jturkel

I was making a couple of quick runs late last night (obviously you can tell from the post time) with nobody around on the highway in the middle of nowhere. The strangest thing happened though. I floored it to 120 twice, but as I hit 120 i felt something. The supercharger like disengaged or something. When i tried flooring it, it was not accelerating quickly at all. Extremely slowly in fact. This is something I have experienced once when I was in dyno mode and put the car into that weird safety mode where the supercharger shuts off for a little bit. However, this was at 120 and it happened twice, both times at the same speed.

This lasted for about a minute and then the supercharger would eventually turn on again. I have no idea why this happened. The temperature was somewhere between 32 and 38 degrees F. I do have a pulley (evosport) and no tune. When I was stock, I had taken it to 145 no problem, but i hadnt tried with the pulley until now.

Any ideas why this occurred? Was it the temp? Or is something wrong with the pulley?

ScottW911

What makes you think it's not the pump? Lower outside temps have little effect on the intake temps. This sure sounds like a dying pump to me.

boohooramblers

+1
Sounds like a classic case of the IC pump.

TheMadDutchman

Sounds like a IC pump failure to me too. Check fuse #4 or 5 in the rear SAM also.

c32used

Ok I had a similar situation yesterday with my upgraded Johnson pump but have a small leak where the hoses attach to the heat exchanger I believe in 0 degree weather....also what seems to be like a jerk from the trans once at about 80 mph the first time after retune but before the heat exchanger and Johnson pump was put in about a month or so and yesterday twice at around
50 mph with steady throttle everytime...what might be my issue? You think the I/C pump is possible loosing pressure since the drop drip leak is there? I have to get the clamps changed on the I/C pump. No jerk issue today when I drove in -4 this morning.

P.S I do have to refill the resevior only(when warning sign for check coolant level comes on) like every three days or so....til I get clamp changed.

neihouma

I'll bet your car is running like this and not knowing it

c32used

I don't know how to read that can you PM me what I am seeing and possible cause?

neihouma

Nothing magical here Victor, it's just showing the intake air temp (IAT)
going into the intake manifold at 250 degrees, which will cause the super
charger to shut down.

I've been telling everyone to go here:

http://www.ramseyelectronics.com/cgi...ction&key=8226

It's the cheapest I've seen anywhere.

jturkel

see, the thing is, i just had the IC pump replaced (i am still under warranty until September) about 5 months ago (less than 5000 miles). it just doesnt seem likely that this is the case. i havent had this problem at any other speed at any other time. you guys really think its some kind of leak in the IC pump still?

neihouma

Yes it can happen, hell you can even hear your new pump wizzing and still
have a bad pump. Ask dkflipse I heard his loud and clear and the datalog
above was that night I heard it.

jturkel

hmm.....well thats rather upsetting. i guess i'll have to go to the stealership and get it replaced. i'd get one of the aftermarket ones that you guys run, but mine is still under warranty.

jturkel

thanks for the input everybody!

c32AMG-DTM

jturkel,

I'd be curious too... I had mine replaced under original MB factory warranty roughly 10k miles ago, back in May, and it's still functioning fine. When mine was bad, at ANY speed, after the engine would heat up, the S/C would cut out with any medium-hard acceleration. Your's, as you point out, isn't doing that; in fact, it sounds like it's working fine except when under serious load high-speed runs. Also important to consider that 1. you have an aftermarket pulley, which generates excess heat vs. stock, 2. you don't yet have an ECU tune to optimize that pulley, and 3. you don't have any cooling upgrades to offset the excess heat.

Since this is ONLY happening when you're running the car pretty hard (i.e. 120mph and higher), I'd be curious to see if a larger/more efficient HE and/or ECU tuning would fix this issue for you.

