Loss of power CQ20V??

Coxy · 11-05-09, 06:33 PM

Alex was driving back from the shops today when the Coupe (B3) decided to lose all power on the slip road off the M54. Luckily only about 800yds from home but an inconvenience as she was about to go to work!
Now, have had the one of the spark plugs out and tried to see if there is a spark, but can't see a spark at all. The engine turns over but doesn't fire. Yes there is fuel!
So, by the grand process of elimination, I would deduce that it would be an electrical fault.
I would point my finger at the moment at the coil pack.
Anywhere else where I can point my finger and phillips screw driver and hammer at for now?

msh · 11-05-09, 06:45 PM

Ahh, Coxy...

7A has the worst engine management [or, let's say, expensive] of all old audis and ke-jet is only next to it

As far as I remember, most latvian 7A users lost spark because of ignition timing sender fault - either some of senders is gone or pin on flywheel is gone. Also there is possibility that igniton distributor gear is gone - sometimes this happens to 7A and 3B.
P.S. All fuses in place?

Coxy · 11-05-09, 06:49 PM

Quote:

Originally Posted by msh

Ahh, Coxy...

7A has the worst engine management [or, let's say, expensive] of all old audis and ke-jet is only next to it

As far as I remember, most latvian 7A users lost spark because of ignition timing sender fault - either some of senders is gone or pin on flywheel is gone. Also there is possibility that igniton distributor gear is gone - sometimes this happens to 7A and 3B.
P.S. All fuses in place?

I'll have a check tomorrow as I've had enough of cars today.
What's the easiest way to find out if it's the ignition timing sender fault without getting dirty?!
Or is there an easy way to trace back what the fault is rather than pulling my hair out in the morning?

vag80 · 11-05-09, 06:58 PM

Try removing the dizzy cap and turn the engine over to see if the rotor arm is turning some times the gear breaks on the end of the shaft

Isimmo · 11-05-09, 07:33 PM

Agree with MSH, also, have a butchers at any after market alarm/immobiliser... They can perform some stunning stunts when they go west.

BW2309 · 11-05-09, 08:03 PM

If there's fuel but no spark it's not likely to be a fuse or relay as these should stop the fuel pump first (the engine ECU is fed power via the fuel pump relay) but still check it's not popped something seemingly insignificant! Power output stage unit can fail but usually starts as intermittant fault.
As mentioned, check the dizzy is turning with engine - common one that. If none of above works then I can PM you copies of the test sequences from my Audi workshop manuals for the 7A, it'll help you find the faulty bit rather than go spending on random bits you dont need!

One question, when you crank it over does the rev counter needle move at all? If it doesn't even twitch when cranking then either the hall sendor (inside dizzy) has fialed, or the dizzy drive wheel. Easy check!!!

Coxy · 11-05-09, 09:13 PM

Quote:

Originally Posted by BW2309

One question, when you crank it over does the rev counter needle move at all? If it doesn't even twitch when cranking then either the hall sendor (inside dizzy) has fialed, or the dizzy drive wheel. Easy check!!!

There's a slight twitching of the rev counter although the battery is a bit low as Alex tried turning it for several minutes before she rang me up.

20vcqdriver · 11-05-09, 10:01 PM

Had this fault when I had the 7A. Distributer gear would be the first thing. Remove the cap and try and see if you can turn the rotor arm. I upgraded to the brass disi gear.
Other poor design is the pin in the flywheel to tell the engine where TDC is. Though this is only used on initial start up. If it falls off once the engine is running it will not stop the engine. I found this out after dropping a nut into the bellhousing (thought it had dropped onto the drive) and on starting the car it ripped the pin off but not before it had started. But next time I came to start....

Coxy · 12-05-09, 08:23 AM

well, as many of you suspected, dizzy out and dizzy gear in 3 bits.
Cheap Chinese plastic me thinks!

So, anyway, what's the best course of action here?
Can I just and the new dizzy gear (upgrade to brass one maybe?).
Or is it easier to get a 2nd hand dizzy off someone like Audibits and fit that?
Then of course all the messing around with the timing.

msh · 12-05-09, 08:26 AM

Was there really "mess with timing"? I remember that some R5 engines u can turn distributor as u wish, as long there is contact, ignition timing doesn't change, 7A isn't one of them?

