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View Full Version : Cranks but no start 2001 tip?



protocol_droid
11-12-2012, 06:57 PM
Okay, my 1.8t car has been running fine with smooth starts every time. Suddenly, this morning, tried turning her over and it cranks and cranks but doesn't fire up. I have no check engine lights and I checked with the vag-com and no codes. I checked fuse #29 near the steering column and it is fine. I tried jumper cables to another running vehicle and still has the same problem. From what I"ve read, check spark. That's the plan tomorrow morning. I also wanted to check the vag-com for the cts however if the car doesn't fire up how would I check to see if the sensor is good or bad? Also, what is the likelihood of the crank position sensor (cps)?

EDIT: Just remembered bout a week ago before the car wouldn't start, i had a dash light for excessive speed or something to that nature along with the EPC light even though I was going like 20 mph. It went away after driving it for a day. I wonder if it is the crank position sensor/speed sensor (one in the same?)

walky_talky20
11-12-2012, 07:06 PM
Crank sensor or coolant temp sensor are likely at this point. Checking for spark is step numero uno (that's "number 1" in spanish, fyi).

To check the CTS, all you need is the key ON and vcds up. You check the measuring block with coolant temp to see if it's within reason (near ambient temp). Compare the values for coolant and intake temp in block 004.

protocol_droid
11-12-2012, 07:23 PM
Crank sensor or coolant temp sensor are likely at this point. Checking for spark is step numero uno (that's "number 1" in spanish, fyi).

To check the CTS, all you need is the key ON and vcds up. You check the measuring block with coolant temp to see if it's within reason (near ambient temp). Compare the values for coolant and intake temp in block 004.

Wow, that was fast. What a resource you are Walky for these boards.

Just to confirm, checking spark first before assuming cps or cts, correct? Also, in the vag, if the ambient coolant temp is not similiar to the intake temps, then the cts would be the culprit more than likely?

contrldsub
11-12-2012, 07:33 PM
i believe that if the cts sensor is not working properly it will read something rediculous. walky? you know these motors, but i think temp sensors default to like -40 when they short out.

protocol_droid
11-12-2012, 07:49 PM
^^if it's not within reason, will look out for the low number. Thanks.

walky_talky20
11-12-2012, 08:17 PM
I've seen them most often give a super high number like 140F or something ridiculous. With such a high temp, it won't give cold start enrichment. The mixture will be so lean it will sound like it's not getting any gas at all. They do have several failure modes though. A super low reading is also possible.

Yes, checking spark first would be a good idea. Basically, you want to be minimally invasive until you narrow it down. You want it to *stay broken* until you figure out exactly why it isn't starting. So don't do anything outlandish like rustle the wiring harness, or unplug and re-plug a bunch of connectors. Should it magically start after doing stuff like that, then you'll definitely not be able to find the fault. Until it crops up again and leaves you somewhere, on a cold and rainy night, hundreds of miles from home. No. You want it to stay broken right now...and find it. Be gentle and methodical.

protocol_droid
11-12-2012, 09:35 PM
yeah, i definitely know about changing one thing at a time.

On a side, note, just remembered about a week ago my esp or epc light came on along with the excessive speed light in the dash...didn't think anything of it since it went away and this starting issue happened a week later...ahh perhaps it is the cps.

protocol_droid
11-14-2012, 07:09 PM
Okay, didnt' check for spark yet...I know I'm lame. I did however run the vag and noticed the coolant and air temps at ambient 18C with battery voltage at 11.9. My multimeter says 12.5 just like it is on my S4. Since I did notice the strange "excessive speed" light up a week ago, I suspected the cps so I picked one up at purems, installed it and still has the same problem. So it's not the CTS or CPS. I also tried jumping the vehicle again and no go...just cranks and doesn't turn over.

walky_talky20
11-14-2012, 08:30 PM
Wait a sec. We *changed the crank sensor*, but still didn't check for spark yet?

Lame.

j/k, that was a good guess with the sensor. I like to have a little more evidence before buying stuff. But that has a lot to do with me being an enormous cheapskate.

protocol_droid
11-17-2012, 08:41 AM
Okay, checked for spark on one cylinder using an inline spark tester with the bulb. Cranked the engine and the bulb didn't light up. Battery registers 12.5V and still doesn't turn over even with a jump. This is strange. I was hoping there would be spark so I could move to fuel pump relay or fuel pump. What's the next line of attack to figure this out?

walky_talky20
11-17-2012, 09:23 AM
- Do you have CEL with key ON?
- Do you have RPM reading in vcds during cranking?
- Do you have 12V+ to the coil pack connectors during cranking? (pin 1, red/green wire)

protocol_droid
11-17-2012, 10:10 AM
[QUOTE=walky_talky20;8183726]- Do you have CEL with key ON?
- Do you have RPM reading in vcds during cranking?
- Do you have 12V+ to the coil pack connectors during cranking? (pin 1, red/green wire)[/QUOTE

1) EPC, Check engine light, battery and brake light up on the dash with the key in in the accessory position just before starting position
2) RPM reading is 160/min when cranking using blocks 1,2,3 I guess rpm (g28) is the same for all of those.
3) I don't see any wires on my coil pack. I couldn't pull back the rubber sheating where it meets the female connector end. Not sure how to access the wires. I feel lame.

walky_talky20
11-17-2012, 10:32 AM
If you pull back the rubber boot a bit off the plastic connector, you'll see all 4 wires. But you just need to unplug it and check pin #1 for 12V+ during cranking. I *think* it should have it anytime the key is on, but it should definitely have it during cranking.

protocol_droid
11-17-2012, 10:52 AM
I just measured at the front of the connector with the red probe, duh and then black probe to the main ground on the valve cover. I tested 2 plugs and they both were ~9.7-10V when cranking. When not cranking, pin#1 measure 12.3V.