I also think you're going to have a hard time getting the dealership to replace your IC pump, unless you have a really, really good relationship with your SA. When mine was replaced, it was obviously bad, but I still got the usual line "when our tech drove the car around the block, he couldn't replicate the problem, so we can't just replace the part... are you sure there's a problem?" I explained that when the car's up to temp, I was confident they could trigger the problem... which they were able to do, so they replaced it. Your dealership is gonna say "hey, we just replaced this 5k miles ago, and in all our testing it's working fine" - you reply "yeah, it seems to work fine until 120 mph, but above that it isn't working, so I'd like it replaced" and they'll probably tell you "uh, 120? sorry, we can't replicate it, so drive safe and have a nice day..."

jturkel

yah that was the weird thing. when my last IC pump went out, it cut out at different times. not always the same speed. i wasnt sure if maybe my lack of a tune, my pulley, and the cold temperature maybe made the boost too high at 120 mph which could have shut it off. i mean, it honestly happened two or three times exactly at 120 mph, not at any other speed.

i actually have a bigger heat exchanger, but i havent had time to install it yet. though, with really cold temps like last night (32-38 degrees) im not sure if it would have made a big difference, though im not entirely sure of that.

now, ive never hit the speed governor/limiter. i wasnt sure if maybe this happened when that number (155) is hit. maybe for some reason, mine got lowered?

idk

dkflipse

Damn Rey - that hurts

As much as you want the warranty to take care of the problem - if you spend the $89 on the Johnson pump and pay an hour of labor for the install the problem will go away. Use an indy mehanic (cheaper). So for $150 you'll be driving a C32 instead of a Camry.

FrankW

supercharger boost is controlled by the pulley, not how cold the temperature is.

neihouma

The C32 is running like a champ when I slapped that SVT IC pump though eh?

Also Johnson pumps are $120+, the low price in ebay is pretty much gone.

When it was 45 degrees Donn's C32 & mine ran 20psi instead of 18.5psi.

gkstar

OK, this is very similar to what I have experienced. I went to the dealer and we drove to that speed to show them (believe it or not).

It is NOT the IC pump. Mine was changed a few months back, and the dealer changed it again just to remove this from the equation - problem still there at 120.

They suspected air pockets in the IC core, used special tool to create vacuum and refill the system making sure there was no air - problem still there.

Last visit, they got recommendation from MB to perform "AMG retrofitting instructions - relocating of relay for the intercooler electric pump in C32 AMG". This involved repair in the rear SAM - apparently there is signal interference they said, which fools the computer to shut down the S/C clutch. This involved soldering new harness, among other things (?).

After the repair, I hit 120 and S/C did not cut off, though the weather got much colder and I am not sure if I can reliably make a conclusion until Winter is over.

One thing to note is that I have CarChip and when the S/C cut off the last few times at 120, IAT was below 200 F. Not sure how to reconcile this with the explanation I was given, though it seems that in that case the computer seems to cut off the S/C for no good reason - perhaps due to the signal noise they were talking about (?).

I am hopeful that problem is solved but not convinced for sure. Waiting for the warm weather.

FrankW

that's interesting. I wonder why tho. The s/c doesn't spin any faster to increase the boost on a cold day, but why is it the boost higher? colder condense air packs more volume in one cube than hotter air maybe.

gkstar

jturkel, any update on this issue. The harness rewiring MB did on my car, which I described earlier, did not help unfortunately. SC still cuts off at 120, exactly as you described. It is NOT the pump - mine was changed twice but no difference.

Have you ever experienced coolant loss before. My last suspect is small intercooler crack which leaks coolant slowly and as coolant dries between the core fins, it clogs the intercooler and decreases its cooling capacity.

Thanks

jturkel

sorry to hear that it didnt work out for you. i have not experienced coolant loss, at least to my knowledge. i havent smelled it and i know it has a rather distinct smell. i also dont know if i still have the problem as i havent pushed it up to 120 recently. i kind of forgot about the problem. but now that you mention it, im going to look into it again b/c i have my stock pullies on now. do you have aftermarket pullies? i dont think i noticed this problem until i had the aftermarket pulley kit on.

1qikctr

keep us posted what happens.

Fifth Ring

Jeebus, a problem that kicks in at 120 mph? How often does that come into play? Sure, it's a problem, but frankly, I could have had that problem for the last three years, and the next three, and not really know about it!

But for the fact that I USED to track my C32, I would go as far as saying that I would never experienced the problem. I did hit 130+ down the front and back straights at VIR.

gkstar

It happens sometimes well below 120 (after acceleration) but not often - cannot tell the exact conditions. The frequency is way less than what used to happen when the IC pump was out.

If it was only happening at 120, I could live with it, I guess... until I decide to go on the track. When car hits 120 though, after being flored, it is 100% reproducible.

1qikctr

After reading this, i have the same issue. I have the Cm30 pump on the car, but the SC would shut down from time to time I know it can't be the pump. i'm living with the problem, only b/c i dont drive my pos 32 everyday.