Rough idle, loss of power.

[oovmiester25]

I have a 1990 Q45. About two weeks ago, I got in my car to drive and I noticed that it was idling rough and at only about 500rpms. After about an hour it just smoothed out all by itself. I never gave it a second thought. Now this morning I let the gas run down right to the empty line, but not below. It started running rough so I pulled into a gas station imediately and put gas in. The car has been running rough all day now and it doesnt seem to be smoothing any at all. I am concerned that the ignition system might be detonating to the block or head and since they are both made of aluminum I know that driving it like that could make the metal look like lava rock. If anybody that knows what they are talking about has a little insight or whatever please. Thank you!

[Haitian_King]

I have a 1990 Q45. About two weeks ago, I got in my car to drive and I noticed that it was idling rough and at only about 500rpms. After about an hour it just smoothed out all by itself. I never gave it a second thought. Now this morning I let the gas run down right to the empty line, but not below. It started running rough so I pulled into a gas station imediately and put gas in. The car has been running rough all day now and it doesnt seem to be smoothing any at all. I am concerned that the ignition system might be detonating to the block or head and since they are both made of aluminum I know that driving it like that could make the metal look like lava rock. If anybody that knows what they are talking about has a little insight or whatever please. Thank you!

9 views and no replies? Tsk Tsk guys.

Ok, here goes.

1. I hope to high heaven it was at least 91 octane you've been filling up with. Cali fuel ithe Devil's prune juice when it comes to early G50 injectors from what I've read on the board.

2. The low idle speed could be MAF related, as well as the rough idle and power loss. It can also be attributed to a possible bad injector.

Here are some tips to help those issues and at least be able to rule them out if the problem isn't resolved.

MAF:http://www.q45.org/maf.html

Fuel Injectors:http://www.q45.org/ohminjectors.html

IAC Cleaning:zerothread?id=33796

Throttle Body:http://www.q45.org/tbclean.html

Checking ECU Codes:zerothread?id=60332

Those are some of the best fixes for rough idles. Go through them, and see what works. Come back when you're done and if it's not sorted out, I'll be here to help along with the rest of the Q45 Brain Trust.


Modified by Haitian_King at 9:25 AM 3/9/2008

[maxnix]

Since you preovide no maintenance history, your most immediate problem could be your timing chain guides. Read the Article that pertains to this before you ever start your car.

Now tell us in particular about intake path and fuel system maintenance. ISO-heet? BG44K? Fuel fiter? Fuel pressure? Power balance test?

[Haitian_King]

Since you preovide no maintenance history, your most immediate problem could be your timing chain guides. Read the Article that pertains to this before you ever start your car.

Now tell us in particular about intake path and fuel system maintenance. ISO-heet? BG44K? Fuel fiter? Fuel pressure? Power balance test?

Ah. I'd forgotten to ask about those issues.

I always address the issues as if they were occuring in favorable conditions.

I always give the free and easy checks first hoping that at least one will be a hit and help us narrow it down. Someone new to the Q wouldn't really be able to do power balance checks in the driveway. (Or would they?)

But with the CG status being the X-factor here, that's another animal altogether.

Hopefully it's not going to be an issue here.

oovmiester25 - If you can get a hold of your Q's maintenance history, it would help you and the rest of us out for this issue and any other future ones. If you know the dealership where the car was purchased and seviced at, they can pull up those records. If you don't know, you can call Infiniti Consumer Affairs and give them your VIN. It will register you in their database as the current owner as well as give you all of the info ever recorded by an Infiniti Dealership. They can only give you an oral history though. What I did was get the name of the original dealership and gave them a call. They faxed me a hard copy of my Q's service records.

ICA's number is: 1-800-662-6200

[goody90q45]

Here are some tips to help those issues and at least be able to rule them out if the problem isn't resolved.

MAF:http://www.q45.org/maf.html

Fuel Injectors:http://www.q45.org/ohminjectors.html

IAC Cleaning:zerothread?id=33796

Throttle Body:http://www.q45.org/tbclean.html

Those are some of the best fixes for rough idles. Go through them, and see what works. Come back when you're done and if it's not sorted out, I'll be here to help along with the rest of the Q45 Brain Trust.

