04 non-turbo v70 ecm-4201- Am I missing anything?

floridavolvo · Post by **floridavolvo** » 11 Mar 2020, 18:02

I have a 2004 V70 with 155,000 miles on it. It regularly gets 28-30 mpg, hwy, and has been very reliable. This is the "good one". Our other Volvo is a 1999 V70 XC with all the usual problems, currently not running and will be a restore project later.

Now for the problem,

Approximately 1 month ago, the car was in a parking lot with a cascade of codes, stalling and such. The first code thrown was the ECM-4201 and all through this it has been the only consistent code. I have an Autel MaxiDiag Elite code scanner- live data and code re-setter.

With my Autel and Fluke meter, I quickly figured out the battery was depleted and the alternator was not charging. I have a spare battery that worked and I reset the codes, immediately the car went from misfire to smooth. I figured I had it nailed in the parking lot and was sceptical (as usual) with the codes, being thrown, being anything more than an electrical problem (supply side), but on my way home....

running rough, misfire, codes (some different), but made it to my driveway. I fooled the rear door into being closed while open so I could put my Fluke in line with the neg post and clamp to measure amp draw with modules awake at approx 1.8 amps, a few minutes later amp draw went down to .020 amps, verifying the modules going to sleep as they should.

I ordered an upgrade alternator from 140 amp to 160 amp and replaced the battery with a yellow top Optima DH6- cleaned ground wires and power leads, power fixed.

With a steady supply of power I started on the misfire, #3 cylinder. I swapped the coil from #4 and now I have a misfire in #4, replaced bad coil. Misfire fixed. The random codes are now just one, ECM-4201.

I drove the car for a 130 mile trip out and back while keeping an eye on the live data from the Autel. What was a concern was the O2 rear sensor reading from 0.0 V to .9 V but mostly .6 V to .8 V while the front O2 was steady at .98 V to 1.01 V. But the code was not tripped during that trip. I returned home and went back out, but drove in traffic and tripped the code within 23 min.

I came home and checked the temp of the cat in the front at approx 410F but the rear was 240F, I could not see any exhaust leaks.

I'm thinking I have a partial melt inside the cat? The alt is putting out a steady 14.3 V with a fully charged battery at 12.9 V (float charge adjusted).

My Question,

Before pulling the exhaust (big job) am I missing something?

Cheers

Post by **oragex** » 11 Mar 2020, 18:12

Hard to speak about melted cat, there is quite a drop in temp indeed. If you drove with a severe misfire, the unburnt gas could damage the cat, and may trigger a Cel intermittently. Your 2004 may also be worth a look at the CEM for any traces of water leak

Post by **abscate** » 11 Mar 2020, 19:42

Using AGM batteries in a car designed for FWC batteries might cause charging issues.

floridavolvo · Post by **floridavolvo** » 12 Mar 2020, 15:52

oragex wrote: ↑11 Mar 2020, 18:12 Hard to speak about melted cat, there is quite a drop in temp indeed. If you drove with a severe misfire, the unburnt gas could damage the cat, and may trigger a Cel intermittently. Your 2004 may also be worth a look at the CEM for any traces of water leak

Thank you for your reply, sounds like you get why I'm a bit puzzled with the last issue and the temp drop.

As to the misfire, since I don't normally drive this car (it's my Wife's) I can't know for sure how long it had been misfiring (the #3 coil was completely dead) but my Wife loves her Volvo's and does come to me quickly when something needs attention (I like them too-they keep what's important to me safe).

This brings me to the CEM, The power supply side of things is strong and works well, (I have done this type of upgrade in all our Volvo's as it has been needed-works well). Supply is only part of the equation since you are bringing up the CEM, have you had experience with water intrusion and an interruption in the CAN "super-highway"? I had considered a CAN interruption, partly why I'm sceptical of codes at first, but wouldn't this also cause other codes or indicate other problems?

I have a front O2 indicating a strong rich mix (.98V to 1.01V), the heat element is on showing cold? (1536 mA) that would go along with a pegged rich signal? And a rear O2 between lean and rich, (all in closed loop .0V to .9V for extremes and .6V to .8V mostly)

Fuel trim short at 1.04 and long at .98 Again rich? Spark advance at idle pegged at 32 BTDC

Idle 750 rpms with plus or minus 10 rpms

ECT 191 F

Fuel pressure is steady at 55 psi

Fuel pump duty 53%

MAP at 1.6V or 320 hPa

Amb temp read at 82F

IAT 178F

Leak detection pump current 65 mA

Voltage as measured by the ECU at 14V unwavering

All this was measured after a long 130 mile drive at steady speed (load), while idle at home in my driveway.

Does anything scream out at you?

Post by **abscate** » 12 Mar 2020, 15:53

Fuel trims are fine.

What is the MAF reading in grams per sec?

Post by **RickHaleParker** » 12 Mar 2020, 16:57

ECM-4201 is Three-way catalytic converter efficiency. Anything that messes with the Air/Fuel ratio or the burn can trip ECM-4201. Including a misfiring cylinder, air leakage in the exhaust system and defective injectors.

floridavolvo · Post by **floridavolvo** » 13 Mar 2020, 08:59

abscate wrote: ↑12 Mar 2020, 15:53 Fuel trims are fine.

What is the MAF reading in grams per sec?

.01 lb/s-

or 4.5 g/s at 750 rpm

Post by **precopster** » 14 Mar 2020, 01:38

That's 16.2kg/hr which is pretty ideal at idle according to Vida.

floridavolvo · Post by **floridavolvo** » 14 Mar 2020, 11:14

precopster wrote: ↑14 Mar 2020, 01:38 That's 16.2kg/hr which is pretty ideal at idle according to Vida.

I appreciate the response, and if the data that I pulled from my Autel is in a proper operating zone, I have to assume that it's correct and actually pointing to the cat failing, right? If I'm not missing anything, then I have a direction at least to prepare for and of course thank all of you that gave this a look.

I will update on what I find in case it might be valuable to someone out there.

Post by **packetfire** » 16 May 2022, 05:29

I have a 2004 v70 non-turbo with an ECM-4201 that has appeared twice so far this year, with no other symptoms, and a fairly steady best "instantaneous mpg" from the Dashboard display of 32 - 36 mpg at 72 mph on highway, depending on slope of roadway.

So, at only 200K, I am thinking I need to hook up VIDA, go for a drive, and watch the sine waves from the O2 sensors.
But what am I looking for - one occasional "missed pulse"? Or something more consistent?

Yes, I could have a random fuel injector issue, but I am not sure how to detect the fault if it is so occasional. Can one read fuel pressure anywhere with VIDA?

I assume that this can't be an exhaust leak, as the code would be thrown more often, I'd have seen "Check Engine" more often, and it would not be so "occasional" in the VIDA fault statistics.