Air flow logged low, IAT logged high.

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Stanleysteamer

Stanleysteamer

Well-Known Member
Full Member
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Location
East Dorset
Hi all, looking for help with a problem that only seems to occur when the engine gets really hot and/or when the weather is hot.
Could this simply be that the MAP/IAT needs replacing?
The Fault is that as I pull away from a standstill, i.e when lights change or when joining a roundabout, the car refuses to rev up, even with my foot flat on the accelerator, until suddenly, whoosh, off it goes.
TD5 10p engine with auto box.
I have recently replaced a split intercooler hose and it does seem to be a lot better. But then the weather isn't hot.
Re the MAF it runs the same with it connected or disconnected, slightly better when connected.
Botht the MAF and the MAP/IAT have been cleaned.
If I do live data, which of the 255 channels should I be looking to try and log?
Thanks in advance for your thoughts.
Stan.
 
To add to the above, have managed to read and save some live data. All done with the vehicle stationary:
at tickover at 2488revs
MAP 15.2 psi 17
Airflow 0.0 kg/hr 0.0
Ambient pressure 14.8psi 14.7
revs 764 2488
coolant temp 134 f 135
Inlet air temp 248 F 248F
Fuel rail temp 119F 121 F
I appreciate that this was done after the vehicle had been standing a while, about 3 hours after a good run.
And I did say that the problem only really occurs when the vehicle is hot and possibly/probably driving around in temps above 30 degs C.
It's taken me a long time to research MAP/IAT and MAF sensors, AND to get to grips with the Foxwell which for a while didn't seem to want to save live data.
Now I know how to use it I may be able to do this again while both hot and being driven.

But does this so far indicate anything obvious?
Airflow 0 seems a bit off for instance?!;)
and should I have recorded other stuff?
Again, thanks in advance.;)
 
Stanleysteamer said:
To add to the above, have managed to read and save some live data. All done with the vehicle stationary:
at tickover at 2488revs
MAP 15.2 psi 17
Airflow 0.0 kg/hr 0.0
Ambient pressure 14.8psi 14.7
revs 764 2488
coolant temp 134 f 135
Inlet air temp 248 F 248F
Fuel rail temp 119F 121 F
I appreciate that this was done after the vehicle had been standing a while, about 3 hours after a good run.
And I did say that the problem only really occurs when the vehicle is hot and possibly/probably driving around in temps above 30 degs C.
It's taken me a long time to research MAP/IAT and MAF sensors, AND to get to grips with the Foxwell which for a while didn't seem to want to save live data.
Now I know how to use it I may be able to do this again while both hot and being driven.

But does this so far indicate anything obvious?
Airflow 0 seems a bit off for instance?!;)
and should I have recorded other stuff?
Again, thanks in advance.;)
Click to expand...
I have a nanocom, so tell me to keep my nose out if I'm going completely down the wrong track, but Inlet air temp of 248F (120C) seems a bit high:eek:, even if you are still in France. Where did that temperature come from? I've looked over a couple of my old nanocom files and the Inlet air temperature is 30-40C with a warmed up engine.

Cheers.

PP.
 
Hi, buy a new MAP sensor ASAP cos your's is certainly fubar on the IAT side and that's the root of your problem. Untill then no need for more diagnostics...and can't you set Foxwell to European units to be easyer in the future? cos i had to use a F to C converter to figure it out
 
sierrafery said:
Hi, buy a new MAP sensor ASAP cos your's is certainly fubar on the IAT side and that's the root of your problem. Untill then no need for more diagnostics...and can't you set Foxwell to European units to be easyer in the future? cos i had to use a F to C converter to figure it out
Click to expand...
Mate, I am so happy, because straight out of the box you have suggested what I thought was wrong and have done so even since before I stuck the Foxwell on it!!!
Considering this, it actually runs not too bad!
I am on it, your advice is exactly the help I needed and I will order one in a few minutes. I understand a Bosch one will be OK. do you agree?
As for the Foxwell, I am not sure but I think it must be of American origin which explains why the Farenheit, and the psi instead of bar, but kgs/hour? Weird! Don't know if it can be changed, I'll have to look! (I was born in 1955 so when I did A levels I had to do everything in both Imperial and SI units!)
What do you think about @PopPops remark, about the MAF seeing as how it was plugged in at the time? do you think that is fubar too?
If so, might as well order one as the same time to save on the Post and Packing!!!:):):)
Thanks so much both of you!!
 
PopPops said:
I've just properly read the title of the thread!

Looks like the MAP/IAT sensor is dead and I am sure the airflow is recorded as 0.0 if the MAF is unplugged.
Click to expand...
At the time of the readings the MAF was plugged in so it does look as if it too is t!ts up!
Amazing it is running so well! It towed a trailer with a Citroen Pluriel on it 550 miles in France up and down the Massif Central with a split intercooler pipe as well.
I suddenly have a bit more respect for it. There was no black smoke and fuel consumption was no worse than usual, mind you I never clock it. :):)
 
The MAF on Eu2 engine is mainly for EGR management it wont affect driveability too much, you can let it unplugged without fear. Anyway, check fuse F2 in the engine bay which powers the MAF just to rule it out cos it can be blown then the wastegate modulator is disabled as well
 
PopPops said:
Sorry, I thought you had said somewhere you had it unplugged.:(

Looks like you are making good progress.
Click to expand...
I did! and I put the Foxwell on it both ways, just for comparison when it came to code reading. I then left it on, did the final code reading then went onto data logging, as I knew @sierrafery would want that. Which I think he did cos he went straight for the jugular of the problem with no messing.
For once i feel I am actually getting on with the electronix just a weeny bit better. But I still need help from peeps like you and SF!
I think a small Laphroaig is now called for!!
Cheers!:):):)
 
sierrafery said:
The MAF on Eu2 engine is mainly for EGR management it wont affect driveability too much, you can let it unplugged without fear. Anyway, check fuse F2 in the engine bay which powers the MAF just to rule it out cos it can be blown then the wastegate modulator is disabled as well
Click to expand...
I did check the f2 fuse and it was OK, (I read that on another of your posts somewhere). I have de-EGRed the vehicle anyway. So am now wondering if there is any point in spending the money on a MAF IF it is doing either nothing or very little?
 
update to all.
New Bosch MAP/IAT fitted
Inlet air temp now read at 72 degs F at 2513 revs.
so this looks a bit more normal!
(And I have set the units up to metric! for @sierrafery , but only just now as I was keen to see the results!
i'll let yo know further if this hasn't cured the problem, and once again.
Ta muchly!:):):)
 
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