Stage two woes

**foxtrot121** · 10-21-2010 05:45 PM

New member here with a stage two 2001 S4.
I've had the car now for about six months and I've been chasing what I think is a missfire or hesitation issue. I only had access to a vagcom once right when I got my car and was having some random missfires at idle and under boost. I don't remember what cyl they were on but, they seemed regular enough to make me want to change the plugs. Pulled several plugs out and they looked respectable so I went ahead and replaced the coilpacks and the plugs. The car seemed to run a fair bit better. It had a little better pickup and the missfire/power loss seemed slightly less noticeable.

Short story though the power losses still there. They're just in some odd places.
I noticed that if I'm going an indicated 4 mph with my food on the brakes, the car missfires, but if my foot is off the brakes it doesn't. Same at about, 6 or 7mph I believe. This happens when the car is coasting, clutch in or in nuetral.

(I went through a long traffic jam that was slightly downhill this gave me an perfect time to find this haha)

Then if I move up the rev range I notice that say I speed up to somewhere above 2,000 rpms, coast back down to 2,000 rpm and roll back onto the power to maintain a constant 2,000 that there is a slightly noticeable hiccup right as power comes back on. Only ONCE though does it hiccup.

Now onto the MUCH more obvious part. Under high load in any gear; Read WOT, there is a very noticable, easily repeatable and annoying hiccup hiccup hiccup hiccup. If my foot is all the way in it from 2,000 the boost comes on good. As I hit about 3,000 it starts going hiccup hiccup hiccup hiccup. All the way to about 4,200 rpm. But from about that point on it pulls like a raped ape all the way to redline.

New coilpacks and plugs, 94,000 miles, apr stage two tune, apr tbe.

OH! And if I switch back to the stock tune it does not hiccup ANYWHERE AT ALL!!!!

Please help, I don't have easy access to a vagcom and am very new to B5 S4's. I'm a E36 M3 guy orginally so this whole thing is new to me.

**SomeDayAS4** · 10-21-2010 06:43 PM

if its stock and runs good, then maybe its your tune?

**csosnowski** · 10-21-2010 07:02 PM

Have you checked for boost/vacuum leaks?

I have an APR tune and had a similar powerband hiccup, but on the stock file it was more or less fine. I remedied this by tightening the gap on my plugs from 0.032 (out of box=crapgap) to .024 and this is with a stage 1 tune 91 oct.

You may want to pull your plugs back out and check the gap. 0.022-0.024 is prolly good for the tune you have.

Also, you may have a bad ICM. The little black boxes on top of your airbox. Without a vag-com to see where the misfires are coming from, the easiest thing to do is swap in a known good one. If the problem ceases then that icm was bad, or if not then swap the known good one in for the other one.

Hope this helps!

**audiSUKKA** · 10-21-2010 07:51 PM

Does your car stutter at a certain psI?

**foxtrot121** · 10-21-2010 07:52 PM

I don't wanna take my plugs back out. *grumble grumble* Its a PAIN in the ASS to take the intake pipes in/out. But I Should regap them to about 22-24 thousandths?

I do NOT have a boost gauge.

**csosnowski** · 10-21-2010 08:28 PM

Did you gap them when you put them in?

Yes, they should be gapped 22-24 thousandths. There are guys that run 16-20 thousandths running higher boost iirc.

What problem do you have taking intake piping off?

Take the engine covers off, unscrew the clamps on the dv's, take out the airbox, take the one 10mm bolt out of the upper inlet bracket, remove whole y-pipe dv's and upper inlets. Make sure you put something in the lower inlets so something doesnt fall in there...

**foxtrot121** · 10-23-2010 10:19 PM

No... I didn't actually gap them. I was in a hurry to get going again, and had good luck with the box gap last time I changed plugs.(Different car)

I hate changing the plugs because I tend to get in arguments with the maf, I have a hard time putting it back in. Not to mention it sounds like I took out my intake pipes the hard way last time. I left the y-pipe and dv's on the car and took out the upper pipes only. Not fun to try to get it all lined back up and get the rubber boots on. Oh, and the 10mm bolt on the drivers-side upper pipe was a huge hastle for me to put in. I couldn't get it threaded and just felt like I didn't have nearly enough room to stick my fingers in there to thread it easily.

Am I supposed to take off the entire y-pipe, dv's and upper intake pipes in one piece? How do I get the PCV breather off the y-pipe? Do I just take the intake off the y-pipe after the maf near the accoordian looking hose?

**csosnowski** · 10-23-2010 10:40 PM

I leave the accordion tube on because its difficult to remove the tubing from the back of it. Yes, remove the accordion clamps from the maf and the y-pipe.

Forgive the bad grammar ive been drinking since 4pm pst.

I take the airbox off and the y-pipe, dv's, and upper inlet tubes off when i do plugs or coils or whatever deals with the valve cover area.

The PCV has 2 sections of the clip that holds it that are serrated, opposite from eachother, that you squeeze together and it releases it from the y-pipe.

Use an 10in extension on the 10mm bolt on the inlet brackets for the psgr side and 3in on the driver side, it makes it easier.

Hope this helps!

**rtl5009** · 10-24-2010 08:09 AM

Originally Posted by foxtrot121

I don't wanna take my plugs back out. *grumble grumble* Its a PAIN in the ASS to take the intake pipes in/out. But I Should regap them to about 22-24 thousandths?

I do NOT have a boost gauge.

Plugs aren't that big of a pain man, and don't have to remove your upper inlet pipes to get to them just loosen the bolts, only your airbox y pipe and silicone hoses. The coil pack will shimmy out.

Buy Denso iridiums gapped to .025 and throw those in.

Get yourself a boost gauge and VAG if your serious about the car too. Otherwise you're going to dump more and more money chasing issues that you can't pin point.

