View Single Post
Alan L Alan L is offline
Registered User
Alan L's Avatar
Join Date: Apr 2006
Location: New Zealand
Posts: 3,247
unstable WUR pressures

This problem is driving me nuts.
I am running the car with a gauge hooked into the WUR at the moment - trying to sort some tuning issues. There are two problems, and I don't know if they are connected.
The CPs fluctuate violently - even on idle. I can stop this by putting my finger on the air plate - which also flutters violently. And I can start it off by tapping the airplate, at idle. The CPs then bounce/pulse at about 10 per second and the gauge simultaneously reads +/- about 5 psi of any mark. In fact the pulsing is probably far worse than this, and the gauge just can't keep up.
What would cause this? It has been a problem from day 1, and seems to come and go. Now it seems here to stay.
There seems to be a lack of damping in the system. I know some CIS fuel heads have a restrictor orifice in the head/WUR line, apparently to dampen a bit. Are these heads supposed to have same. My fuel system has been so mucked around by PO I have no idea what is right/wrong.
It also had a diaphragm chamber hooked into the WUR/fuel head line (off a Mercedes). Supposedly a fuel enrichment device, but I'm wondering if it was supposed to stablise the system. I had removed it, trying to get back to base conditions to get it running right. I'd fit it back on - but can't find it at moment.
The engine hates this fuel/airplate pulsing.
Secondly, whatever warm CP I set it at, it wont stay with 10 psi of it next time I start it up, or after a short hard burst (full boost).
Any suggestions where I should be looking, to try and stabilise this system (yes I have a digi WUR on order). But if this pulsing is not caused in the WUR, it will play havoc with a digi WUR trying to also pulse at about 10 cycles/sec.
Any suggestions other than chuck the car over a cliff.
Old 10-29-2008, 09:35 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)