Excellent post Reji. The links pretty much sum up the free and easy stuff (except for $15 worth of gaskets and some brake parts cleaner) and give the owner a good start towards troubleshooting the basic problems. Add a link to pulling ECU codes and it's all there.

[Haitian_King]

Excellent post Reji. The links pretty much sum up the free and easy stuff (except for $15 worth of gaskets and some brake parts cleaner) and give the owner a good start towards troubleshooting the basic problems. Add a link to pulling ECU codes and it's all there.

Thanks Mike.

I try. But Brian also brought up some good issues as well, which will be incredibly helpful for the more advanced issues.

[oovmiester25]

Thank you for your help. I ended up taking the plenum off to replace a lot of the hoses that were so hard and brittle that the cracks in them were probably a leak. This would explain the hissing noise that I could hear while it was running but could not pinpoint to one spot. Now that I have the plenum and everything back into place, the car will not start! It did fire a couple of times and even `idle for a brief minute but never smoothed out. I notice that some of the connectors on the passenger side of the engine were similar. Two of them are the same size making it possible to have them hooked up to the wrong thing! Would this mistake be able to cause any short or damage my injectors or something? Thank you for your help, Im gonna post a picture of my car very soon!

[maxnix]

So did you clean anything? Readjust the IAC valve? New gaskets?

[oovmiester25]

I did take the fuel rail out and remove the injectors because there was like mud inside. I took each injector out and cleaned the rail and checked the o rings on the injectors wich all looked like they were new. The wires that go to injectors look like they are different because they have been clipped and joined together with new ones using blue butt crimp connectors.

[oovmiester25]

can anybody show me a picture or give me a good description of where to find the mode switch on the ECM. I want to see what the fault codes are and I cannot find the switch that you are supposed to turn with a small screwdriver.

[Q45tech]

Page EF/EC-49 in FSM shows where and how to switch modes.

"clipped and joined together with new ones using blue butt crimp connectors." ....................obviously some incompetent mechanic/owners chose the short cut to replacing the harness.

[Haitian_King]

I did take the fuel rail out and remove the injectors because there was like mud inside. I took each injector out and cleaned the rail and checked the o rings on the injectors wich all looked like they were new. The wires that go to injectors look like they are different because they have been clipped and joined together with new ones using blue butt crimp connectors.

Mud? In the injectors? BG Fuel Rail Flush immediately.

Well, I don't really know, but muddy fuel rail sounds awful and sounds like it need to be remedied ASAP.

When you put the injectors back in, did you lube them a little? It's best to just do that, so they don't tear going back in. (Or is the lube only really necessary when putting on new O-Rings?)

[oovmiester25]

Yes I put the injectors back in lubed up in petroleum jelly (vaseline). I am now thinking that maybe the injectors are wired back up in the wrong order because the car is trying very hard to start. Is there any way to differentiate the connectors that go to the injectors? Is there a diagram somewhere?

[Q45tech]

Why not acquire a brand new harness and avoid the possibility of intermitents in the splices and connectors?

[Haitian_King]

Why not acquire a brand new harness and avoid the possibility of intermitents in the splices and connectors?

Exactly. It'll save you from a massive headache.

[oovmiester25]

The wire splices were in place before I took the plenum off and the car was running just fine. I did not undo the wire splices, I only took the connectors off of the tops of the injectors. So the wires are all connected to the black clip-on connector correctly. The diagram that I need is for the eight different connectors and wich injector they are connected to!

[maxnix]

The diagram that I need is for the eight different connectors and wich injector they are connected to!

http://www.nicoclub.com/FSM/Q45/

I wouldn't trust those spade insulators not to leak.

[elwesso]

sounds like we have a hack job going on. Not saying its your fault, Bryan.

People are very quick to blame the MAF, when compared to the fuel pump its not common for them to give you actual component problems... You need to get a fuel pressure gauge and see what your fuel pressure is doing. T it in after the fuel filter, make sure pressure goes up to about 40 PSI when you turn the key on.. Then make sure it holds decent pressure...

Sounds kind like you caused more problems by taking the plenum off, sounds like its going to provide lots of fun to get it back together and running right.