New 928 S4 owner with stalling problems. Need your help and wisdom
10-17-2017, 01:35 PM
#1
New 928 S4 owner with stalling problems. Need your help and wisdom
Just bought a 928s4 auto and drove it 6 hours back home, barely..
Here' how the story goes:
Bought the car on Saturday, noticed slight hesitation at low rpm but did not stall or have any issues idling. Owner 'says' timing belt was changed 40k ago and he resealed the engine this summer.
Came back on Monday to drive it home. When I first started it it stalled, second try I gave it gas and for 5 seconds and then all was good.
I let it warm up for 5 minutes and took off to the nearest parking lot to take some photos. 5 minutes later while I was pulling to the parking it stalled. I started it up, it idled rough but I managed to to park it. Any other attempts it starts and stalls right away without gas. Went on the forums and looked it up. Thrust bearing was what made me worry the most even though When it starts the starter turns the engine fast. Called the owner, he gave me the address to the porsche specialist he dealt with. I managed to get it there by putting it in neutral and keeping it at 1000 rpm while using left foot to brake (first time doing this, seat belts works great!
)
Mechanic had lots of aircooled porsches outside and a 928 gts and seemed very knowledgeable. When I told him about the thrust bearing he said he doesn't think that's the culprit but he put a metal rod inside the check port and didn't notice anything lose (From what I've read this isn't how it's checked at all but ok. Then we removed the oil filter and drained some oil to check for metal shavings and there wasn't any. I kept the oil filter to open it up and check the inside. After that he said that most probably it is running rich caused but the LH unit. He told me it was ok to drive back home 6 hours and that he recommends a rebuild for the unit. He also swapped the Maf from the GTS with no change and also checked the Lh unit connector if it's lose but it wasn't.
On my way back I noticed that it always starts in first and holds the gear till 3000 rpm. Seems that after it notices something is not right while taking off it immediately shifts into first. Shifts are a bit hard. In 3rd or second, 1000-2000 rpm it feels sluggish and engine shakes a bit, 2000-4000 pulls smoothly never drove a 928 s4 before but for 320 hp I think it's lacking a bit of power, 4000-red line all hell breaks loose and engine comes to life.
I noticed that the warning lamp in the center console comes on when I restart it after it stalls, it goes off if I push it.
When I got home I gave it a bath and tried to see if any wires are not connected and I found a couple in the 14 pin connector. I will add photos. I also disconnected one of the connectors on one of the ecu to look for corrosion but found out it is held by a screw so I decided to give up for the day and park it.
After I finished I started it up and guess what..it idles perfectly so I decided to take it for a drive. Drove for about 30 min. 90% of the time ran perfectly, stalled once when I stopped and steered suddenly. Still hesitant under 2000 rpm and still starts in first gear.
I've owned many cars before but I don't have deep pockets, still a student. This replaced a 944 which has been the most reliable of all of them. I would love to keep it for long but I'm really hesitant at this point. After 6 hours drive I would guess if it has been the thrust bearing it would have left me stranded. Another possibility is the timing belt (which is one of the causes the warning light would come on) I also noticed that when looking through the timing cover where the intake tube connects, I can see the belt move side to side about 1-1.5 mm side to side. Is that normal? Can't see how a loose or worn belt can cause these issues though..
I really enjoyed the ride and I think it is the absolute perfect car for me with just enough power, just enough road feel, just enough comfort. On the reliability level I'm not so sure after reading some threads
Here' how the story goes:
Bought the car on Saturday, noticed slight hesitation at low rpm but did not stall or have any issues idling. Owner 'says' timing belt was changed 40k ago and he resealed the engine this summer.
Came back on Monday to drive it home. When I first started it it stalled, second try I gave it gas and for 5 seconds and then all was good.
I let it warm up for 5 minutes and took off to the nearest parking lot to take some photos. 5 minutes later while I was pulling to the parking it stalled. I started it up, it idled rough but I managed to to park it. Any other attempts it starts and stalls right away without gas. Went on the forums and looked it up. Thrust bearing was what made me worry the most even though When it starts the starter turns the engine fast. Called the owner, he gave me the address to the porsche specialist he dealt with. I managed to get it there by putting it in neutral and keeping it at 1000 rpm while using left foot to brake (first time doing this, seat belts works great!
) Mechanic had lots of aircooled porsches outside and a 928 gts and seemed very knowledgeable. When I told him about the thrust bearing he said he doesn't think that's the culprit but he put a metal rod inside the check port and didn't notice anything lose (From what I've read this isn't how it's checked at all but ok. Then we removed the oil filter and drained some oil to check for metal shavings and there wasn't any. I kept the oil filter to open it up and check the inside. After that he said that most probably it is running rich caused but the LH unit. He told me it was ok to drive back home 6 hours and that he recommends a rebuild for the unit. He also swapped the Maf from the GTS with no change and also checked the Lh unit connector if it's lose but it wasn't.
