W210 E300 TD lack of power - Intermittent

[Stagman]

Advice please. My 1998 105,000 miles E300TD estate has recently been reverting to 'limp home' mode. However, when it does this there are no warning lamps illuminating on the dash, just a lack of power; kicking down will facilitate the gearbox to change down, but there is no / little increase in road speed - bearing in mind the RH pedal is buried in the carpet, just an increase in revs corresponding to the downshift. If the engine is turned off for a few seconds, then upon restarting, all appears to be back to normal until the fault decides to manifest itself again.
I took a trip to my local indy this morning to have the fault codes read, but the car behaved normally. Consequently once there I was told, that with no fault present and no engine warning lights, it was no point in connecting the car up to read the fault codes as none would be recorded.
I don't wish to randomly look at / clean / change components. However, from my research on the forum etc. I am thinking it may be an EGR fault, but would welcome views from others before I proceed further. Is disabling the EGR the way forward? Or can someone guide me through a systematic set of tests that I should follow to establish what needs sorting.
Thank you.

 

[bob 6600]

No current fault doesn't mean there isn't a stored fault.

These limp mode faults do not put any warning up onto the dash.

 

[charlysays]

I would advise getting it remapped by seanyt off the superturbodiesel forum. Will cost less than a superchip and you'll end up with 220hp and no MAF or EGR to cause problems anymore.
Failing that boost leaks are a common cause of limp mode on these. Every limp mode I had was due to a split in a 20yr old flexible intake hose which looked fine but opened up a hole under boost... ECU compensates to a degree but when it determines that the wastegate is too far closed and the turbos at risk of overspinning it'll just limp.

 

[Stagman]

I had the fault codes read today and ended up with a P1470. Am consequently looking for a leak on the vacuum pipes. From others' experience, are there any know weak spots please?
Thank you.

 

[Some guy on the internet]

Start with the easy to reach ones & check all the rubber hoses that comprise the induction system, including the in & out of the intercooler. It'll be one of them, and some of them are surprisingly expensive!

 

[Stagman]

Thanks for this advice; do the rigid plastic pipes cause trouble or should the focus be on the rubber ones? Also it probably gets worse the hotter the engine bay; a cold / still not fully warmed engine is fine. Then once the engine has been on for 25 mins then the issue occurs. Also yesterday it didn't appear to drop into a full limp home mode as the engine would still pull to about 4100 rpm on kick-down but there was insufficient power to allow the gearbox to change up. Stopping the engine for a short time (~1 minute) and the fault is temporarily rectified.

 

[LostKiwi]

Rigid plastic pipes rarely cause issues. Check all the rubber ones.You need to check carefully as some failures can be very hard to spot.
For example a favourite on Land Rovers was for the inner surface of the pipe to delaminate. Under boost air would get behind the delamination and force the inner surface to bulge downwards into the airflow blocking the inlet tract. As you can imagine - hard to see as once boost was removed the surface would return to its normal position.
If a hose feels wrong replace it.

 

[Stagman]

Nothing obvious has shown up re a leak. A couple of queries where I would welcome advice:

Is it possible for the leak to be associated with the headlight height adjustment?

Why when I turn of the ignition for half a minute or so, does it permit the car to work normally, i.e. not in 'limp home' mode?

Many thanks.

 

[Steve@Avantgarde]

I would carry out a charge air pressure test and smoke test and that would identify the leak.

Inlet manifold gaskets leak on these engines, as do the EGR systems. But a leak test is the way forward rather than guess

 

[Stagman]

Thank you for this advice. Will proceed with this.