CTS always reading 30.0'C at the cluster
03-26-2015, 03:01 PM
#11
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That handy Bentley manual of yours... it doesn't happen to touch on fuel delivery, level senders, pickup etc..? (quattro)
Still having those warm starting issues. Not quite sure if its related to warm engine / runtime, or movement (I always give it a goot 3-4 seconds after the "OK" goes away, before cranking). Fuel gauge I /know/ is out of wack, I suspect a sender. But here's the thing; I took extra note today, as I had it on a lift to change fuel filter, rear diff fluid and check compression. I noticed after doing a short 2-minute pitstop on the way home; Its like the engine started on the first half-revolution of the starter (= very snappy, as expected with an already warm engine), but it dies and falls back on the still cranking starter motor after like 0.3 seconds. It then cranks on the starter like mad for 4-5 seconds, and then it slowly comes along firing up again.
This had me thinking the following; Maybe its a fuel delivery issue. The Fuel pipes still hold pressure after shutting off the engine. When starting warm, somehow the fuel pump/delivery isn't working correctly. It fires up on the residual pressure in the pipes/hoses, but as the pump isn't running (or picking up fuel), that pressure will drop like a stone once the injectors start cycling.
Still having those warm starting issues. Not quite sure if its related to warm engine / runtime, or movement (I always give it a goot 3-4 seconds after the "OK" goes away, before cranking). Fuel gauge I /know/ is out of wack, I suspect a sender. But here's the thing; I took extra note today, as I had it on a lift to change fuel filter, rear diff fluid and check compression. I noticed after doing a short 2-minute pitstop on the way home; Its like the engine started on the first half-revolution of the starter (= very snappy, as expected with an already warm engine), but it dies and falls back on the still cranking starter motor after like 0.3 seconds. It then cranks on the starter like mad for 4-5 seconds, and then it slowly comes along firing up again.
This had me thinking the following; Maybe its a fuel delivery issue. The Fuel pipes still hold pressure after shutting off the engine. When starting warm, somehow the fuel pump/delivery isn't working correctly. It fires up on the residual pressure in the pipes/hoses, but as the pump isn't running (or picking up fuel), that pressure will drop like a stone once the injectors start cycling.
03-26-2015, 03:56 PM
#12
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That handy Bentley manual of yours... it doesn't happen to touch on fuel delivery, level senders, pickup etc..? (quattro)
Still having those warm starting issues. Not quite sure if its related to warm engine / runtime, or movement (I always give it a goot 3-4 seconds after the "OK" goes away, before cranking). Fuel gauge I /know/ is out of wack, I suspect a sender. But here's the thing; I took extra note today, as I had it on a lift to change fuel filter, rear diff fluid and check compression. I noticed after doing a short 2-minute pitstop on the way home; Its like the engine started on the first half-revolution of the starter (= very snappy, as expected with an already warm engine), but it dies and falls back on the still cranking starter motor after like 0.3 seconds. It then cranks on the starter like mad for 4-5 seconds, and then it slowly comes along firing up again.
This had me thinking the following; Maybe its a fuel delivery issue. The Fuel pipes still hold pressure after shutting off the engine. When starting warm, somehow the fuel pump/delivery isn't working correctly. It fires up on the residual pressure in the pipes/hoses, but as the pump isn't running (or picking up fuel), that pressure will drop like a stone once the injectors start cycling.
Still having those warm starting issues. Not quite sure if its related to warm engine / runtime, or movement (I always give it a goot 3-4 seconds after the "OK" goes away, before cranking). Fuel gauge I /know/ is out of wack, I suspect a sender. But here's the thing; I took extra note today, as I had it on a lift to change fuel filter, rear diff fluid and check compression. I noticed after doing a short 2-minute pitstop on the way home; Its like the engine started on the first half-revolution of the starter (= very snappy, as expected with an already warm engine), but it dies and falls back on the still cranking starter motor after like 0.3 seconds. It then cranks on the starter like mad for 4-5 seconds, and then it slowly comes along firing up again.
This had me thinking the following; Maybe its a fuel delivery issue. The Fuel pipes still hold pressure after shutting off the engine. When starting warm, somehow the fuel pump/delivery isn't working correctly. It fires up on the residual pressure in the pipes/hoses, but as the pump isn't running (or picking up fuel), that pressure will drop like a stone once the injectors start cycling.
