Check Engine On- P0170, Right Bank

97 E420

I researched the posts on this, but most of the diagnosis has revolved around both a 0170 and a 0173 code, indicating a MAF problem. I am showing only a P0170 right bank reading and the check engine light stays on. I opened things up and found a completely decomposed vacuum line (from valve cover to throttle body) which I have replaced. It still takes half pedal to get the car moving, but after that its a rocket ship. With the hose replaced, why do I still have sluggish get up from a stop light? Is it something that must be reset before the on board knows its fixed? Or was the hose just a side trip and the real deal is gonna cost me?

I disconnected the battery and it all cleared up for a few minutes. One hot lap around the subdivision and it came back on. In fact for the first time the car stalled at a stop sign and the ASR light came on. Restarted no problem, but I am back to where I was.

 

Sounds like an O2sensor, but if it is stalling it could a maf sensor or the hot film sensor. The hose most likely had nothing to do with it and if it set a hard error,which it did P0170 then most of the time it will have to be reset at the dealer. Autogunner.

 

Hello,
I just wanted to get an update to your problem. I have a 97 E420 with the same problem of asr light and idle high and low at a stop sign. I change the same crankcase ventalation hose and cleaned the throttle body and still same problem after clearing code with my autozone code reader. I got p0507 which is manufacture control vehicle speed control auxliary input and p1580 idle control system rpm high. Let me know if you got any answers or if anyone out there has some help. please
andye420

 

The code is not enough to determine the fault. This is what you need to do...

1. Find a mechanic with SDS to read the adaptation values. With that code pay close attention to the fuel trim values. If they are 1.15-1.32, then odds are that you have an Air Mass Meter (on that engine, you only measure mass, not flow rates...) problem. Swap out the AMM for a fresh one and reset the adaptations. Drive it and re-check the values.

2. If the adaptations for fuel trim are <1.00 (.67) then you probably have a bad pressure regulator.

If the fuel trim adaptation values are good, then look closely for a misfire. This is a measure that uses the crank angle sensor and rpm. Things that can cause a misfire include bad plug wire ends, bad plugs, bad coils. Pull the plugs and look at their condition.

If you had fixed the problem by repairing the vacuum line, the CEL might go out, but you really should reset the adaptation values and recheck. We can speculate on here 'till the cows come home, but without some real diagnostic work, not a lot of progress can be made...

 

Usally a P0170 and P0173 are the Mass Air Flow sensor.
Also listen to see if you have a vacuum leak.

 

Yes, those two codes usually point to an Air Mass Meter (on that car, the metering system only measures the density of the incoming air charge, not the flow rate) but they can be other things as well. Before spending the dough on an AMM, it would be wise to properly diagnose the problem. If you have a willing mechanic, you could replace the AMM and see if the problem is solved and if not, return the part. Most dealers won't allow the return of an AMM, so you'd be out the money unless you have some sort of up-front arrangement.

The intake "boot" can crack, allowing air to leak in behind the AMM, and this will provide symptoms just like a failing AMM, as the air charge has not been properly metered.

In the case of the original poster, we can speculate until the cows come home, but until the adaptation values are learned, we won't make much progress.