Help me please..
Discussion
hello chaps it is i, my 85 280i hesitates in 3rd 4th 5th at the high end of rev range, definately not in 1st and 2nd when you get to about 4,900 rpm it pulls back on me like its missing or something i have only noticed this recently after swithing from lrp to optmax, it is perfect round town and it idles ok just when i go lange in the higher gears.. i have Crane cams coil, hotwire leads, and bosh spark plugs so there should be a huge spark, also k @ n air filter so no restrictions there either. i went to a show yesterday and crused along motorway at about 70-80 no probs but if i go anything over 130 it sort of misses almost like a lack of fuel but i had a good uprated pump fitted about august time, i hope i have not damaged my engine due to running unleaded optimax no smoke at all out the back, could this be something simple like the timing needs setting properly. My thanks in advance for all your help..
I have 280 too!
Assuming it is not the fuel filter, you may want to think about the warm-up regulator. It modifies the fuel pressure to the metering head for cold enrichment, and has a vacuum tube on it for full load enrichment (ie no vacuum).
How does the car drive when you first start her from cold ?
Does she start okay from hot ?
-Jim
Assuming it is not the fuel filter, you may want to think about the warm-up regulator. It modifies the fuel pressure to the metering head for cold enrichment, and has a vacuum tube on it for full load enrichment (ie no vacuum).
How does the car drive when you first start her from cold ?
Does she start okay from hot ?
-Jim
sorry been away for so long, dont know when the fuel filter has been changed i have had the car 2 years and not done it, been told they are expensive though and prone to blockages, the car starts first time every time really runs like a dream exept when at the high rev range in high gears, i am a big fan of good quality injection cleaners as well so should not be any fault there. does it matter that i dont do many long journeys either. the car is perfect exept at over 4900 rpm in 3rd 4th and 5th really wouldnt have noticed exept i have a very long straight near were i live. how often do i need to change fuel filter,, and what is that other thing that sounded expensive on the other reply. i really appreciate your help..... sorry chaps swapped to my laptop and its got a fuuny mouse button, keep pushing wrong button. the car starts exelent from cold and only takes second or two to start from hot, really runs well though, i did notice earlier though that it seemed to miss for a plit second when i was just depressed clutch aproaching roand about, never happened since... my spark plugs are about due a change but i am running car on a shoe string in the short term due to serious CSA commitments,
>> Edited by wedget on Monday 31st May 22:39
>> Edited by wedget on Monday 31st May 22:40
>> Edited by wedget on Monday 31st May 22:47
>> Edited by wedget on Monday 31st May 22:39
>> Edited by wedget on Monday 31st May 22:40
>> Edited by wedget on Monday 31st May 22:47
Hi Wedget,
Well, if you have no problems related to temperature I would suggest you have a fuel flow problem into the fuel distributor, as opposed to a metering problem.
(Assuming that the metering flap is not sticking of course!)
Either a blocked fuel filter, or the fuel pump cannot deliver the flow rate at the k-jetronic pressures. New fuel filter methinks, unless you have access to a fuel pressure tester and a rolling road... (I imagine you could check flow rate at operating pressure with a suitably raised bucket and a stop watch - no hang on, you'd need 32 feet of pipe for each 1Bar raise in pressure - forget that!!! - Oh yes, take the return pipe from the fuel distributor and measure the flow there - of course. Still no idea what it should be though! You'd need to work out the fuel flow at 130MPH, at say 10 MPG is 13 gallons an Hour - about ( 4.56 * 13 /60 = 0.98 litres per minute - I take no responsibilty if you set yerself alight, or get petrol in yer eye from trying this!!)
-Jim
Well, if you have no problems related to temperature I would suggest you have a fuel flow problem into the fuel distributor, as opposed to a metering problem.
(Assuming that the metering flap is not sticking of course!)
Either a blocked fuel filter, or the fuel pump cannot deliver the flow rate at the k-jetronic pressures. New fuel filter methinks, unless you have access to a fuel pressure tester and a rolling road... (I imagine you could check flow rate at operating pressure with a suitably raised bucket and a stop watch - no hang on, you'd need 32 feet of pipe for each 1Bar raise in pressure - forget that!!! - Oh yes, take the return pipe from the fuel distributor and measure the flow there - of course. Still no idea what it should be though! You'd need to work out the fuel flow at 130MPH, at say 10 MPG is 13 gallons an Hour - about ( 4.56 * 13 /60 = 0.98 litres per minute - I take no responsibilty if you set yerself alight, or get petrol in yer eye from trying this!!)
-Jim
Wow - Be easier to change the filter and you need to do it anyway. Not to mention (that for a TVR) the filter is almost unique: it's reasonably easy to change, is easily sourced and doesn't very cost much.
In fact, that sounds so good, I think I'll stop looking for my bad ground and change my filter again. - Maybe my lights will come back on.
In fact, that sounds so good, I think I'll stop looking for my bad ground and change my filter again. - Maybe my lights will come back on.
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