2005 Toyota Corolla 1.6 Manual, Surging High Idle When Cold

Hi all. I have a 2005 1.6 Corolla (I believe aka Matrix / Vibe), Idles very high (around 2k) when cold, and also often surging up and down around that 2k point. If any of you have seen Paul's "Honda-Acura Surging Idle Speed" video it does that does this exact same thing. I can actually hear the injectors shut off to stop the surge. Unlike the Honda in the video, this problem on this car only occurs when cold - it's fine when fully warmed up.

I know an inlet manifold leak on these can cause this problem, but the fuel trims are good (both around 0) which makes me think it must be something else (car has a MAF not MAP, with electronic throttle, and is a manual. No DTCs. TPS values look normal to me on a basic live data scanner). I was wondering if anyone had any tips on the best way to proceed from here (I have a vid of the surging if anyone is interested in taking a look maybe I could post on YT or something - I don't believe I am able to post it on here). Thanks in advance .

From your description it really sounds like a major vacuum leak that is closing up when the engine warms up. I would try either Paul's water spray method or using a length of garden or heater hose as a stethoscope to try and find although the extreme rising and falling RPM might make that difficult or impossible, so viisual inspection or try push and pulling at the inlet manifold with the engine running while listen to the engine note.

Hey iofix! Whereabouts are you? Because I don't believe they sold the Corolla with a 1.6L engine in the US market. Not a problem, just curious!

We'd love to see that high idle video, if possible. You're right, the forums don't support direct uploading, but YouTube and Vimeo are good options.

Thankfully, the electronic throttle makes the list of suspects pretty short. :lol: Has the throttle been cleaned, or has the battery gone dead recently? Both will throw off the PCM's learned idle strategy. Before going much further, I'd suggest cleaning the throttle, disconnecting both battery cables, and running a jumper across them. This'll reset the idle strategy and allow the PCM to start from scratch.

Tyler, jumping the battery cables is to bring residual voltage throughout the ECU to zero Instead of leaving the battery disconnected for a certain period?

Scannerfanner wrote: Tyler, jumping the battery cables is to bring residual voltage throughout the ECU to zero Instead of leaving the battery disconnected for a certain period?

That's the idea, anyway? :silly: I've never taken direct measurements on a circuit board to prove that connecting the cables together makes any specific difference. But, this is the method that's worked best for me in the past.

I've also heard of techs jumping the cables with a test light, or just stepping on the brake pedal a few times (closing the brake light switch) with the cables disconnected. I believe all of these methods would do the same thing.

Hi Andy, thanks for getting back to me on that. I take on board all you say. I know SD loves that water test - and does it with such confidence! - but I feel cautious about spraying water all over the electrics (for example the injector connectors etc), so tried the propane test instead and that did not reveal any leaks. Do you think the water test is better than propane? Thanks (in case you might want to have a look this is a vid of the problem which I just put on YT: )

Hi Tyler, thanks for getting back on that. Yes I'm based in the UK and we much smaller engines over here! - LOL

Yes I've cleaned the throttle body and the MAF, although neither were actually too dirty to start with. But also YES car did have a flat battery. I've read about the touch the battery cables together PCM reset but was cautious of doing that because I wondered if it could damage the PCM, so I did the let it idle for 10-15 minutes thing which I thought was also supposed to relearn the idle(?). But you suggesting the touch the battery cables together technique gives me a lot more confidence to try it! - Is there any particular procedure to follow after? Thanks (I've just put a vid of the problem here: )

:lol: Yeah, the ECM is not happy with that idle speed, huh?

But also YES car did have a flat battery.

Gotcha. In this case, I'd absolutely try the battery cable technique. For what it's worth, I find that it's LOW battery voltage (like, 7-8V) that causes module issues, not necessarily connecting and reconnecting.

If you're still hesitant, there's another way of doing the same thing. On most Toyota models with an electronic throttle, there's an EFI fuse (for general ECM power) and an ETCS fuse (which powers the throttle control system inside the ECM). Pulling both of these fuses for 10-ish minutes can also work to reset the idle strategy.

Afterwards, just let the engine idle with no loads until the engine warms up. As a general procedure, I also like to allow the engine to idle for two minutes in the following states:

- Park, A/C on
- Park, A/C off
- In gear, A/C on
- In gear, A/C off

Afterwards, you should be good to go!

iofix wrote: Hi Tyler, thanks for getting back on that. Yes I'm based in the UK and we much smaller engines over here! - LOL

I'm jealous! :lol: There's so many awesome engines that never made it to the US market for whatever reason. But, it gives me hope that if I ever needed to work in the UK, I wouldn't be completely out to sea. :silly:

Tyler wrote:

iofix wrote: Hi Tyler, thanks for getting back on that. Yes I'm based in the UK and we much smaller engines over here! - LOL

I'm jealous! :lol: There's so many awesome engines that never made it to the US market for whatever reason. But, it gives me hope that if I ever needed to work in the UK, I wouldn't be completely out to sea. :silly:

Hey Tyler, based on what I've seen on youtube etc I think you boys would be ahead of the game over here. But you might have to get up to speed on diesel engines because we drive a lot of diesel cars over here!

Going back to that Corolla... I tried the connect battery leads together and let the ECU relearn thing we discussed, but unfortunately it has not made any difference. If you have any other suggestions that would be great. Also do u mind if I ask you the following: 1) As I said before, my first suspicion on this was an intake leak but moved away from that due to the fact that my fuel trims are good, is it possible, on a MAF car, to have an air intake leak but still have normal FTs? 2) Also I tried the propane method to check for an air leak and did not find anything, I know SD likes the water method - in your opinion is the water method better than propane? Thanks again - Ian

iofix wrote: Hey Tyler, based on what I've seen on youtube etc I think you boys would be ahead of the game over here. But you might have to get up to speed on diesel engines because we drive a lot of diesel cars over here!

