I've been trouble shooting an occasional hard start / rich running condition and after checking the basics (fuel pump check valve, temp sensor) considered that it could be a leaking or faulty cold start valve.

I checked the resistance across the terminal (should be 4 ohms IIRC) and there was none, i.e. 0 ohms which leads me to two questions:

1. Could continuity across the cold start valve indicate that the valve which is basically an extra fuel injector is always "on"? I would have liked to just unbolt the valve, run the car and see if fuel starts flowing from it but it's a pain to get to the nut closest to the block so I'll have to wait for a day when I have more time to mess with it.

2. The 928 is the first car I've had that uses hard fuel lines for everything. I'm sure they last, but they are a total PITA to work around. The cold start valve has a hard fuel line on one side and the hard intake line on the other. Once I get it unbolted is there a trick to removing it or will it just slide out?

Thanks.

 

for starters whats the year of your car??

 

Sorry - US '84 L-Jet 16V.

I read over the hot start problem posted by 90 S-4 and mine is very similar. You had some great tips on checking the FRP / FPD for a leaking diaphragm which I will do as well this weekend.

Basically I beleive the car is getting too rich at start up causing it to occasionally flood. I theorized based on testing the cold start valve that it could be at least part of the problem.

 

Yep, the whole system needs to be right to give you flawless cold/hot starts. Leaky, broken, generally disfunctional cold start valves are common. Your aux air valve is also probably sticky, few squirts of wd40 should fix that. temp/time may also be a culprit. Your fuel pressure could be too high from tired pressure regulator/dampers. The brain sits almost directly underneath the passenger drain system... and can get wet, fouling cold start logic at times as well as plenty of other aspects. Highly recommend a pressure gauge on the end of the pass. fuel rail. You'll get used to the fuel lines, make sure the rubber portions are in good shape, counter-hold all the hard fittings. hth

Mike
84 black
80 white

 

not familiar with the CS valve in your car but presume it is the same as the one in the 944S2 cars

O ohms would indicate that the coil inside the injector has gone open circuit which means the injector solenoid cannot pulse the fuel from the injector.
If its stuck in the open position then you could be getting continuous leaking and an over fueling condition. As the injector solenoids are sprung I would expect it to stick in the default (closed) position not open.

If you cannot remove the CS injector have you tried removing the electrical connector to one of the other injectors and see what happens to the running ?
In an overfueling condition I would expect a slight improvement allbeit rough running.

Worth checking the spark plugs to see if any are showing an overly rich mixture in one particular bore which could indicate one of the main injectors are leaking.

To test any of the injectors you could disconnect the electrical connector and flash the injector terminals using a 9v+ DC battery (PP3 type ) with a couple of short leads attached. You should hear the injector solenoid click as it hits one end of the chamber then returns under spring prssure and hits the other end

 

at the top of the page click on userCP
Then click on edit signature
then enter your car model year auto or stick and any other info like colors or added options .
this will give others an easier way to assist you

 

Thanks for the suggestions. BTW - a quick test for hearing the injector functioning I learned from my Nissan days; With the car running put the tip of a long screwdriver to the top of the injector and ear to the handle. You'll actually hear the injector clicking. Its a quick way to diagnose if an injector is firing (although it won't tell you if a problem is the injector or the signal). Z cars and 240SXs injecotrs were common to fail with infinite resistance rather than continuity - so the CS valve test result was a little unexpected.

It's been interesting to research the common issues on these cars. Mine has actually been extremely reliable over the 18 months I've had it. It's my daily driver but the PO was very thorough in keeping up with all the maintenance and repairs. This is the first real issue I've had to trouble shoot.

I pulled a few of the plugs and they actually looked pretty good, although I didn't pull the back plugs.

I'm sure I can get the CS valve out with some patience over the weekend. I just didn't have time this morning before work to get it out - then all back together in time to drive to the office.

However, since its showing 0 ohms I'll probably just order a new one anyway, but test the FPRs and FPD as well.