1999 A4 1.8t Auto - Does a Bad O2 /EGT cause RPM not to go over 4000?

stupid question but does a 1.8T have EGT where is it located? diagram?

I read EGT can leave the Wastegate open causing no boost after certain RPM's

I have replaced Coils/ Plugs / ICM/ MAF/ checked for leaks ...also No codes

no codes or jsut no cel? you might have a code stored. it sort of sounds like you're inlimp mode.

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01.5 2.8qm: Custom CAI, 18" Hp Lightning on 245/40/18 Kuhmo Ecsta MX, CC mod, tinted tails, 2x 12" Jensen sub with a 300 watt Bazooka Amp, Asian driver....

no codes...no cel.. checked them again?? how do you reset limp mode

I did reset the ECU..actually put another one in...but still the same

Only the 2.7T has EGT sensors, you can re-set limp mode just be erasing the faults. But something is causing you to go into limp mode.
Is this an automatic?

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00 A4 1.8T

01 S4 SOLD!!!

yes Auto... but its changing through all gears... does a bad O2 cause this ?

Still check the fault memory in the gearbox and brake electronics. A faulty brake light switch can cause this, so could a faulty TR (transmission range) switch.
A bad O2 sensor would most likely throw a fault code.

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00 A4 1.8T

01 S4 SOLD!!!

I dont have VAG can I try it with something else...? take the battery off? im sure thre are no brake light off

where is transmission range switch? also the location of transmission ecu

You need a VAG COM to test these systems.
The TR switch is the entire circuit board under the shifter assembly. The brake light switch does a lot more than just turn on the brake lights.

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00 A4 1.8T

01 S4 SOLD!!!