Idle Problems - ECU Change??

[RNP]

Alright I am getting desperate. I have been having idling issues, and have combed through literally all the threads on the issue on this forum but have not found a solution. I will start by giving a description of my car, followed by what steps I have taken to remedy each idle issue I have faced.

Initial Car Description:
- 05 Facelift DC5R
- Owned for 5 years
- Spoon 421 header
- Fuji mid-pipe and muffler
- Stock airbox
- Stock throttle body and sensors
- No tuning

Problem 1 (3 years ago)
- Idle hunting+checklight
- remedied by changing with a second hand throttle body and second hand TPS sensor

Problem 2 (2 years ago)
- Changed stock airbox to mugen
- Checklight on.
- Attributed to primary O2 sensor. Seems that it could not 'keep up' with new intake characterstics
- remedied situation with new primary O2 sensor

Problem 3 (1 year ago)
- Idle hunting
- TPS seemed to not be able to hold lower bound voltage
- Changed TPS to Ktuned V2
- Cleaned TB, IACV
- Problem cleared after ECU reset

Problem 4 (0.5 years ago)
- Rev hang on cold start, rev maintains around 1200 after warm up, sometimes reverts back to normal 800-880
- Checked IAAV, no blockage
- Checked ECU wirings, all OK
- TPS holding voltage
- No audible/visible air leaks using carb cleaner
- TB and IACV removed and cleaned
- ECU reset and coldstart was ok for the first day, but after a day of driving, above symptoms returned
- Changed Spoon header back to stock as the location of the primary O2 sensor is slightly different, and the Spoon header doesn't have a cat like the stock header setup.
- ECU reset, ok for the first day of drive, problem returns after.
- Bought new IACV (2 weeks ago)
- Problem persists

Current Car Description:
- 05 Facelift DC5R
- Stock header
- Fuji mid-pipe and muffler
- Mugen airbox
- Stock throttle body, Ktuned V2 TPS sensor, new IACV
- No tuning

What's next?
- As you may agree, I have done quite a fair bit to sort this out. My engine is healthy (getting about 10.8km/l mileage on average), with 130,000 km on the clock.
- The throttle body does not seem to have any leaks, and I have stopped short of buying a new one for about 600 quid ($1000+ in my Singaproe currency)
- My mechanic is at a loss of how to remedy the situation and postulates it may be ECU related and the chip controlling idle is faulty
- He has proposed I borrow another stock ECU to diagnose, but I have never ever heard of swapping out an ECU. The only modification I have to the ECU harness is a lead to my RSM, so it's practically undisturbed. Can repeatedly resetting the ECU take a toll?
- I have had large periods of good idling with the Spoon header and Mugen airbox, and I would think the ECU should be able to compensate for the AFR in these conditions.


I would appreciate any input in solving this. Thanks in advance.

 

[Johngreen537]

Idle air assist valve maybe at fault?

Simple test is to remove the intake tube on the picture and block it off at the air intake and the tube.

If your problem vanishes, then ktuned sell a delete kit for around £20.

Think there's also an Idle assist screw on the throttle body. Might be worth a look.

Sent from my HTC 10 using Tapatalk

 

[RNP]

Thanks, but if you look at Problem 4 I have already checked the IAAV. When you mean Idle Assist screw on the throttle body, do you mean the one on the IACV?

 

[kyle'87]

I won't have thought constantly resetting the ECU would do any damage, I used to have to put my Cupra ECU in the oven to try and fix the dry joints on the PCB. Worked a treat every 6 months.

In terms of idling, IF you had a Hondata Kpro or K100 on the ECU, you could always set the idle higher using the Kpro. The car might just idle low every so often as a "feature" and artificially moving it higher would solve this.

I saw in another thread recently that someone adjusted the TB stop screw to open the butterfly plate ever so slightly to help idle.

EDIT: Looking over your problems and how they return after the first day, correct me if I am wrong, but it sounds like the ECU learning process. The ECU learns the idle it requires and then sticks with it, which is why it always returns after a days driving.

 

[MissMyDC2]

Not sure what alternatives there are to the k-tuned delete kit but dont buy one. They are a poor fit.

I had a similar issue and fitted the delete kit which leaked like a sieve. I even tried ptfe tape and it still leaked.

Eventually ended up buying a second hand IAAV from here. But to be honest it was better when I just had it blocked off.

 

[kyle'87]

Not sure what alternatives there are to the k-tuned delete kit but dont buy one. They are a poor fit.

I had a similar issue and fitted the delete kit which leaked like a sieve. I even tried ptfe tape and it still leaked.

Eventually ended up buying a second hand IAAV from here. But to be honest it was better when I just had it blocked off.

You can try one of these... Blanking Plug and then plug up the vac lines with vac plugs, will also need some PTFE tape to stop any coolant leaks.

 

[Brecht]

i've cleaned the IAAV multiple times , worked for 1-2 days and would go back to rev hang especially on cold starts.
cleaned it again but always comes back.
last time it had it again the day after but after a good blast down the highway it's been good for 2 weeks now.. fingers crossed
even if you clean it , it could still be doing it... you really have to clean it out the best you can..
sprayed some "kent 91 in 1" in there to lubricate it a bit and seems like it helps

 

[RNP]

I won't have thought constantly resetting the ECU would do any damage, I used to have to put my Cupra ECU in the oven to try and fix the dry joints on the PCB. Worked a treat every 6 months.

In terms of idling, IF you had a Hondata Kpro or K100 on the ECU, you could always set the idle higher using the Kpro. The car might just idle low every so often as a "feature" and artificially moving it higher would solve this.

I saw in another thread recently that someone adjusted the TB stop screw to open the butterfly plate ever so slightly to help idle.

EDIT: Looking over your problems and how they return after the first day, correct me if I am wrong, but it sounds like the ECU learning process. The ECU learns the idle it requires and then sticks with it, which is why it always returns after a days driving.

Not quite sure if I'm putting my ECU in the oven! but I see what you're trying to do in liquefying the solder. Yes I do believe the problem can be solved with Kpro with open loop settings but I wanted to try and solve this with a 'stock' approach, but it has been draining. It does seem that the ECU learning process is affected, I'm not quite sure why it starts out ok, but a day later it learns to be stupid. haha

Not sure what alternatives there are to the k-tuned delete kit but dont buy one. They are a poor fit.

I had a similar issue and fitted the delete kit which leaked like a sieve. I even tried ptfe tape and it still leaked.

Eventually ended up buying a second hand IAAV from here. But to be honest it was better when I just had it blocked off.

I don't plan to mess around with the IAAV yet as when I've done ECU resets the cold starts the next morning seemed fine. I've tried manually blocking the tubes when the revs were messed up and they haven't caused a difference either. So I doubt its to do with the IAAV.

i've cleaned the IAAV multiple times , worked for 1-2 days and would go back to rev hang especially on cold starts.
cleaned it again but always comes back.
last time it had it again the day after but after a good blast down the highway it's been good for 2 weeks now.. fingers crossed
even if you clean it , it could still be doing it... you really have to clean it out the best you can..
sprayed some "kent 91 in 1" in there to lubricate it a bit and seems like it helps

I've heard this theory with VTEC blasts and I have done that together with actually cleaning the TB, IACV and what can be done with the IAAV bar removing it and cleaning it.

Update:
I went to the mechanic's yesterday and he put in a hondata chipped ECU and for the most part the problem went away. Unfortunately I only have two days with the ECU before he has to sell it to another customer so I can't definitively prove that changing the ECU/hondata is the solution (i.e. the problem is ECU-centric).

The problem I may have with this is that chipping my possibly 'faulty' ECU with hondata may not change the poor idling as idle functions are still controlled by the ECU, just that hondata sets the parameters. So it now seems I'm staring down the barrel of buying a new ECU and chipping it, unless anyone else has other suggestions.

 

[RNP]

Just a quick update to those interested, I've tried to go down the route of checking more closely for air leaks. Changed the throttle body gasket, intake manifold gasket, and checked associated tubings, but the problem still persists. When the intake manifold was removed, there is a small spring-loaded valve at the left hand side of the engine connected via tube to the intake manifold (the valve is screw on, looks like a spark plug), and it was found that the spring inside wasn't that taut. Replaced that with a better condition one but no change at all to the symptoms of high idle (about 1200-1300) and some rev hunting. Diagnostics show that all parameters (TPS voltage, TPS angle, MAP sensor, 02 sensors) seem fine. The next step would be to do an ECU swap with my friend tomorrow, he's been kind enough to help me out. If anyone has any other suggestions, it would be greatly appreciated but I'm at my wits end really.

 

[MilanoChris]

I'll have a read tonight if I remember and see if I can think of anything.

Did you do an ECU reset after you changed the spring just recently?

 

[MilanoChris]

Just looked again, I think the car is breathing too well with the intake, exhaust and larger TB. Try finding a stock TB and see if that helps. Also what brand O2 sensors did you use?

 

[RNP]

Didn't manage to the the ecu swap as yet as my friend needed the car. Hoping to do it in the next few days.
I'm on Honda stock o2 sensors, and stock throttle body except for the ktuned v2 tps on it. But using the diagnostic tool, the tps is holding voltage at 0.43v and 0deg at closed throttle so I don't think that could be the reason. I'm on a mugen intake but I doubt that could be the issue either.

 

[RNP]

Tried the ecu change, it didn't work- the idling was just as bad really. Now I'm back to looking at the tps, just to eliminate variables that aren't stock (I'm on a new ktuned v2). Updates to follow.

 

[stumatt]

Hi guys, been lurking on here a few weeks, had a DC5 a week now and I'm working through small issues with the car to get it into shape. I will join in on the forum with a build thread etc Ive had both an EP3 many years ago and a DC2 a few years back (missed it massively).

Im having idle issues and cleaned all parts: Throttle body, ICAV, new Tegiwa TPS and I'm having massive issues setting it up. Ive got it set to 4.55v (closest it will go to 4.5v unless I modify the fixing holes) and 0.48v idle. It will idle lovely at this but will not drive! Just found this little gem and it makes sense, I will do this tomorrow.

Having trawled through loads of TPS and rough idle threads I have only just come across a idle learning/reset process for the ecu. Makes sense as I was effectively having to get my new TPS to mimic the old TPS. This could be the answer to a lot of peoples idle problems after cleaning all parts, unless I've missed this on this forum:

When u do all this.. you HAVE TO do the IDLE RELEARN procedure.
if you didn't do this... then do this word for word as these are instructions from HONDA direct.

1. Remove the FI ECU (15A) fuse from your underhood fuse box for 10 seconds.

2. Insert the FI ECU fuse back into the box. (to find out where this is look in your owners manual diagram)

3. Start the engine. while in neutral. Rev your enginge to 3000 RPM and hold until the radiator fans come on. (have a friend help you) This should take between 5-10 mins. Trust me, u need to rev and hold @ 3000 RPM.

4. Once the radiator fan comes on, let the engine idle for 5 minutes on its own.

5. When 5 mins is up, turn off the car. You should have complted the procedure and your idle should be good.


​Anyone on here done this procedure?

Stu

 

[RNP]

Hi Stu, my mech performed this procedure (not disconnecting the fuse but disconnecting and reconnecting the ecu) followed by idle learning. This was to no avail. But worth a try of course.
Sad to say ive took the plunge and ordered a brand new throttle body. Its a shame because i previously ordered a brand new iacv and thats gonna be spare since it didnt solve the prob. Still no idea if a new tb would solve it but at least im narrowing it down going to a more stock configuration by excluding the ktuned tps v2 from the equation.

 

[stumatt]

Ah, quite an expensive fix. Hope it works for you.

Well the idle 'teach' hasn't solved my issues. I have returned to the stock TPS as I could only get as low as 4.7v WOT with the Hall effect TPS and no lower than 0.47v Throttle closed. With the old TPS I could get from 0v-5.2v range.

I have a new gasket for the TB now and a new IACV on the way. The car idles fine, runs well but not 100%perfect, its a little jumpy at small amounts of throttle. I can live with it but I won't. The idle once warmed up (dropped off 2000rpm) will take two or three attempts to settle at 900rpm. Driving then going to Zero throttle and the idle takes a while to settle form a 1-2000rpm 'hunt' if at all. It's a pain in the ass now. I will sort it though, last thing i tried was unplugging the IACV connector and the idle went bat shit crazy so its doing something.....

Ongoing I guess for now. Let us know how the new TB goes ;-)

 

[Matt-DC5]

Had this problem myself when I changed ecu's. plugged in an OBD reader to calibrate the TPS on % rather then voltage and then set the limits on ecu. Was fine after that

 

[stumatt]

Can you tell me what OBD reader you used to do this? and I guess at idle it was zero and WOT was 100%? Interested to know the exact procedure you used.

 

[Matt-DC5]

Was just a maxiscan, think I set it to 90% at WOT which equated to 8% on 0 throttle. As the tps wouldn't allow for 0% and 100%. At 0%, WOT was 80ish% and when WOT was at 100%, 0 was at 19% hence it idled like shit

 

[stumatt]

Hmm, well I set mine to 7.8% Idle I think it is and 90% WOT. That was the best 'feel' I could achieve. I have a OBD2 wireless transmitter and run Torque on a Android Head Unit. It drives great but the idle takes a while to settle when in traffic. I have a new IACV on the way.

Thanks for the info!