNING: Hand tighten the o'ring end of the adapter into the fuel distributor. DO NOT wrench tighten.

I am disconnecting the fuel line from the center of the fuel distributor ... this is where the gauge is to be connected ... and YES this is the same line that runs to the WUR.

I suppose that if I don't use the adapter with the o'ring then I can wrench tighten ... I just wanted to be sure.

mca · 09-10-2007, 04:33 PM

Ok - got a solid reading of 69 psi this evening.

Now what?

holtjv · 09-10-2007, 06:29 PM

Quote:

Originally Posted by mca

UPDATE:

I finally got a fuel pressure gauge specifically for CIS systems (from JC Whitney as suggested by another Pelican) and a jumper wire with a 25 amp inline fuse.

I attempted to run some cold pressure tests today but I had MAJOR fuel leakage at the distributor line. For the life of me I couldn't eliminate the leak no matter what fittings I used.

The Bentley manual specifically says NOT to wrench tighten the connection to the distributor line ... yet this is where the leak occurs ... am I missing something?

mca--you mind sharing the item #/model for the gauge and jumper? I'm having the same problem and just looked at the price for a new WUR..yikes. thanks, jack

Jim Williams · 09-10-2007, 07:09 PM

The next thing to check is the control pressures of the WUR, first cold and then hot. Then compare them against the pressures listed for your WUR. You can find the nominal pressures listed in the little Porsche spec books for your year model or find them here on my website.

http://members.rennlist.com/jimwms/CIS/wur_specs.html

There is also a guide on using the pressure gauges there. Start at

http://members.rennlist.com/jimwms/CIS/CIShome.html and look under Testing (Fuel pressures).

Hope this helps.