ECU prob

[Gran]

Hi again JJ

Already changed the plugs,as you say for the price not worth messing about with. The dizzy cap was suffering from a build up on the terminals but a clean up didn't clear the problem.
Rogue are going to change it for a blueprint one, I tried to get one of Benf with the copper mod but it wouldn't have arrived in time for Rogue.
I thought about the timing, what do you remove/change to get basic timing, the last time I did a check was on an Escort & removed the vaccuum pipe, is it the same on an MR ? Basic timing is 0 ?
I am thinking now it could be fuel related... I am running a shed load of injector cleaner through it , don't know how effective it is but who knows.
Got to go & see if I've still got a timing gun...or have I lent it somebody......GGrrrrr

Regards

Keith.

[JJ]

Well your right in removing the vac pipe on a carb fed engine... these are electronically controlled, so you have to disable its electronic spark advance mechanism - this is done by going into your little diagnostic port at the back of the engine bay - bridging terminals TE and E1.

Strap the timing light ( if its one that dependant on power, theres a battery feed in the rear fuse box ! ) Stick the timing light towards the bottom pully and you'll see the marks - the timing mark and a small notch out of the bottom pulley.

That need to be bang on 10 degrees BTDC or advance it to 12 for more response, but run on higher octane fuel.

Injectors, perhaps need a clean - injector cleaner won't do it though.. I've never found an improvements with injector detergent .. they either have to be pulled which is a bit of a major job on the normally aspirated engine due to the manifolds covering the entire cam cover.

I wouldn't go down this fuelling route until you've checked the ignition timing first.

Adjustment, well loosen the two bolts off the distributer and rotate clockwise / anticlockwise accordingly.

[Gran]

Hi JJ

The timing is spot on & the advance mechanism is OK too.

What controls the amount of fuel shoved through the injectors,could it be a variation on this that causes the hunting ?

Later....

keith.

[JJ]

Hi JJ

The timing is spot on & the advance mechanism is OK too.

What controls the amount of fuel shoved through the injectors,could it be a variation on this that causes the hunting ?

Later....

keith.

Hey keith, its the map that dictates the fuelling on the ecu - millisecond pulse when it open.

Perhaps a faulty plug ? I've had a faulty new plug before, engine used to just hesitate like mad when on the first takeoff.

Variation causing the hunting.. unlikely.. the ecu is programmed for different conditions - so that will control the engine to whats programmed. If the conditions have changed ( too much air drawn in ) thats when you have issues like you having.

Something to try with the ecu... it has a self learning period in the first 5 mins after reset. This irons out ignition imperfections but on the later versions, also alters the position in which it idles.

Stab in the dark, why not try it out !! Drive the car till its warm, then pull up and pull the efi / ecu fuses out in the engine bay fuse box for two minutes. Refit them, then take it for a 5 minute thrash. In theory, will correct itself of any minor hiccups ( misfire / idling issues ! )

[Gran]

Hi JJ

I've reset the ECU this morning after checking the timing. On the idle valve on the opposite end to the spring that controls cold idle there is a plug that at a guess contains an electro magnet, is this how the ECU controls tickover ?
Just a thought, what bit of kit tells the ECU the rpm's of the engine ?

later

Keith.

[JJ]

is this how the ECU controls tickover ?
Just a thought, what bit of kit tells the ECU the rpm's of the engine ?

The bit that tells the ecu the engines running too fast is the distributer - most cars have crank position sensors in them, but on the MR2, the pickups built into the distributer.

So if the ecu knows the engines running fast, it can counter this with the idle control.

The valve works on temperature too, cold start if you've noticed, theres coolant hoses going to the idle control... this is what expands / contracts the spring ( the heat from it ) - the spring is directly coupled up to the air channel valve that you've been cleaning up. The electromagnetic switch in the idle control valve is there to stop the sudden drop in throttle, so it opens the channel to allow more air through - ecu can detect if the cars on its way to stalling, so does something about it !!

there has been a few cases on the turbo models where the loom has actually ingressed water and its managed to rot the feed wire to this idle control valve - the result is ecu has no control over it.

Am I still making sense ?

My big critisisms with the post 93 engines both turbo and normally aspirated is too reliant on the ecu controlling the idle speed, there is no manual adjustment like the earlier models !

[Gran]

Hi
This is what I think is happening the ECU is telling the idle valve to do something & its not getting the correct voltage & opens too far letting in too much air or not open enough & starving the engine, then the ECU over compensates until it sorts its self out after a couple of rev bounces.

Grasping at straws or what.........could always be an air leak

One more session then Rogue can have it, got a new pup coming Monday & will be busy with him.
Any way I can check the power supply to the electro magnetic control ?

Regards

Keith

[JJ]

Any way I can check the power supply to the electro magnetic control ?

If your bored keith, pull your ecu out of the car, lift up the cover and look for the IDL pinout on the board, make a note of the position of the pin out to the wiring loom.

( you'll probably have that other kicking about still ?? )

Check for continuity between that pinout and the idle control valve firstly, then check for voltage output..... I'm not sure how many volts it should be ( needs looking up ), but most of the ancillaries work with a 0-5v signals normally, perhaps its a 12v supply your looking for.

[Gran]

The wire from the IDL pin out is pink but the wires on the idle control plug are red,black or green, so no continuity & I don't have a S3-GE wiring diagram to see where the pink one goes before it gets to the plug.
After putting everything back together I rechecked the error codes & now have a 4-1, TPS error ? & resetting the ECU won't get rid of it.
I'm going to swap the TPS switch off the spare throttle body to eliminate the original one.
After that it can swivel......

