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I've been using the Torque ODB2 app to check engine data and identify possible causes for having reduced MPG.
When accelerating moderately fast from rest, I noticed that the manifold reading goes to +5 or +10Hg which is really boost pressure rather than vacuum. I would think that manifold can only go to 0 since this is a naturally aspirated engine. At idle the manifold reads around -22Hg. This is a 2007 Toyota Tarago (Previa) 2.4L, non-turbo. Is this normal for this engine? I'm wondering if this is due to the VVTi system or is there a problem with the manifold which I need to address.
Can someone tell me if this is normal engine behaviour?
Last edit: 8 years 7 months ago by philpreston3072.
What is the reading Key On Engine Off? Also what is the Loop Status of the engine when warm is it going Closed Loop?
Also try one of the alternatives to Torque OBD Car Doctor Pro is very good There is also OBD Fusion and EOBD Facile.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
I checked the manifold reading with another app (Dash Command) and it turns out that this engine doesn't have a built in vacuum guage. It estimates the vacuum from other sensor readings, so probably isn't that accurate.
So with key on and engine off, there is no reading at all. Engine does show closed loop when warm.
I tried the ODB2 adaptor on my mum's 2000 RAV4 VVTi but strangely it couldn't obtain data from the ECU.
Thanks for the advice. Looks like I'll need a proper vacuum gauge to diagnose the engine.
What kind of fuel trims are you seeing while driving? It's possible that the trims are out far enough to cause a fuel consumption problem, but not enough to set a code.
Short term FT is +/- 5%.
Long Term FT is also around +/-5%
The MAF readings are out of spec though.
MAF at idle is 2.7g/sec and reference range is 1 to 3 g/sec. This is ok.
MAF at 2,500 rpm unloaded is 8g/sec and reference range is 2 to 6 g/sec. This is a bit high.
I'm guessing 8g/sec reading is related to higher fuel consumption. Do you think it's either the spark plugs are worn or there's a partial exhaust clog?
A blocked exhaust won't let the engine breathe. The maf should surely be lower than normal. Probably more pit of spec the higher the revs too.
What sort of mileage you get out of it? Does yours have 4 o2 sensors? Over here they do.
In the EU OBD2 (strictly speaking. EOBD) was not compulsory on petrol cars until 2003, on vehicles from before 2005 even if a vehicle has a 16 pin diagnostic socket don't assume it is OBD2 compliant.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
I'm only getting about 18mpg whereas reviews of the car when new are 23mpg.
I can only find 1 o2 sensor on the car. It is Pre-Cat. But I am able to get a reading of sensor 2 through OBD so might be hidden.
Andy.MacFadyen wrote: In the EU OBD2 (strictly speaking. EOBD) was not compulsory on petrol cars until 2003, on vehicles from before 2005 even if a vehicle has a 16 pin diagnostic socket don't assume it is OBD2 compliant.
Thanks for that. Explains why I couldn't get any readings from mum's RAV4.
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