2003 M45 high idle problem [SOLVED - throttle body]

[Tim/M45]

I have only owned this car a couple months now. 99,000 miles and very clean condition. The idle is too high though. It sets a P0507 code regularly. I cleaned the MAF sensor and throttle body shortly after purchasing the car because of a rough idle issue which ended up being related to bad coils. The rough idle is resolved so next is the high idle issue. I have checked it for vacuum leaks and am confident there are none.

The car runs strong and smooth above idle. Once warmed up, it idles between 1,000 and 1,300 RPMs in neutral or park and between 850 to 1,100 RPMs in drive. I performed all of the suggested relearn procedures, which went well except for the Idle Air Volume Learn. I tried it dozens of times with no joy. The IAVL procedure does reduce the idle but not to within specs, and it goes back up after a short while. I figured the TB was toast so I installed a rebuilt TB. The exact same problem remains so I took it to Infiniti. They were unable to get the car to idle properly either. They say I need to replace the ECM. They want $1,900 for that. They are confident it will fix the problem. I said no thanks.

I am leaning towards buying a used ECM (available for under $200 on e-bay) but I want to see if anyone has any insights on the issue before I spend more time and money on it. I have done a lot of reading on this problem, probably too much. In all my research I have not seen anyone with this problem resolve it by replacing the ECM, so I am a bit hesitant to do so.

Thank you for any input.

[Ilya]

So the only way to adjust idle is via relearn? I know on older Nissan engines there was an IACV (Idle Air Control Valve) that you could spin a nut clockwise or counter-clockwise to adjust idle...anything like that on the 2003 motors?

[Tim/M45]

I wish. Nothing like that that I am aware of. It is all electric.

[EdBwoy]

Howdy Tim,
Actually there might be a way. I had an obnoxiously high idle after replacing my 03 engine. This was more pronounced after driving and I figured the throttle valve wasn't fully closing. At startup, the idle was fine.

I warmed it up by driving around and went and adjusted the nuts on the cruise and throttle cable. Loosened both all the way till the engine calmed down; then tightened the "gas cable" for the appropriate pedal snappiness. Then I adjusted the cruise to match the throttle. That's worked for me so far.

[Tim/M45]

I'll try that today EdBwoy.
Thanks.

[Tim/M45]

I double checked the tension on the throttle cables. No problems with them. I redid the IAVL procedure about a dozen times. It seems to idle ok every time but as soon as I turn it off and restart it goes back to high idle. What exactly are the factory specs for idle anyway?

I found a reference to doing a "manual" idle adjust which entails disconnecting injectors one at a time until the idle is within specs while doinf the IAVL procedure but I cannot locate the full tech bulletin. It is referred to as ITB05042. I cannot seem to find the full procedure anywhere. Suggestions welcome.
Thanks.

[Ilya]

Hopefully our member BlackCat81 sees this...he's an Infiniti tech.

[EdBwoy]

Factory specs are usually 650+/- 50 or is it +/-100? I might be getting my cars confused, but the spec is in the owners manual and also FSM.

Hopefully someone who's familiar with the bulletin lets us know.

[BlackCat81]

I'll look into it tomorrow, I just saw this thread and am heading home now.

[EdBwoy]

I'll look into it tomorrow, I just saw this thread and am heading home now.

BlackCat, I sent you a PM on an unrelated matter. Let me know if you get a chance to look at it some time.

Tim, excuse my off topic interjection.

[BlackCat81]

I double checked the tension on the throttle cables. No problems with them. I redid the IAVL procedure about a dozen times. It seems to idle ok every time but as soon as I turn it off and restart it goes back to high idle. What exactly are t he factory specs for idle anyway?

I found a reference to doing a "manual" idle adjust which entails disconnecting injectors one at a time until the idle is within specs while doinf the IAVL procedure but I cannot locate the full tech bulletin. It is referred to as ITB05042. I cannot seem to find the full procedure anywhere. Suggestions welcome.
Thanks.

