2000 sl2 no low end power
 

I purchased a 2000 sl2 with a blown engine. rebuilt it top to bottom, new everything. runs perfect at idle make no unusual noises. now the hard part--- if you just barely give it gas going up hill it will almost come to a complete stop, it acts like it does not want to take the fuel but, if you drive it hard it acts fine. Any ideas?---Thanks

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Any ideas?---Thanks
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Assuming ignition timing and fuel pressures are correct which can cause the problems your not going to like my idea
You did not get the chain to cam shaft to crank shaft orientation correct and one or more of the cams are out of sync with each other.
Been there and done that. Hate the thought, but
that's my idea and I'm sticking to it.

I had exactly the same thought so yesterday before I even posted my question I took the timing cover and the head back off. Everything was in order, all marks are where they should be, pistons looked good and tight, valves and head are good. I did the reassembly and the car still runs the same (perfect idle but no low end power). I'm wondering if it could be a sensor or computer glich

I would imagine that if you ran a computer check of the engine control computer if there was something wrong some where an error code may show up. Moving the Accelerator wiggles the throttle plate, the position sensor determines where the throttle plate is, the mmap sensor pretty much senses vacuum which would drop when the throttle is open and the mass air flow sensor would determine how much air is coming through (I'm trying to remember if there is one and should not answer this from memory because if there isn't than the algorithms would work as a Speed/Density system and assume air flow for a given throttle position, rpm required and size of engine rather than measure so I apologize for the moment for not remembering whether the car uses one or not and not looking it up to be sure )
The engine would then accelerate based on fuel pressure (controlled by vacuum and pressure regulator on the fuel rail) pulse width to the injectors (controlled by the engine control computer, sensors etc.) and ignition timing (controlled by engine control computer and the mmap sensor)
If the chain driving the cams is indeed NOT out of sync then something else could be hooked up wrong. A sensor cross coupled (that would make it 2 sensors) a vacuum line not correct. Which probably makes it two vacuum lines.
I once owned a used Camero IROC Z-28 under the same circumstances that pinged badly.
I finally found out why, the engine heat sensor and the knock detector sensor were hooked up backwards. When the engine started to ping or knock, the heat gauge would show you running hot! This was a result of having the engine rebuild before I bought the car.
Once traced down and connected correctly it ran fine for a long time.
It is not absolute the if a sensor is the fault, than it be an engine sensor. Road Speed and engine rpm all are a variable including what gear it is in too.

We are on the same page. I am in the process of going thru the sensors one by one. Since the car was inop when I purchased it I do not know if it had this problem before. I've rebuilt 20 of these engines and this is the first one that has acted like this. Also the computer shows no codes on my hand held diagnostic computer which makes it even harder to find out what's wrong. Thanks for the help.

Good throttle body cleaning? Throttle plate maybe hanging up?
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ECTS -- engine coolant temp sensor -- the bane of s car engines
creates way too rich a fuel mixture

30 for sensor (brass style), 15 for connector dealer only (replace if internally corroded)

I already cleaned the throttle body and installed a new cts but anyway I decided to try another new cts(borg warner) and it actually seems a little better. I'm going to drive the hell out of it and see if it straightens out in the next couple hundred miles. Thanks for the help!

Did you replace the ECTS connector? if not get one from the dealer .....

update
 

believe it or not I fixed the damn thing!!! I started swaping out sensors one by one and it was the knock sensor that was causing the problem and it never showed a code for it. Thanks for all the help.

I wonder if loading that bad boy up with 94 octane would have made it run good.

Like maybe the knock sensor was being too picky about the fuel, but if it had higher octane it would have worked...

And then you would have known it was a knock/sensor issue.