3sgte hesitation

[solitaire]

Understood... thanks buddy.

So the long term solution is going to be to get my af down to 11 really?

[sergei]

I don't know about MR2s, but my GT4 with 16.5psi did not had any knock problems and A/F was between 10.5 and 12... I think your problem might be in the intercooling...That is if you don't have any fault codes back.
Oh and BTW oxygen sensor does nothing on those engines under load - it is working only on very light loads, mine has it plug brocken off dangling in the air - it does not even brings up the code...

[solitaire]

Thanks Sergei, To be honest the intercooler does look like it has been in a fight...

Is there any point in turning the boost down to 8 or so untill i get better intercooling? Or does the ecu enrich the mixture as the boost grows?

[sergei]

On those engines (if it is gen2 3SGTE) the ecu guesses what boost you are running even if you have boost pressure sensor it is there just for dash guage and cutoff.
Your problem with detonation (if you have that) might be not only in bad intercooling (which was just a guess) but also in ignition timing (too advanced),or even air pockets in the cooling system (MR2s are prone to cooling problems). Little hesitation even might be just a miss (spark plugs, leads, distributor rotor and cap and coil might be at fault). Heavy knocking usually kills knock sensor after a while. Also you have (i think) a fan on the intercooler check if that running (I guess it is temperature/load controlled by ECU).

[solitaire]

Yeah its a Gen1 Sw20 with the standard Gen2 3s.

So upping the boost does not influence the mixture? Thanks i had wondered about that. The fuel mixture itself is handled by the afm i assume?

The only way to change timing is with a light gun isnt it?

I will change the engine coolant this weekend - its probably never been done.

The fan on the intercooler does work, but it only really runs when its burning up... any harm in running the fan all the time or will it burn out really quickly?

The hesitation on happens on a hot day at the lights... so hopfully the rotor & dizzy etc are ok

[fivebob]

Dont unplug the knock sensor the car will go into limp home mode.

Ah ok... given that the boys at tp says is was knocking a little bit is it likely to be safe to run without it? or do most cars knock every now and again?

Hmm its a little unprofessional for them to say that...

If the ecu cant see a knock sensor it'll think 'oh crap must protect engine' and kill all power to the engine, only providing enough to 'limp home' really slowly.

Not really, all it does is massively retard the ignition, and if the stock boost control is still active it limits boost to about 7psi. You still get full rpm, though power is reduced and the exhaust manifold heats up rather quickly. A by product of the retarded ignition is that the turbo spools a lot quicker bit the engine is producing less power

The way to blow your 3S-GTE is unbolt the sensor from the block and earth it manually while having it plugged into the ECU. The ECU can still see the knock sensor it because its plugged in but it will never detect knock because it is not in the block

Corrected for truth

The flip side is if you get a bad tank of gas on a really hot day, bad things could happen

No the flip side on a 3S-GTE is that bad things will happen....unless you're running an aftermarket ECU. These engines need the knock sensor with the stock ignition map and NZ fuel

[Caveman]

Dont unplug the knock sensor the car will go into limp home mode.

Ah ok... given that the boys at tp says is was knocking a little bit is it likely to be safe to run without it? or do most cars knock every now and again?

Hmm its a little unprofessional for them to say that...

If the ecu cant see a knock sensor it'll think 'oh crap must protect engine' and kill all power to the engine, only providing enough to 'limp home' really slowly.

Not really, all it does is massively retard the ignition, and if the stock boost control is still active it limits boost to about 7psi. You still get full rpm, though power is reduced and the exhaust manifold heats up rather quickly. A by product of the retarded ignition is that the turbo spools a lot quicker bit the engine is producing less power

The way to blow your 3S-GTE is unbolt the sensor from the block and earth it manually while having it plugged into the ECU. The ECU can still see the knock sensor it because its plugged in but it will never detect knock because it is not in the block

Corrected for truth

The flip side is if you get a bad tank of gas on a really hot day, bad things could happen

No the flip side on a 3S-GTE is that bad things will happen....unless you're running an aftermarket ECU. These engines need the knock sensor with the stock ignition map and NZ fuel

Thanks for correction fivebob, looks like 4age is much more robust than 3sgte then but in the end your word is truth when it comes to these engines

[vvega]

