ArrayMFC

2002 S4 with 12K on it.

Had GIACX chip for 10 months, about 10K miles. Also had GIAC TIP CHIP, Baileys, AMS TBB and SS exhaust.

About three months ago had a big time coolant leak. Flatbedded to dealer. Thank goodness, it happened in my development, and was able to put back in stock ECU and all other parts (TBB, etc) and Vag all.

Get car back and feels like hell. I say, WOW the upgrades made a huge difference. So put all mods back in. Reset all and ran simple for a few days. Then on WOT car bucks and goes limp.

Well Vag, reset ECU and ran it for a few more days...bamm ran like hell. Limp mode a few times and Overcharge pressure a few times. So check all connections, reattach all clamps and clear codes. Same thing again. So I put all the stock stuff back in to see if still have problem.

No codes, no CEL. Three months later still on stock, not one code. But the car feels horrible (worse than my brothers stock s4), and slower than my Xterra (almost ok). It feels very "vacuumy" like I have to move alot of air thru it to get any boost. Also notice much more turbo lag from standstill. So I am back to stock, not throwing any codes, but feels terrible.

All attachements and hoses are good. So I have narrowed it to five scenarios. 1) turbos are dying...are noisier than I remember 2) leak somewhere still 3) MAF sensor bad 4) SS exhaust has a leak 5) somehow the wastegate is shot

So guys, I do have a Vag but never logged anything. How and what would help ID the problem. Second, any way to tell if the wastegate or MAF is shot? Any idea why the car feels like its got some huge vacuum dulling pedal response until I stand on it, and then only marginal at best.

Thanks for the expertise. I can use my S2000 in the snowy weather...HELP.

Happy Holidays and a sincere thanks (as dealer is worthless..no code, nothing wrong).

NEPaNogaro

Could also be a bad N75 valve. Where are you located?

ArrayMFC

When I reassembled the car back to its mod state, I completely took apart the Baileys, and regreased and reassembled. I then put my mouth on it had they (as well as the barely used stock ones) all held pressure.

What is the pressure tester?

I did notice that the dealer did take the engine apart to get to the coolant sensor blowup. I replaced all the clamps with the good ones (from AMS).

Thanks for the help..I really appreciate it.

MC

NEPaNogaro

You might be able to find someone locally that has one, hence why I asked where you are located.

ArrayMFC

any ideas on the wastegate or MAF checking. Others have mentioned that.

Thanks again.

NEPaNogaro

I wrote an article sometime ago regarding how to use block 211 to check the MAF. If you can't find it, let me know. I can't see the MAF causing the car to buck and go into LIMP, at least without a MAF error code.

Wastegate - it's a good possibility. Try logging block 115 using your stock chip. Give it a good 3rd gear WOT to redline run after oil is warmed up. Post the results. Actually - graph blocks 115 and 211. Turn your sampling rate up in vagcom (see ross-tech faq's on their web site).

Ron O

Mine is running fantastic.. My son just got a BMW 745 and my S4 is faster and I like the drive better.. you should be able to get back to how it was new..

AlanL

<center><img src="http://pictureposter.audiworld.com/14388/boostlog.jpg"></center><p>A boost leak is very easy to spot because actual boost will not match requested boost. The plot shown here demonstrates a very nasty boost leak that turned out to a hose that wasn't properly clamped down between the turbos and the IC after a dealership turbo replacement.

No CEL ever came on and the only real sympthom when driving the car was very anemic response. A pressure test resulted in a very obvious air leak well out of sight in the depths of the engine bay.

J4SON

I think AOL will just try to give him a few hours of free service. :-)

Ghant TMK

Are they misfire codes?

It only happens with my X CHIP. White stock car runs fine. HAve you check your coilpacks? Could be them if its misfires.