Hi to all, 2003 XC70 AWD, 2.5T, 218xxx miles - question about reduced engine performance (REP). Is this mode designed to respond to components failures, or is it designed to respond to driving conditions? Thank you.

Bill
Hedgesville, WV

 

its meant to be a way of protecting the engne should a potentially damaging fault condition arise, not related to driving conditions. Say the ECU detects a high number of misfires - it will cap the power/rpm to allow you to "limp" to a safe stop without further damage to the engine. Older models called this feature "limp mode".

 

Hi mt6127, thank you for the explanation. My 2003 XC70 has this "reduced engine performance" fault that shows up occasionally. Not as bad as it used to be, but still shows up. No way do I want this intermittent fault to pop up every now and then!

Bill P

 

Have you had the car's OBD2 codes scanned for stored fault codes? that would give you an indication of what event triggered the warning. My guess is you are seeing something like a fuel trim issue or a high number of misfires (ie a P0300 code that says misfires were detected on multiple cylinders).

 

Hi again, appreciate you getting back to me. Yes, the mechanic - an independent - who owned the car before me has the VIDA software and had pulled code ECM-981A repeatedly. He replaced the ECM, installed updated firmware and software, and replaced the wiring harness going from the ECM to the Engine Throttle Module (ETM). In addition, he replaced several other modules after conferring with fellow professional mechanics. I'm interested in the fuel trim issue because I have the impression the mode is triggered by (1) something having to do with the transmission shifting, possibly causing a brief interruption in fuel flow, because the shifting is not smooth, (2) being in cruise control and (3) going uphill. I don't think the misfires are a suspect because the plugs are new as of 210K miles, every plugs seems to be firing okay, the gas mileage is up around 25 to 26 mpg, and the mechanic has never pulled the P0300 code. Here's what's been refreshed/replaced:

PCV tested and passed w/ room to spare
PCV changed (or just cleaned, not sure which) at 160K miles
New plugs at 210K miles (car now at 218xxx miles)
Used but known good boost pressure control valve
Calibrated the turbo boost pressure
New vacuum hoses between intake manifold and brake booster
New boost pressure sensor
new mass air flow sensor
new engine speed sensor
new accelerator position sensor
new throttle body
instrument cluster was reconditioned (replaced to new) by Xemodex (unable to switch between T1 and T2 trip odometers, trip odometers would reset to 0.0, then return to previous value, and clock constantly scrolling backwards fast. Also two bell tones sounded after startup, about one or two minutes apart. Also, the text "058" or "O58" appeared in the message window from time to time. These might be spurious info, and thus unreliable for troubleshooting)

The mechanic thinks the next move might be to replace the ABS module, since the speed signal comes through the module to the speedometer. He also might confirm good grounds on all the ECM wiring, which he says is about 70 connections.

At this point, I'm not sure if I want to spend any more money on the car, since the mechanic assured me he had road-tested the car enough to satisfy him the problem had been solved, I believed him and bought the car, and yet the car still has the problem. But I am willing to look at, and welcome, your suggestions for fixing this problem. I'll bring up the fuel trim issue and misfiring with him and see what he says.

Thank you again, I really appreciate your thoughts on this issue. I love the car and would like to keep it, but my wife will not drive the car nor be a passenger in the car, even if I'm driving.

Bill P

 

I'd think that if the ABS module was at fault you'd see some additional fault codes - but you can see what Xemodex has in their typical symptoms list for a failing ABS controller. Given your reluctance to throw more parts at this, I think inspecting and cleaning connectors is a good next step. My related experience was with my son's 2000 S40, when it started having shifting issues. That issue was resolved by unseating the TCU connectors/cleaning and reinserting. It took a seasoned Volvo tech to suggest that as a next step.

 

I have contacted xemodex about the ABS module being at the heart of the Reduced Engine Performance mode trigger. Will let you know what they say.

Bill P