I've been helping someone figure out why they haven't gotten results from a grooved TB on their SUV.
It has involved phone calls and text messages and screenshots, across this continent and 3 time zones...but we found it, and pointed it out, and the problem was resolved.
He has very quickly reported increasing mileage.
If you're focusing too intently on fixing a problem, you may just miss what the problem actually IS.
In this case it was a bad IAT sensor in the MAF. It wasn't leaky manifolds or hoses or exhaust - one of the key factors in measuring the air was wrong, so the computer did what it was programmed by the factory to do, and that's overdeliver fuel and disregard sensor inputs until all of the sensors agree.
A thrown code might not make sense, so you have to go to the raw data - and luckily in this case, the person has a scan app on their phone.
I pointed out that the reported intake air temp was probably higher than what I suspected the actual air temperature was at their location, and it turned out that I was right. Cleaning the MAF wires wouldn't (and didn't) help because they were working fine - it was something in the mechanism that determines air temp that was wrong.
Our Groove won't help until you get the vehicle working as the factory intended...so that's where to start if you've come here because of decreasing mileage/increasing consumption.
I look forward to reading this person's story when they've got a tank or two's worth of data on the odometer.
Most Active Member
The following user(s) said Thank You: Tracy Gallaway, Johnathan, CLAUDIO CORDOVA
As an update to the above, last night I was notified by the thrilled owner that they have seen a 25% increase in mileage/decrease in consumption since we tracked the problem down and remedied it. "Best mileage we've ever seen on this truck," a 2005 Chevy Suburban 1500. Just from changing a sensor out so the Groove could do it's thing. This may not mean much to many, with fuel prices falling at the moment, but it means a 25% reduction in carbon emissions and corresponding drop in taxes on fuel consumption, keeping money in his pocket and the air cleaner for all of us.
Now we're going to dig deeper, as he has already installed (but not yet calibrated) the MAP sensor modification and EFIEs for the upstream o2 sensors...and I seem to recall that he's sitting on a full Snake Oil treatment as well...
Stay tuned for future updates!
It works, folks. Follow the program and you'll see results.
Most Active Member
The following user(s) said Thank You: Tracy Gallaway, CLAUDIO CORDOVA
So, if I read this right, the IAT sensor was giving a value corresponding to a warmer air temp than the actual air temp? You asked about the conditions the vehicle was driving in... you mentally pulled back and thought about the situaton. Looked at things from a different angle.
So I'd suppose that if the IAT was telling ECU that the air was warmer than actually it was, then it would result in a decrease of injector pulse width. Making it run too lean... IF I'm right, then the owner is gonna feel forced to use more throttle, increasing load and throttle angle. Or the ecu justs resorts to dumping more fuel . Either way MPG goes down.
I admire the fact that you thought of local real-time driving conditions i.e. temperature.
That's GOOD diagnostics. I have a few times figured out problems for folks at a distance. I once asked q/a on the mobile phone with a customer stuck on the side of a busy freeway with the family in their van. I analyzed what had happened, told 'em what to do, and they got it started and got out of the predicament in 5 minutes.
That feels pretty good.
Good on You, Greg!!
Founder and Constant Aide to Gadgetman
Gadgetman Reno, NV
Correct, Tracy - the Intake Air Temp sensor part of the MAF was over-reporting the intake air temp, and causing havoc with fuel delivery. It was reporting late spring air temps in early March for that location, and when I asked him what the weather was like, he told me that it was cooler than the sensor seemed to think. (low 70s F vs low 40s...quite a difference). Even Idling in the driveway, there should be no way that amount of heat would creep through the intake tube - it would be melting, and obviously wasn't.
From what I recall from the before and after screenshots of his scantool app, after swapping the sensor out, the throttle angle decreased as well, confirming your supposition about why the MPG was lower than expected/hoped.
he didn't notice it, or wasn't looking for it as the answer, but I was sitting in my car at pretty much the other end of the country thinking how chilly I was when my eye caught that tidbit. A quick convo about speed-density, a test of the MAF (pulling the connector while it was running should kill fuel delivery because it's not meterng air, but it didn't, so it was temperature)...and a quick search of Rock Auto showed that the Delco part specifically stated it measured air temp. Kudos to him for trusting me and ordering the replacement sensor quickly....and the ensuing fuel savings offset the price of the sensor.
BAM! back on track for the groove to do it's thing.
Again, if you're stuck and in a place where something doesn't make sense, ask for help from someone. That's what we're here for, and we're happy to help. #ThisIsTheWay of Gadgetfolk.