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View Full Version : Drops a gear, falls on it's face.


BAD MERC
07-23-2017, 09:33 AM
Had an interesting drive last night. Drove the Merc to work and on the way home a guy I work with in a Scion tC is beside me at 45mph. As I stomp 3/4 throttle and hit passing gear the car fell on it's face and acted like it was running out of gas near 5000rpm. If I tip into the throttle it's fine but as soon as I demanded passing gear I was outpaced by a freaking Scion. No CEL and the Lidio tune hasn't been altered since the 4.10 swap a decade ago.

I don't trust anyone to take it out driving to troubleshoot at WOT all day long. I am open to suggestions.
fastblackmerc
07-23-2017, 10:09 AM
Had an interesting drive last night. Drove the Merc to work and on the way home a guy I work with in a Scion tC is beside me at 45mph. As I stomp 3/4 throttle and hit passing gear the car fell on it's face and acted like it was running out of gas near 5000rpm. If I tip into the throttle it's fine but as soon as I demanded passing gear I was outpaced by a freaking Scion. No CEL and the Lidio tune hasn't been altered since the 4.10 swap a decade ago.

I don't trust anyone to take it out driving to troubleshoot at WOT all day long. I am open to suggestions.

When was the last time the fuel filter was replaced?

MAF cleaned?
justbob
07-23-2017, 10:12 AM
Fuel filter or pump. My pump did that off and on for a year. It was only the upper RPMS, all else was 100% normal. Data log it.


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BAD MERC
07-23-2017, 11:24 AM
Filter was replaced 7K ago. MAF hasn't been looked at. I'll try the fuel pump and go from there. It was a discouraging feel. Thank you much for the input.
Turbov6Bryan
07-23-2017, 02:16 PM
I was working on a different car and swapped a used fuel pressure rail sensor onto my DD DTR. 99% of the time it now bucks at wot. Wot only. Does yours fall on its face then comes back?
BAD MERC
07-23-2017, 05:27 PM
Yes. It acted like the rev limiter just killed it and immediately came back to life. I don't drive to the redline nor do I beat the hell out of it. Very discouraging but I am gonna get in and troubleshoot the simple stuff. Might even put Carfixer in it and see what he says.
loud2004marquis
07-23-2017, 05:57 PM
MAF cleaned?

^^^+1 on cleaning the MAF!^^^


Data log it.

^^^X2 on datalogging it!!!!

Mine had similar issues, ended up being the COPs.
johnjamis
07-24-2017, 03:33 AM
+2 on cleaning the MAF. It caused this exact symptom on my 2003.