FDPP #2

Post by **abscate** » 28 Aug 2020, 04:49

I don’t think 6-10 seconds difference is meaningful

While the data looks nasty the scale is tiny on the left. The only thing jumping is theMAF READING AT IDLE, thats all over the place. Check all the induction hoses for clamps by removing, inspecting , and reclamping, just labor

Post by **mkc1** » 28 Aug 2020, 06:07

abscate wrote: 28 Aug 2020, 04:49While the data looks nasty the scale is tiny on the left.

If I'm reading the graph correctly, the desired value for the throttle angle varies from 3 - 6% but the actual value varies from 1 - 20%. That doesn't seem right, does it? I'm no expert, especially as my 850 doesn't have an ETM.

Post by **gnalan** » 28 Aug 2020, 07:05

These were both done at operating temp, with the MAF unplugged. Everything still jumps around on the graphs, and the car still acts like it did when it was plugged in.

Why am I still getting a "g/s" reading if the MAF is unplugged? Shouldn't it read 0, or is this normal? Can someone verify on their car and see if there's any MAF signal with it unplugged? I mapped the MAF voltage unplugged also, but it stayed at 0V the whole time so I took it off of the graph so it wasn't too cluttered.

Post by **abscate** » 28 Aug 2020, 09:15

With the MAF unplugged, the ECM calculates air flow based on rpm and uses that value to determine air, and hence fuel, to inject. That’s why the practice of trying to diagnose bad MAFS by unplugging them is poor. My guess is you are observing the calculated air flow from that lookup table

Post by **bmdubya1198** » 28 Aug 2020, 09:16

That would make sense that it's calculated airflow. I wouldn't look too far into that. I think the ETM is probably on its way out, just looking at these charts and knowing your symptoms.

Post by **gnalan** » 28 Aug 2020, 09:49

Can anyone help me get an ETM? Should I replace the MAF too? I saw on the XeMODeX that they should usually be replaced together.

I really hope this is the last thing I need to fix. I don't know if the timing belt/water pump has ever been changed. Is there any markings on the belt that I can see with the top cover off to tell whether it's the original one or not?

Post by **bmdubya1198** » 28 Aug 2020, 10:46

It's not totally necessary to replace the MAF along with the ETM.

Post by **gnalan** » 28 Aug 2020, 10:59

That's expensive! I'm lucky if I have a tenth of that left at the end of the month, and even that's difficult to do right now.

Post by **volvolugnut** » 28 Aug 2020, 11:13

bmdubya1198 wrote: 28 Aug 2020, 10:46 It's not totally necessary to replace the MAF along with the ETM.

I agree, there is some evidence MAF fails when ETM fails, but I would not change your MAF yet. I think XeModex used to offer a test for about $150 and will return your ETM if it passes their test. They do this on a machine. You may also pay shipping both ways.

Does anyone have a working, used ETM to try?

volvolugnut

Post by **bmdubya1198** » 28 Aug 2020, 11:43

$150 just to test? Ouch! The test on VIDA costs nothing.