Just finished up replacing the water pump on my '07 G35 Journey. Filled the system with coolant and started her up. Started first try and all sounds normal. While I was topping it off as it let out air the idle wasn't coming down. It's staying between 1400 - 1700 rpm. Temp came up to middle pretty quickly, but this has been the case with this car since I bought it 4 years ago. I'm thinking an air leak, but so far can't find any. I'm pretty sure all hoses are connected, but it's certainly possible I missed one. Any other ideas for me to look for?

Also, the coolant started coming out of the fill neck. I believe this is due to the t-stat not being opened yet (I didn't give it that much time).

Tom

 

Do you have an OBD2 device that can read live data?

If so I'd take a look at your short-term and long-term fuel trims. That will tell you real easy if you have a vacuum leak. After that you'll have to find where it is occurring and I built a homemade smoke machine to find a large leak in my car.

If you can read the live data you want to view short-term trims when the car gets to operating temperature and they should be close to 0. Long-term should also be reviewed, since that's kind of a baseline for how much fuel the engine requires to remain that 0% ratio.

So, if your long term on bank 1 is like +15% that means your car is adding 15% more fuel to even out how much extra air is getting in. The opposite would mean your car is reducing -15% of fuel being delivered.

That would be the easiest and first place I would start. You could also try doing an idle relearn, clean MAF, or possibly the throttle body (I would be careful about that though).

 

Thanks for the response. I do not have an obdii that can give live data. It seems to be improving, but I just dropped it off at an indy to be checked or the throttle relearning done again.

 

I just got a BlueDriver OBD2 scanner that gives live data. It shows bank 2 short term fuel trim around -0.0% but long term trim of 7.8%. Bank 1 is pretty even at 2.3-3.1% short term and 3.1% long term. O2 sensor voltages show .45 bank 1, .887 bank 2. Looks like I may have a vacuum leak on the driver side bank. Hmmm.....

 

Or a fuel pressure damper is crapping out on that side.

 

There is only one fuel pressure regulator for the entire fuel rail.

 

No the HR has 3 fuel dampers, at the feed hose that connects to the little metal intermediary tube that actually connects to the fuel rails then on each rail at the front outboard side there is another damper on each rail. Use a mechanics stethoscope right on the damper itself it should be pretty quiet if you hear a loud clicking/thumping sound then it's probably shot and needs replacing. Scope all 3 of them they should sound basically the same.

 

I stand corrected. I only saw the one on the fuel line and assumed (yeah I know what you do when you assume) it was the only one. That said, I wouldn't expect one to suddenly stop functioning simply because it sat idle for a couple of weeks when it was working fine before. Also, that doesn't explain the higher O2 sensor voltage. I'd expect the control module to compensate, at least some, by decreasing or increasing the injector time. I will check it though.

 

Well the system IS compensating for fuel, it has a trim of +/- 25% before it will send a CEL and even then it can continue to trim up to +/- 50% I think. I would get it on a real-time OBD2 scanner and watch the fluctuations in the O2 signal to make sure it's switching rich/lean properly, this wouldn't explain the high idle but there could be a sensor problem still.

I would still remove the intake tract all the way including the MAF, spray clean the MAF while it's off and inspect everything THOROUGHLY for any rips/cracks/etc. Take off the PCV valve and make sure it rattles when you shake it, inspect the pcv hose, the bank connecter hose, and especially that one from the driver valve cover up to the intake tube because I don't think it has a hose clamp on it from the factory.

Just to verify when you did all the resets you did it on a HOT engine, the AC was turned off, the vehicle was parked in neutral, correct?

 

I'm pretty sure cleric knows what he is talking about. On my DE motor it looks like there is only one dampner, but there is a second one hidden under everything.

you might have a tiny air leak and need a smoke machine to find it. I made my own smoke machine to find a leak, I was having.

I'd try the idle relearn again it took me about 20 times once to get it to work. The dealer can also use their Consut to do it as well. Will probably cost minimum of 100 bucks though.

 

I did find the fuel dampeners and listened to both. They sound the same. I pulled the intake on bank 2 and did not find anything. I sprayed MAPP gas around the intake on both sides - no change in engine speed. I did get a scanner that gives live data and it's now showing short term and long term fuel trims nearly the same although the bank 2 O2 sensor voltage is twice what bank 1 is. Idle did come down to the 900 rpm range for a bit and when I blip the throttle it doesn't go hunting like it was doing.

I've attached a csv file with the readout from a drive into town.

 

Bank2 O2 sensor voltage is off, it shouldn't be higher than 1 volt but it looks like it's still switching properly. I'd check the engine grounds because something is definitely wrong and the grounds had to be removed from the timing cover when you did the water pump probably. There is a big wire on the passenger side of the timing cover that goes below the coolant reservoir, check that bonding jumper as well as the main jumper from the negative battery post to the chassis.

What exactly was removed for the water pump replacement?

 

It's constantly capping out the voltage value of 1.25 volts, this makes me think that something electrically didn't get hooked up properly because it should NEVER be going that high, it should be switching back as soon as it hits 1 volt.

 

Half the engine. JK. Everything called for in both the Haynes and FSM's. Front timing chain cover, PS pump, intake plenum (don't think this is really necessary), TB's, Air boxes. I'll recheck the grounds, but pretty sure I got them all back on tight.

 

I checked the wiring and grounds are good and tight. I also tried swapping the MAF's to see if the O2 sensor outputs would change but they did not. Now, though, I'm getting ABS codes. C1130, engine signal 1 & C1185 accelerator control. Not sure what these are pointing to. Doing some research.

Edit: research on ABS codes shows they aren't anything to worry about right now. Likely a side effect of whatever is going on with the idle.