ST185 problems

[Toymota]

My car seems to idle a little funny, sounds almost like a lawn mower engine, like it is misfiring. It does it quite a lot when idling sometimes and I also might have the occasional hiccup when decelerating in gear.

Sometimes when I come to a stop quickly and push the clutch in the idle will kind of fluctuate a couple of times. Another weird thing is that sometimes the engine will take ages (around 3 seconds) to start and then other times it will start straight away.

I also have this extremely annoying engine hesitation or misfiring when I floor it. But, if I ease the throttle on then its all good and still pretty quick. It seems to be the same problem that solitaire has with his MR2 turbo as explained in his thread "3sgte hesitation".

Could a minor air leak before the turbodo this? The intake hose that connects on right before the turbo has gone real hard and cracked. I did my best to seal it up but there still might be an air leak. I haven't been able to find a silicone joiner to replace it with anywhere (2.75" 45deg).

I also get the code 24 "open or short in intake air temp. sensor circuit for 0.5 sec or more. (THA)" but when I tested the actual temp. sensor it seems to be within the right resistances so I guess the problem is with the wiring somewhere? What does the intake air temperature sensor do anyway? Is it really that important?

The last thing is the screw that is on the top of the AFM unit. I messed around with this a while back and I don't know what the setting is supposed to be. I think it controls how much air passes through a passage that bypasses the AFM flap but there is nothing about this screw in the manual.

As far as I know the car is stock besides HKS air filter but it actually has a Ramflo foam and some type of exhaust mod but not exactly sure what it is its just a little louder.

If anyone has experienced anything like any of these things or has any opinions or suggestions it would be very much appreciated.

[Toymota]

Well after searching around on the net I found this awesome website; Autoshop101.com, which has loads of Toyota technical information. This article explains about the Idle mixture by-pass circuit which is what that screw on top of the AFM is for.

According to the article there is a 2 digit number stamped on the AFM near the adjusting screw. This number represents the distance that the flat surface of the screw should be from the casting. What do they mean by casting?

Another thing I cant figure out is which way I read the digits from. I cant figure out if my number is 89 or 68. Perhaps one of you guys with a 3S-GTE with this type of AFM has a number that has an obvious direction like 5 or 7 and could tell me what way the numbers are stamped on?

Once again any help would be greatly appreciated.

[Boosted_162]

Where abouts on the AFM is it? Ill check against my facelift ST185 one.

[Barks]

I just had a look at the autoshop101 website and Boosted_162 is right, it's a fantastic website....

Mods: Can one of you sticky the link to it in the Tech F.A.Q's? It's a fantastic resource and it deals entirely with Toyota stuff.

[Toymota]

Where abouts on the AFM is it? Ill check against my facelift ST185 one.

AFM Picture

This pic I just took of my AFM shows where the adjustment screw is located. The number is stamped next to it, on the lower part of the AFM casting.

If you manage to find the number could you just measure the distance between the flat surface of the adjusting screw and the top edge of AFM casting around it. If your number matches up to that distance you measure then I'll know that that is the measurement that I will need to make on mine.

Its just that I don't understand what they mean by "casting" in that article when they say "This number indicates the distance from the casting to the flat surface of the screw..."

[Crimson Tears]

The easiest way is to measure with a pair of vernier calipers. When they say casting they mean to measure from the top of the screw housing to the flat surface of the screw. Bear in mind that number is truncated - 89 would become 18.9mm.

The symptoms you are describing would point to an air leak, I believe those motors are quite common for splitting the rubber air intake hoses to the turbo. Any air leak after the air flow meter is going to give you serious problems. I would try to source another hose, it's difficult to seal them up properly. You can search for air leaks by spraying a solvent like carburettor cleaner round the suspected leak area, if the engine idles up you have found a leak. You could also try giving your idle speed control valve a clean, they get gummed up and give idle problems. The intake air temperature sensor is more for fuel fine trimming, I've seen plenty of them unplugged and they don't seem to give too many problems.

Hope this helps,



Mike.