IAVL procedures are very finicky with these cars. It must not have a check engine light on, turn all the loads off as well. Radio, heated seats, heat, headlights, etc. Here are the relearn specs for the bulletin posted.


And here are the parameters that need to be met in order for it to complete. Interesting fact is that it mentions updated ECM programming. It doesn't mention that it needs the most current update to be able to complete the learn, but in my experience, it's probably going to need an update if there is one available. I've never done a relearn without consult, it doesn't appear like it'll be much fun. Let me know if there's any other info you may need

[Tim/M45]

Thanks BlackCat81.
I have tried the IAVL manual method of reducing the RPMs by disconnecting injectors. I disconnected 1, 2, 3 then 4 injectors but still cannot get the RPMs down below 850. It seems to just work harder to keep it revving high. I went back to Infiniti yesterday and spoke with the service rep about whether the tech even looked to see if the car had a ECM software update done when I brought it to them last week. He said he will have to check with the Master Tech to see what was done and whether there is a software update available for my car. They should call me today, he said. Fingers crossed.

[BlackCat81]

Interesting, as they'd actually need the car there to see if it had an update available. Sounds like they have no idea what they're doing. They physically need to scan the ECM to get the part number, then see if there's an update. When doing software updates, once they're complete they change the part number of whatever module you're reprogramming.

[Ilya]

My service department does the same thing I think...they tell me there is no updates when I ask via email. Good to know that it actually has to be plugged in...

[Tim/M45]

Latest update: I went back to Infiniti, twice, to get an answer about whether there was a ECM update available or done when they had my car. Both times the service rep said the tech was not available and he would have to call me after he spoke to him. I finally got a call yesterday. Service rep said he spoke with the techs. He advised me the bulletin I referenced, ITB05-042, does not apply to my vehicle so I need a new ECM. I have no confidence in this guy, so I think I am done with them. There is another Infiniti shop nearby plus a Nissan dealership with a good reputation. If I buy a used ECM does it need to be reprogrammed using the dealers computer or can I just do the relearns myself and be done.

Where is the ECM. I see references to it behind the passenger kick panel and also behind the glove box. I took all the screws out of the glove box but there appears to be something still holding it in.

Thanks again for your help.

[Tim/M45]

Any input is appreciated:

If I buy a used ECM does it need to be reprogrammed using the dealers computer or can I just do the relearns myself and be done.
Where is the ECM? I see references to it being behind the passenger kick panel and also behind the glove box. I took all the screws out of the glove box but there appears to be something still holding it in.

Thanks.

[EdBwoy]

Any input is appreciated:

If I buy a used ECM does it need to be reprogrammed using the dealers computer or can I just do the relearns myself and be done.
Where is the ECM? I see references to it being behind the passenger kick panel and also behind the glove box. I took all the screws out of the glove box but there appears to be something still holding it in.

Thanks.

To the first part, I believe it needs to be programmed by a dealer to work with your existing electronics: security and probably BCM and TCU as well.

And I have not tried to locate my ECM yet, so I'd have to look that up. To be clear, is your main hindrance at this point problems with removing the glovebox?

[EdBwoy]

...
Where is the ECM? I see references to it being behind the passenger kick panel and also behind the glove box. I took all the screws out of the glove box but there appears to be something still holding it in...

Location, behind the glovebox, beside the blower motor. This is an old pic I found that I took as I was replacing the in-cabin filter. See the copper-colored plate with a screw?


And these might not be clear either, since I probably had other intentions taking the pictures 2 years ago, but what seems to be holding your glovebox - top/bottom/side?

Before removal


After all the screws had been removed, right before pulling it out


Edit.
And would you lookie here: http://www.nicoclub.com/FSM/M/2003/ec.pdf. Page 99 shows you where it's located, but I don't believe I ever saw/followed any instructions on removing the glovebox.

[Tim/M45]

Thanks EdBwoy. I am not sure what is holding mine in after screws are removed. The whole box seems like it is just in there tight. Instead of forcing it out I put it back together to wait until I had the ECM replacement. I'll double check for fasteners then just pull a bit harder when I replace it. The pictures are a big help. I have difficulty with some of the illustrations in the manuals.

