Hi Scotty,
I'm in the UK and I have a Toyota Auris 1.6 litre DOHC, 16 valve, dual VTDI manual 5 speed. Chassis number SB1KV56E00F030224, Engine Number 1ZR-FE
I've been told by various mechanics that compression on cylinder 1 is low but cannot determine the cause. So the engine is basically running on three cylinders. When picked up speed in gear 3,4+ the vehicle is fine, not an issue. The issue is during stand still idling the engine fluctuates from 900 down to 350 rpm and sometimes cuts out. During pull off slight gas has to be applied or the vehicle will stall.
As this model has an automatic throttle I was wondering if there was any way to adjust the throttle so I can increase the stand still idle to 950/1000. As this will solve the rising, dipping and stalling all at the same time. I do know on the older cable run throttle bodies you could adjust them, but these auto throttle I'm assuming work from information given to and from the ECU and Airflow/Maf sensors.
Thanks.
Year? Mileage? Do you mean dual VVT-i?
Fix the low compression issue first.
You need to find to a shop that knows what they're doing. The cause of low compression can be determined with a dry/wet compression test and a leakdown test. Chances are though you need the engine replaced or rebuilt and I don't know what the economics of that are in the UK versus just getting another car. There can be no expectation of that engine running properly on 3 cylinders.
Hi there sir, yes whatever the cause, an engine rebuild or tear down is necessary but given the age and current value vs a proper repair is not economically viable as the repair cost will outweigh the value. so in this case a quick fix is the best option. Like I said iv been driving it for 6 months & when picked up to higher speeds 3/4/5 gears car drives fine.
Only issue is idle peaks between 800 & drops to about 350, & sometimes stalls at junctions. If I can only adjust electronic throttle idle to 950/1000 than the dip wont be so low, so should be better to drive faster pickup & stronger on pull off. Problem solved for as long as engine holds up.
There aint no quick fix for low compression in worn cylinders 🙁
RU sure the fluctuation is due to this reason? Could be a ton of different things - from AC compressor to alternator or temp sensor.
@chucktobias need to check few things I would start with MAF sensor. Find it on hose leading form air box to throttle body. Make a wee investment buying obd scanner (vgate for example). Download a free app (car scanner, torque etc). Find OBD port right handside under the steering wheel. Instructions how to pair device with the phone will find in the box. Run full DTC scan. If no codes, have look at live data. Reasons RPMs going up and down are quite a few. First look at MAF reading. There should be roughly 1.6g/s on worked up idling with stable throttle opened around 15.7% . If MAF readings are either much higher randomly changing or throttle % changes a lot when not touching acceleration pedal try to clean MAF sensor itself. Look at the readings of O2 sensor ((S1B1 - pre cat). Should fluctuate between 0.1 and 0.9v on warmed up every second or so, crossing 0.45v which stands for perfect AF ratio. Have a look at fuel trims (STFT and LTFT). Mind You check these readings on idle warmed up no lights/ac/wipers heating anything.
Easy to check s also fuel tank breather valve /purge valve (disconnect hose leading from fuel tank to it, start the engine and if the valve suck the air straight after You start the engine (start on cold engine - should stay closed no suck until engine warms up.
But first 3 readings: throttle/MAF/O2 sensor. The reason engine RPMs fluctuate could be incorrect AF ratio which ECU trying to sort out by adding more or less fuel.
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