A couple things to check would be the fuel regulator that is vacuum operated, another one just mentioned recently would be fuel injector O-rings that can cause vac leaks and idle stumbles. The fuel pump access cover is under the rear seat, I'd check to see if constant power is present when the key is in the run/on position also you should be able to hear it run.
03-26-2015, 05:16 PM
#13
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Actually I don't have any manual in any format. Just google. Well SWIM might have some older ELSA software available - some times useful, some times completely useless unless you have $5000 in special tools, and more often than not - issue/part/assembly not covered at all.
I was hoping to check fuel pressure before and after regulator with a gauge - after checking the layout, I'm not quite sure how to pull that "after" bit off - it goes part-to-part, metal-to-metal straight into the fuel rail. Can't afford a fuel guage right now either, this car has me completely tapped out. Any other way to check operation/condition of the regulator?
I'm going to have to have another look to see how to get the fuel rails off - won't be able to get to the injectors (and seals) without it. But at idle, there was no reaction when hosing down that area with propane. Should probably have another go at that gas test, now that I fixed several large leaks. If I smoke test under sliiight pressure - wouldn't smoke come out around the culprit injector?
I've tried logging cam / crankshaft posistion sensor during start, but VCDS always lose contact during cranking. If its a quick start, it might "come back again", but there will be no data logged for the cranking period. If its a "long crank", it'll hang and lose contact with the module.
Lastly for tonight... The tank is "split" back there - surely there must be two pumps somehow..? And of such, could failure of one of them, cause this?
I was hoping to check fuel pressure before and after regulator with a gauge - after checking the layout, I'm not quite sure how to pull that "after" bit off - it goes part-to-part, metal-to-metal straight into the fuel rail. Can't afford a fuel guage right now either, this car has me completely tapped out. Any other way to check operation/condition of the regulator?
I'm going to have to have another look to see how to get the fuel rails off - won't be able to get to the injectors (and seals) without it. But at idle, there was no reaction when hosing down that area with propane. Should probably have another go at that gas test, now that I fixed several large leaks. If I smoke test under sliiight pressure - wouldn't smoke come out around the culprit injector?
I've tried logging cam / crankshaft posistion sensor during start, but VCDS always lose contact during cranking. If its a quick start, it might "come back again", but there will be no data logged for the cranking period. If its a "long crank", it'll hang and lose contact with the module.
Lastly for tonight... The tank is "split" back there - surely there must be two pumps somehow..? And of such, could failure of one of them, cause this?
03-26-2015, 05:45 PM
#14
AudiWorld Super User
Actually I don't have any manual in any format. Just google. Well SWIM might have some older ELSA software available - some times useful, some times completely useless unless you have $5000 in special tools, and more often than not - issue/part/assembly not covered at all.
I was hoping to check fuel pressure before and after regulator with a gauge - after checking the layout, I'm not quite sure how to pull that "after" bit off - it goes part-to-part, metal-to-metal straight into the fuel rail. Can't afford a fuel guage right now either, this car has me completely tapped out. Any other way to check operation/condition of the regulator?
I'm going to have to have another look to see how to get the fuel rails off - won't be able to get to the injectors (and seals) without it. But at idle, there was no reaction when hosing down that area with propane. Should probably have another go at that gas test, now that I fixed several large leaks. If I smoke test under sliiight pressure - wouldn't smoke come out around the culprit injector?
I've tried logging cam / crankshaft posistion sensor during start, but VCDS always lose contact during cranking. If its a quick start, it might "come back again", but there will be no data logged for the cranking period. If its a "long crank", it'll hang and lose contact with the module.
Lastly for tonight... The tank is "split" back there - surely there must be two pumps somehow..? And of such, could failure of one of them, cause this?
I was hoping to check fuel pressure before and after regulator with a gauge - after checking the layout, I'm not quite sure how to pull that "after" bit off - it goes part-to-part, metal-to-metal straight into the fuel rail. Can't afford a fuel guage right now either, this car has me completely tapped out. Any other way to check operation/condition of the regulator?
I'm going to have to have another look to see how to get the fuel rails off - won't be able to get to the injectors (and seals) without it. But at idle, there was no reaction when hosing down that area with propane. Should probably have another go at that gas test, now that I fixed several large leaks. If I smoke test under sliiight pressure - wouldn't smoke come out around the culprit injector?
I've tried logging cam / crankshaft posistion sensor during start, but VCDS always lose contact during cranking. If its a quick start, it might "come back again", but there will be no data logged for the cranking period. If its a "long crank", it'll hang and lose contact with the module.