Yeah, I'd be sunk on that stuff. :silly: I'd be completely lost on Citroen, Peugeot, and Seat, too.

Going back to that Corolla... I tried the connect battery leads together and let the ECU relearn thing we discussed, but unfortunately it has not made any difference.

Awwww, that's disappointing. :lol: To be clear, you let it idle until it warmed up?

Also do u mind if I ask you the following: 1) As I said before, my first suspicion on this was an intake leak but moved away from that due to the fact that my fuel trims are good, is it possible, on a MAF car, to have an air intake leak but still have normal FTs?

It is, but only in very specific ways. Intake gaskets that leak when cold (and the vehicle isn't in closed loop yet) is one. Stuck open PCV valves are another.

2) Also I tried the propane method to check for an air leak and did not find anything, I know SD likes the water method - in your opinion is the water method better than propane? Thanks again - Ian

I dunno that one is better than the other? Two different tools in the box, IMO. For what it's worth, I like water because it's a very 'positive' test. If you hear the water getting sucked in, you have your answer. Propane (and other external fuel sources) can be somewhat vague, because it can be difficult to control where the fuel goes. On the other hand, external fuel can sometimes find leaks that water will miss. :silly:

You can check for a stuck open PCV valve by plugging the vacuum hose to the valve itself, and plugging the end of valve. Or, pinch the vacuum hose closed with needle nose pliers.

What's the g/s reading from the MAF at a hot idle with no loads?

Hey Tyler, thanks for getting back to me with all that.

Yes did leave the engine idling until it warmed right up after the battery leads procedure.

Really thought you might be on to something with the PCV valve, but just tried crimping off the hose from it and no difference unfortunately .

The MAF reading is around 1.5 to 2 g/s at hot engine idle, rising to about 8 with the engine being reved (car at standstill) to 3k. Just to let u know this car is a manual - or 'stick' as I believe u boys call it!

Any other thoughts would be much appreciated mate. Thanks

iofix wrote: Really thought you might be on to something with the PCV valve, but just tried crimping off the hose from it and no difference unfortunately .

Crap, struck out. :silly: Thanks for checking anyway!

The MAF reading is around 1.5 to 2 g/s at hot engine idle, rising to about 8 with the engine being reved (car at standstill) to 3k. Just to let u know this car is a manual - or 'stick' as I believe u boys call it!

These numbers sound reasonable for your engine, based on the g/s = engine displacement @ idle rule.

Perhaps a quick check of inputs would be a good idea? Mostly wondering about the ECT sensor and if it's reading rationally when cold. The best check of this is to see what temperatures the ECT and IAT sensors are reporting KOEO after sitting overnight. They should read the same thing, within a few degrees.

I really don't expect you to find something wrong, but I think it's a worthwhile check.

"Idles very high (around 2k) when cold, and also often surging up and down around that 2k point"
Does gradually come down as engine warms and settle to a fixed idle at operating temp?
If so seems kind of normal.

Tyler wrote:

iofix wrote: Really thought you might be on to something with the PCV valve, but just tried crimping off the hose from it and no difference unfortunately .

Crap, struck out. :silly: Thanks for checking anyway!

The MAF reading is around 1.5 to 2 g/s at hot engine idle, rising to about 8 with the engine being reved (car at standstill) to 3k. Just to let u know this car is a manual - or 'stick' as I believe u boys call it!

These numbers sound reasonable for your engine, based on the g/s = engine displacement @ idle rule.

Perhaps a quick check of inputs would be a good idea? Mostly wondering about the ECT sensor and if it's reading rationally when cold. The best check of this is to see what temperatures the ECT and IAT sensors are reporting KOEO after sitting overnight. They should read the same thing, within a few degrees.

I really don't expect you to find something wrong, but I think it's a worthwhile check.

Hi Tyler, thanks once again for getting back to me - I feel a bit guilty for taking up too much of your time!

Yes the ECT, IAT, and ambient temps all match closely when engine is cold. When hot the IAT shows about 20 degrees higher than ambient, but I'm guessing that's normal due to heat soak.

cj1 wrote: "Idles very high (around 2k) when cold, and also often surging up and down around that 2k point"
Does gradually come down as engine warms and settle to a fixed idle at operating temp?
If so seems kind of normal.

Hi cj5, thanks for your point. Maybe I didn't explain clearly; it actually revs up to over 2k (maybe say 2300), at which point the injectors cut out so revs come back down (to say 1500), at which point the injectors cut back in and the revs climb to over 2k again and the injectors cut out again..., keeps doing this until it warms up a bit (say about 5 minutes) then behaves more normally.

iofix wrote: Hi Tyler, thanks once again for getting back to me - I feel a bit guilty for taking up too much of your time!

Nah man, this is why I'm here! I feel bad that we've struck out on everything I've suggested.

Yes the ECT, IAT, and ambient temps all match closely when engine is cold. When hot the IAT shows about 20 degrees higher than ambient, but I'm guessing that's normal due to heat soak.

Yeah, I figure that's OK. Thanks for verifying that!

So this all started after the battery went dead, correct? I still feel like we're chasing an idle strategy issue. May need to do some more digging on relearning these throttles. What I described above has always worked for me, but maybe this one needs a special song/dance... :silly: