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View Full Version : 1.8t misfire under boost



s4boost
03-01-2009, 03:17 PM
my friends 1.8t is acting weird. today he shifted to third and boosted alittle bit and his car shutoff. tried to start it three times and it finally started. he came home, took me for a ride and as soon as he boosted we got 12 misfires on multiple cylinders. so something is definetly wrong. any ideas as to what it could be? i have an s4 and dont know much about the 1.8t platform but could it be ICM's? TIA

speedydragon
03-01-2009, 03:23 PM
coilpacks?

bassed
03-01-2009, 03:30 PM
coilpacks?
And plugs, check them as well.




We do kinda need to know the year as well, it makes a difference in narrowing things down considerably.

bob12312357
03-01-2009, 04:44 PM
Coil pack or MAF if it really bad. Try unplugging and seeing if it still goes misfires, or clear the codes and pull the maf the CEL will still be on, but it will say something like low MAF reading, not misfires, and multiple random misfires. You getting a lean code 2? Hows the idle? What kind of trouble when starting?

v1nyd
03-01-2009, 04:46 PM
if the car is bucking a lot before it shuts off then it's definitely your coilpacks, change your spark plugs as well since they are inexpensive

black99.5a4
03-01-2009, 04:49 PM
i only got a small bucking under hard load.. it was my plugs. i'd def change those and start there.

s4boost
03-01-2009, 05:03 PM
the car isnt throwing cel's as of now... but i vaged blocks 15 and 16 and saw the misfires as soon as he hit full boost. ok, i'll unplug the maf and give it a test drive. other than that he said he hasnt done plugs in quite sometime, so thats next. the car has only died once, but when it misfires, it bucks pretty bad

s4boost
03-01-2009, 05:05 PM
he just said his coils are all new... so maf and plugs are next... anything else?

black99.5a4
03-01-2009, 05:07 PM
if it was a coil, you would of gotten a CEL.. anytime i've had friends with a bad coil, it came up rather instantly with a CEL.

mine showed no CEL and it was plugs. if he doesnt get into boost often, then he'd never really know they were bad.. mine had ~8k on them, NGK copper tips. if i didnt get on it with a hard load, i prob wouldnt know till i got to a situation like your friend.

if he's running the copper tips, they need to be changed every 3-5k, depending on boost levels, what heat and gap he's running too.

s4boost
03-01-2009, 05:09 PM
i only got a small bucking under hard load.. it was my plugs. i'd def change those and start there.

thanks... i'll report back when we find the issue

turboquattro068
03-01-2009, 09:21 PM
maf or plugs, my guess is plugs

mark_2328
03-01-2009, 11:33 PM
I had the same problem. It was the plugs.

bassed
03-02-2009, 06:23 AM
if it was a coil, you would of gotten a CEL.. anytime i've had friends with a bad coil, it came up rather instantly with a CEL.

mine showed no CEL and it was plugs. if he doesnt get into boost often, then he'd never really know they were bad.. mine had ~8k on them, NGK copper tips. if i didnt get on it with a hard load, i prob wouldnt know till i got to a situation like your friend.

if he's running the copper tips, they need to be changed every 3-5k, depending on boost levels, what heat and gap he's running too.

FWIW and for general knowledge with the DBW and particularly the AWM (2001-2001.5) a CEL doesn't always come on. It may flash for a brief moment or sometimes not at all. The AWMs eat coil packs like crazy unless you grab the BERU bolt down style replacments. This is also why I asked what year the vehicle is, but no answer on that yet.

bob12312357
03-02-2009, 09:52 AM
My 2001 would flash the CEL when I floored it and misfire like crazy. The CEl would flash for another 30 seconds or so then go away. Pulled codes, cleaned MAF. Then 2 months later coming home from Brooklyn car lost power at a light nursed it off the side of the road and died.

Yevmeister
03-02-2009, 10:34 AM
my input,

coil packs, get beru bolt on ones, make sure you get new wires/sleeves too

Yev

s4boost
03-03-2009, 12:46 AM
FWIW and for general knowledge with the DBW and particularly the AWM (2001-2001.5) a CEL doesn't always come on. It may flash for a brief moment or sometimes not at all. The AWMs eat coil packs like crazy unless you grab the BERU bolt down style replacments. This is also why I asked what year the vehicle is, but no answer on that yet.

its an 01

bassed
03-03-2009, 06:52 PM
its an 01

1) Coilpacks doesn't matter if he changed them all last week any one if OEM and even "R" release could go bad already, it's an 01' issue unless you run the Beru's I mentioned way earlier
2) Change all plugs
3) pull the injectors and clean them

Milage? Fuel filter ever replaced? You can unplug the MAF and narrow that out, since you don't need a MAF on the 01's. Start there and get back to us if it works or if we need to go into some other possibilities.

b6a4sline
07-27-2012, 07:20 AM
Got the same issue here. I unplug the maf and the car runs fine but looks like it came back to stock mode, I am unitronic 1+ right now. I'll change the maf and see what it does. Coils, plugs and wiring harness have been done couple of weeks ago.