Kevin Bacon 5 Posted March 10, 2011 190k miles. New chains and valve guides. That didn't make huge difference, but is smoother at some revs. I suspect thererfore that the garage got the sprocket on the right way! Were your MAF wire or film types? I've tried three (6-pin) replacements in total: two scrap and one from VW dealer, to no effect. Performance off - it's like a 2 litre. I get 23mpg on a 10 mile commute which is 60% country lanes and 30% urban. When she was working properly, I'd get 30mpg. Assumption is the mother.... :) My MAFs were the 6 pin wire flavour. I got 2 direct from Bosch. I first tried an exchange unit @ £150 and then a full unit @ £200. Both were DOA. I took one of them down to a local Bosch agent and they analysed the output signal on their Oscilloscope and found it to be 'within tolerance', but it made no difference to the engine performance / behaviour. Finally, I bought a s/hand one from a breaker IIRC and it changed the car. Go figure! Anyway, your current symptoms are exactly the same as mine when my the cam timing was a tooth out. I.e. everything seemed normal, except it was slower and burned more fuel. I know it was out a tooth because I was the person responsible :) I corrected the timing and all was right in the world again. It's very easy to fudge up the timing, even the pros do it. Even if just to outrule it, I would get the cam timing double checked. It's just a case of whipping the rocker cover off, timing the motor to TDC on cyl 1 (there is a notch in the crank pulley and a marker on the crank seal housing to aid this), pop a dental mirror down the side of the chains adjacent to cyl 5 and using a torch, examine the intermediate shaft pulley's position. What you want to see is the arrow pointing to a notch on the head. If it's pointing anywhere else, you will need to get the cam timing readjusted. [ATTACH=CONFIG]45242[/ATTACH] Quote Share this post Link to post Share on other sites
ismith 0 Posted March 11, 2011 I've had my 1993 VR6 for 12 years and when she was young (under 150k), a motorway journey keeping under 75mph would give me 35mpg. A mixed commute of 10 miles would get me 30mpg. I'd have to be urban and under 5 miles to get 25mpg. Now 23mph on 10 miles :-( and the diagnostics show it is not happy. Quote Share this post Link to post Share on other sites
ismith 0 Posted March 11, 2011 kevhaywire - Thanks for your tips. I could do this inspection, but the car was performing well for many years and then badly with nobody touching the chain. It performed exactly the same after chain replacement and same again after the cyclinder head valves were replaced, so I think it's probably ok. From what you say, I could have three suspect MAFs, or lambda/MAF wiring with an intermittent fault I can't find. Oh to find a car technician old enough to remember how to find these problems! Quote Share this post Link to post Share on other sites
ismith 0 Posted March 11, 2011 So you still havent found the problem.... I would like ro know what it was in the end, I average 25mpg and this was after changing relay box and ecu. I can only get around 30 mpg in the motorway. Keep us updated Have you had a diagnostics readout? It really is useful. If you are doing 85-90 on the motorway, then 30 is about right. 65-70 would get you 35-37mpg. Quote Share this post Link to post Share on other sites
Conker 0 Posted March 11, 2011 Have you had a diagnostics readout? It really is useful. If you are doing 85-90 on the motorway, then 30 is about right. 65-70 would get you 35-37mpg. He can't possibly be doing 85-90 mph because thats illegal. :-D Quote Share this post Link to post Share on other sites
Critical_Mass 10 Posted March 11, 2011 He can't possibly be doing 85-90 mph because thats illegal. :-D Illegal but unlikely to be pulled for doing those speeds. Assuming the conditions allow. ;) Quote Share this post Link to post Share on other sites
