Hi All,
Having read some high quality technical input on this forum, I?d like to pick everyone?s brains on an issue that is vexing me but one you probably haven?t come across before: that of running modern car engines on LEADED fuel.

Background

Here in Jordan almost all the second-hand cars imported into the country are sourced from Europe (Germany provides 75% of total, mostly BMWs and Mercs) or the USA, i.e. are catalyst equipped. However, you can only get UNLEADED fuel at a few fuel stations here in the capital, Amman. UNLEADED is simply not available at all outside the capital. So most people just fill up with the 4 star or 2 star that is widely available and cheaper than unleaded to boot. Crazy government policy, I know, and this is before we get into the discussion of the total prohibition of diesel-engined passenger cars and station wagons!

After a while, most cars suffer a significant performance drop which is normally resolved simply by sawing off the now-blocked catalyst?(The all-too-true joke goes: You can give a [insert Third World nationality] a brand new, top-of-the-range car and he?ll bu66er it up in two weeks but keep it going for 30 years?) Anyway?

My question is:

What are the long-term effects of running cars designed to use UNLEADED on leaded fuel? Either in general terms or vehicle specific.

Issues to consider might be: fuel injection system, ECU control of timing, combustion temps, combustion chamber materials, spark plugs, Lambda sensor. Some vehicles have an additional sensor in the catalyst itself ? what happens when that is removed/ disconnected (apart from a dashboard light coming on)?

A subsequent issue is that of the removal of the catalyst itself and the subsequent change of exhaust backpressure that may have a detrimental effect on engine longevity. What effect might this have on exhaust valve temperature?

Whilst most interested in people?s opinions, I am also looking for research papers and test results, both lab-controlled and any owner?s experiences.

Of course, much has been written about using UNLEADED in old LEADED-spec engines e.g. valve seat and ignition timing issues. Looking for answers to my question I have spent many an hour with search engines, but as yet to no avail. Here is where any web whizzos might be able to help. Obviously, there is not going to be a huge amount of info to answer my question, as it is not relevant to most car users. But I would hope that somewhere there might be something useful or interesting.

The reason I would like this information is that many of my acquaintances know I am an automotive engineer so I get constantly asked for advice on this one. Until now, I can only offer second-hand anecdotal evidence, which I will gladly offer if anyone is interested.

I would be delighted to discuss this at length on email wilson@nol.com.jo

Sorry for the long post and I hope someone can help,

CMark
"Don't tell him, Pike!"
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Rover 220 Coupe N Reg 96 2.0L DOHC Engine

Problem:

Engine cuts out when the car is in traffic (idling for long time after long runs) and won't idle until temperature under the hood drops.

I've tried disconnecting the following to determine a problem:

Lambda Sensor
ATS
CTS
TPS
Idle control stepper motor

Changed fuel relay, HT Coil, rotor arm and lead to distributor.

Rover dealer had the car for a week and found no problem but tightened an earth connection. Problem returned the next hot day.

Really stratching my head now and would appreciate any help.


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I hope someone out there can help me . On the way home today I decided that I want to see how fast and how well my car handles at high speeds. Trying this out to the public highway is impossible for thereat of loosing my licene so the only option I can come to think of it a track day the problems however are:
1: My car is presently in a 1years free insurance with reanult and the insurance doesn't cover track days. SO how do I get insurance for the day and would having two sets of insurance on one car be odd/ illegal.
2: My car is a 1.5 65hp diesal so isn't exactly a world car performance car. So I don't want to try and race a Supra or other very quick car I just want to see how fast and well it handles for my own benefit and to for once see how much faster than the book it will achually go
3: I've never been to a race meeting or track in my life before and what exactly happens?
Any help please
Many thanks
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Can anyone suggest a reason why my 95 A6 2.0 misfires between 2-3Krpm, usually when under a light rather than hard load? Also, the idle speed oscillates intermittently. The main dealer has done a negative diagnostic test, and a good independant guy didn't find much either. I've tried fuel additive, at their suggestion, but to no effect. Read more

Hi folks,

I've noticed recently that there's a lack of decent car ads on the "idiot lantern". So that got me thinking - what's the best-ever car ad you've seen on the telly?

Probably for me, it's got to have been the Nissan Almera ads from a few years back, aping The Sweeney and The Professionals. Spot-on impersonations and very entertaining.

Going back even further to the late 80s, the Montego ad where the car was put through it's paces in a works car park (handbrake turns etc - was the wheelman the renowned stunt driver Russ Swift?) was pretty good, of course the ASA would never allow such wanton displays of speed these days!

Any other suggestions? Read more