StratfordShark

I've always had a problem with warm starts. I suspect leaky injectors as plugs in at least 4 cylinders smell of fuel, and I've changed the check valve at the fuel pump. No fuel in the vac lines to the fuel pressure regulator or damper under the air box.

Cold starts were never a problem - would fire virtually instantly.

However recently I discovered after an emissions test that the mixture was far too rich. It's now in spec (1% CO) after I adjusted the CO pot above the CE (that's where it lives on non-Cat S4s).

Now here's the thing. It's now hard to start when cold. It will always start if I give it a blip of throttle, or if I bump the starter a couple of times to build fuel pressure and then crank.

I changed all the plugs as old ones had got sooty with the rich mixture, but behaviour is the same.

Any ideas on why having correct mixture set would cause this, and does it help diagnose the hot start problem?

Thanks

jpitman2

Temp Sensor II ? Check its resistance cold - should be ~3k IIRC, going down to ~300 hot. If it meters ok, check that its connections to ECU are good.
jp 83 Euro S AT 50k

IcemanG17

Odd.....the temp sensors failure or default mode is infinite resitance...which tends to mirror a cold start feature.....so when the sensor fails the the car is hot it is hard to start since the computer sends a full rich "Cold" start all the time.....

Fixing the check valve & its harder to start cold.....that is really odd....it starts "if" you give it throttle or build up fuel pressure...which again seems to be a more typical hot start? Very odd....maybe some of the inputs to the EZK-LH are slow to react....time to break out the multi testor and pull the EZK-LH plugs and start testing! Rich Andrade has a great 9 page not start diagnosis that help me alot determining my bad fuel pump a while back!

StratfordShark

Thanks for suggestions. I checked Temp II last week and resistance correct over range of temps. Checked at the sensor though so didn't directly check wiring to LH, but JDS Spanner reported no Temp II problems.

Tonight I noticed I'd left door light in 'on' position! Hadn't looked at car at night for several days. May have been like this for days or I may have knocked it during a trip today. If it's been like this for a few days (and I've driven car most days so battery may have held up without draining completely) then I may just have been starting with sub-par battery which explains cold starts. Will investigate further and thanks for the tip about Rich Andrade's article!

IcemanG17

A weak battery shouldn't cause the problem...once it gets below starting voltage it switches over to the click-click-click anyway?