**foxtrot121** · 10-27-2010 01:39 AM

I'll have to get to it in a couple days... could it be that my car doesn't like NGK's?

**AvantGuard** · 10-27-2010 03:12 AM

Just a suggestion, you may want to check your brake booster vacuum line check valve and the line itself.

**s4bg1089** · 10-27-2010 04:10 PM

Boost leak? Check for a tear in the throttle body boot on the bottom side. I had the same issue after I chipped mine. The boost was strong enough to open the tear with the reflash but once I put my stock ecu in, the car ran a lot better considering the lower boost. From that point I just switched to an APR bi-pipe. Just a thought.

**foxtrot121** · 10-29-2010 12:15 AM

well I checked my plugs tonight, they were clean and properly gapped....

I have an Apr bi-pipe so I don't have to worry about a tbb boot, but a boost leak isn't out of the question. I guess I need to bug my friend that has a vag-com ... I'd be looking for missfires and requested vs. actual boost right?

I still think its odd that it doesn't happen on my stock tune. (same ecu different program accessed through cruise buttons).

**Yesmar** · 10-29-2010 01:08 AM

ive had a problem with what you are discribing in the past i switched to bosch sidefire plugs and it sorted my problem out.

**Nadrealista** · 10-29-2010 08:07 AM

first make sure you don't have any vacuum leaks..run two bottles of techron FI cleaner in half tank of gas with lot of WOT/high rpm driving...put in new air and fuel filter

hesitation under WOT(boost) is often caused by EGT(s) sensors on their way out

and once you take care of it slap VAST meth kit on it... you will love it!

also get a boost gauge if you don't have one

**Nadrealista** · 10-29-2010 08:19 AM

Originally Posted by csosnowski

Did you gap them when you put them in?

Yes, they should be gapped 22-24 thousandths. There are guys that run 16-20 thousandths running higher boost iirc.

What problem do you have taking intake piping off?

Take the engine covers off, unscrew the clamps on the dv's, take out the airbox, take the one 10mm bolt out of the upper inlet bracket, remove whole y-pipe dv's and upper inlets. Make sure you put something in the lower inlets so something doesnt fall in there...

Stock plug gap on stage 2 car should be fine..gap is not the issue here

**fazda** · 10-29-2010 09:07 AM

fack i just went stg2+ about 3 weeks ago and have yet to gap my plugs, although it doesn't seem to be blowing out spark, looks like i will do that this weekend.

thanks for the reminder!

**csosnowski** · 10-29-2010 10:58 AM

Originally Posted by Nadrealista

Stock plug gap on stage 2 car should be fine..gap is not the issue here

it may be for some, however my car had noticable misses when the gap was upwards of .024 (where it is now).

my car=stage 1

**foxtrot121** · 10-29-2010 04:31 PM

So I should vag-com the car and look for odd readings from my icm's and egt sensors????

What kinda things do I look for? What channels? Should I look at requested vs actual boost?

Whe I got my car there was a stored code for egt sensor improbable reading or something ....

**foxtrot121** · 10-31-2010 02:53 PM

I've never used vag-com before so I don't know what.I'm looking for.

**lilsoccerstar** · 10-31-2010 06:39 PM

yes look at requested vs actual boost... block 115

Also look at blocks 13,14,15,16 they are the cylinder misfire blocks.

I had the same issue as you. Misfires here and there and stuttering / hesitation. All these symptoms werent enough to trigger the CEL. The vagcom refreshes every minute and throughout one minute I would have 3 or 4 misfires usually out of cylinder 4. I replaced the ignition control module coilpack and spark plug.

Then I checked block 115 for requested vs actual boost as the car was still hesitating / stuttering. I found that there was quite a large difference in requested vs actual which led me to believe it was a leak. I plugged the air system right before the bi pipe and put air pressure through it with shop air ( I had a pressure regulator on there so I don't blow anything) It ended up being a tear in one of my intercooler hoses.

Now the car runs amaaaaziing.

**foxtrot121** · 11-02-2010 10:09 PM

I'm trying to arrange to find someone with a vagcom to help me, but I'm having a very hard time getting a hold of my buddy. So I might as well check for boost leaks because it couldn't hurt.
Where/how do I pressure test my intake? From the y-pipe near the accordion hose to the throttle body?
How do I bock off the intake? What pressure am I going to be checking it at?

I need a local to help. Haha.

**foxtrot121** · 11-02-2010 10:23 PM

Interesting thought.... My stepfather has a TT225 that runs very well, I assume it has an N75 valve? If I wanted to check to see that mine was ok could I swap his onto my car to see if it acted any different?

**foxtrot121** · 11-04-2010 01:13 AM

Got the car vagcommed tonight, it appears that I have a boost leak above stock boost levels.

I suppose that narrows it down to the pressurized hoses? Or no?

**foxtrot121** · 11-09-2010 09:42 PM

Made a pressure tester tonight and hooked the car up at ~15psig. No leaks found, even using a mechanics stethescope.

:(

What do I do now?

**foxtrot121** · 11-10-2010 10:49 PM

I don't really want to take it to a shop...

**Nadrealista** · 11-11-2010 07:08 AM

good now see if you have vacuum leak..did VAG show any EGT codes?

**foxtrot121** · 11-11-2010 01:52 PM

Originally Posted by Nadrealista

good now see if you have vacuum leak..did VAG show any EGT codes?

I smoked the car for probably just more than an hour. No smoke to be found except on a loose dv connection.

Yes I did have codes stored for egt sensors. The two timed codes have been in the computer they have been the same codes. One bank says intermittent ground... or something like that and the other bank says........ I can't really remember. Improbable readings?
Bad grounds on one and the other dying?