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hey this site and the information is great. have been worried about the electrical side of motors for a while and stumbled onto this site in a search session. awesomely informative with good examples of application. Thanks again-Brilliant!

Russell Elliott
New Zealand


Hi there from the UK! I love your site and I agree with your review on the Fiesta Zetec, its a great handling car and was well reviewed here as well. I only drove one for a few days but it was great, I went berserk on a favourite back road and it held its composure much better than my old Fiesta, and even a Peugeot 306 I remember driving. As you said the problem is they should have given it more power, but the higher insurance rating wouldn't be friendly for young drivers here (we get a slightly bodykitted 'warm hatch' version of the 1.6 Zetec as a Zetec S) and also the gearbox can't take the torque. Really Ford should have designed a new gearbox for the Ford Puma 1.7, as the torque was restricted in 1st gear to prevent damage to the box. That's also why they had to put a completely different gearbox/engine series in the 2.0 ST they market over here, with 150bhp it would have been playing Russian Roulette with the old IB5 box. Sorry for such a geeky response, keep up the good work.

United Kingdom

Airflow Meter Change

The time has come to seek your expert advice. I am about to replace the MAF sensor on my car with a MAP sensor. I read your article on teh subject, and I know you do not recommend it, but this is last resort. I have a 1991 Mercedes w124, 2,3L petrol engine with KE-Jetronic continuous injection. It measures arflow with a vane type MAF. Problem is after 200 000 miles on it, the tracks on the little pot are gone, Bosch does not offer the little pot as a separate part,and the whole MAF unit costs about half the car - almost 1000 Eur. Buying a second hand replacemnet does not guarantee trouble free installation. I have to adjust fuel mixtrue every day - after a while the ECU enters into trouble mode, and I have to delete the 4 flashes trouble code, and readjust mixture after that. I am planning to leave the vane intact, as it is also mechanically coupled to the KE-Jetronic fuel distributor, and use a MAP to measure air volume instead of the potentiometer. I measured 0.5 bar of vacuum at idle, will a 1 bar MAP work? Originally, at idle the pot should give betweem 0,5-0,7, and about 5V at WOT

Stanislav Randjev

We've said it all at Why to Not Swap Airflow Meters


Referring to an article of Real World Air/Fuel Ratio Tuning by Julian Edgar. The scope meter readings look as if they could have been subjected to impulse or alternator noise, resulting in incorrect values. Was the scope meter used as a scope or a meter (if that is possible?), I am thinking here that the volt meter mode may sample at a lower samples per sec? Was any averaging used?

Bryan Davis
New Zealand

The Scopemeter trace looks fine to us – in the pic it is showing closed loop cycling.


I have been a keen reader of Autospeed for quite a few years now. It's the only site I can think of where the "technical info" presented isn't subtly linked to selling something. Reading your articles on parts, books, new cars etc., makes much other motoring journalism seem overly enthusiastic and conspicuously non-critical. I guess that's why you have a longish lists of car manufactures that won't loan you cars! So long as your opinions are based on your observations and facts, good on you. There is so little non-commercially motivated information around as it is.

The other thing I like about your site is the sprit of science that permeates it. I'll bet at least one of you is an ex school teacher in science. (Or wanted to be one.)

Finally, re your "Autospeed in 2008" blog on December 17th, 2007. I believe your new approach is wise and very timely. For example, I have a mildly modified R33 GT-R Skyline which I enjoy a great deal, including its high performance and handling. Bottom line though, I am probably not going to be able to justify that as a daily drive in 5 years, when I am semi-retired and high octane petrol is between $3-$5 a litre. Consequently, my mind has also turned to hybrid petrol-electric, ethanol and biodiesel as alternates. You are also right that this is a very significant turning point in transport technology. The world is changing irrevocably due to the impending end of the age of oil.

At least until discarded  fish and chip shop oil becomes a valuable commodity, I like the biodiesel option the best. (I suspect if you have a look at, you inner science teacher(s) won't be able to resist it either fat fryer oil, methanol and caustic soda yummm!)

