No EML, no MAF data, low tick over but....

[bootzey]

Hi All.

Just got a 51 2.0 VVT-I petrol hatchback. 

It has a low tick over of roughly 500-550 rpm and the fuel consumption seems very high (35 miles from a tenner at £1.16/litre) and the cat smells with medium to hard acceleration.

It has a history of EML on but not got any details as to why.

The guy I brought it off (trader) suggested the tick over had been reduced to save fuel which seemed plausible. However, I now know that's not the case.

When I had the car connected to Android Torque I wasn't getting any data for the MAF sensor and I noticed both after cat 02 sensors weren't "flipping" as they should. The precat ones were regularly and rhythmically "flipping". All four sensors are newish.

After about 10 minutes of ticking over mixed with a bit of revving the tick over suddenly increased to a very smooth 750/800 and the after cat sensors started to flip. Still no MAF data coming through though.

So I'm confused as to why this should happen.

Have a feeling it might be something to do with the car getting hotter than it does whilst driving?

Maybe the cat got warmer and started working properly so the after cat sensors registered the change?

Coolant temperature increased so maybe coolant temperature switch?

I'm going to unplug the MAF to see if it makes a difference to the engine and registers a code.

Anyone got any ideas please?

Cheers.

Dave

[Konrad C]

Maybe the car has not been in use recently and the new sensors have not settled in. I would check, clean or replace as much of the intake side, like the air filter. Toyotas have a learning ECU and you could pull the EFI fuse in the engine bay for about a minute, then go on a drive. The ECU can then relearn the settings and adjust to the new sensors. I would look at the injection system - this engine is direct injection! Make sure there are no leaks.

Overall, it sounds like the car needs a good drive, and good petrol to get the car smooth again.

[bootzey]

Thanks Konrad.

The trader I got it off used it as a daily driver but just around central London. I was thinking about an "Italian tune up" with an injector/cat cleaner.

Now you mention it, I've noticed the rpm increase if I pump the brake pedal. So this could be the leak you mention.

I've also thought about disconnecting the Battery for half an hour to reset the ecu but I don't have the code for the stereo/computer.

I've also been thinking the thermostat might be playing up because the car never reaches normal temperature if started from cold with the heater on full blast and just left to tick over. Or perhaps an air lock in the cooling system which I wouldn't know how to get rid of.

It's just bugging me as to why the tick over and both post cat sensors should suddenly spring in to life after idling for a long time.

Thanks again.

[frankie406]

If your stereo is the original manufacturer type it shouldn't need a code.have you tried letting it idle with the heater switched off? 

[Konrad C]

I didn't think the stereo need a code unless, the unit had been changed. Regarding vacuum leak on the brake servo and inlet, do you have to press the brake hard? Spray some liquid on the hoses to see if that effects the vacuum performance. To get rid of air locks, I normally squeeze the all pipes including the heater hoses.

You know how to test the thermostat by dropping it in a container of boiling water, and watch it open, unless it has stuck open. 

[bootzey]

Hope you're right as I've unplugged the Battery lol

Yep, I've just left it to tick over this morning. Eventually got up to temp with a bit of revving after about half an hour, left it an hour and the radiator fan eventually came on. Turn the heater on full blast and the temperature took about 10 minutes to drop to 80 but the gauge didn't drop and even when the fan came on the gauge didn't rise either, it just stays in the middle regardless.

Rpm this morning settled at around 650, pressed brake pedal down, kept it pressed and revs went up to a high of 714 then settled back down, released brake pedal and revs increased to 805 but settled at 650.

Pump the brake pedal and revs hit a high of 900 after four pumps of the pedal, then settle back down to 650. Sensor 2 bank 1 got alot more lively 0.1 to 0.8 but then went to between 0.6 to 0.8 on tick over. Sensor 2 bank 2 is always at between 0.6 to 0.8.

Intake psi stays between 3.3 and 4.4 regardless of rpm.

Just reconnected the Battery...you're both correct...no code needed...phew.

Temperature gauge was roughly 25% up so it had cooled a bit and the rpm was 400. Rpm increased when temperature increased to normal.

Thermostat looks like a bugger to get out and test but it does seem to be a bit lazy and maybe not opening fully. Looks like I've gotta take the alternator off and a few other bits just to get it out.

Thanks again both of you.

 

[Konrad C]

I forgot to add, and you may already know this - Haynes manual covers this car and engine combo. Also I can assume you have an OBD2 scanner, since you are getting readings. Winter tends to cause higher fuel consumption in most cars. 

[frankie406]

Check and clean throttle body and pcv on rocker cover.is your plugs OK also. Try a drop of millers ecomax petrol additive. 

[bootzey]

Thanks both.

I've just put a bottle of Cataclean in so fingers crossed. Sparks are next on the list, then coolant temperature switch, then thermostat if I'm feeling brave.

Done a bit of Googling and it seems it's natural for the revs to increase a bit, mine goes up by 200 revs, then settle back to what the were almost immediately. I've pressed the brake pedal then started the car and the pedal drops a bit, revs settle then increase (again by 200) when the pedal is released.

The problem seems to be when the temperature is in the mid range, like the car can't decide what amount of fuel to inject. It also happens when restarting the car after a few minutes which is what leads me to think of the CTS. 

Yep, I've got Android Torque, which has served me quite well for the last 3 years and various cars...You've just gotta pay out about 50 quid for a decent adapter. Even though there's new 02 sensors, I'm going to see when the go closed loop, somethings definitely lazy.

I've read a previous thread on here where similar problems were described, especially at mid range temperature, but the solution wasn't stated. Hopefully someone will see this who's cured the problem or it helps others.

Cheers.

 

[bootzey]

Think mines sorted for now.

Thanks frankie406.

Removed, cleaned, made sure the PCV valve rattled when shaken and squirted a lot of carb cleaner into the intake manifold hole for the PCV pipe, replaced the pipe with a vauxhall corsa one.

Jammed the throttle pedal to rev at 2.5k and got squinting in 1/2 second bursts. Then revved it at 4k for a minute or so

I now have no issues with low tick over. Cold start ticks over at 1800 instead of 1000. Within a few minutes, with the temperature gauge barely moved it's purring steady at 800 instead of struggling on its way down to 500. No flat spot either.

Checked the valve again and crud is already on it, so when it's warmer the cam cover will be removed and cleaned.

Thanks for the input.

Hope this helps.

Dave