Lastly for tonight... The tank is "split" back there - surely there must be two pumps somehow..? And of such, could failure of one of them, cause this?
I'm actually not sure how to check the fuel pressure regulator right now to be honest but being that it's probably been done and posted in AudiWorld I'm very sure that could be a STF aka "Search the Forums"
Why are you concerned about the crank/cam data logging? if you don't have CEL codes relative.
Yes the tank is a saddle design with one pump and balance transfer tube or something of the sort.
03-27-2015, 02:34 AM
#15
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I've already become quite aware of the caveats of not having a decent manual, especially for these rather complex cars. But when you're broke you're broke, so it'll have to wait. Definitely (high) on the list though! 
Reason I want to try to log for those sensors (or other things, like injectors) was I've read about those sensors causing similar issues. I've also already, like the CTS, experienced how some parts' failure (or operating out of spec) can have rather significant effects, yet not even throw a code. I was just blanketing here, trying to figure out what I can check with the equipment I have available right now - without just tossing parts at it blindly. Since my discoveries yesterday regarding what I strongly believe to be fuel delivery - I'm trying to think of anything that could signal the pump to not run / shut off.
How long should the fuel pump be priming at ign on, engine off? I had a friend come by and jog the ignition while I was in the back, I only heard a short (1 sec max) wirr. Car had been sitting for a day though, so when cranking it fired up "normally".
Reason I want to try to log for those sensors (or other things, like injectors) was I've read about those sensors causing similar issues. I've also already, like the CTS, experienced how some parts' failure (or operating out of spec) can have rather significant effects, yet not even throw a code. I was just blanketing here, trying to figure out what I can check with the equipment I have available right now - without just tossing parts at it blindly. Since my discoveries yesterday regarding what I strongly believe to be fuel delivery - I'm trying to think of anything that could signal the pump to not run / shut off.
How long should the fuel pump be priming at ign on, engine off? I had a friend come by and jog the ignition while I was in the back, I only heard a short (1 sec max) wirr. Car had been sitting for a day though, so when cranking it fired up "normally".
03-27-2015, 12:31 PM
#16
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I've already become quite aware of the caveats of not having a decent manual, especially for these rather complex cars. But when you're broke you're broke, so it'll have to wait. Definitely (high) on the list though!
Reason I want to try to log for those sensors (or other things, like injectors) was I've read about those sensors causing similar issues. I've also already, like the CTS, experienced how some parts' failure (or operating out of spec) can have rather significant effects, yet not even throw a code. I was just blanketing here, trying to figure out what I can check with the equipment I have available right now - without just tossing parts at it blindly. Since my discoveries yesterday regarding what I strongly believe to be fuel delivery - I'm trying to think of anything that could signal the pump to not run / shut off.
How long should the fuel pump be priming at ign on, engine off? I had a friend come by and jog the ignition while I was in the back, I only heard a short (1 sec max) wirr. Car had been sitting for a day though, so when cranking it fired up "normally".
Reason I want to try to log for those sensors (or other things, like injectors) was I've read about those sensors causing similar issues. I've also already, like the CTS, experienced how some parts' failure (or operating out of spec) can have rather significant effects, yet not even throw a code. I was just blanketing here, trying to figure out what I can check with the equipment I have available right now - without just tossing parts at it blindly. Since my discoveries yesterday regarding what I strongly believe to be fuel delivery - I'm trying to think of anything that could signal the pump to not run / shut off.
How long should the fuel pump be priming at ign on, engine off? I had a friend come by and jog the ignition while I was in the back, I only heard a short (1 sec max) wirr. Car had been sitting for a day though, so when cranking it fired up "normally".
I just side on the "If it's not broke don't fix it" no vagcom codes no problems.
Sorry, what I meant was with the car running then the fuel pump will be running continuously until the key is off, if the pump is cutting out then you have a potential total failure ahead.
03-27-2015, 01:42 PM
#17
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Yep got it money is tight.
I just side on the "If it's not broke don't fix it" no vagcom codes no problems.
Sorry, what I meant was with the car running then the fuel pump will be running continuously until the key is off, if the pump is cutting out then you have a potential total failure ahead.
I just side on the "If it's not broke don't fix it" no vagcom codes no problems.
Sorry, what I meant was with the car running then the fuel pump will be running continuously until the key is off, if the pump is cutting out then you have a potential total failure ahead.