So I thought, hmmmm, maybe I could buy a cheap, second hand diesel car and give it a go running home made biodiesel. (eg. rather than wreck an expensive new car.) My search on Autospeed led me to one of your project cars, the Peugeot 405 SRDT. What was missing though - I thought - was the “is biodiesel a suitable fuel" perspective.

Perhaps, for our collective benefit, you guys could take the next step and identify common, affordable and robust second hand diesel cars, that best lend themselves to running  100% biodiesel. You can see from the biofuel forums that the issues of degradation of plastic and rubber engine parts, cold starts and clogging fuel filters, seems to be critical issues. (Eg. See Australian Biofuels forum

Perhaps that is another useful topic for Autospeed to explore in 2008?

Anyway, best wishes and thanks for a really great automotive site, which is obviously a labour of great love!

Stephen Patat

We expect to DIY cover bio-fuels in 2008. Julian Edgar worked as a secondary school humanities teacher for 8 years.


Re throttle body story, "AUD$" is like "PIN number".

Gordon Drennan

Hmm, AC current anyone?

Prius HV Batteries

Does Julian still have any NiMH bats left from his attempt to charge his battery externally?

David Sharpe

Some, but he is keeping them.

Boost Control

I was looking into the audi boost mod> The Audi's DIY Boost Control - Part 2 now in article one, you say that you un-plumb the solenoid (n75 valve) but leave the loom fitted, i take it that you then do not use the solenoids fittings at all and dimply use it to say its still plugged in? but with air not going through it, would the ecu not realise this? or do you put  your regulators inline with the solenoid. im getting kinda confused as you can tell

Jake Walsh
United Kingdom

The ECU doesn’t know that no air is passing through the solenoid.

Closed Loop

I read your articles about ignition timing, ram-air and closed-loop monitor with great interest! This is very good information.

I have a question about closed loop cars. Is every car with an O2-sensor equipped with a real closed loop mode ecu? I heard about self-learning ECUs, and that real-closed loop cars were built not before 1999. Is that true?


Perhaps some early cars using oxy sensors for closed loop did not have any self-learning (ie they just used a fast feedback) but certainly most have long and short-term fuel trims (ie self-learning).

Human Powered Vehicles

I have been reading your "Building a Human Powered Vehicle" series with great relish. Julian Edgar has done a marvelous job of communicating the ups and downs of creating what at first appears to be a child’s toy but instead turns into an unexpected drama of  applying exuberant creativity and exhaustive energy to higher engineering. The highly sought-after technical information for this class of vehicle is presented is such a practical and matter-of fact manner that I sometimes forget that much of it is over my head.

I hope Mr. Edger has come across the web site below as it has a level of engineering sophistication that I have not seen elsewhere. More academic yet lacking polish as the author was busy with school and real life.I hope he comes back and finishes.

To the matter at hand, I can not find the conclusion (i.e., part 8) of the first HPV series, No matter how hard I look! I wish to finish the series before I go to the next one, "Another HPV". My son and I are designing and building an HPV (maybe with electric assist). We want to design it as "high-tech" as possible, yet still keep the project within reach of an average DIY guy without a welder (I.e. me). Your HPV series has become invaluable for us on many design challenges, especially suspension and steering.

I am encouraging my son to continue his interest partly to foster his interest in dealing with global warming, partly to have a tangible teaching tool for math, science, geometry, physics and the like, and lastly because my son has a dream of building a car (like I have always had.).

Please send a hyperlink to the final installment of Building a Human Powered Vehicle, Part 8 - conclusion. Then I can read Another HPV as soon as possible to continue my HPV education.

Tom Furie
United States

We suggest you go onto the next series, which is a much better design.

LS1 V8

I read with interest the article on MODIFYING THE COMMODORE'S LS1 5.7-LITRE V8 & am now wondering if I am wasting my time with Over the radiator air induction,extractors,2 1/2 system etc ?? Every article I read on otrai claims better performance etc !!  Are they kidding themselves? I don't want to waste money if it's a 3 day wonder ??

Danny Heaver

We’ve never seen an engine that doesn’t improve in some way – be it fuel economy, power or throttle response – with better breathing.

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