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View Full Version : Broke down again... MAF?


DRTDEVL
05-10-2018, 03:55 AM
Ok, my driver broke down today in Del Rio, TX. He tried describing the sound to me poorly, then I tried to listen over the phone, but it sounded horrible/nonsensical. Being that he struck a deer last weekend, I assumed he had some sort of boost leak. He couldn't find it.

I loaded up my spare parts, scanner, and tools, hopped in the car, and drove 8 hours to where he was sitting all day.

No codes. Nothing showing wrong on the live stream that I could find.

When lightly throttling up, it would run smooth. Once you apply actual amounts of fuel, the engine would surge and bog rapidly, with copious amounts of unburned fuel smoke from the exhaust and a strong exhaust odor.

I wanted to check the turbo actuator, so I unplugged the MAF. It worked as it should. Just on a whim, I revved it with the MAF unplugged, and it revved beautifully. I had him test drive it to see how it would do, and it will get up to 64, so it has a limp mode of some sort without the MAF ( I assume its limiting boost).

He's going to drive it home tomorrow, and I already ordered a MAF online, but I wanted to run this past y'all... with limited diagnosis at night in a Wal-Mart parking lot. Could this odd operation be the MAF? I found no boost leaks, but unplugging the MAF cleared the symptoms.

Edit: 2004 T1N FedEx

SneakyAnarchistVanCamper
05-10-2018, 04:57 AM
Yep, classic MAF failure symptoms. Good work. If it runs fine with the MAF sensor unplugged, all the air sensor values are defaulted (MAF, intake air temp sensor, boost pressure sensor/MAP). So it could be any one of these things. Pretty sure the MAF often doesn't throw a code though, so it's a good shot, although the most expensive of the three.

DRTDEVL
05-10-2018, 11:33 AM
If it runs fine with the MAF sensor unplugged, all the air sensor values are defaulted (MAF, intake air temp sensor, boost pressure sensor/MAP). So it could be any one of these things.

The cool part is that I have a parts van, so I have all of these parts in working condition except the MAF (it was already harvested by the time I bought it). If the MAF doesn't work, he'll be home, and I'll be able to toss the spares on it until I figure out which one (MAS or MAP) is bad, and I'll toss the MAF into my spare parts bin.

If any of you have the means, a place to put it, and the ability to logically figure stuff out, I would highly suggest picking up a parts van. I paid $1500 after shipping for mine, and I have already harvested injection lines, the turbo, the center console, right rear light contact panel, rear door contact switch, the combination switch, the cruise switch and wiring (still have to wire that up and get it activated), the bumper, right headlight, right signal lens, bumper brackets (the last 4 from the deer strike), the driver's seat back with armrest, and various switches and trim pieces inside. It has already paid for itself numerous times over. I also have a nice parts box of injectors, lines, bolts, and sensors to take on the road in case it breaks too far from home, and I have injectors, sensors, gaskets, and the entire front cooling pack (radiator, PS cooler, intercooler, and condenser) in case something damages the front end (somehow only the condenser was bent during the deer incident, but its maintaining refrigerant levels) sitting in my garage at the ready.

NelsonSprinter
05-10-2018, 08:17 PM
Inspect the MAF sensor for dirt, if any dirt found inside MAF housing there is a chance the deer hit has warped the air filter housing enough for air to bypass the filter, clog the MAF and dirty air will enter and destroy the engine in time

Midwestdrifter
05-11-2018, 12:30 AM
Inspect the MAF sensor for dirt, if any dirt found inside MAF housing there is a chance the deer hit has warped the air filter housing enough for air to bypass the filter, clog the MAF and dirty air will enter and destroy the engine in time


This.

The headlight will easily crack the filter housing when pushed back (around the pressure sensor). Ingested water and/or dirt can easily damage or foul a MAF. Sometimes a can of MAF cleaner will remedy the issue.

autostaretx
05-11-2018, 12:54 AM
The MAF not throwing a code is part (all?) of what the (notorious) T21 recall is trying to fix.

--dick

DRTDEVL
05-11-2018, 01:06 PM
There was a little dust in the MAF, but that's pretty normal in the desert here. The only thing that broke on the headlight were the two inner mounting tabs, it wasn't that bad of a hit at all. The light works and is aimed properly, but if I have the part, why not fix it 100%? I'll inspect the filter housing anyway and if suspect, I can grab that off the parts van as well.

I tried MAF cleaner, but the symptoms immediately returned when plugging it back in.

The van has 364,000 miles on what is possibly the original MAF. I know I never changed it, and my company has put 58,000 miles on it since purchasing it in July (and that was being parked for all of July, September for the birth of my son, October to be there for my new family, half of November until I hired a contractor to drive for me, and January, when the first contractor flaked... yup, we average 10,000 miles per month).

DRTDEVL
05-16-2018, 12:13 AM
UPDATE:

So, I did a bit of research on the MAF threads here and came up with an idea... apparently the ECM reads the ambient air temp sensor as part of the air intake values. I searched out the sensor. Lo and behold, it had been knocked out of its clip and was wedged under the radiator. The dash reading was over 100*f in the shade on a mid-80s day.

I pulled it out, rerouted the wires, and clipped it in place (holding it with zip ties). The dash read normal again. I plugged the old MAF in and voila! Huge plume of soot out of the exhaust (ran 500 miles with MAF unplugged), no limp, full power restored without surging.

So a clue to those looking for the answer: it might not be what you think it is. Research here. The answer might be what you least expected.