Clark Rupp

Car drives great for a 4 cylinder Civic ! .Within 1 mile car went from robust to missing on top end to barely crawling. Confirmed 100% functionality of coil packs, voltage transformer/ignition control unit, MAF, TPS assy. No CEL, no backfiring, smooth idle can force a downshift but wont realistically rev beyond 2,500. Rail pressure at 56 lbs.Only rock left to look under is the throttle body that I can think of... thoughts ???

MrTracy

How did you test the coil packs? Do you have a check engine light?

Clark Rupp

I rebuild these packs for a living..... http://V12icpack.com but to eliminate any assumptions I transferred them off my AMG CL65 after a test drive....... No codes, no errors, no hints..............

MrTracy

That is truly a "Head scratcher" With no check engine light on, there is nowhere to start.

Clark Rupp

Exactly.....02 sensors have been added to my suspect list along with the throttle body. No other takers on this thread and I was looking forward to some other ideas !

MrTracy

This V12 beast is challenging at times. Now the none TT models have severe oil leak in the middle of the engine issues and cylinder shut off issues.

HopefullyE63

Vacuum leaks?

Clark Rupp

Vacuum leaks will give you a rough idle, maybe throw a secondary air injection code but not kill power in the upper rpm ranges...... Keep thinking about it !

ctravis595

im willing to bet on clogged cat. Not being able to rev over2-3k rpm is classic symptom of cat blockage. I’ve had two OEM cats fail and one aftermarket car fail from running rich, too much fuel gets in the exhaust and the cats stay too hot for too long

ctravis595

o2 sensors won’t cause issues this severe, just bad fuel trims in my experience

another thing is maybe accelerator pedal module is failing, common failure on w215’s

tim687

What where you suspecting to be wrong with the throttle body?

I'm just wondering if this issue was ever resolved

tim687

Whilst rereading this thread again, @Clark Rupp assuming that you've got DAS, please rewrite the correct variant coding to the ECU. It's quite common for owners of the car to turn off certain diagnostics, such as SAI (SLP diag), catalytic converters (hinter kat diag) and O2 sensor (O2 diag)

It might just trigger the codes to come back

If you write these settings through developer mode, don't forget to turn the ignition off for 10 seconds before trying anything else.

ejenner

I'd say fuel pump. There's enough pressure for idling but won't let you drive anywhere.

When you're doing tests you're probably sitting stationary rather than checking it at the time there is going to be a problem.

If the fuel pump is only delivering 70% of what it should you won't be able to drive the car but it'll start and idle okay and test fine. It's just when you're demanding greater volume it can't deliver.

SOME diagnostics systems will give you pump RPM. I dunno if that's available in this case. If it is then you should verify the pump RPM is correct.