Hi Guy's. This sounds very similar to my problem see thread
http://www.omegaowners.com/forum/index.php?topic=106685.0 Thanks for the input on that one. Had a miraculous recovery with it. Put a coil pack from Steve at Omega Spares on, which didn't cure it. However, a couple of mornings later it started no problem but after this is when I noticed the MPG drastically dropping.
So, I too have high consumption if you watch the fuel gauge but the instant cons on the mid is telling me she's doing 38 at 30-40mph, when I release the throttle and free wheel it goes upto 999.9! Which may well be normal.
I noticed the fuel pressure vacume pipe was disconnected n thought, wahey that's it! No chance lol. My injectors sound like they are really working hard, they are loud and can be heard in the car. Could the fuel pressure too high if the release valve doesn't work? I don't know how it works i.e. does the vacume increase or decrease the fuel pressure?
Had the plenum off the other day, really clean, breathers too. But I have a slight hissing sound coming from the rear of the plenum on the drivers side, hopefully I'll have the scuttle off today n get my head in as far as I can to find it. The hissing changes when I move the pipes around, so something ain't right. Other than the split breather mentioned here is there anything else I should look for?
When I disconnect the battery the rough startup happens every time I reconnect it, almost like the ECU has senile dementia lol. The EML doesn't light up and the fault codes (0170, 0173) are also gone then after about 8 miles they are all back. If I disconnect the MAF (thanks to a hint on here) when rough starting she rev's sweetly at 1500 no problem. Reconnect the MAF and idle drops to 500 revs. Does this indicate a knackered MAF.
Sorry Webby, didn't mean to hijack you're thread but thought you might recognise my car's problems.
Cheers in advance
Dave