On my way back I noticed that it always starts in first and holds the gear till 3000 rpm. Seems that after it notices something is not right while taking off it immediately shifts into first. Shifts are a bit hard. In 3rd or second, 1000-2000 rpm it feels sluggish and engine shakes a bit, 2000-4000 pulls smoothly never drove a 928 s4 before but for 320 hp I think it's lacking a bit of power, 4000-red line all hell breaks loose and engine comes to life.
I noticed that the warning lamp in the center console comes on when I restart it after it stalls, it goes off if I push it.
When I got home I gave it a bath and tried to see if any wires are not connected and I found a couple in the 14 pin connector. I will add photos. I also disconnected one of the connectors on one of the ecu to look for corrosion but found out it is held by a screw so I decided to give up for the day and park it.
After I finished I started it up and guess what..it idles perfectly so I decided to take it for a drive. Drove for about 30 min. 90% of the time ran perfectly, stalled once when I stopped and steered suddenly. Still hesitant under 2000 rpm and still starts in first gear.
I've owned many cars before but I don't have deep pockets, still a student. This replaced a 944 which has been the most reliable of all of them. I would love to keep it for long but I'm really hesitant at this point. After 6 hours drive I would guess if it has been the thrust bearing it would have left me stranded. Another possibility is the timing belt (which is one of the causes the warning light would come on) I also noticed that when looking through the timing cover where the intake tube connects, I can see the belt move side to side about 1-1.5 mm side to side. Is that normal? Can't see how a loose or worn belt can cause these issues though..
I really enjoyed the ride and I think it is the absolute perfect car for me with just enough power, just enough road feel, just enough comfort. On the reliability level I'm not so sure after reading some threads
10-17-2017, 01:58 PM
#3
Looks like you could use a new harness for that 14 pin connector. Get to know Roger @928sRus and he can fix you up on parts.
As to the way it's running, could be any number of things and there are a lot of parts that need checking. Starting off with the vacuum off the intake can tell you quite a bit.
As to the way it's running, could be any number of things and there are a lot of parts that need checking. Starting off with the vacuum off the intake can tell you quite a bit.
10-17-2017, 03:17 PM
#4
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Welcome and congrats. Sean has a lot of experience with this, so I'd go with his advice first.
Next, the idle stabilizer valve is under the center intake. They can get sticky. Vac or idle stabilizer valve sounds most likely. It may not be frozen when cold, but as the car warms up, the shutter may become sticky. Can be cleaned, but no guarantees. Hard to reach.
http://jenniskens.livedsl.nl/Technic.../MyTip1110.htm
Once exposed, you can also check all the vac lines. Expect many of them to be in rough shape. Roger at 928sRUS has all you will need.
Put your location in your sig block. I had a 92 968 for a while, it was a nice car, but the 928 is way, way different.
Next, the idle stabilizer valve is under the center intake. They can get sticky. Vac or idle stabilizer valve sounds most likely. It may not be frozen when cold, but as the car warms up, the shutter may become sticky. Can be cleaned, but no guarantees. Hard to reach.
http://jenniskens.livedsl.nl/Technic.../MyTip1110.htm
Once exposed, you can also check all the vac lines. Expect many of them to be in rough shape. Roger at 928sRUS has all you will need.
Put your location in your sig block. I had a 92 968 for a while, it was a nice car, but the 928 is way, way different.
10-17-2017, 03:24 PM
#5
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BTW, thrust bearing failure is a real concern. It is a required remediation for all S4 auto cars. Requires removal of the front exh header section, cats, and the bellhousing to check and resolve. Many threads here about TBF. Do it sooner than later.
10-17-2017, 06:42 PM
#6
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The words "student" and "928" do not sit well together. You might get a 928 for bargain basement money but you do not get to maintain at bargain basement.
Your wiring at the 14 pin connector is standard fare- they all look like that [and much worse] if they have not been replaced yet.
As a new S4 automatic owner you must benchmark the crank end float and ensure that the flexplate clamp cannot slip. Various ways of doing this- I have successfully used Loctite for 18 years- some think it does not work!
As for your immediate problem you need to ensure the idle switch contact is functioning and that the idle stabiliser valve is functioning correctly. Many of the original items are now falling by the wayside and replacement is now a common item.
