Help with these DTCs please
07-16-2002, 08:16 AM
#1
AudiWorld Member
Thread Starter
Join Date: Jun 2000
Posts: 312
Likes: 0
Received 0 Likes
on
0 Posts
Help with these DTCs please
Last night I posted that my 98 1.8T has starting running really rough and losing power. The DTCS were:
16684 - General misfire
16687 - Cylinder 3 misfire
I swapped the coil packs and plugs between cylinders and three and four and the problem seemed to go away for a short time. This morning it came back. I checked the codes again and got the same ones but also got one new one.
17658 - Fuel level low
Any clues on what to do next?
16684 - General misfire
16687 - Cylinder 3 misfire
I swapped the coil packs and plugs between cylinders and three and four and the problem seemed to go away for a short time. This morning it came back. I checked the codes again and got the same ones but also got one new one.
17658 - Fuel level low
Any clues on what to do next?
07-16-2002, 08:23 AM
#3
don't swap plugs and coilpacks at the same time. It prevents you from seeing which is the problem,
the plug or the coilpack.
if it was originally saying misfire in cyl 3, swap JUST the coilpacks at first. This way you'll see if it's the coilpack that's failed. If the problem comes back on cyl 4 for example(3 swap with 4), then you know it's the pack. If it still misfires in 3, it's either the plugs, or the wires. Fuel level low often comes with a faulty coil pack, i've seen that DTC appear with 2 separate coil pack failures.
if it was originally saying misfire in cyl 3, swap JUST the coilpacks at first. This way you'll see if it's the coilpack that's failed. If the problem comes back on cyl 4 for example(3 swap with 4), then you know it's the pack. If it still misfires in 3, it's either the plugs, or the wires. Fuel level low often comes with a faulty coil pack, i've seen that DTC appear with 2 separate coil pack failures.
07-16-2002, 08:33 AM
#7
AudiWorld Super User
Have you checked plug gap?
The first time I had misfiring problems, re-gapping my Densos to ~.030" (temporarily) solved the problem. I'm getting them again some, but haven't had the energy to get out there and figure out what the deal is this time. I suspect yanking the Densos might do it....they've been known to be very iffy. Good luck
Andy
Andy
Trending Topics
07-16-2002, 09:26 AM
#10
Member
Join Date: May 2001
Posts: 17,322
Likes: 0
Received 0 Likes
on
0 Posts
For some reason #3 is the most likely to misfire. I suspect cylinder temps are a tad higher in three
for some reason. I would guess the issue is the plugs and/or plug gap and likely you have a fair amount of carbon build up in the head. How old are the plugs, what brand and what gap are you at?
You might toss a can of BG44 in the tank and see if that doesn't help. Be careful of going WOT with the BG44 tho as I've talked with folks who say it tends to increase pinging.
And yes plug gap or worn plugs can indeed cause massive misfiring.
You might toss a can of BG44 in the tank and see if that doesn't help. Be careful of going WOT with the BG44 tho as I've talked with folks who say it tends to increase pinging.
And yes plug gap or worn plugs can indeed cause massive misfiring.