Quote:
Originally Posted by daverods
If you are reading this you are most likely a Toyota owner or have owned one in the past. I have grown up with Toyotas my entire life, mainly because my dad was a fully certified Toyota mechanic. We all know that 90% of Toyotas older cars are virtually indestructible, unless they fall victim of being hit by a large truck. 
This brings to my current dilemma. I am currently driving a 91' Toyota Paseo, 5 Speed Manual, with roughly 280,000km, and no modifications as of right now. I was initially impressed to see that I got 18% above the estimated fuel mileage of my vehicle but now after seeing the numbers from some of the other members of ecomodder I realise there is alot of room for improvement.
I know that the smaller displacement Toyota engines aren't very thirsty for fuel so im pretty confused why im not getting below 7L/100km (33.6 mpg) combined highway and city. 
I have a handful of theories as to why this might be happening. - Unusually high idle on cold start (2000rpm)
- Warm idle speed of 1000rpm (seems a bit high)
- Known vacuum leak on intake (intake pipe is broken right after the fitting on the throttle body )
- Alignment issue with front suspension (had rotten right lower control arm replace 4-5 months ago without re-alignment
 )
- The front of the car sits considerably higher than the rear (looks about 2-3 inches) essentially turning the car into a sailing ship on the highway when it is slightly windy
 (my guess is front springs were replace with aftermarket springs that are for the wrong application)
Now before anyone tears me apart and says, "WHY DOESNT YOUR DAD JUST FIX IT!?!" I'm just wondering if these issues would be enough to keep me from getting 6L/100km (39.2 mpg) or even better? I am already implementing an extremely conservative driving style, incorporating hypermiling driving skills.
Oh BTW everyone is allowed to post suggestions, not just the Toyota owners! 
Keep on hypermiling!  |
A broken intake pipe, before the throttle body is not a vacuum leak. Vacuum can only exist after the restriction of the throttle plate. This is assuming you are talking about the pipe from the air filter to the throttle body (not sure the information is confusing, at least to me).
No vacuum leak exists after your clarification just unfiltered air entering the engine through the defective pipe. It would not be "after" the throttle body or it would be a vacuum leak. It must be before the throttle body to NOT be a vacuum leak. Regardless, something is affecting the idle speed which should be around 600-700 RPM and it may also be affecting the cold high idle speed since it is affecting the hot idle speed.
Possibly a leaking intake manifold gasket, or some other loss of integrity in the pathway from the throttle plate to the intake valves. If this exists then what I said earlier still applies. The crack in the intake pipe does not explain the high idle.
regards
Mech