[Mk2] [NA] Engine Hesitation Under WOT at High Revs - Rubbish MPG During Normal Use

[MR2HOT]

I just had a look at your video and to be honest my car idles at just below 2k revs when first started in the cold and it will take a fair while for the idle to drop down to the normal 850 - 900 rpm at idle if the car is just sat on tick over without driving. I personally don't think anything is wrong with your idle speed and we have been having very cold weather at the moment which wont help matters so the car will idle high. I could be wrong but i think this is normal from your video and i would not worry to much.

How does the car idle once you have warmed the engine by going for a drive, does it still idle at 2k?

[Loque]

Not sure if this is a bit left field but could it be a dying fuel pump?

Leftfield indeed. Anyone got a way of testing fuel pressure that doesn't involve being covered in fuel? Can't be ruled out...

There has been a development in that the car won't start at the moment. I went out to start the car yesterday and it began to crank quite slowly. I thought, ah, the battery's dead, and began to think further about how cars to tend to react strangely when the battery is on it's way out, so I stuck the battery on charge for 24h expecting it to work just fine today.

It doesn't. It just about stammered into life earlier on, but immediately died before it could even think about maintaining an idle. Any ideas?

[Loque]

Just as an FYI, this might be worth a read:

http://www.mkivsupra.net/vbb/showthread ... ng-Problem

[bobhatton]

Not sure if this is a bit left field but could it be a dying fuel pump?

Leftfield indeed. Anyone got a way of testing fuel pressure that doesn't involve being covered in fuel? Can't be ruled out...

There has been a development in that the car won't start at the moment. I went out to start the car yesterday and it began to crank quite slowly. I thought, ah, the battery's dead, and began to think further about how cars to tend to react strangely when the battery is on it's way out, so I stuck the battery on charge for 24h expecting it to work just fine today.

It doesn't. It just about stammered into life earlier on, but immediately died before it could even think about maintaining an idle. Any ideas?

If a cell has gone in the battery charging it will do nothing, you may just need a new one, get it tested

[dan4]

Just as an FYI, this might be worth a read:

http://www.mkivsupra.net/vbb/showthread ... ng-Problem

Had an ecu failure on my rev1 but i dont think these problems are ecu related. Mine seems to be running sweetly after doing almost everything you could imagine, still idling little high like yours though

[Loque]

Well as a bit of an update I have got the car running again. The battery was something close to flat as a pancake this morning, although I managed to get a couple of cranks from it as expected she wouldn't take. So I set up the jump leads and connected them to a 4L V8 Jag that I happened to have handy. Considering this thing has a battery that was appropriated from the QE2 I was expecting the '2 to spring to life with a gusto of a dog to a bone.
I was wrong. It sat there for about 20 seconds quite happily cranking with nothing going on. I tried again and after about 10 seconds with the clutched opened and the accelerator down it stuttered into life. It wouldn't idle on its own as the revs would just fall away and die, so I manually maintained the idle for about 30 seconds, at which point the car seemed to take over.

Now of course this has made everything clear as mud. I'd be tempted to say it's not the battery due to the fact that even with power it still refused to start. As I mentioned in the previous link, I'm now looking at buying an ECU (does anybody know if there are any immobiliser problems with doing this, or will another rev3 ECU just go straight in?) as well as getting hold of another igniter and coil. I'm also considering replacing all the major relays in the car as apparently they can wear out...

Had an ecu failure on my rev1 but i dont think these problems are ecu related. Mine seems to be running sweetly after doing almost everything you could imagine, still idling little high like yours though

Hmm, what were the symptoms when the ECU had failed?

[dan4]

Missfiring on one cylinder, took the plate off the ecu and it was scorched. I think it was due to a lambda short but i couldnt be sure

[Loque]

Silly question, and one borne completely from laziness to trawl the BGB; where is the ECU located?

[Peter Gidden]

Silly question, and one borne completely from laziness to trawl the BGB; where is the ECU located?

In the boot, behind firewall carpet.

[Loque]

Silly question, and one borne completely from laziness to trawl the BGB; where is the ECU located?

In the boot, behind firewall carpet.

Thanks Peter,
And from what I'm reading it's completely fine just to wing an ECU with the same part number in there. There's nothing to worry about with immobilisers and such?

Cheers

[Peter Gidden]

Silly question, and one borne completely from laziness to trawl the BGB; where is the ECU located?

In the boot, behind firewall carpet.

Thanks Peter,
And from what I'm reading it's completely fine just to wing an ECU with the same part number in there. There's nothing to worry about with immobilisers and such?

Cheers

On your revision no problem.

[dan4]

My rev3 has a security light which my rev1 didnt, is that a basis for immoblilised ecu's on these?

Loque the fuel connection is m12 x 1.25, im yet to find a banjo adaptor i want to use, ive tried to use one of the ebay ones from the states on a honda in the past and had a petrol bath

[Peter Gidden]

My rev3 has a security light which my rev1 didnt, is that a basis for immoblilised ecu's on these?