Cheers

Keith.

[JJ]

I'm going to swap the TPS switch off the spare throttle body to eliminate the original one.

Good man, this is what I wanted to hear regarding the TPS.

The ecu is designed to chuck an error code out if its out of adjustment - this enables you to set the TPS up in the right place - this is likely to have affected your idling too as the TPS is indicating to the ecu its in open loop ( off idle position ! )

To set it up... loosen the TPS screws, bridge the TE E1 terminals.... error code will be flashing... turn the TPS till the engine light starts to flash continuously.. then its set.

That ought to do it !

[Gran]

Hi JJ

swapped the TPS over & removed ECU fuses to clear errors but when I check errors they're still there & I can move the TPS to its full range both ways & still the codes showing. Swapped it back to original TPS & tried again but no improvement.
This is the first error that it has shown.

Only 13 days until Rogue get their turn, Best of British to em'.

Fridayish...

Keith.

p.s. just been out & its not dying if I rev to 2000rpm & release the throttle maybe thats because the idle valve is cleaner & lubed up ?
Out of curiosity where is the idle valve when the throttle is open ?does the ECU close it off ?

[JJ]

Out of curiosity where is the idle valve when the throttle is open ?does the ECU close it off ?

Ecu should close it off !

And perhaps the lubed up unit is now working a tad better !

Cant help you with the TPS then as you have both of them and both spill out an error code. can only suggest checking the wiring to the ecu - check the ecu connector blocks are definitely making contact - unclip, reclip back in.

Oh ! You are resettting the ecu each time when you change them out... because the error code is normally kicked out under two circumstances - setting up and total loss of signal.

If your changing it out and not resetting it, then the error code will be stored.

Yup ! we're getting kinda saturated here. In this given situation if it were me, I'd simply rewire the signals to and from the ecu which usually resolves it. Finding a break in the loom is too time consuming when you can just run some new wires and cut the old and leave them in the loom !

[Gran]

Top man JJ

Pulled the ECU fuses,unplugged the ECU plugs, plugged em back in replaced ECU fuses = no error.
Can I now do the setting of the TPS ? set up for error check then rotate TPS until error shows then return slightly ?? nothing is that simple..is it?

When I was banging my head against the engine mounts in frustration I heard a what can only be described as a "fffffzzzzsssttt" from what appears to be a black canister near the air intake pipe,one small pipe in,one small pipe out looks like it disappears near the fuel tank.

Bl**dy hell wheres the light at the end of the tunnel...

Keith.

[JJ]

Bl**dy hell wheres the light at the end of the tunnel...

Good man keith, most people give up when i'm asking them to try different things !! Your obviously the type that won't be beaten by a cars engine management system !!!!

I've had many a heartache over ecus and problems... aftermarket !!! My last installment i threw the towel in... just couldn't get the engine to run right at all !!! turned out that the ecu was faulty !!! hahahaha !!!

Dont' worry about the charcoal cannister, its designed to absorb some of the vapour from the fuel tank, reusuable energy !!! Occasionally, there is a build up in pressure... this is then dragged into the intake occasionally ( little VSV opens ) then allows the gas to be burned off.

Most cars vent to atmosphere, but I guess thats why toyota have won awards for thinking about just about anything.

You can block it off and polute the atmosphere if you want !! You can also vent that crank case breather too as it just makes a mess of the internals of the intake.... notice it when you removed the throttle body ???

Normally cap it at the throttle body, and stick one of those bling vent filters on the end of it.

Can I now do the setting of the TPS ? set up for error check then rotate TPS until error shows then return slightly ?? nothing is that simple..is it?

You got it !

[Gran]

I've loosened the screws on the TPS,set the car to check for errors (none) & then rotated the TPS both ways to maximum but the error signal doesn't change,is this how you do it or do you have to move it then take out the bridge,switch off ignition & recheck it every move.

Still Fridayish...

Keith.

[JJ]

Sorry keith, engine running, and terminals bridged whilst your doing this !

[Gran]

Don't apologise,I think you've got the patience of an angel.
I can't get an error turning the TPS switch but it does stall the engine, so I presume this is when the butterflies are shut but the TPS isn't telling the ECU to open the idle valve....so I've backed it up a bit & locked it up.
The revs are still bouncing but it doesn't seem to drop the revs off as bad & the rpm is a little high but I can live with that until it goes in.

My lads in a Taekwondo competition tomorrow,Sunday I'm moving step sister in to new house, Monday is new dog day, so it can stay as it is now & wait for Rogue.

Thanks for your edification into the inner workings of an MR2.

Roll on the 17th.

Regards

Keith.

[JJ]

Thanks for your edification into the inner workings of an MR2.

Obliged !

Report back if they resolve it !

[Gran]

Report back if they resolve it !

If..If...bl**dy hell I hadn't thought beyond them fixing it..OOOeerrr

Keith

[Gran]

Finally I can put this one to bed, had a phone call from Patrick at Rogue & its sorted now. It turned out to be a dodgy cam belt tensioner allowing the belt to jump & the TPS had gone open circuit. I am picking it up Tuesday & by all accounts its singing like a good un again.
Many thanks to JJ but I take my hat off to the Rogue boys...

Cheers

Gran.