Quote:
The way to blow your 3S-GTE is unbolt the sensor from the block and earth it manually while having it plugged into the ECU. The ECU can still see the knock sensor it because its plugged in but it will never detect knock because it is not in the block

doing that wont help
the knock control on toyota's listens for amibiant noise as well as a method to "fliter" true knock signals
if it dosent hear the ambiant noise it will go into limp mode anyways

been there tried this ...when i was younger and considerably more stupid
the only way i found that works reliably to defeat the knock sensor is to advance the timming far enough that under full retard it sits at about normal advance(read very good way to $&#$% your engine)

had i of spent as much time tring to fix the problem rather than finding a way around it then it woudl have been sorted properly and teh issue wuould have been there

just for intrest the shielded cable mod works quite well
its comons because its also comon for teh knock sensor wire to have issues and is the way it needs to be replaced

....note
only connect the shield to ground on one end
connecting it on both ends turns it into a ariel rather than a shield

v

[solitaire]

First of all thanks to all of you for all the replies... I have learnt a lot from this thread already

I have unplugged the engine bay temp sensor for the meantime to try and keep the temp down.

tomorow, weather permitting i will:

1. Shielded cable for the knock sensor
2. Check afm resistances are within the limits
3. Change the coolant

big question: Anybody have any advice or know any gotchas changing the coolant on a SW20? I have the bgb of course but to be honest changing the coolant on this car scares the crap out of me...

Side question: Any other suggestions for trying to get the mixture down to 11? (i have done fuel filter)

[Akane]

You know, you can always just come around to my place and I'll take a look at your car. I'm on the shore as well.... That's only if you trust the pixel mechanic.

[solitaire]

You know, you can always just come around to my place and I'll take a look at your car. I'm on the shore as well.... That's only if you trust the pixel mechanic.

Sweeet! PM'd

[Akane]

It's okay, cash, grass or arse, nobody gets their crap fixed for free

[Toymota]

Solitaire, sounds like you have the same problem as me. My ST185 has that hesitation at WOT to and my ECU comes up with code 24 as well. I also have a screwed up idle which seems to misfire a lot.

I might have a vacuum leak somewhere on the section of the intake pipe right before the turbo but I haven't been able to fix it yet.

Be sure to let us know how you fix it when you do manage to.

[solitaire]

Hi Mate.... It seems directly related to high ambient temperatures... as auckland is have a shit weather patch im stuffed until it gets hot again...

I reset the ecu and the issue has not re-occured...

I will keep this post up to date when i discover anything...

[sk8dude]

Hi - I have a very similar issue as this thread/post and wondering if I can get some advice on what to check?
I am a novice and would like to cover off the obvious solutions if any?

Quick background : Caldina GTT 1998, engine replaced due to overheating (excessive).
I got the Caldina back from the mechanixs the other day. They did a pretty good job all in all but found an issue when we took the car down to Napier (from Auckland) over labour weekend. The issue didn't exist at first and only became apparent after an hour of driving??

Engine runs fine when idling and normal acceleration - however when the foot is planted (WOT) and the boost kicks fully in there is some "hesitation" from the engine. Kind of like a limiter kicking in? This doesn't seem to be related to a particular rev count and seems to be more related to the boost level. (I have no boost gauge installed currently). Boost wants to go high but flutters across various lower levels

My research suggests that there could be a leak from the turbo/intercooler lines perhaps giving a false reading and this a rich or perhaps a lean mix?? I have attempted to look for obvious leaks and seems ok.

There's no check engine lights so not sure if it's the ECU detecting something (e.g. knocking, or too high boost) and possibly kicking in a fail safe to limit the boost and protect the engine. Is it possible to check diags without a check engine light being registered?

Some other things I have heard is:
faulty wastegate spring, faulty catalytic convertor, fuel pump, fuel cut / lack of fuel pressure. MAP sensor??

I took the car back to the mechanic today and they gave it a look over. They have said the engine is running fine etc and have admitted that they are not turbo specialists and would be better off taking to a specialist. I'll probably have to do this but would like to explore the easier options if possible.

What might be the issue? And if I have to get it checked out buy someone more experienced (in Auckland) where should I take it (and not get screwed over)?

[kim0663]

Check wastegate if it has a hole in the diaphragm, like spray wd40 and blow air into nipple, and see if it blows out the other side where the actuator arm comes out of. You might be hitting boost cut and that wastegate actuator is common to tear apart

[jbod]

Sorry havent read all the replies, if no one has said, gap and clean plugs. The countless amount of times i have had this on manys 3sgtes ive had/have.

[sk8dude]

Thanks for the replies (Sorry I didn't notice the replies until now).
I'll take a closer look at the wastgate actuator diaphram this evening.
In any case can anyone recommend a competent organisation that I could take it to to look further at?
I would "prefer" to try and get this sorted this side of xmas if possible - pushing my luck though.

[DeeCee]

you'll need to provide a location so we know where to direct you to a local shop or good bastard who will check it for you

[sk8dude]

Of course :
Auckland, preferably South AKL or CBD?