07-23-2007, 09:20 AM
ok so ive had a hard starting problem for a while. sometimes it takes 2 or three cranks to get the car started and when it does it sputters up and finally runs at full power after revving it. i thought it was a badly worn distributor, so i replaced all plugs and wires, cap and rotor and the air filter for good measure.
the problem persists. could this be related to my oil problems (<a href="http://forums.audiworld.com/4000/msgs/135269.phtml">see thread here</a>) or could this be something with fuel filters as previously suggested? please help
07-23-2007, 12:29 PM
If I understand correctly, I think I have the same issue. After reading a bunch of related posts here on the forum and a few other places, Im fairly certain it has something to do with he cold-start valve being sticky. I havent tackled mine yet, but it seems to make sense.
Let one of the experts confirm this though, as Ive been wrong once before ;)
07-23-2007, 03:04 PM
It didnt make sense to me that it would be the CSV, but here is my reasoning. The CSV only sprays when the car is attempting to start and gets its signal from a coolant sensor at the rear of the head. Now if the ambient temperature outside was 90 degrees the CSV shouldnt spray (correct?). At least thats how I interpret it. Even though the coolant may be cooler than the air, it still wouldnt make sense that the CSV would spray when the temperatures are above a certain temp.
Again, this is my reasoning only and could potentially be false.
07-23-2007, 06:28 PM
FIrst, read the link below.
Cold Start Injector:
Mike is pretty well right..
Cold start injector only sprays fuel WHEN CRANKING, and only then when fairly cold out, and even then, only for a few cranks. After that, or when it's warm out, no more cold start Injector in the picture when starting.
Life *will* go on without it working. For example, it probably won't work if you have really crusty wires at the starter. My friend's 4k starter doesn't even HAVE the terminal on it for the cold start injector, as the starter is from a turbo motor. He doesn't know this, as his 4kq starts ok.
CS injector Does the same thing as pumping the pedal before starting on a carbed motor. LOads up the system with fuel, but WHILE CRANKING ONLY, and only when cold out.
Coolant Temp Sensor:
Richens the mixture when the motor is cold, and gradually leans the mixture out to normal over time ( a few minutes), as the motor warms up.
Fairly important for the first few minutes of running. WAY more important then the cold start injector.
Same idea as the choke (that you gradually push in as the motor warms up) on a carbed motor.
See the difference? Kind of related, but not the same thing.
So.. Crappy starting, but ok when warmed up a bit? Could be many things, but easy to check the coolant temp sensor.
A high resistance value of the sensor makes the ecu think the motor is cold.
To fake that out, just disconnect the coolant temp sensor. THat'll make a pretty high resistance! ECU will then set mixture quite rich.
So, try pulling off the coolant temp sensor connector. TOp rad hose, head end on the metal hose fitting. COnnector with the metal clip, usually on the bottom on the metal housing.
Then try starting the motor. If it starts better with the connector off, then good chance coolant temp sensor is bad.
Once it's started, let it run for a bit, then put on the connector before the motor runs too long. (Same idea as pushing in the choke knob. If you leve the connector off, the ECU will never know the motor is warm)
Coolant temp sensor can fail the other way too, in that it's always a high resistance. In that case, the motor will start well, but run like crap and use lots of gas when warm. (Acting like the chok knob is never getting pushed in as the motor warms up!)
Test for that by shorting the two pins in the coolant temp sensor connector together. Low resistance sensor (short across the sensor connector pins)= ECU thinks Warm motor
Hopefully, this all makes sense..?<ul><li><a href="http://forums.audiworld.com/4000/msgs/135230.phtml">cold start vs Coolant temp sensor</a></li></ul>
07-24-2007, 06:36 AM
I feel like I'm almost 'preaching' sometimes.
I don't really know if what I write helps anyone or not?
I'm thinking I should do a real good writeup (with pictures), and just put it up permananently.
That, and explain some troubleshooting 'techniques', so we don't just go around guessing what's wrong.. :-)
07-24-2007, 05:25 PM
and yes what you write always inspires if it doesent already help.
frank the guru