I think I might try to wire up some extensions to my multimeter and splicing them into the fuel pump feed somehow. That way I could get an indication if something is off, when the "long crank" happens - without having someone with me in the car.
Really would prefer to avoid total failure, but if its going, I guess it isn't servicable for the unexperienced. I haven't really experienced any issues with running once it starts (a few times I've needed to keep it above 12-1300rpm for 20-30 seconds right after a really cold start, otherwise it would die if I let it fall to idle).
03-27-2015, 01:57 PM
#18
AudiWorld Super User
Indeed, but then again there are some parts that can throw a fit or tap out, that don't have a code - or no electrical components. Some are "obvious", others I might not know about. Thats why I'm brainstorming out loud a bit here
I think I might try to wire up some extensions to my multimeter and splicing them into the fuel pump feed somehow. That way I could get an indication if something is off, when the "long crank" happens - without having someone with me in the car.
Really would prefer to avoid total failure, but if its going, I guess it isn't servicable for the unexperienced. I haven't really experienced any issues with running once it starts (a few times I've needed to keep it above 12-1300rpm for 20-30 seconds right after a really cold start, otherwise it would die if I let it fall to idle).
I think I might try to wire up some extensions to my multimeter and splicing them into the fuel pump feed somehow. That way I could get an indication if something is off, when the "long crank" happens - without having someone with me in the car.
Really would prefer to avoid total failure, but if its going, I guess it isn't servicable for the unexperienced. I haven't really experienced any issues with running once it starts (a few times I've needed to keep it above 12-1300rpm for 20-30 seconds right after a really cold start, otherwise it would die if I let it fall to idle).
Check out the Features/Tech Articles section at the top of the page, plenty of good info there and excellent guides even on fuel pumps, wiring and ect.
03-31-2015, 04:16 PM
#19
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All sounds logical, I know one thing for sure that if the fuel pump is going the ecu won't even throw a bone about it and one other issues that can arise is people who run on low levels of gas or if the tank has water in it from condensation and even though your in a super cold region it can happen.
Check out the Features/Tech Articles section at the top of the page, plenty of good info there and excellent guides even on fuel pumps, wiring and ect.
Check out the Features/Tech Articles section at the top of the page, plenty of good info there and excellent guides even on fuel pumps, wiring and ect.
I figure I had ~1/3-1/4 tank when checking the resistance on the fuel pump-attached sender, and it showed 274 ohm. Thats way too much if I understand correctly.
Wired up a multimeter to the pump connector, so I could have it up front when driving, turn it on before cranking. When this looong crank happens, the pump never goes below 10.8 volts (during cranking). No sign of power cut. So if this is fuel delivery related - either the pump has mechanical trouble starting , or (more likely?) something is stopping the fuel from reaching the injectors. I've already ordered a fuel pressure tester, but its gonna take weeks to arrive.
04-01-2015, 04:47 PM
#20
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I've been crawling around the articles, this and other forums - picked up a few things to test etc. I know something is wonky with one or more of the fuel senders (guage usually showing waaay to much - on a very rare occation it seems almost correct) I guess I'll just have to open the tank and pull them one by one...? As far as I could understand, they're all wired together/in series inside the tank - and thus you need to separate them to check them separately..?
I figure I had ~1/3-1/4 tank when checking the resistance on the fuel pump-attached sender, and it showed 274 ohm. Thats way too much if I understand correctly.
Wired up a multimeter to the pump connector, so I could have it up front when driving, turn it on before cranking. When this looong crank happens, the pump never goes below 10.8 volts (during cranking). No sign of power cut. So if this is fuel delivery related - either the pump has mechanical trouble starting , or (more likely?) something is stopping the fuel from reaching the injectors. I've already ordered a fuel pressure tester, but its gonna take weeks to arrive.
I figure I had ~1/3-1/4 tank when checking the resistance on the fuel pump-attached sender, and it showed 274 ohm. Thats way too much if I understand correctly.
Wired up a multimeter to the pump connector, so I could have it up front when driving, turn it on before cranking. When this looong crank happens, the pump never goes below 10.8 volts (during cranking). No sign of power cut. So if this is fuel delivery related - either the pump has mechanical trouble starting , or (more likely?) something is stopping the fuel from reaching the injectors. I've already ordered a fuel pressure tester, but its gonna take weeks to arrive.
The pump has a mesh filter on the pick-up this could be restricted with crap also, this is something you will see with a pressure gauge...Yep.