Rough Idle (only when cold)

[Whisperhead]

Hello all,

2000 MR-S JDM import
1ZZ engine
SMT transmission
Toyosports Stainless Header (just 2 O2 sensors)

My first issue to deal with, thankfully it's nothing terrifying - the car is driving so it can be an ongoing fix. I'm hoping some more experienced folks here can help me out.

The car runs great when at operating temperature, but on start-up until the car is warm, the idle is odd. For the last week or so, it's sat around 1000rpm and the engine is noticeably shuddering. It's not horrendous, but definitely can be felt inside the car. Car does have a whiff of fuel, as if it's running rich.

I have a JDM car so no code reader assistance unfortunately - that would've been my first port of call.

- Turning on the AC bumps the idle up, so I'm fairly sure the IACV is okay.
- Recently replaced the PCV valve with a genuine Toyota part, the old one was a still okay but I don't know it's age so changed it.
- Spark plugs and ignition coils are 4 months old, plugs look good
- MAF cleaned last week, and also once before that on purchase (March) - both times it needed cleaning
- Air filter is 6 months old, air hose just past the MAF has the metal circlip missing (need the size of it if anyone knows so I can find a replacement?)


Where do y'all think I should look next?

[Carolyn]

A code reader CAN assist.  You need a JOBD reader, which can be bought, OR you can put in a special line of code into torque Pro and it will read connect too.

Step 1: go out and buy an OBD2 Bluetooth adapter.

Step 2: Purchase the  app "Torque Pro" from the google play market for Android. (For you apple guys, the App Store does not have this exact app on there so I am unsure if any of the steps after this are valid) Any android powered tablet or phone should work here.

Step 3: Inside the app you can create car profiles for different vehicles (This app is incredible and is by far the most useful thing I've ever bought as an app because this app and the adapter can be used on ANY obd2 car) In the vehicle profile at the bottom of the profile page is a line that says Very Advanced ELM327. There is a line in that section to add text. The following text should be added to that line:

ATIB 96 \n ATIIA 13 \n ATSH8213F0 \n ATSP4 \n 0100

Once that is complete, hit SAVE and go back into the app. The app is now configured to see the JDM ecu's (that code changed the searching frequencies and some other protocol stuff in the app to be able to read the JDM ecu's)

I have an MR-S and I use this to check on my car.

That missing hose clip could be your idle problem.

[Gaz mr-s]

Remove the hose & measure the diameter. Get a stainless jubilee clamp.  For an SMT car you'll probably need a copy of Techstream, a laptop, & a J2534 cable.  I never usually recommend Facebook for a car 'forum', but I recommend the MR2 Spyder SMT group.  There a very knowledgeable & helpful people on it.

Fluctuating idle can be caused by air in the coolant.  Keep an eye on your coolant level. Get it properly hot & try bleeding the radiator. (top left corner as you look at it)  If you get a puff of air repeat the process next engine cycle.  And check the radiator for leaks.  Bottom right corner is most common.

[Alex Knight]

I could read the ECU code(s) from my old JDM Celica ST205 by bridging the E1 and TE1 pins on the diagnostic port with a paperclip.

Does the MR-S have the same functionality?

[Beachbum957]

We had exactly the same symptoms on a 2002 5 speed with a similar header. Idle was rough and erratic when cold, but fine after the engine warmed up a bit.  The only codes were random misfire codes that were only recorded at cold start. The cause was a sticky IAC valve.  When it was taken apart, the valve was gummed up, and also showed a lot of wear.  Replacing with a new valve from Toyota (NOT aftermarket), and cleaning a very dirty throttle body completely cured the problem.

[Whisperhead]

Firstly, thank you for that suggestion of using Torque Pro Carolyn, very helpful - I realised that I actually already had Torque Pro purchased a few years back, so have re-installed it on my phone. Excellent app I agree.

I also have a BT OBD Module somewhere, I'll track that down. Thank you very much for that advice, I'll definitely get on that. I was a bit miffed when I read elsewhere online that you can't use standard ELM327 or OBD readers on JDM cars.

I'll also sort out that clip, as I've heard any air leaks on the intake side can cause idle problems.

The car also has a little oil leak I've noticed, which appears to be that sodding O-Ring on the chain tensioner, I'm sure I've seen the spec for that here in the forum so I'll hunt one of those down. I noticed Carolyn has made a replacement guide which I shall be following.

The air in the coolant suggestion is a possibility also, but I'm replacing the coolant soon so I'll make sure to bleed it properly with the silicon hoses (one has vanished but I can source a replacement bit of hose).

I'll check for codes next opportunity I get. I remember using that paperclip trick on my old 93 Corvette back in the day, it had an OBD port but was on OBD1, so had to bridge pins etc. If all else fails, I'll give that a go too.

Learning a lot today haha! Thank you for the help so far everyone, I'm really grateful.

[Carolyn]

PM me your address and I'll send the improved O ring, courtesy of the club.

[Whisperhead]

Rather than opening a new thread, I thought I'd continue in here, as the issue is the same.

Torque has successfully connected to the car, and gave me a P0135 (Bank 1 O2 Sensor Heater Circuit).
Any suggestions for that? I'm guessing the sensor is having an issue - I found the EFI2 7.5A mini blade fuse blown the other week in the engine bay fuse box, research tells me it controls the O2 sensors in some way.

Have replaced that fuse, but no change. Could a bad sensor have taken that fuse out too?


Second I noticed while browsing the JapanParts site that I might have something missing from my engine bay, images attached.

...is there supposed to be a canister of some kind to the right side of the engine block? I appear to have a metal return (?) line there, and the solenoid to the left of the engine has an open nozzle... Also shown.

Plus, I'm pretty sure there is supposed to be a rubber hose clipped up top top? The clips are there but... No hose? What's missing? Or is this a JDM thing?

I hope that makes some sense!

[Carolyn]

You are missing the cannister that catches fuel vapour from the tank breather.  You don't really need it, but it is designed as an environmental aid.  The blue solenoid opens to let the vapour into the inlet.  The metal pipe coming from the bulkhead is the breather.  Other hoses connect the missing canister via the metal pipe clipped above the engine, to the blue solenoid.

It's not a 'JDM thing'.  Mine's JDM and it has the cannister.

You need to make sure no open hoses are leading to the inlet - that will bugger up the idle.

The cannister is not essential - but I (personally) think it's good to have it. 

I might have a spare one kicking about,  but I won't have the mounting bracket that is also absent from your car.  I'll have a look in the morning.  Otherwise J-Spec would send you one (with the mounting bracket) for peanuts, I'm sure. 

If you choose to just block up any hoses and live without the cannister, I might suggest a bit of hose to direct the breather vapour down and out of the engine compartment.

[Whisperhead]

Ah, I see. I'll double check those hoses. I struggled to find a part number for that canister, so if anyone has that, I'll try to source

Still discovering little things as I go, it's all helpful, so thank you for the responses

[Carolyn]

@Whisperhead :

I do have a spare cannister which you are welcome to.  I can't find the mounting bracket though.

You will get one From J-spec for not much more than the cost of postage.

[Whisperhead]

That's very kind of you Carolyn. I'll contact J-Spec and see if they can source the bracket and hose for me.

I'll send you a PM.