I'm trying to save this mr2!!

[Jamez87]

Hi guys this is going to be my welcome post mixed with a few issues!

Firstly, I saved this white rev4 turbo from certain doom a couple of weeks ago.

(Can't up load image!!!)

I picked her up knowing she had a lumpy idle and blowing exhaust. I traded a civic I was selling for it and was prepared to but some work in. I didn't get to test drive but the seller took me out in her due to insurance bla bla bla but thats fair enough.

I've quickly found out the brakes were bloody awful with no bite what so ever and the coilovers have absolutely no movement in them what so ever! Oh and the spigot rings for the wheels are not the right size!

It looks to me that in a past life an enthusiast has owned her and spent a good chunk money on some good parts, just a shame that the last owner couldn't even give her a bath let alone look after her!

Any way bits I know about are, Cusco front and rear strut bars, arc airbox, samco hoses, uprated intercooler with fan, hks bov, NGK leads, Berk exhaust and decat, hsd coilovers and greddy boost controller.

Anyway brake fluid has been flushed and bled today which has brought a 80% improvement, new discs and pads to go on soon. Berk exhaust has bren swapped for a japspeed system. New denso plugs, distributor cap and arm also went on today. I was hoping the lumpy idle would have been down to lack of recent maintenance but not quite, although it has improved a fair bit.

So basically wandering if anyone could help point me in the right direction for the hunting idle? It seems to want to idle at almost 1100rpm and will start dropping to about 600 at times but not all the time. Driving seems fine until I come to slow down and it starts getting a bit jumpy at times and boost is fine. Fault codes showed 21 and 25 if that helps!

Sorry for the loooonnnng first post, I personally never thought id own a mr2 but I can see some fun potential in the future, I just want to show her some love first![/img]

[CalMac]

My MR2 gets a bits lumpy if I don't drive her for a couple of weeks, a good ragging might sort it out.

If not that I'd try changing the HT leads for standard Toyota.

Could be old fuel if the previous owner wasn't driving much, or a gunged up fuel filter perhaps? Maybe even a dirty sensor/breather outlet in the throttle body or inlet manifold, or possibly a damaged breather hose.

Have you checked the air filter in ARC box? FD Rx7 filters are the correct size if it needs replacing.

I suppose it might be an electrical issue - I had idling issues when my last battery was on it's way out

[mrhappy62]

Fault code 21 is o2 sensor so that would make sense ! not surewhat 25 is but will look it up and report back. Welcome to MR2 world

[mrhappy62]

25 is also O2 sensor or injector circuit so I would start with replacing the O2 sensor.

[Jamez87]

Thank you very much for the reply guys!

I've just found a method of testing the o2 sensor so will try that first, we did pull it out today just to check condition and it was overly dirty or anything but it could make sense due to the blwoing flexi I guess?

[Jamez87]

Right, think I may have got myself going in the right direction...

I had an idea in my head that the o2 sensor was playing up because of the leak in the exhaust. Maybe that caused the plugs to foul too....

Anyway with the parts refreshed and the o2 sensor cleaned I thought maybe I should reset the ecu codes. Done that and let the car idle for a few mins, the revs dipped to 500rpm then raised to 1500rpm and have stayed steady since, went for a drive too! Fault codes have not returned yet.

So fingers crossed that part might be cured but obviously the idle is too high, so I think someone raised it to compensate for the faults...so I need to try get it down again.

Could some one please tell me how? And where should it idle?

[mrfil13]

Normal idle is about 850/900 rpm.

Resetting the ECU causes the idle to be off for the first 10 minutes, found it can do the drop down to 500rpm so let it run for over 10 mins before changing the idle after resetting the ecu.

[Jamez87]

OK so went back out today and started from cold, revs bounce around 500rpm and as the temp starts to climb the idle starts to settle at about 1500 as I said last night and seems steady, though it can be a little lumpy until the temp has reached half way.

Surely it should rise to 1500 ish when cold and drop once warm?

[Rob]

Have you tried cleaning the throttle body butterfly valve and the iacv hole?

Also, did you take the Berk exhaust off? Interested if us for sale....

[Pauln]

Have you tried cleaning the throttle body butterfly valve and the iacv hole

+ 1 for cleaning the throttle body, checking the icv is clean and moving freely, and also checking the fit of the throttle butterfly when closed.

It would also be worth checking the throttle position sensor is setup correctly.

If you have aircon, it might also be worth checking the idle up valve on the firewall between engine and boot is working correctly. This raises the idle speed when the aircon compressor is working.

Final thought, are the speedo cluster dials stock. I thought I had a high idle speed on my tubby, but it turned out that when a previous owner fitted Speedhut dials he hadn't put the needle back on the tach correctly and it was consequently over reading. A long shot but worth bearing in mind.

Paul

[Jamez87]

Thanks, I'm going to try clean out the throttle body today.

The clocks are standard km clocks that came with the car, the needles rest on the pegs and look to me that they work as they should, the fact the rev needle can hunt tells me there is an issue....plus at 1500rpm the car is pretty loud on idle haha!

How do you set up the tps?

Also worth noting...car warms up to half way (as it should), I've pulled out the green coolant sensor which brought up an engine light and idle was very poor, does that mean the coolant sensor is fine? And I'm assuming a rev4 doesn't have a air flow meter?

Cheers

Edit: car has aircon but I've not turned aircon on yet, if that matters?

[Pauln]

I have a rev 2 which has an AFM, but there's no AFM on rev3 onward.

I've extracted the TPS page from the manual I have, and believe the procedure is the same for rev3+:
Checking & setting the TPS

If the aircon is switched off that should have no effect on idle speed, assuming the idle up valve isn't leaking.

What your describing does sound as though it could be an ICV issue, and as these can get gummed up over time and quite sticky it's possible it's not closing properly when the engine is warmed up.

So taking the throttle body off and giving everything a good clean and check has to be a good starting point. If your taking the ICV apart don't forget to get a new internal rubber gasket. Also check the resistance changes smoothly on the tps as you open the throttle - quick check for any damaged sections on the internal track. Finally don't forget to make sure you a little bit of slack on the throttle cable and the control arm is resting against the end stop.

Hope that helps

Worth noting that the throttle body is connected to the cooling system.

Good luck.

Paul

[Jamez87]

Right, I havnt quite had the time to pull the throttle body off and clean everything up but I've just been having a play around, to find any leaks etc.

Havnt foubd much other then some throttle body screws weren't tight.

Anyway, pulled the efi fuse and started her up again, all of a sudden idle has dropped back down to under 1k, I thought result but instead of being steady like it was at 1500 its now back to being lumpy/rough and you can here the exhaust pulsating if you know what I mean. Also noted that on a quick test drive the throttle got stuck until I applied some force, could be a one off or could be related.

So yeah, idle back to the right place just not smooth. I did see the throttle bodies was really clean and the plate looked to open/close easily. Thought I'd update this but do you guy think I should still be looking at pulling the throttle body off?

[Pauln]

If your saying that some of the nuts/bolts that hold the throttle body in place were loose, it sounds like this may have resulted in a small air leak which was enough to upset the idle speed, but not noticeable when driving.

I would however be concerned about the throttle sticking when your driving, and want to get to the bottom of that. If it was sticking when the throttle butterfly was partially open when you were driving along, I wouldn't have thought that was related to a lumpy idle.

So either butterfly mechanism sticking, or a problem with the throttle cable, or the throttle pedal mechanism.

When you say the throttle body was clean and the butterfly working OK, did you drop the hose off to take a look inside, or are you just going by the outside.

This was my throttle body before I gave it a clean:


I don't have a photo unfortunately, but the icv was similarly covered in muck. There are also small internal bleed channels either side of the butterfly that can easily get clogged up with gunk over time. Whilst there's no guarantee cleaning this up will fix the lumpy idle, it would at least eliminate that as a possible cause. So it's worth doing when you have the time.

In the short term, if you have a meter, you can check and adjust the tps without dismantling anything. You just need to drop the plug off and measure the resistance on the appropriate terminals. I made up a little adapter with a bit of terminal block and a length of wire with small blade push connectors at the other end that I could slip on the terminals in the tps to make life a bit easier.

I take it you didn't find any other vac leaks elsewhere.

Paul

[Jamez87]

Sprayed some carb cleaner about but engine didnt respond..so I can only assume no leaks, everything looks pretty secure and clean too.

What I meant about the throttle pedal was it became stuck at a stand still but a little bit of pressure and it was free again. Only happened the once and not whilst moving.

Regarding the throttle plate, that was really clean compared to the picture you have put up and as I pulled on the throttle I watched the plate open and close freely, intake hose disconnceted. Though I can't comment on the other parts of the throttle body as I'm yet to pull it apart. It seems really strange that the idle went back down to roughly where it should be though but why is it rough again when it was steady at 1500? I keep seeing the coolant sensor mentioned, is this possible systems?

[Rob]

If the throttle stuck when you were driving it sounds like dirt around the TB butterfly plate where it seals against the internal housing chamber.

[Pauln]

OK, sounds like nothing else is leaking now.

If the throttle stuck when you were idling at standstill it's probably just the butterfly catching a bit when fully closed. Either as Rob mentioned the body is just a bit grubby around the throttle closed position and needs cleaning, or it's just a tight fit. If it's just a tight fit, you could try adjusting the throttle stop screw very very slightly to stop that happening again, but not enough to raise the idly speed unduly if you see what I mean.

In terms of the rough idle at 800 rpm compared to when it was idling at 1500 rpm, if you increase the revs to 1500 and hold it there is it steady again. If so the roughness has just appeared because you've lowered the idle speed.

Bottom line is that I think anything that is slightly out of adjustment is likely to show up more as you lower the throttle speed.

I don't think there's a magic bullet for a rough idle, it's just a case of making sure everything is setup correctly and performing as it should.

As you've swapped exhausts now I assume it's no longer blowing?

Paul

[Jamez87]

I'll keep my eye on the sticky pedal but as it only happened just the once and never before or since, then I'll put it to the back of my mind for now, until it happens again!

The exhaust has been changed, the flexi was completely shot on the Berk exhaust and I think that was causing o2 sensor issues, cleared the faults and they havnt been back since and that is also when the idle when to 1500rpm.

I didn't really do much today, so im un sure how i got the idle down. maybe the bolts I tightened brought the idle back down and I pulled the efi fuse again but it wasn't at 1500 before I cleared the o2 codes anyway, so I'm not convinced!

I will definetly get the throttle body out and pull it apart for a clean! Im also tempted to try a coolant sensor....would this bring the same symptoms?

Cheers for all the help by the way!

[Pauln]

It's always tricky when there are multiple issues. But my gut feeling is that after you changed the sensor you still had a small leak on the throttle body which you cleared by tightening the bolts.

When I was cleaning up my throttle body and checking everything was working OK, I more or less decided that I'd try changing the green coolant temp sensor if sorting out the throttle body didn't do the trick.

This often seems to be suggested as a possible cause of a rough idle, so it's not unreasonable to give that a try.

But as the work I did on the throttle body did the trick and gave me a reasonably smooth idle at around 850 rpm, I never got around to changing the sensor.

Personally I'd go with cleaning and checking the throttle body before I started replacing other bits. But that's just my 2ps worth, it's up to you

Paul

[Jamez87]

This is where I'm at now.....

Found the cause of the sticky throttle and why it was possibly idling high before. The throttle stop/butt had come loose, so throttle wasn't returning to where it should be, possible loose throttle cable too I guess. Anyway got that sorted.

At the moment, from cold, I turn the car on and the revs raise above 1k like they should and then drop down to roughly 900. At this point with the gauge still cold the idle jumps between 900 and 500 and the car smells really rich.

As soon as the gauge hits half way, the revs stabilize around 900, though it is still hunting and not steady but its not trying to cut out and it sounds better etc.

So its better then it has been. I'm now wandering if there is a link to the temp, instead of the throttle body? (Don't worry I'll still get this cleaned, hopefully at the weekend!)