11-05-09, 06:58 PM	#4
vag80 Senior Member Classic Audi Club Member Join Date: Oct 2008 Location: Bracknell Posts: 1,967	Try removing the dizzy cap and turn the engine over to see if the rotor arm is turning some times the gear breaks on the end of the shaft __________________ nothing like a bit of deep dish 200k club member 87-b3 80 83-4000 2 door

11-05-09, 07:33 PM	#5
Isimmo Super Moderator Classic Audi Club Member Join Date: Jul 2007 Location: Sissix-by-the-sea Posts: 15,218	Agree with MSH, also, have a butchers at any after market alarm/immobiliser... They can perform some stunning stunts when they go west. __________________ 1985 WR quattro, 1985 20vT RallyRep, 1993 MTM ABY S2 Avant. 2010 S3 Sportback.

11-05-09, 10:01 PM	#8
20vcqdriver 4 ring whore! Classic Audi Club Member Join Date: Dec 2007 Location: Wirral Posts: 3,910	Had this fault when I had the 7A. Distributer gear would be the first thing. Remove the cap and try and see if you can turn the rotor arm. I upgraded to the brass disi gear. Other poor design is the pin in the flywheel to tell the engine where TDC is. Though this is only used on initial start up. If it falls off once the engine is running it will not stop the engine. I found this out after dropping a nut into the bellhousing (thought it had dropped onto the drive) and on starting the car it ripped the pin off but not before it had started. But next time I came to start.... __________________ Coupe quattro 1986:-~450bhp + loooong list of mods! Audi A7 Bi-TDI SLine Black edition 2015 mapped to produce 600lb/ft torque! Audi S4 4.2 V8 cabriolet 2004:-

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11-05-09, 06:45 PM	#2
msh 4 ring whore! Join Date: Jun 2008 Location: Rucava, Latvija Posts: 3,816	Ahh, Coxy... 7A has the worst engine management [or, let's say, expensive] of all old audis and ke-jet is only next to it As far as I remember, most latvian 7A users lost spark because of ignition timing sender fault - either some of senders is gone or pin on flywheel is gone. Also there is possibility that igniton distributor gear is gone - sometimes this happens to 7A and 3B. P.S. All fuses in place?

11-05-09, 08:03 PM	#6
BW2309 Banned Join Date: Sep 2008 Location: Derby Posts: 1,245	If there's fuel but no spark it's not likely to be a fuse or relay as these should stop the fuel pump first (the engine ECU is fed power via the fuel pump relay) but still check it's not popped something seemingly insignificant! Power output stage unit can fail but usually starts as intermittant fault. As mentioned, check the dizzy is turning with engine - common one that. If none of above works then I can PM you copies of the test sequences from my Audi workshop manuals for the 7A, it'll help you find the faulty bit rather than go spending on random bits you dont need! One question, when you crank it over does the rev counter needle move at all? If it doesn't even twitch when cranking then either the hall sendor (inside dizzy) has fialed, or the dizzy drive wheel. Easy check!!!

12-05-09, 08:23 AM	#9
Coxy 4 Ring Mafia Classic Audi Club Member Join Date: Jul 2007 Location: on the side of a hill in Shropshire! Posts: 28,215	well, as many of you suspected, dizzy out and dizzy gear in 3 bits. Cheap Chinese plastic me thinks! So, anyway, what's the best course of action here? Can I just and the new dizzy gear (upgrade to brass one maybe?). Or is it easier to get a 2nd hand dizzy off someone like Audibits and fit that? Then of course all the messing around with the timing.

12-05-09, 08:26 AM	#10
msh 4 ring whore! Join Date: Jun 2008 Location: Rucava, Latvija Posts: 3,816	Was there really "mess with timing"? I remember that some R5 engines u can turn distributor as u wish, as long there is contact, ignition timing doesn't change, 7A isn't one of them?