Non Start No Faults Stored. Using Substitute Values to Prove Fault

In this video you'll see how substitute values can be used to prove a component fault.
2008 Renault Keleos DCI
Same engine as Vivaro, Trafic, Primastar (TVP)

[@ritchieschofield1185]

Learning something everyday off these videos. Thank you. Funny how the ECM didn't record implausible data from the MAF. A stuck open EGR was what I 1st thought? What's the quickest easiest way to test this? I guess look at EGR live data? Thanks for another great video

[@ianhenderson4441]

Very informative Video ...Nice work with the scan-tool...live Data ..👍👍

[@the_retired_mechanic]

Yay I guessed right just before you unplugged it. Brilliant

[@iankelly2110]

good diag Gary. The diamond of doom I love it.

[@robbocop33r12]

Brilliant video,as usual with KZbin i randomly stumbled across your channel,and i'm staying,subscribed,keep up the good work!

[@jamesstevens5627]

That's a really good video I haven't seen a video like that before showing what data pids to use and how to fix it

[@2stroke2smoke34]

Another awesome video 🤟🤟🙌🙌

[@campen777]

Great diag procedure , great use of the pids 👍

[@richardostrowski6420]

Great video on using common sense in diagnosing a problem. Well done sir.

[@ezeedazit8270]

great quick diag ! Nice !!!

[@lawsonthursfield6950]

great video Gary , too many people out there doing cleans and static regenerations with out any foresight to what the problem is or even if this is required at all . keep up the sterling work .

[@DJ-tn7vj]

Really like the break down

[@andywitz5993]

Nice job. Never had a bad MAF stop an engine running before. Learning all the time!

[@intelligentauto737]

This is the diamond of doom remember

[@jaykent6645]

Great work Gary, ive learned something here, i thought the data pids on a scan tool were directly showing the data produced by the sensor, i assumed that if you unplugged a sensor you would see zero on a data pid, i was aware that the ecu has default maps as per when running cold in open loop, but learned today via your great skills that the pid data appears to be coming from the ecu and not the sensor as such. Thanks mate. Regards Jay

[@michaelagnew7825]

I assume substitute values are available only with open loop, scan tool is plugged to ecu and not the sensors, therefore ecu data is what your watching

[@gcmd5852]

Nice work.

[@LLcoolthings9]

Great lesson here. Thank you!!

[@gavingibson7471]

i know it is kinda off topic but does anyone know a good site to stream new series online?

[@elishavincenzo1833]

@Gavin Gibson flixportal xD

[@gavingibson7471]

@Elisha Vincenzo Thank you, I signed up and it seems to work :D I appreciate it!

[@elishavincenzo1833]

@Gavin Gibson Glad I could help =)

[@wardybasher]

Had a similar fault on a qashai with the same engine. It would start and run but with reduced power. The air filter was so blocked it had collapsed. Thanks for sharing!

[@intelligentauto737]

I see lots of Renault & Nissan vehicles with manky air filters, I suppose a 40k service schedule don’t help

[@beetboob]

Nice video had one or two the same but always had fault as air flow sensor

[@aymenmohamed1134]

👍🏻

[@Adicarr]

👍🍻

[@JoeBob79569]

It's a bit of a counterintuitive concept, unplugging something to get a car running, but definitely something to store away in the back of the brain for future reference.

[@alrifainidal]

Smarty way to find the issue. Well don sir .. 550 mgs stroke is that applying to fuel engine also ore just Diesel engine???

[@intelligentauto737]

That applies to a 2ltr 4cyl engine running with a manifold pressure at atmosphere Petrols running with closed throttle plate will be much much lower. To calculate MAF in mg/stroke you need to know air temp, capacity and manifold pressure

[@alrifainidal]

@@intelligentauto737 yes sir i got it .. thanks

[@rogerriehl1612]

Great video, great lesson. Thanks for sharing this. I'm having a similar condition with a Mercedes-Benz CLC200 Kompressor (CL203 2009, engine M271 with 84K km, about 51K miles)). Engine, sometimes, cranks and have difficulties to start (hot or cold). Then it starts and works perfectly, no fault codes stored. Cleaned MAF, TBI, injectors, checked fuel pressure after the filter (where the pressure regulator is), everything is fine. New air filter, spark plugs, but still shows the problem. Any advice about where I should look at? Thanks.

[@intelligentauto737]

Without the vehicle infront of me any advice would be pure speculation, my advice would be get the vehicle to a local diagnostic specialist such as myself

[@rogerriehl1612]

@@intelligentauto737 thanks for your reply. I would certainly take my car to you, but since I'm on the other side of the Atlantic, I'm afraid it won't be possible :) I've already taken the car to 2 shops and neither could find what's going on. This morning I unplugged the MAF connector and cranked the car, which started up right away. I then checked the connector and found some oil in it. Used some electric contact cleaner, dried it really well, and plugged it again. Then I cranked the car again and it started right up. Your video helped a lot. Thanks so much for sharing your knowledge.

[@Stoney3K]

So how come this one did not set a P00BC? Was the flow just above the threshold to set a code?

[@michaelagnew7825]

I assume substituted value is only while open loop?

[@DanWallis86]

Great Diag mate. On a side note. Any info on the bike?

[@intelligentauto737]

What bike

[@DanWallis86]

@@intelligentauto737 was that a motorbike I saw as you were getting out of the car?

[@intelligentauto737]

@@DanWallis86 ah yes there’s a motorbike next to the car. It’s one of my own bikes

[@simonrawle7885]

was thinking bad pcv for the cause

[@blow0me]

substitute values can be a PITA though. When the ecu is doing this, the value should also have a flag attached so it is crystal clear to the technician this is the case

[@intelligentauto737]

If the job was that easy everyone would be at it

[@intelligentauto737]

It dies flag it in a round about way, it logs a fault for MAF short to b+ and IAT short to b+

[@rdaleyj1]

Does substituting value work with all vehicles?

[@intelligentauto737]

Not all but it’s easy enough to check, unplug the sensor in question and compare the live data

[@zbigniewczajka4442]

Could I have an address for your garage, I'd like to know what's wrong with my car.🙂

[@intelligentauto737]

Www.fb.com/testingnotguessing