View Full Version : EGR on/off ratio 6% no codes or lights

05-10-2019, 11:10 PM
My DD, an 05 w/ 475k, has been a bit weak on power for months and I have eliminated all possibilities I can think of. No engine light and no codes. I get glow plug codes and engine light occasionally with low battery start and have read/cleared them many times. Exploring the iCarsoft MBII, I noticed my EGR on/off ratio is solid 6% no matter what I do.

I compared this to another van, it shows 6% only when engine is off. When running the value varies with pedal pressing as one would expect, but is much higher than 6% even at idle. After installing a shelf spare EGR and no change I swapped EGR van for van and the problem remains in my DD.

I've checked the wire harness and tried to ohm some wires for shorts, finding nothing different between the two vans. I've followed the wire diagrams and find the 3 wires at EGR essentially route to the turbo actuator, the O2 sensor and the ECU, with one wire to each.

Hoses have been checked and resonator is aluminum.
Fuel filter is new (no change).
The block, head, all 5 injectors, turbo and EGR have been replaced (long litigious story).
The weak power persists. Note: the HPFP was reused when engine swapped.
I noticed the EGR value Wednesday and said Ah Ha! This must be my issue!
But still have not sorted out why the value remains 6%.
Anybody got ideas? ...no codes. :bash:

I read somewhere outside of the T1N world vehicle speed sensors can stop EGR action. I wonder if this has anything to do with my front left wheel reading 4.07mph while I'm parked. Does the front wheel speed sensor play in this EGR activation on T1Ns? This wheel speed was also noticed accidentally the same day as EGR 6% was found. With no codes and 475k miles I just lived with the low power a while. Eventually I took it to a Sprinter shop who says my motor blew up on a test drive. They replaced the motor and it runs same as when they got it. No codes, just weak, especially between 45 - 75 and slow to shift because of it.

05-11-2019, 04:26 PM
I think it more likely that your EGR’s low commanded value (as opposed to being stuck open or closed) is a symptom, not a primary cause. A low egr wouldn’t affect power the way you describe.

Is exhaust clear? (look at lack of air if it’s dark)
What does you MAP value look like? Does intake air pressure match the ambient sensor?
How does O2 sensor voltage behave?
When you mash the pedal the O2 voltage should drop, with the lambda value (an SAE pid, oxygen surplus ratio) dropping under 2.0 (the sae max value... diesels run much higher so it’s only useful to observe it near the top of the load range)

It’s possible you have a HPFS issue, but then you’d expect to see a code. The rail pressure sensor could be sending false readings, which would throw fueling off? Or if the HPFS is worn and unable to build pressure and volume your injection events would take longer, retarding timing and losing torque. But again, there should be a code if pressure is lower than commanded.


05-11-2019, 10:21 PM
I spoke with Dr A a few days ago about MAF issues. He said 20% of the T1Ns he sees without the T21 recall never activate their EGR system (which is what you describe) due to incorrect MAF adaptation. Sounds like the T21 recall would "fix" your EGR problem, but most people would think a dormant EGR is a benefit not a flaw. Unfortunately, the EPA does not agree, which is why Mercedes was forced to update the software (ie recall) for our 15 year old vans. If it were me, I'd be thankful my EGR doesn't activate.

I'm no expert, but perhaps your lack of EGR and power loss are unrelated. Maybe your compression is down due to worn rings or something else? I have Honda that made 175 psi in all cylinders when it had 250k miles. Now that it has 350k+ I am close to 100psi and I am way down on power and fuel mileage. I replaced the head gasket (which did permanently fix a very small compression leak into the coolant), but I am still low on compression so I assume it is rings. Unlike these vans, I sourced a "low mileage" Honda engine from Japan for $400. If only the fix for high mileage sprinter engines was so easy...

05-12-2019, 12:50 AM
Those who are curious about EGR operation, here's a plot of interstate travel. Around the 40 min mark there's a long down hill and EGR goes to 5%.

05-12-2019, 01:08 AM
I thought it was rings too, until a shop replaced the engine, injectors, turbo, and EGR but nothing changed. The replacement engine drinks less oil, but it still takes almost a quart every 1,000 miles, so I guess the replacement may be almost as bad as my old engine. The shop is as crooked as a camel's leg and racist as a grand knight.
Of my 4 on the road T1N vans, this is the only one that takes more than one top off of oil between oil changes, and it takes it 5 times. So something isn't right, and when the replacement engine didn't fix Anything, I started looking at what didn't change. Perhaps that was an error since I don't know anything about the used one.

05-12-2019, 06:52 AM
Not to hijack your thread, but having a similar issue with a van here. MAF shows constant 0 under live data, and the EGR shows constant 6%. Strange seemingly random power loss issues that put the van at idle and no acceleration, that are not LHM, and can be resolved just by taking foot off the throttle and reapplying throttle. I'll be following this thread to see what comes up.

05-13-2019, 03:54 PM
Zero MAF implies a sensor or wiring fault... Without MAF data the ECM will fall back to its default induction table and relies more on the O2 sensor to manage fueling rates. This comes at a cost, and the engine will lose some precision, maybe felt as a loss of responsiveness? (The T21 recall makes the ECM report a “no MAF data” condition and lights the “Check Engine” lamp).