AirtekHVAC

Good work guy! I also found replacing the injectors easy....and mine had been installed for a looooooong time. I also did the Mercedes ones....they were cheap, and shiny!

Guy

Managed about 25 miles on the new injectors and tons of starts under a variety of conditions. Car drives totally different. Revs smoother and drives nicely especially at higher RPMs.

Cold starts take a bit longer but not terrible. Idles very smooth when cold

Warm starts are easier but still not right. Has a little rough warm idle and takes a while to start. Usually starts then stalls. Seems like this is the often complained about "CIS vapor lock" due to residual pressure loss. Problem is that pump (w/internal check valve) and accumulator are new. FD is rebuilt as well so I need to break out the fuel pressure gauges and get some new readings. This is still an improvement over the old injectors which made the car IMPOSSIBLE to start when warm.

I think I am running a little rich and need to lean out which may smooth out the warm idle. I am not going to worry about the settings until I can figure out the rest pressure loss (assuming that I have a problem)

Will likely post some readings within the next week.

linderpat

great progress Guy. This car is really comming alive! Will you be able to bring it to Hershey in April? Would love to see it.

Guy

Thank you! I am certain it would make the trip well and look positively scary doing it! I want to get a few more things tackled and I am not sure time will allow it! We shall see!

Guy

CIS testing

Cold control pressure 55
System pressure 77

Warm control pressure 70 (engine at 110 degrees)


Ambient is 60 degrees

Rest pressure starts at 42 down to zero in 5 minutes.

Jadz928

http://928classics.com/4/post/2014/0...ide-78-79.html

Check this and get back to us with your thoughts.

Guy

Will do, thanks! Checking rest pressure now with the gauge valve closed . Not surprisingly, no loss in rest pressure yet and I am 15 minutes into it. I believe that would eliminate the accumulator and check valve as culprits for the rest pressure loss.

Jadz928

Me comfoosed. So are you still experiencing rest pressure loss?

Guy

With the valve on the gauge open (WUR in play), yes, it quickly loses pressure in 5 minutes.

With valve on gauge closed (isolating WUR and everything after it). It kept 35lbs for 20 minutes but then lost it all immediately afterward

Jadz928

I'm still learning too, but that reads okay to me. Someone more knowledgeable please correct me if I'm wrong.

Leakdown in-spec on system pressure is what keep blood flowing to the injectors.

______

Your cold & warm control pressure are way high. Use an IR temp gauge to check temp at the WUR for accurate ambient spec. If WUR is warm, you will need to remove bimetallic from WUR or wait 'til 'cold' again. Start with cold spec.

Guy

Agreed. I used the IR and found the WUR to be 68 degrees when doing the cold test and 110 when doing the warm. I think the WUR may be causing multiple problems. I have had it apart multiple times.

Jadz928

May just need to drive down the pin with the gauge hooked up, while cold (or heatstrip removed).

Guy

Yes. That may be whats needed. I am going to disassemble and clean again just to be sure. It actually makes sense. My symptoms seem to match a high control pressure and my spark plugs show signs of a lean mixture. If it runs this good the way it is, can't wait to drive it when it is all sorted out

Guy

Here is a little lesson worthy of posting.

We stress CLEAN CLEAN CLEAN with CIS systems. That should include our GAUGE sets! Last time I used this set, car was all gummed up from bad fuel. I never flushed it......so I filled my WUR screen up on first use (from debris in the gauge set) which explains why the car ran so good with such high pressure readings. A quick clean of the WUR screen dropped cold control pressure to 45 psi. I am still going to tear into the WUR but at least its a bit more realistic. AND that is with only a quickie clean

Didn't do warm testing, too nasty out to move the car out of the garage.

Jadz928

Thanks for the update.

You can do warm testing using just the WUR heating element. No need to run the engine, just plug in 2-pin conn on WUR, then turn key to acc.