New(to me) truck with unknown tuning.

[Rawze]

(07-23-2023 )mattdm Wrote:  Sent you a file after a drive with some notes. Feels good and smooth driving, but did throw a MAP sensor fault when I got into it going up a hill. Power was surging.

It is not normal at all to get IMAP sensor alarms so something is definitely wrong.

Maybe IMAP sensor could be not plugged in all the way?. This is a very common issue if someone tries to plug it in and its mounted in its hole already. Connector does not slide all the way up sometimes. Could be bad sensor, covered in carbon and soot, etc.. or maybe someone tried to clean it with some spray cleaner or something instead of replacing it with a new one. Another no-no, as it cannot be properly cleaned.

Also, that code is thrown sometimes by mistake if the barro sensor is reading way off, or the exhaust back-pressure sensor is not reading right.

ISX's are also notorious for getting the exhaust (gas) back-pressure sensor circuit clogged up really bad and then it does not read correctly. The sensor itself is also only good for about 4 or 5 years, and/or about 400k miles or so too. - Could be an old sensor reading incorrectly, but there is an even heavier chance that the feed circuit is either clogged up for it going thru the thermostat housing, or the little cross-tube gong between the bottom of the thermostat housing to the exhaust manifold is broken off, missing, etc. too.

(this tube sometimes breaks off, or is mistakenly removed by bad delete places)..


One way to check the exhaust gas pressure sensor circuit is clogged up is to remove the sensor itself and spray a liberal amount of brake-cleaner into the hole where it mounts. If it pools up, then the the circuit thru the thermostat housing is clogged up and needs to be cleared out. Also use your fingers to tug a bit on the little tube that makes a sort-of 'u-turn' going to the exhaust manifold near cylinder-#1 to ensure it is not broken off at the manifold etc.

If the passage is clogged up, then remove the upper cross-pipe fitting (not the end on the manifold, as it tends to break off) .. and clean out the passage with a long drill-bit (by hand just to dig the packed up carbon out, not a drill) or piece of stiff wire, etc.. and get it opened up again.




I also hope that some moron has not removed it. Some places that do de-mandates remove that tube and section of exhaust like fools and then the exhaust back-pressure sensor can no longer read anything. It was indeed shut off (and should not have been) in your bad delete program you originally sent me.

That sensor not working properly makes the engine unable to detect miss-fire and other cylinder balancing conditions, and results in all sorts of other negative effects.

you could also have some wiring issues to one of those sensors too.

-============

I.E.> Something is causing the surging and making it act up + throw those faults.

Tags:

ISX exhaust gas pressure sensor issues, ISX surging, Exhaust gas tube, exhaust back-pressure sensor issues, ISX miss-fire codes