The limp mode code could be N75 related, but before replacing I'd check all it's connections and make sure there isn't a vac leak or something.

The other codes are fuel injector problems, I'd check the fuel injector fuse and make sure the wiring harness is connected properly and doesn't look cut or corroded. You can test the resistance and replace them if the injectors themselves are the cause. Quick job.

 

Are you chipped or completely stock?


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Its completely stock.
The hesitation only happens when I kick it down quickly. No problem if I accelerate gradually.

 

Update . I found that that the intake boot had split where one of the hoses entered it. I bought a new intake boot and installed it but I still have the same hesitation when I try to accelerate rapidly. No CEL . THe N75 valve also popped of fits connection and this little plunger thing fell out . I put it back together. Wondering if I should just get a new one. I'm starting to think the hesitation could be a delay in shifting . Its a tiptronic .Never had a problem wit ht he tranny.

 

Another Update: I kept driving the car with this hesitation problem until it started stalling out immediatley after starting. I found that the vacuum elbow that comes out the back of the intake and goes to the brake booster had a large hole in it. Replaced it . That solved the stalling problem but I still had the hesitation problem and a CEL light. Code was for a Cylinder 2 misfire. Switched coil on # 2 with # 1 and misfire followed the coil. Replaced coil. Still had the hesitation - read several posts that referred to this as "stumbling" on acceleration. Today I got a CEL again. Auto Zone scanned the codes and there was the Random Cylinder Misfire on Cylinder # 2 again, less than a week after replacing the coil. That was the only code . What else can cause this code ? Bad plug wire ? Note : I had a hard time pulling the bad coil off the plug .

 

With the 1999 AEB, the ICM is more likely to give you a #2 cylinder misfire than a bad coil.

Boost leak test it to uncover any more hidden leaks in the system. You're lucky you found the one. Sometimes they hide really really well.

Unlike the later designs, the AEB does not have a charge pressure sensor. The ECM can only "guess" at the charge pressure by watching other sensors and coming up with an estimate (MAF flow, RPM). If you're leaking boost the MAF will be telling the ECM that more air is going into the engine than there actually is. I'm guessing something like that might trigger the P1555 code. Intake leaks often also trigger lean or rich trouble codes.

What type of plugs are you running and at what gap? Inspected them to see how they look and what the gap is. The 1.8t seems to work the best with the factory plugs and not Champion or Autolite equivalents.

 

I was running NGK plugs BKUR6ET 10. I just replaced them last wk. with NGK BKUR6ET 6437. No more codes but I still have the same problem of stumbling or missing when I try to accelerate quickly. I did replace the ICM about 9 months ago. It was an aftermarket brand. I'm thinking I should just get a new N75 valve and at least eliminate that from the checklist. Maybe cleaning it out firsdtwith something like MAF cleaner would help .

 

Update: I ran the car another 500+ miles and continued to have the problem . I had the codes checked again and the 17963 P1555 Charge pressure upper limit exceeded code was there. So I bit the bullet and got a new N75 valve installed and that solved the problem . Finally.

 

Thanks for updating us, glad it worked out!

 

Well I'm having the same problem again , less than a year later. Can the N75 valve be failing already ? Its under warranty yet .
My garage scanned the codes : 16487 -Mass Air Flow Sensor P103-35-10 Signal too high -Intermittant
17963- Charge Pressure P155-35-00 Maximum Limit Exceeded
I put a different (used ) MAF in and it stumbled just as bad , if not worse.

 

Try a boost leak test to see if you're pumping air out of the system when in boost.

 

If I was pumping air out when in boost why would the code say "Maximum Limit Exceeded '? Sounds like its over -boosting which puts it into a momentary limp mode.

 

Your 99 AEB engine management does not have a charge pressure sensor like the later systems have. It has no way of knowing actual boost pressure but it does look at MAF flow and RPM and come up with a guess. If it sees huge MAF numbers at a moderate RPM it's going to think boost pressure is through the roof.

 

I had stumbling problems last year. With maf code. Went to AutoZone and bought a maf.. problem stayed.. went to vw and bought a maf.. fixed problem. You could have got a. Bad used maf I mean I even got a new one that didn't work.