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4x4mama · 07-07-2025, **(Subject: 2000 isx15 turbo issue )**

So we have 2000 isx15 in a 2001 Freightliner century. We aren't getting full turbo all the time. It had a bad clamp on the exhaust side that we replaced. There's a hose that was pinched off intake side to the waistegate actuator. Undid it and didn't seem to make a difference. Typically getting 20-27 boost in cold temps. In hotter temps 18-20. But it will also just all of a sudden give a burst of boost sometimes in all temps.

Any ideas on what could be going on? Thanks

marek4792 · 07-07-2025, **(Subject: 2000 isx15 turbo issue )**

Sounds like a sensor failing in range, go on insite and look at your boost pressure, barometric pressure, intake temperature, fuel pressure etc. Then see if the wastewate diaphragm isn't leaking with shop air and a handheld regulator at various pressures <30psi.

4x4mama · 07-07-2025, **(Subject: 2000 isx15 turbo issue )**

(07-07-2025 )mikkhh Wrote: Is the IMAP sens[/b]or original? When it was changed last time? When was the last time the sensors and intake was cleaned?

IS the e gr system intact and working? Has somebody pulled the magic plug on it?

[b]

The sensors are either original or not been changed in a long time. The truck sat in a barn for a few years. As far as I know egr is in tact. It's pre all the really bad things lol. Where is this magic plug you speak of?

Mr Hagg · 07-07-2025, **(Subject: 2000 isx15 turbo issue )**

2000 dont have egr.... Id hook up insite and read what boost is it seeing. maybe have yo a manual test gauge to verify its right. these are simple back then so if intermittent got to be a sensor reading so bad sensor or harness...

Truckdriven · 07-07-2025, **(Subject: 2000 isx15 turbo issue )**

I've had one same year with the exact symptoms you describe, found the barometric pressure sensor was reading around 6 instead of the normal 30+/- range and that fixed it

4x4mama · 07-07-2025, **(Subject: 2000 isx15 turbo issue )**

(07-07-2025 )Truckdriven Wrote: I've had one same year with the exact symptoms you describe, found the barometric pressure sensor was reading around 6 instead of the normal 30+/- range and that fixed it

Where would the barometric pressure sensor be? I appreciate the help

Rawze

What is the engine ser#?.

Also, do not put that block-off clamp back onto the wastegate for the turbo.. anything more than about 36 lbs boost on it is EXTREMELY HARMFUL to those old ISX CM570's.

ad as well... if sensors are old.. replace any of them that are more than about 5-6 years old. - Do some actual tune-up work on it if it has not been done in several years. The engine will overall run much better.