No.

Immobiliser ECUs also have matching chipped keyfobs. Inly fitted to late cars.

Withe the right kit, this problem should be diagnosable within a couple of hours at the most. A scope with 4 channel ignition trace will 99% on a road test show any ingntion issues under load. If all OK, that leaves not much to be substituted to find the problem. Wherabouts are you?

[Peter Gidden]

Just notices. Southampton. Shame you're not closer.

[Loque]

Just notices. Southampton. Shame you're not closer.

Trust me chap, had you been closer I'd have sent the car to you months ago!

Thanks Dan, I have a fuel filter to change, so I'm getting a petrol bath either way

[Loque]

Right. okay, little update on this:

I have just changed out the ECU for another unit. I am not exactly sure this will change anything, but I'm now at the stage of throwing money at it, changing each part that *might* be causing problems and hoping for the best. I've been to my local garage, and they don't really have a clue at what is wrong with it. Having said that, it's running pretty well at the moment, in particular the throttle is nice and smooth and the fuel consumption is not too bad. It has however done this before, so I am in now way counting any chickens just yet.

I have compiled a list of things that I need to replace. If anyone has anything reasonable to add, then feel free to chime in.

• 
• Coil
  I have one of these coming in the next few days, see what it does.
  
• Throttle Position Sensor
  Might explain why the throttle is so jumpy when the fault is present?
  
• Idle Control Valve
  Might explain the dicky idle?
  
• Battery
  I have had it tested - it's been confirmed as working, but it's not exactly new and in A1 condition.
  
• ECU Temperature Sensor
  I can't remember if that is the correct name for it, but the part that tells the ECU the car has warmed up, so it can switch over to a 'normal' map, rather than a 'cold' map.
  

I had considered a vacuum leak until reading this post:

...If you have a vacuum leak, while the engine is cold, the ecu will not open the ICV to 90% like it should as it will detect the high idle rpm as being too high, instead it will open just enough to make 1200rpm 10% say? Therefore you will not notice that you have a vacuum leak while its cold. But when the engine warms up and wants to set the ICV back to 20% (its warm open state,which will usually drop the idle from 1200 to 900) the revs then actually Increase instead of drop.

This explicitly details that you wouldn't notice a leak when it is cold. I do, so I could potentially rule that one out. Having said this, I still wouldn't mind the ability to check all the hoses over, yet I can find no easy way of testing the pipes. I also have no idea which pipes do what and how to access them. If anyone has any diagrams or explanations of which vacuum hoses do what they'd be greatly received.

As far as changing out the TPS/ICV goes, I'd buy a whole new throttle body assembly of eBay as it's cheaper to get both units than buy them individually. This would mean that I would need to obtain the gasket between the throttle body and the intake manifold. Does anyone know where I can get this gasket?

[bobhatton]

Toyota

[Peter Gidden]

Take it to a specialist who can diagnose the issue using a little more than guesswork and spending a fortune unnecessarily.

[dan4]

Don't worry about gaskets just yet, swap the bits over you need to first as if careful the metal gaskets are reusable

A garage will do various checks like i did with sod all coming from it amd most likely start swapping bits to test it anyway. Its so cheap for parts you may as well do it yourself...

Oh and check for air leaks with carb cleaner

[Loque]

I bet everyone is getting sick and tired of my ramblings on my thread right, now. But I think I've one last thing to try.

I reset the car's ECU a couple of days ago and took it for a run to see what I could get out of it. Turns out I averaged about 35 and I wasn't actually being that much of a tart with the throttle for some of it. The car also felt markedly more pokey - to the point that when I booted the throttle the brake fluid level light came on. [this has of course been topped up since] This has never happened before though, so it lead me to believe some ponies came back to the corral.

However, invariably yesterday it was back to its old self, enjoying crap MPG & low power. Due to the fact it seems that the ECU has 'learned' these settings from somewhere I'm now inclined to believe it's a sensor of some description. So, tonight I have been compiling a list of all the sensors in the car and various voltages at which I can test them tomorrow. Tonight I have learned that the car has a MAP sensor. Something I was completely unaware of, so I am looking to test that tomorrow, first on the list.

Presumably this sensor works on vacuum pressure. Let's assume for a minute that the sensor is found to be working correctly. Which vacuum lines are part of the circuit that the MAP Sensor uses in its bid to maintain stoichiometric value? Should these lines be found to be leaky, would it cause a fault which would build up over time, or would it be evident from the moment I reset the ECU?

I think this is probably my last throw of the dice on it really, so can anybody recommend a MR-2/3SGE specialist in the Hampshire area? I've done a little bit of research and it seems the closest that I am aware of is Pacific Works, up near Luton. At the end of the day it's a 200 mile round trip in a car that drinks fuel after 50 miles, a few hours labour + parts on top of that, so I'd like something a little bit closer really!

Thanks for your persistent help chaps.