928 S4 starting trouble
10-16-2007, 08:12 PM
#16
Paal, sorry to hear about your troubles.
I also had starting troubles early on with my car, with the engine cutting out again after starting. If this happened a couple of times in a row, it typically wouldn't start again (cranking, but not firing).
One time I tried a trick I read about elsewhere: pull a plug and if it's wet do the following:
1. Remove fuel pump relay.
2. Press accelerator fully.
3. Turn key to start.
Car should then start briefly and then die, after which you replace the fuel pump relay and it should start normally.
In my case, I couldn't pull a plug, but suspected it was 'drowned' after a few starting attempts. Tried the rest of the procedure and it worked exactly as described. Started with a roar for ½ a second and then died, after which it started normally again when I put the relay back in.
Just something that might get you going again if you find yourself stranded somewhere with a possibly drowned engine.
Only a novice myself of course, so if anyone thinks there's any danger in following the above procedure, then please say so!
Hope you get the problems solved soon so you can concentrate on enjoying the car
Cheers,
Erling
I also had starting troubles early on with my car, with the engine cutting out again after starting. If this happened a couple of times in a row, it typically wouldn't start again (cranking, but not firing).
One time I tried a trick I read about elsewhere: pull a plug and if it's wet do the following:
1. Remove fuel pump relay.
2. Press accelerator fully.
3. Turn key to start.
Car should then start briefly and then die, after which you replace the fuel pump relay and it should start normally.
In my case, I couldn't pull a plug, but suspected it was 'drowned' after a few starting attempts. Tried the rest of the procedure and it worked exactly as described. Started with a roar for ½ a second and then died, after which it started normally again when I put the relay back in.
Just something that might get you going again if you find yourself stranded somewhere with a possibly drowned engine.
Only a novice myself of course, so if anyone thinks there's any danger in following the above procedure, then please say so!
Hope you get the problems solved soon so you can concentrate on enjoying the car
Cheers,
Erling
10-17-2007, 03:07 AM
#17
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Thread Starter
hej Erling, and thanks for the advice. good to know there might be a trick if i am stranded. But i seem to have found the temporary solution to always get it starting(if i dont forget it the first time, that is) by holding the gas pedal a bit in and then cranking. then it fires straight up. I guess something is wrong somewhere since i have to do this, will get a diagnose on it and see if anything shows there.
When i cold start the car, it runs at high idle(1200rmp) for app 20 mins(with 20-50l/100km on the fuel usage). Then it suddenly drops to normal idle and fuel consumtion is how it shoud be.
Is this normal?
If not, might the WD40 trick help this?
When i cold start the car, it runs at high idle(1200rmp) for app 20 mins(with 20-50l/100km on the fuel usage). Then it suddenly drops to normal idle and fuel consumtion is how it shoud be.
Is this normal?
If not, might the WD40 trick help this?
Last edited by paalw; 10-17-2007 at 03:57 AM.
10-17-2007, 03:50 AM
#18
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10-17-2007, 04:19 AM
#19
Hi Paal,
I haven't seen the cold start behaviour you describe in my own car, but then I've only had it since late June this year, so temperatures haven't been really low here yet.
What are the temperatures like at the moment at your location in Norway ?
Hopefully others can chime in and tell if it's normal cold-weather behaviour - IF it is cold where you are.
Cheers,
Erling
I haven't seen the cold start behaviour you describe in my own car, but then I've only had it since late June this year, so temperatures haven't been really low here yet.
What are the temperatures like at the moment at your location in Norway ?
Hopefully others can chime in and tell if it's normal cold-weather behaviour - IF it is cold where you are.
Cheers,
Erling
10-17-2007, 04:37 AM
#20
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Thread Starter
this morning it was about 5 degrees celsius. Went 20 mins for it to suddenly jump down to normal idle and fuel consumption.
An example of mine: Cold start, after 15 mins, water 80 degrees(idle 1100rpm). If i drive it up to 80kmh and release the throttle it shows 18.5l/100km when released and will not drop. After the idle suddenly drops at around 20minutes(to 750-800rpm) , if i do the same it shows 0.0l/100km and gradually starts to rise slowly when i go down to 70-60kmh(ex 5.5l/100km), which is like it should be i guess.
Erling, how is your car behaving at cold start? is the idle under 1000rpm right after you start it? or does it go gradually down after a while? is the fuel consumtion showing crazy usage(on normal driving 20-60L/100km) the first minutes?