An offline question with no relation to my issue if you have had experience...do you know where the cruise control vacuum pump on a 1998 a6 avant is located?

walky_talky20
11-17-2012, 11:29 AM
Power, ground, and rpm signal in vcds, eh? You're sure you don't have spark? I don't know what kind of device you're using, but I'd suggest you get a long screwdriver (preferably a thin phillips driver) and stuff it in the end of the coil pack. Hold the shaft 1/16" off the valve cover and have somebody hit the key. You can also use a spark plug for this test. Just make sure the end is touching the valve cover.

protocol_droid
11-17-2012, 11:57 AM
I have this one: http://www.pepboys.com/product/details/438566/

oem inline spark tester. It didn't light up when I was cranking so I assumed no spark. Does the 10V when cranking seem okay?

walky_talky20
11-17-2012, 03:28 PM
Have you seen your actual device work before? Is it a tested-good tool? It could be broken. We don't want to sidetrack our entire diagnosis based on data from a questionable tool.

protocol_droid
11-17-2012, 08:20 PM
OKay, the inline tester is a dead tool. Pulled the plug out and stuck it into the coil pack, cranked her up and there's definitely spark. That POS tester is going back to pepboys.

Okay, so I decided to swap out the fuel filter and found out it was the stock one from 150K ago (bought car used)...it was extremely dirty and you couldn't blow through the other end. Tried firing up the car again and still no go it cranks but no start. I did this 8-9 times with rests in between to see if I could purge the fuel lines. It didn't work. I can also hear the fuel pump when I turn on the ignition before cranking. Can I have bad fuel relay or a dead pump and still hear the humming noise from the fuel pump?

ddillenger
11-17-2012, 09:16 PM
are your cams turning?

protocol_droid
11-18-2012, 11:35 AM
are your cams turning?

Yes, the cams are turning when cranking. Also, is there supposed to be an extra washer for the cps? My stock one didn't look like it had one and the new one didn't come with one however it goes in just fine and sits flush. There didn't appear to be on in the valley of the block either. I only ask because of this: http://www.audizine.com/forum/showthread.php/513516-Crank-position-sensor-will-not-go-in

Still dumbfounded

walky_talky20
11-18-2012, 12:41 PM
- If you have spark, your crank sensor is doing A-OK.
- Are the plugs wet if you pull them out?

The last one would indicate fuel delivery to the cylinders. If you have fuel and spark, the thing should fire. It may be flooded. I usually pull the plugs out, unplug the injectors, and crank the motor a bit to clear the cylinders. Install new plugs and plug in the coil packs (but not the injectors). Crank the motor a bit more. If it coughs and tries to start, keep cranking until it stops doing that. The flood should be sufficiently cleared at this point. Then plug your injectors back in and try again.

- 10v during cranking is sufficient.

protocol_droid
11-18-2012, 02:14 PM
- If you have spark, your crank sensor is doing A-OK.
- Are the plugs wet if you pull them out?

The last one would indicate fuel delivery to the cylinders. If you have fuel and spark, the thing should fire. It may be flooded. I usually pull the plugs out, unplug the injectors, and crank the motor a bit to clear the cylinders. Install new plugs and plug in the coil packs (but not the injectors). Crank the motor a bit more. If it coughs and tries to start, keep cranking until it stops doing that. The flood should be sufficiently cleared at this point. Then plug your injectors back in and try again.

- 10v during cranking is sufficient.

so when I pulled the plugs, I did notice that they were dry and didn't have any gas smell on the plugs themselves or by putting my sniffer into the valve cover. I will try your recommendation and post back.

walky_talky20
11-18-2012, 04:16 PM
After cranking it a bit, the plugs should be wet. Sounds like you might have a fuel delivery problem. Maybe you're missing injector pulse or power to injectors. Or maybe you're missing fuel pressure. You can use an LED test light to check power and ground pulse to injectors during cranking. You can check fuel pressure with a gauge.

protocol_droid
11-26-2012, 09:59 AM
Okay so after trying to find a fitting that would fit on the fuel line and not finding one (pepboys, autozone or oreilly), I gave up. Luckily one of my neighbors is a mechanic and came to take a look. Fuel pump appeared to be just fine. He checked for spark and said, it looked pretty weak. We swapped plugs and once I cranked it for a while, the flooded engine finally came to and turned over. No problems ever since. I guess I know what a good spark looks like now. The spark definitely looked stronger and more prounounced after changing the plugs. Rookie maneuver.

walky_talky20
11-26-2012, 01:31 PM
Yeah, these engines do seem to flood and foul plugs with relative ease. Mine flooded out the other day for no apparent reason. Left it in the shop for 2 days went to start it and it cranked but no fire. I immediately checked the t-belt - all good. Kept cranking with pedal at WOT (clear flood mode) and it slowly started to fire. Very strange, and it never did that before.

protocol_droid
11-27-2012, 07:59 AM
Yeah, these engines do seem to flood and foul plugs with relative ease. Mine flooded out the other day for no apparent reason. Left it in the shop for 2 days went to start it and it cranked but no fire. I immediately checked the t-belt - all good. Kept cranking with pedal at WOT (clear flood mode) and it slowly started to fire. Very strange, and it never did that before.

He made me put the pedal to the medal to clear the flood. I was totally dumbfounded about the plugs. I will be changing them more often.

Thanks for your help walky!