So if I just swap out the ECM on my own and try to do the relearns I will still have problems with starting the car due to security features that the dealer has to reprogram?
My concern is that a dealership will not want to work with my used parts if I bring it to them.

Oh, and Merry Christmas!

[EdBwoy]

...So if I just swap out the ECM on my own and try to do the relearns I will still have problems with starting the car due to security features that the dealer has to reprogram?
My concern is that a dealership will not want to work with my used parts if I bring it to them...

You're most welcome man.
Yes to the reprogramming issue. I personally haven't heard of y34 ECM's going bad, but anything is possible. So, the used ECM you buy might end up working fine. If it is a good enough unit, I think they just have to program the security modulesto be accepted by the ECM. Otherwise the relearns should be manageable.
Also, I have to go over this in the manual again to confirm what components the ECM communicates with. Is it the security module or is it the key ID, or both? Secondly, is this something a locksmith can do? Because if it is possible, for the price of a used ECM and around 40 bucks for a locksmith, you could have a working ECM

I also went back to the top and read that you replaced the throttle body with little improvement. How did you know the first throttle body was shot?
I also have some questions about your air intake, which might not lead to much, but some tidbits in the FSM make me curious:
-How clean is the air filter?
-How about the MAF sensor - , I see you cleaned it as well. Is the harness on there tight?
-What chemicals have you been using to clean your throttle body? What methods are you using?
-Do you still have your coolant lines passing through the throttle body?
-Factory intake tube? If so, does it have 2 vacuum lines (one large and one skinny) connected to it?

any other trouble codes apart from the P0507, even pending ones?


Btw, I think some dealerships will work with you on programming your ECM. Just have to make it clear that you're not holding them liable for any unforeseen issues - within reason, I'd say.

[Tim/M45]

EdBwoy,
Sorry for the delay in responding, the wife and I had to go to Salt Lake City for a funeral. I haven't done anything about this issue since my last post. To your questions:
-After cleaning the throttle body and MAF, I could not clear the high idle problem so I bought the rebuilt TB for $100. The old one had what appeared to be corrosion on the plate so it seemed worth the $100 to replace it.
-Air filter is like new.
-MAF cleaned with CRC MAF cleaner. Sprayed on and did not touch it with anything, at all. Reinstalled and double checked for tightness and air leaks. Harness snapped on tight.
-I used CRC throttle body cleaner on the TB. I used a soft brush to clean around in there and moved the plate by hand, so I was pretty sure I messed up the TB (after reading about that issue).
-Yes, the coolant lines are still running through the plate behind the TB. I used new gaskets when installing the TB and checked for air leaks there.
-Intake is factory and has the small and large vacuum lines installed. Checked all for air leaks too.

The only other trouble code was for the misfire, which was the reason I cleaned the MAF and TB in the first place. That was fixed with a set of used coil packs from e-bay.
No pending codes. The car runs nice and strong. Idle is 950 in drive. About 1,000 to 1,100 in neutral. Usually sets the P0507 code when idling in neutral. Occasionally sets it when I am stopped for a while at a red light, in drive.

Could the high idle be caused by a faulty MAF? It runs well other than the idle issue. If I purchase a used ECM I will probably ask the dealer if they will install and do the programming.

Thanks for your input.

[BlackCat81]

Yes, a bad MAF sensor can cause a high idle. I'd still look into your used throttle body, since correct me if I'm wrong, your high idle started after replacing it. I can't stress enough how sensitive Infiniti throttle bodies are. If it was dropped, it's junk. It was thrown in a parts bin, it's junk. If it was slid across a counter, it's junk. They're that sensitive.

[EdBwoy]

If I were in your position, I'd hold of on the ECU route for a while. Your idle is not horribly off spec and the car seems to run fine.

MAF cleaned with CRC MAF cleaner. Sprayed on and did not touch it with anything, at all. Reinstalled and double checked for tightness and air leaks. Harness snapped on tight

Seems like you cleaned it the right way. Did you also wait for it to be cool? Takes quite some time, so it's best to do it before driving the car for the day.
The sensor didn't show any signs of corrosion like the old throttle body, right?

