Intermittent power loss 2003 C32
Original owner 40,000 miles. Do not drive car much. Over the past four years I have been trying to find and fix an intermittent loss of power.

The symptoms are:
Runs OK (full power, no strange noises, etc.) for about approx. 6 miles.
Power loss occurs when floored, it downshifts, engine note changes and power loss.

Attempts to fix:
Replaced inter-cooler pump with Johnson CM30.
Replaced supercharger clutch.
Replaced fuse and relay.
Replaced belt.
Valeo raditor and torque converter replaced in the past.
Transmission recently inspected and serviced.

Pump working OK, when shutoff engine pump runs for a few seconds.

Any clues, advice, suggestions, hints, etc. will be appreciated. Great car when it runs correctly, would like to fix and keep. This issue is driving me crazy.

Last attempt. If not fixed will consider selling.

 

Any coolant loss lately? If your intercooler is leaking you won't see any coolant around (it's being sucked into the intake charge) and could lead to power loss. You'll get an occasional low coolant warning.

 

find someone with a mb star computer.

 

is this a problem when the car is hot?

 

Any update to this? I'm in the same situation; replaced everything but still have intermittent sc cutoff.

 

Check gas pedal assembly, same thing happened to me, or throttle body

 

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Changed​​ the following : IC pump, fuse 18 (I have an 04) , added relay to C (04 apparently doesn't have this), MAP sensor, IAT sensor, cleaned throttle body, bled cooling system . I did all these but yet I am still getting intermittent s/c cutoff. I can usually feel when SC will not work because of a slight jerk. After driving a lilttle more, slight jerk and s/c works again. It does this cyclically. It doesn't matter how hot or cool the weather is--same s/c behavior.

Any ideas what's going on? Such a pita. Don't think it's a gas pedal thing either. .

 

Gotta look at the actual values when the blower is cutting out. It's either not seeing 100% throttle, or it's seeing a temp sensor or something it doesn't like and disabling the blower. Get someone with SDS to drive it when it occurs with the scanner connected and see what changes.

 

any codes?

 

Have you checked for power going to the pulley after it starts acting up? Also, it's unlikely but theres a chance there may be something wrong with the engagement of the pulley itself.

 

No codes
No access to anyone with SDS from where I live

Temp sensor, as in coolant temp sensor?
I've changed the intake air temperature sensor already, no change.

on a side note, I've never heard or felt the vibration from the IC running for 10-15 seconds after shutdown either, and that's after a good run with the S/C engaged too.

 

Get one of those wifi or bluetooth OBD2 plug-in devices you can read with your smart phone (<$20). Get an app for the phone that reads the outputs (<$20).
Set the intake air temp as one of the gauges. It should be 20-25 degrees higher than ambient most of the time. If it gets over a certain level (180??) it will shut down the SC, and let you know the SC pump is not working because it is not cooling the intake air.
It will also tell you a whole bunch of info about the car as it is operating, so you may be able to lead you to the problem.
Let us know how it turns out.

 

Data logged the car this morning. Engine coolant temp stayed steady for the most part around 194F, while the IAT was hovering around 208-214F. IAT would not drop below this temperature range during normal cruising. SC still engaged at this point. After a brief acceleration, IAT went to 220-222F, at this point SC disengaged.

As I continue normal cruising with no SC, the IAT starts dropping—drops into the previous range of 208-214F and continues to drop, but SC still did not engage. IAT finally bottoms out around the 190s range, at this point SC can be engaged. SC stays engaged until IAT starts climbing to 220F+ range after spirited accelerations. This temperature behavior repeats over and over.

So I guess this points towards an intercooler pump not working all the time. It’s a brand new, revised Bosch pump. 04 does not have RELAY C, fuse 18 (equiv. fuse 5 for 02-03) for IC pump is good. Any other suggestions? Maybe clean connector contacts?

 

Those temps are extreme. So you are not cooling through the IC/SC pump, that is pretty well known.

First - see if the pump works. You can use an SDS to turn the pump on.
If no SDS - Apply power to the pump leads and see if it runs. If it does not run, the pump is bad. If it runs, it may be in the electrical not supplying power through the relays and fuses. That requires tracking down.

If it runs, see if it flows through the system. You can pinch one of the hoses above the alternator and it should flow into the reservoir when the pump is running. If no flow, something is blocking it.

Go from there and see what you find. Keep us posted.

 

This probably explains why my MPG is so far off the on-board computer.
I will perform these tests and report back..

 

Just an update. Still haven't fixed this yet, but recently had the opportunity to do the above tests. Pump works--jumped with a 12V battery (how strong is the pump supposed to be? I hear it working, but it's not loud). However, there seems to be a clog somewhere in the system as I don't see any flow back into the reservoir.

Could there be anything in the radiator that was left plugged or not removed during installation? Radiator is a couple months new.

 

could be air in the system

 

Pump is pretty quiet.

Here is how to bleed air. There are 2 hoses from the pump. Pinch off The top one just below the WYE. This will force air from the supercharger 'charge air cooler' into the reservoir. Open the reservoir cap to see if pinching causes the flow to happen through the small feed hose. If your pump is running backwards this may cause the flow to be weak or backwards. I don't know if these pumps can be made to run backwards.

Here is a DIY from another post...

In the course of events leading to my quest for a better cooling system(s) I have drained the coolant
several dozen times over the summer.
All above is true, however I have added a relay and a switch to power on my pump at will when the
motor is off. I use it to do some testing but have found that the pump runs all the time you are
driving, pretty much anyway. Engine on pump on but you want to be wary of the belts and fan start
up, so use the clamp below and save a 911 call.
To bleed the system you partially pinch the return hose as described and drive around a bit and you
will purge the air pronto. Just driving will do very little as bubbles will stream forth for a long time.
How do you pinch the hose and drive around without getting hurt?
TA DAAA, get a hose clamp, open it and slip it around the 5/8" rubber hose below (lower) than the
wye at the i/c tubing as shown (aluminum) and tighten it slightly (pinch hose about 1/3 closed - 2/3
normal diameter). This will add enough restriction to raise the pressure in the hose and force coolant
to flow into the recovery tank purging the air more rapidly.
I’d do this with the cap loose as it will be cool enough to not need it and the lower pressure will make
the bubbles more buoyant (bigger). Take a gentle spin down the street or idle for a while and return
the i/c pump will be fully on, doing the purge. Stay out of the moving pieces and parts please.
Remember to loosen the clamp, you can leave it on for next time and with this approach you don’t
need to have the STAR gizmos.