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General Public Area >> News >> Pico Newsletter Jan 2015 https://www.autonerdz.com/cgi/yabb2/YaBB.pl?num=1422649679 Message started by Logic on Jan 30th, 2015 at 12:27pm |
Title: Pico Newsletter Jan 2015 Post by Logic on Jan 30th, 2015 at 12:27pm
I bring your attention to this article in the Pico Newsletter.
1. Case Study: Celica brings Scope and Scan Tool together ========================================================= This month Steve Smith demonstrates how PicoScope fits within the diagnostic jigsaw when resolving seemingly complex issues. The analogy of a jigsaw fits well if we look at the essential pieces required for a successful diagnosis. ~ The relevant Scan Tool ~ Accurate technical information ~ Experience gained as a direct result of training ~ PicoScope The vehicle in question is a 2001 Toyota Celica 1.8 190 PS utilising variable valve timing and lift. The complaint from the customer was poor idling, heavy fuel consumption, lack of power, periodic cutting out on over run and the all-important engine warning light was illuminated. As always the customer interview is vital, and in this case revealed that extensive engine work had been carried out including a cylinder head replacement due to severe overheating. At this point it is very easy to jump to conclusions and assume "doom and gloom" when a customer arrives having experienced numerous attempted repairs after a major engine overhaul. However, by maintaining a methodical approach throughout the diagnostic procedure we can present our customer with not just a bill, but a working vehicle and the evidence and data trail that supports the necessary rectification. A basic inspection revealed the tell-tale signs of intrusion about the engine to include, a new cylinder head, VVT oil control valve, coolant temperature sensor, catalyst, pre-catalyst O2 sensor accompanied with a punctured and misrouted wiring harness that resembled a pincushion! A brief road test confirmed the customer's complaint but also revealed the engine to sound fine with no knocks or rattles, or smoke from the exhaust and both coolant temperature and pressure to be correct. Note: The exhaust fumes did emit the sulphur odor associated with over fuelling or a catalyst working overtime! It is essential to establish the engine condition before spending the customer's money... You can continue reading the Toyota Celica case study online: http://www.picoauto.com/tutorials/celica-faulty-maf.html |
Title: Re: Pico Newsletter Jan 2015 Post by Robski on Jan 30th, 2015 at 1:05pm
I don't understand towards the end he mentions 'doner car' is this how he fixed the faulty one ? :-/
"Below we have the waveforms from our donor Celica" |
Title: Re: Pico Newsletter Jan 2015 Post by autosparky on Jan 30th, 2015 at 6:32pm
he also takes about theoretical MAF math channel, while this sounds very clever, how accurate can this be??
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Title: Re: Pico Newsletter Jan 2015 Post by JOHNNY5 on Feb 13th, 2015 at 8:09am
I believe there are two critical miscalculations in his MAF formula calculation. Please Correct me if I'm wrong.
MAF miscalculation I believe there may be 2 miscalculations in the MAF formula. ---First, the weight of air is 1.286 grams per liter as nitrogen alone weighs 1 gram per liter almost exactly and the remaining oxygen weighs .286 grams (air is 80% N and 20% O) Almost 30% more. -Second is where we calculate 25 intake strokes by 1.8 liters. The entire 4 cylinder engine is 1.8 resulting in each cylinder and therefore each intake stroke to be only .450 liters. 25x.450 = 11.25 liters 11.25 liters x 1.286 = 14.47 grams |
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