I used CRC throttle body cleaner on the TB. I used a soft brush to clean around in there and moved the plate by hand, so I was pretty sure I messed up the TB (after reading about that issue).

I happen to be an anomaly in the statistics. Not to jinx myself but the few throttle bodies I have cleaned have not given me any issues.
With regards to operating the plate by hand, I don't do it to WOT, just enough to let a thin napkin through.

At this point the manual points at intake leaks, bad throttle actuator or the PCV system.
I know you said you looked for vacuum leaks and are confident there are none. Is your intake tube clamped down tightly on the throttle body?

Forgive me if I've asked this on the other thread, but did you replace the PCV valves and inspect those hoses as well?

[Tim/M45]

I cannot be sure when I first noticed the high idle. I am pretty sure it was there before replacing the TB. I did not get the P0507 code before replacing the TB but with the constant misfire it was not running right anyway. I still have the original TB and may reinstall it to see if there is a difference.
I did not replace the PCV valves. I took them out and cleaned them. They rattled and seemed OK so I put them back in. I replaced both hoses since they were cracked. I may buy new PCVs and try that too.
I used most of a can of starting fluid when looking for air leaks. Intake tube is tight and I'm pretty sure the rest of the tubing is tight but I will check again.
Thanks.

[JOHNQ]

I had this same high idle problem and after replacing the throttle body with a used one from a 2003 q45 and not even cleaning it at all idle is back to normal

[EdBwoy]

JohnQ, did you have the code as well? Did your idle issue just pop out of the blue or had you done some work to the engine?

[Tim/M45]

I've still got the same problem. Nothing I've tried worked. I talked to the manager at Goodyear about the recommendation to replace the ECM with a used one. He said it would not work unless "re-flashed" by the dealer. I am still not convinced it is the ECM though. I may ask the dealer to re-flash the ECM I have now.
Still open to input and suggestions.

[JOHNQ]

JohnQ, did you have the code as well? Did your idle issue just pop out of the blue or had you done some work to the engine?

I had the code after valve cover gaskets were replaced and I asked the mechanic to clean the throttle body. I'm assuming he used his hand to open and close the butterfly valve when he cleaned it and threw it out of spec and calibration.

[Gene Ln]

wow this is interesting information, so your telling me if you open the butterfly the throttle body is then junk?

I just bought this car and I had 2 codes, first was for gas gauge which the dealer took care of as a recall item, and the second is code p0507, I tried spraying throttle body cleaner into it while the car was running to clean out didn't help tried the relearn, turn key on wait 3 seconds press the pedal to the floor 5 times quickly, wait 7 seconds press the pedal to the floor and hold until the service engine light starts, then stops blinking then let up and start the car, the car idles about 850 to 1100 normally when I do this it drops to 700 to 900, it doesn't hunt or fluctuate, it just idles steady somewhere between those ranges. I clear the code and drive for a while, and in 10-40 miles the code comes back.
So yesterday I though well they say if the butterfly is dirty any carbon build up may hold it open so I cleaned it by spraying inside with the intake tube off and spraying a shop towel and wiping it out, it worked well I removed quite a few black swipes, however I did manually open the butterfly

[ArmedAviator]

You can open the throttle butterfly. It will cause no damage. The butterfly is spring loaded internally to return to idle.

It's best to remove the throttle body and clean it well using shop towels and parts cleaners. Be sure to clean the gasket carefully and inspect it for tears - replace as necessary.

Not sure about the OP's high idle but the chances of it being an ECU issue is 1 in 1,000,000,000 since no other issues are present.

Is the 2003 M45 throttle via cable or electronic? Is there an idle acrew present? This may be keeping the throttle open too much.

To me it almost sounds like your car is remaining in open-loop mode. Does your engine coolant temperature reach normal operating temp? And by normal, I mean factory normal - no colder thermostat. If the engine doesn't get to normal temp, it will remain in open-loop mode.