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"Re-programming" after cleaning MAF

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I had a problem with my Defender Td5 juddering at high revs (70 in 5th, equivalent in lower gears), and having wiggled the turbo wastegate actuator, I have now serviced it, cleaned the MAP/IAT, cleaned the MAF (both with electrical contact cleaner, plenty of "how-to" videos on YouTube.) The MAP/IAT was FILTHY. I had never considered blanking off the EGR before, but it's definitely on my to-do list now; I understand this is a common issue.

Anyway, no more juddering at high revs, but still down on power, but I have heard that the ECU "learns" over time to adjust fuelling etc, based on sensor readings, so the question is: how long will it take to "unlearn", or should I take it to garage to have it reset? Can this reset be carried out on a Nanocom/Hawkeye type thingummy? I guess it's a 10 minute job at a garage, but my nearest Indy is 40 miles away, and I don't want to pay Stealer prices.

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Don't know whether the same would apply to a Td5, but when I had problems on my old company Mondeo there was a procedure for clearing the fine tuning in the ECU and the "best" way to reprogramme. It didn't clear fault codes, just sensor tuning settings. The ECU contained a default mapping, as you drove it would adjust to your set of sensors and a target. With the Ford, it would only learn during the initial stages after a reset and not continue learning as the sensor degraded. That's how and why, I learned to reset and tune the car.

To reset, the sensor settings to default you disconnected the battery, turned on ignition and radio (or other non-relay switched load), left it for >30 minutes then re-connected, reprogrammed radio codes etc. The >30 minutes with effectively a short across the power terminals was to discharge the memory inside the ECU.

After this procedure, the engine was a little lacking. Nothing that you could put your finger on, just lacklustre. You then needed to drive in the manner to which you wanted the car best tuned - carefully for economy, like a lunatic for performance. There was also something about transitioning between 40 and 60 mph at least three times before the re-programming sequence finished.

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I'm happy to plug my Nanocom Evo into your truck to check for errors if you like....

I will also add, changing the MAF for a new Genuine one changed my truck performance. Changing the MAP sensor did'nt have much effect.

I'm guessing that these parts wear and need replacing over time, regardless of error's being kicked out.

Contact me by PM if you want to check for errors etc.



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  • 3 weeks later...

Met Neil (V8 Freak) yesterday so he coudl look at my ECU faults with his Nanocom. No faults read, except the air conditioning fan. Since I don't have A/C, I think we can safely ignore that. The turbo wastegate was stuck, so wiggled that. Sees to be a bit better. Still down on power though, so next things to look at are to remove the EGR, replace the hoses with silicone, then look at the MAP/MAF and IAT sensors. A few people have said these should be considered as service items.

Thanks again Neil.

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No problem at all.... Pleased to meet you and now you know where I hide most weekends...

Do the serviceable parts first... I recon you should change MAF / MAP sensors and remove EGR as discussed.

Hoses looked ok but I would replace them to be sure there are no pin sized leaks helping you to lose pressure.

I'd also keep working the turbo waste gate... As it was stuck and therefore not working as it should and make sure it stays free as far as you can with a regular workout for a while.

When was the fuel filter last changed?


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