[Boosted_162]

On mine, all 3 rubber hoses have cracked in some way (AFM->turbo, turbo->ic and ic->tb). Have a check of those. Ill check my AFM when i get home from work tomorrow, too dark now.

[Malcolm]

the number on the afm is read from the plug side

[Cakky]

a bit different car

but my dad had a similar thing with his volvo lately..
sounded like a tractor on idle, but was generally fine on boost.

ended up being a small crack in the intake manifold gasket.
hope this is of some help

matt

[Toymota]

Cheers everyone for you help and suggestions! Now I know that my distance is 16.8mm and where it is measured from.

The intake air temperature sensor is more for fuel fine trimming, I've seen plenty of them unplugged and they don't seem to give too many problems.

Its great to hear that, I always thought that the intake air temp sensor wasn't a major part of EFI system.

Previously I had 2 major air leaks, one of them being on the P/S pump air valve which was quite possibly also letting some P/S fluid get sucked up into the engine. When I had these leaks the car was running so crap it was virtually impossible to drive. Now the car has improved heaps but still not perfect so this main intake hose could be the last one I need to fix.

Also, I can hear my turbo hissing as it spins up. This could be sound coming out the air leak?

I finally found a Samco 70mm 45 deg silicone bend at KiwiRE but its $117!! I know Toyota original parts are real expensive but do you guys reckon that an original rubber hose will be more expensive than that?

Oh yeah, one thing that I forgot to mention is that this misfiring problem is 10 times worse when the engine is cold. Would an air leak in a hose still have this characteristic?

One other thing. This is most likely just a coincidence but I'll say it anyway; all the problems that I've had with this car - I've had it for 6 months - happened after I did an oil change and put in Castrol GTX Protec. Anyone think this could have anything to do with anything?

Thanks again everyone for your help.

[postfach]

I finally found a Samco 70mm 45 deg silicone bend at KiwiRE but its $117!! I know Toyota original parts are real expensive but do you guys reckon that an original rubber hose will be more expensive than that?

http://www.trademe.co.nz/Trade-Me-Motor ... 508438.htm

I use that stuff for my IC piping and it works fine, don't need to spend $120 on name brand stuff when you can get the same stuff for $50

[Toymota]

I finally found a Samco 70mm 45 deg silicone bend at KiwiRE but its $117!! I know Toyota original parts are real expensive but do you guys reckon that an original rubber hose will be more expensive than that?

http://www.trademe.co.nz/Trade-Me-Motor ... 508438.htm

I use that stuff for my IC piping and it works fine, don't need to spend $120 on name brand stuff when you can get the same stuff for $50

I would use a cheap brand if I could but none of those cheap brands make the size and angle that I want. I asked pretty much every seller I could find on TM if they have 2.75" (70mm) 45 degree bends. Repco and Supercheap don't have.

[Anth_555]

use a 3" thats what mine had when i got it

[Crimson Tears]

I work at a Toyota dealership and I priced the rubber hoses a while back, from memory they were in the $180-300 vincinity. Not cheap by any means. They were also ex Japan. I think your best bet is to persue with the samco joiners path. Get those hoses replaced before any further diagnosis.

As for the oil change, no, it shouldn't have caused any problems.


Cheers,



Mike.

[Toymota]

Ok, well I'll probably be going to go down the road to KiwiRE tomorrow and see what they have. I think they also got turbosmart ones which are cheaper but when I last asked they didn't have them in stock.

One thing I was wondering is will the silicone hose stuff up my oxygen sensor or is it all good?

[Toymota]

Well I was just thinking about something yesterday and I thought I might just revive my old thread.

The main problem I have is engine misfiring and hesitation under acceleration only when the engine is cold. Once it's hot it runs good. The other thing is just random missing when idling. Doesn't matter if it's hot or cold, it does it all the time. But at high idle (1100rpm) it seems to idle fine particularly once the engine heats up.

So, the thing I wanted to know about was spark plug heat ranges. If I put a hotter plug in there do you think it could help my engine run better? Since the problems occur mainly when the engine is cold plus my plugs are showing some fouling as well.