There are quite a number of things that generally need attending to if they are still original and knowledge of what your PO did or did not do is really quite imperative. The timing belt should not be bobbling about on the cam sprocket- your description suggests something wrong in that section- most likely an idler pulley bearing.
Nothing unusual but most likely you are a few grand short of a correctly running 928- I hope not but experience suggests otherwise sad to say. Still, keep an open mind until such time as you know for sure that your piggy bank is going to take a hammering.
Your wiring at the 14 pin connector is standard fare- they all look like that [and much worse] if they have not been replaced yet.
As a new S4 automatic owner you must benchmark the crank end float and ensure that the flexplate clamp cannot slip. Various ways of doing this- I have successfully used Loctite for 18 years- some think it does not work!
As for your immediate problem you need to ensure the idle switch contact is functioning and that the idle stabiliser valve is functioning correctly. Many of the original items are now falling by the wayside and replacement is now a common item.
There are quite a number of things that generally need attending to if they are still original and knowledge of what your PO did or did not do is really quite imperative. The timing belt should not be bobbling about on the cam sprocket- your description suggests something wrong in that section- most likely an idler pulley bearing.
Nothing unusual but most likely you are a few grand short of a correctly running 928- I hope not but experience suggests otherwise sad to say. Still, keep an open mind until such time as you know for sure that your piggy bank is going to take a hammering.
10-17-2017, 07:59 PM
#7
Thanks for your help appreciate it! A quick update. I took it for a drive on some twisty roads today and I'm really impressed. It was a really nice cruiser on the highway and after reading that the 928 is just a GT car and not a sports car I expected that it would handle like an 8 series bimmer but that was not the case at all.
It stalled once, didn't have to give it gas at all. Two things to add that might help. The idle is still a bit rough while stopped most of the time, doesn't make a difference if in gear or neutral. However, if I put in neutral while cruising it would idle perfectly at 1000 rpm. While stopped I can hear a slight whine, something like a pump turning on and the idle immediately becomes rough. The previous owner did an engine reseal this summer. Intake manifold was removed and powder quoted. I'm trying to get the invoice to see what exactly was replaced. One last thing I just remembered. I test drove it on Saturday and idle was fine, slight hesitation at low rpm as mentioned. Sunday there was a big storm in the area. My daily honda crv that I was driving started flickering battery light, all passenger windows stopped working. Dash lights would only work if I press the window switches. Anyway, could rain water make its way to some kind of an electrical system that causes this? Symptoms are getting less apparent with time, not complaining..
It stalled once, didn't have to give it gas at all. Two things to add that might help. The idle is still a bit rough while stopped most of the time, doesn't make a difference if in gear or neutral. However, if I put in neutral while cruising it would idle perfectly at 1000 rpm. While stopped I can hear a slight whine, something like a pump turning on and the idle immediately becomes rough. The previous owner did an engine reseal this summer. Intake manifold was removed and powder quoted. I'm trying to get the invoice to see what exactly was replaced. One last thing I just remembered. I test drove it on Saturday and idle was fine, slight hesitation at low rpm as mentioned. Sunday there was a big storm in the area. My daily honda crv that I was driving started flickering battery light, all passenger windows stopped working. Dash lights would only work if I press the window switches. Anyway, could rain water make its way to some kind of an electrical system that causes this? Symptoms are getting less apparent with time, not complaining..
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10-17-2017, 11:01 PM
#8
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For an intermittant problem, yes absolutely rain or water ingress could have an effect. The CE panel resides directly below the lower windscreen bezel so water in the footwell is fairly common.
But - it could be a dozen things, or a half dozen combination of things. Please follow logical directions already given, or you can just go shotgun and guess. Vac, idle stab valve. Once you confirm those are fine the forum will proceed. If you go on your own, well, not going to make friends.
But - it could be a dozen things, or a half dozen combination of things. Please follow logical directions already given, or you can just go shotgun and guess. Vac, idle stab valve. Once you confirm those are fine the forum will proceed. If you go on your own, well, not going to make friends.
10-18-2017, 12:21 AM
#9
For an intermittant problem, yes absolutely rain or water ingress could have an effect. The CE panel resides directly below the lower windscreen bezel so water in the footwell is fairly common.
But - it could be a dozen things, or a half dozen combination of things. Please follow logical directions already given, or you can just go shotgun and guess. Vac, idle stab valve. Once you confirm those are fine the forum will proceed. If you go on your own, well, not going to make friends.
But - it could be a dozen things, or a half dozen combination of things. Please follow logical directions already given, or you can just go shotgun and guess. Vac, idle stab valve. Once you confirm those are fine the forum will proceed. If you go on your own, well, not going to make friends.
