samir1621

Hey guys, after reviewing previous post and listening to the sound of the SL55 with the resonators removed on youtube, I went out and had it done today. I have an 05 SL55 with stock exhaust, perfect mechanical condition, went to a local muffler shop, and had the resonators replaced only (not 2nd cats) with new piping. It was tested for leaks, no issues. Car sounded great, nice and deep same results as all the posted videos.
Took the car out and drove out and after a minute noticed a significant loss of power. The tach would climb to redline but the power seemed sapped out. Then after a 2 min or so, it would be right back to normal (nice and strong). I stopped the car, turned the engine off, restarted, thinking it may have been computer issue, the car pulled strong from the start this time, then once I slowed down at the next light,again...power sapped out for 1-min or so, then kicked up again.
I drove 12miles back home with normal power, shut he car off, started it back then took it around the block. Same issue, had strong power, but then bogged down for a min. No check engine light, nothing.
Have any others experienced the same issues? Could all this really be due from a loss of back pressure from the resonators? Does the computer software need time to adjust?
Any help would really be appreciated.

Thanks,

Sam

Sunir

may be your I/C pump...the SC engine should not have an issue with backpressure like a turbo. SC forced induction is pulley driven as opposed to turbo which is driven off of exhaust backpressure...

charles pearson

+1, it's the IC pump for sure. I had a similar fate and just installed a Johnson pump on it. Search the threads on IC pump failures and you will learn a great deal about your situation just as I have.

RNSL65

@sunir
Turbo engines needs as little backpressure or resistance in the exhaust as possible. So the more “free” the exhaust is, the better!

Sunir

ahh ok so if a turbo car increases exhaust piping diameter, thus reducing backpressure...it's better correct?

now what about a SC car, to be more benefical would you want to reduce exhaust pipe diameter or increase it? in other words what effect does backpressure play here?

150shot

IC Pump....in reagards to the backpressure- I honestly believe these cars are way fast enough to worry about loss in backpressure.

YOu probably wont feel a difference and the sound is well worth it.

FLSL55

I bought my scanguage II JUST for this purpose.

I can see intake temps and boost pressure. I will know the second something is wrong with either my IC pump or anything else related to the supercharger. Well worth the money IMHO.

If you can, get the new stock OEM pump. They have worked the kinks out and IMHO is better than the CM30 pump.

charles pearson

"Really", I gave up the opportunity under warranty to go with the CM30 Johnson, the dealership was willing to replace the pump w the OEM, WTF Over, Ranger's make mistakes I cannot believe it.

FLSL55

Charles,

Some say the CM30 is the same as the OEM but I think the new OEM pump actually flows better under pressure than the CM30.

The OEM keeps my IAT's cooler by over 10 degree's. You never know though. I might have had a bad CM30....?

From my experience, your IAT's need to be lower than 110 to get full power from the 55 engines.

charles pearson

K, thanks Bro