1996 406td no boost and poor fuel economy.

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g60uk
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1996 406td no boost and poor fuel economy.

Post by g60uk »

I have a 1996 406 1.9td with a kkk turbo, and i have two problems, the first is that it feels like it hasn't got a turbo, you can hear it ever so slightly, i've checked the pipe work for any splits, checked the pipe from the top of fuel pump and changed air and fuel filters also, but no difference! Also it has really poor fuel economy, possibly a related problem but £40 of diesel to 130 miles! Something definately not right there, tried the same journey in a friends xantia 1.9td and cost £15! Is there anything else i can try on this heap, if not i'll have to burn it! :twisted:
Thanks for your time,
Kevin.
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CitroJim
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Post by CitroJim »

Hi Kevin and welcome to the forum :D

Apart from the incredibly poor fuel economy and lack of boost, does the engine sound OK? Does it smoke excessively? If so, what colour? How does it start? Did this happen suddenly or gradually?

Are you sure you have checked the turbo pipes and intercooler very carefully for leaks? Also, don't dismiss the notion that one of the pipes may be severly kinked, thus severly restricting airflow, likewise intercooler.

There is an easy way to test the turbo. Disconnet the hose leading to the intercooler from the turbo and start up. From this hose you should feel a considerable breeze as you rev the engine. At the same time you can see how much suck the engine is making on the intercooler by carefully placing your hand across the intercooler inlet. You should be able to feel quite a suck but be careful. A healthy engine can exert enough suck to cause a nasty injury so don't cover too much of the inlet. Just feel for a good suck.

The other possibilities are an EGR valve stuck open (if you have one - it looks like a little lantern on the exhaust manifiold with a small black vacuum pipe going to it), a choked cat or exhaust back box, a leak on the exhaust manifold or an internal turbo problem such as a wastegate stuck open. This last possibility though is very rare and unusual.

Finally, I have known this problem on the semi electronic pump be caused by the TDC Sensor or Needle Lift Sensor packing up and causing the pump and ECU to fall into "limp home" mode. Is your engine management (K) light on at any time?


Let us know how it goes..
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
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