An example of mine: Cold start, after 15 mins, water 80 degrees(idle 1100rpm). If i drive it up to 80kmh and release the throttle it shows 18.5l/100km when released and will not drop. After the idle suddenly drops at around 20minutes(to 750-800rpm) , if i do the same it shows 0.0l/100km and gradually starts to rise slowly when i go down to 70-60kmh(ex 5.5l/100km), which is like it should be i guess.
Erling, how is your car behaving at cold start? is the idle under 1000rpm right after you start it? or does it go gradually down after a while? is the fuel consumtion showing crazy usage(on normal driving 20-60L/100km) the first minutes?
10-17-2007, 06:24 AM
#21
Hi again Paal,
The lowest temp I've started mine in so far has been in the 5-10 deg interval, and I didn't notice anything different from starting at higher temps.
After having my Idle Speed Valve replaced, it goes a little higher right at the moment of starting; around 1200rpm, but it immediately drops down to 900-1000 rpm, which is its normal level. (Maybe GT idles a little higher than S4 ?)
Fuel consumption displayed varies enormously, depending on whether I'm accelerating, coasting or engine braking. I can only remember seeing the crazy high values when accelerating though; not when just idling or engine braking after a cold start. Will check just to make sure next time I drive it, but it won't be until Friday morning at the earliest.
Cheers,
Erling
The lowest temp I've started mine in so far has been in the 5-10 deg interval, and I didn't notice anything different from starting at higher temps.
After having my Idle Speed Valve replaced, it goes a little higher right at the moment of starting; around 1200rpm, but it immediately drops down to 900-1000 rpm, which is its normal level. (Maybe GT idles a little higher than S4 ?)
Fuel consumption displayed varies enormously, depending on whether I'm accelerating, coasting or engine braking. I can only remember seeing the crazy high values when accelerating though; not when just idling or engine braking after a cold start. Will check just to make sure next time I drive it, but it won't be until Friday morning at the earliest.
Cheers,
Erling
12-14-2007, 11:24 PM
#22
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I have a '79 928 that is hard to start cold, otherwise it runs fine.
Looking at the wiring diagram for the '79 the power to the cold start valve is connected to the wire that goes to the starter solenoid. T14, #14, that would indicate the cold start valve would only squirt fuel when the engine is cranking and the temp switch makes the ground connection, which it does.
My aux. air valve is fine, open when cold and closes when it warms up.
No power to the cold start valve even when cranking, will track that down, probably at the 14 pin connector T14.
My question is:
Does the cold start valve only squirt fuel while the engine is cranking, seems like it should until the temp switch warms up and breaks the connection to ground??
With the aux. air valve open this would lean it further or is there something other than the cold start valve to compensate for the extra air?
Looking at the wiring diagram for the '79 the power to the cold start valve is connected to the wire that goes to the starter solenoid. T14, #14, that would indicate the cold start valve would only squirt fuel when the engine is cranking and the temp switch makes the ground connection, which it does.
My aux. air valve is fine, open when cold and closes when it warms up.
No power to the cold start valve even when cranking, will track that down, probably at the 14 pin connector T14.
My question is:
Does the cold start valve only squirt fuel while the engine is cranking, seems like it should until the temp switch warms up and breaks the connection to ground??
With the aux. air valve open this would lean it further or is there something other than the cold start valve to compensate for the extra air?
12-15-2007, 03:44 AM
#23
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Paal,
First hello to Norway and welcome to Rennlist, all you guys have good taste when buying cars (I know from my own experience)
When the car refuses to start, try the following:
Disconnect the battery remove the air filter box and unplug the MAF. Connect the battery and try again. The car is now in limp home mode and if it starts fine, I would recommend to get a rebuilt MAF from John.
There should be no need to depress the accellerator when starting, regardless of engine temperatrue or how long it ran.
Is the area around the LH and EZK ECU dry after washing the car? Take a close look for old water stains...
Paal,
Just read your last post. Whith the engine off do your hear a quiet klick when you release the throttle (hood open). This is the throttle switch that activates the ISV.
First hello to Norway and welcome to Rennlist, all you guys have good taste when buying cars
(I know from my own experience)When the car refuses to start, try the following:
Disconnect the battery remove the air filter box and unplug the MAF. Connect the battery and try again. The car is now in limp home mode and if it starts fine, I would recommend to get a rebuilt MAF from John.
There should be no need to depress the accellerator when starting, regardless of engine temperatrue or how long it ran.
Is the area around the LH and EZK ECU dry after washing the car? Take a close look for old water stains...
Paal,
Just read your last post. Whith the engine off do your hear a quiet klick when you release the throttle (hood open). This is the throttle switch that activates the ISV.
