strange issue, no cel and no limp mode

[S4evr]

first time i noticed this was yesterday, but i didnt think anything of it for some reason. until today when it continued to happen today. regular driving around is fine, and i can boost up to 15 lbs just fine as well. anything more than 15lbs (mbc is set to 21-22 roughly) and its almost like the car is backfiring, yet still accelerating. you can feel the loss of power as well. power cuts in and out almost like im hitting fuel cut or something. I previously had a cel due to "overboosting" so i cleared my codes last night, and lowered my mbc from 24 lbs to 21 lbs.

as of now, there is no cel, and i am not triggering limp mode. anything above 15 psi and the car hesitates and sputters. could this be as simple as a boost leak? where should i start if the car is not throwing any codes? should i continue to drive and wait for a cel, then check it?

my gut feeling is that it is a boost leak. i've never had one before so i cant compare it to one, but it is strange how everything is fine up until 15 lbs. i cant pressure test right now because i dont have access to any kind of compressor. if you guys think its a boost leak ill start going over the common places first (tbb, f hose, ic piping)

[turboquattro068]

Since your a fellow NY'er, I'll chime in. I'd say start with spark plugs, I had the same problem when I first put my big turbo in, I started buying all sorts of stuff to replace, I replaced my ICM, Coilpacks, etc. Didn't think the easy route and to change the plugs, they didn't look terrible, but once you go up into high boost you need a good spark. Atleast try checking them first.

[S4evr]

ill take a look at them. they were changed when i went stage 3 about 15,000 miles ago.

[S4evr]

ttt! anything more i should check today?

[espo4442]

is the boost surging?

[RolledMySTi]

Pressure test first before you spend any money.

[s2the4]

ttt! anything more i should check today?

EMIL 15K on your plugs! I change mine every 3K I also buy the cheapo NGK plugs. Check that it sounds like your plugs are fouled out! same thing happened to me down at H20 last year against that corvette

[J-tec]

Plugs mang! i'm tellin you!

What do you fellow Stg 3 guys run?

I'm running NGK Bkr7e's in my ko4-20 jetta and change them every 5k

[J-tec]

http://www.audizine.com/forum/showth...=238650&page=2

[S4evr]

will check plugs in an hour or two!

[AielloS4]

bkr7e's are good plugs, its what im running. i'd try a set of those plus you can pick them up for cheap.

[S4evr]

^did they come pre-gapped?


Just checked the plugs. for 15,000+ miles they dont look TOO bad but regardless they do look fairly worn. ima pick some up since i should either way. Tony, ill try the plugs you recommended

[b5rs4]

I had a very similar issue long time ago and it was a bad coil pack but if you are not getting a code it might be hard to determine.

[AielloS4]

emil, gap them to .028"

[S4evr]

i've never gapped plugs, i have the gap-measurement "disc" or w/e you wanna call it but ive never actually used it. how delicate do i have to be with the tip/electrode when i'm gapping them?

[s2the4]

bkr7e's are good plugs, its what im running. i'd try a set of those plus you can pick them up for cheap.

I run the same plugs in my S. After running about 100miles + of race gas I don't think they are going to last to much longer. Start up on cold days are not so good now. I normally change those plugs every oil change.

[s2the4]

i've never gapped plugs, i have the gap-measurement "disc" or w/e you wanna call it but ive never actually used it. how delicate do i have to be with the tip/electrode when i'm gapping them?

be rough and hard Germans love that shit!

[AielloS4]

I run the same plugs in my S. After running about 100miles + of race gas I don't think they are going to last to much longer. Start up on cold days are not so good now. I normally change those plugs every oil change.

hey whatsup man? when are we meeting up and doing a few pulls?

[s2the4]

hey whatsup man? when are we meeting up and doing a few pulls?

before it snows for sure

[J-tec]

chief, bang the top of the electrode on a table or something, not very hard, but enough to make it move a little. Then check the gap, do it again, etc.

[infinkc]

did you try and vag the car even though no cel was on the dash? I had a similar prob when my egt sensor died, was a "soft" code. My car seemed like it fuel cut about 4200 rpm.

[S4evr]

putting in new plugs tomorrow. rpm does not affect it, i can cruise all the way to 7100 w/o any problems but as soon as boost comes on im done. well see what tomorrow brings

[S4evr]

all fixed! plugs were the trick lol

[S4evr]

TTT!

problem just came back. i installed the new plugs and the problem went away for 2 days, and just came back today. now however, i have a CEL. it'll still drive fine normally, but as soon as i hit high boost it sputters similar to fuel cut and a flashing CEL came on. i let off the gas to coast and it smelled like burnt something for a few seconds, then the smell went away and the CEL went to a solid state. i dont have VAG, but i've got a friend coming next who has it so i can scan the car next week.

up until then, is there anything i can do? can i continue to drive the car normally, w/o high boost?

[highPSI-S4]

my car does the same so i'm subscribed for now. Sputters when i boost past 10psi also i get the flashing CEL. I'm being lazy but i have a set of injectors to throw in and see if that helps. Plus my plugs are new Denso Iridiums IK22 i believe.

[xx_s4quattro_xx]

first time i noticed this was yesterday, but i didnt think anything of it for some reason. until today when it continued to happen today. regular driving around is fine, and i can boost up to 15 lbs just fine as well. anything more than 15lbs (mbc is set to 21-22 roughly) and its almost like the car is backfiring, yet still accelerating. you can feel the loss of power as well. power cuts in and out almost like im hitting fuel cut or something. I previously had a cel due to "overboosting" so i cleared my codes last night, and lowered my mbc from 24 lbs to 21 lbs.

as of now, there is no cel, and i am not triggering limp mode. anything above 15 psi and the car hesitates and sputters. could this be as simple as a boost leak? where should i start if the car is not throwing any codes? should i continue to drive and wait for a cel, then check it?

my gut feeling is that it is a boost leak. i've never had one before so i cant compare it to one, but it is strange how everything is fine up until 15 lbs. i cant pressure test right now because i dont have access to any kind of compressor. if you guys think its a boost leak ill start going over the common places first (tbb, f hose, ic piping)

This happen to my b5 a4 after i upgraded to k04 and a new ecu it stopped. I think i know what your talkin about when you gas the car the car makes like a constent popping noise right? Sputters real bad then it picks up and go. I think it could be ecu because when i upgraded the turbo they sed my ecu was soldered incorrect. Is your car flashed or chipped?

[S4evr]

my car is stage 3 from awe, the older non-mbc version. i dont think it is ecu related because everywhere in the rpm band is fine, idle is fine, even 3/4 throttle is fine. im going to take a closer look at spark/ignition, and even fueling.

i also need to figure what i was smelling when my car had the flashing cel under heavy boost.

[s2000_s4_525]

If it sputters when you punch the gas, then its because your running to rich. Has to do with tune my bet. This happend with my s2000 when i first put the turbo kit in it would sputter befor load.

[highPSI-S4]

I smell something to after boosting, it smells like burnt oil almost to me.

[S4evr]

To bring this back.. I fixed the problem long ago and ended up being my MAP sensor. (Boost pressure sensor on TBB)