Q45 Check Engine and Running Problems

[rover3l]

Hello everyone long time no see.

After spending months in Asia and Europe with the job I am now in the process of relocation from Western NY to Massachusetts. We are moving in early August and I will be on the look out for any Q45 experts in the area. I know there is no T3 equivalent but is there anything worth checking out?

To my current issue. This week the Q45 started playing up in that the acceleration was slow at low speed and it then would seem to clear and go off as normal past a certain point. Today the check engine light has come on, the idle is really bad and acceleration feels like I am running on only 6 cylinders. I am not sure where to start but is there a test I can run to see what is wrong. Could it be an 02 sensor or an injector?

[DAEDALUS]

Have you ever replaced the fuel pump? Can you measure the fuel pressure? Try wiggling the MAF connector too.

[rover3l]

Yes I replaced the fuel pump with a new one from Scottsdale in October last year and also replaced the fuel filter at the same time. I did try moving the connection to the MAF but it did not improve matters. Is it better to remove it and plug back in or just move it around?.

[DAEDALUS]

Pull the code at least. Wiggling the MAF is usually enough to detect changes in idle if that's the problem, but disconnecting it is necessary to clean it.

[rover3l]

I have looked at the ECU in the footwell but don't see any LED's. Do you have to remove the ECU to get access to these?. I did try but the two phillips screws were really tight. Before I go any further just want to check if I need to remove it to pull the code

[DAEDALUS]

Yes, unfortunately the good designers thought all owners of 10-year-old Qs would have Consults. Unhook the battery first just in case. Then remove the harness. Remove the 3 ECU screws and the ECU. Then hook the harness back up and power up the car. It seems with the battery unhooked you might actually lose the code, but that hasn't happened to me yet. If so just start the car again with the ECU hanging out.

[rover3l]

ok I removed the ECU and reconnected the harness and ran the diagnostics. For the first few cycles it gave code 51 (injector analysis??). Then I turned the ECU screw until the LED stopped flashing and then back again and the code now gave 55 (everything ok). I restarted the engine but the check engine light is still on and the idle is still lumpy?

[911/Q45]

You cleared the code, but the injector is still bad. Check the archives for Daedalus' great tutorial on how to check injectors and knock sensors with an ohmeter at the harness.

[rover3l]

Sorry I looked for this but couldn't find it. What key words should I use?

If I have an injector gone bad is this something a typical Nissan dealer can repair and how many hours should it take?

[maxnix]

Depends on which injector. If the plenum has to come off, you should schecule other services so you don't have to repay for repetitive labor in the future.

One last question, did you clean your tank when you replaced the fuel pump? Did you blow out and/or replace your fuel lines? Loosened gradoo could be causing your problems.

[DAEDALUS]

I'm having server problems on my end. I'll have to find a backup and email it to you.

[rover3l]

To Manix - no I did not clean the fuel tank etc when I changed the pump so I guess this could be related. This evening I was looking in the engine bay when the car was idling and I notice that one of the right angled short hoses at the right rear corner of the plenum (when looking from the front of the car) is colapsed. I am going to try to replace this over the weekend to see if this is in anyway connected.

[DAEDALUS]

The hose feeds into the plenum? If it's the hose I'm thinking of then it's a likely candidate if it's letting air in. Vacuum leaks wreak havoc.

[rover3l]

I left the Q at my local garage shop, while I have been to MA for the last few days related to my relocation. He found that injector #6 is bad and is replacing it tomorrow along with the collapsed vacuum hose to the plenum.

I will report back to advise if this provides a fix

[rover3l]

Got the Q back. It was injector #6 which has now been replaced. What a difference. The car now goes like stink!. No stuttering just smooth acceleration all the way through the rev range.

[Chally]

It's amazing just HOW BAD the Q's go with a crook (bad for you yankees) injector. When 1 of mine went out, I thought there was something else wrong, as I thought 1 injector would only reduce the power slightly. Wrong!!! It felt like it took 1/4 to 1/3 of the power away.Glad it's all going well again.

[kman2k1]

You cleared the code, but the injector is still bad. Check the archives for Daedalus' great tutorial on how to check injectors and knock sensors with an ohmeter at the harness.

Can you link to that tutorial? I just got back from the dealer who tested my engine and told me both 6 and 8 are dead. Bleh.

Is it possible that the problem could be bad injector insulators or something cheaper? Maybe I'm just dreaming.

[911/Q45]

I printed that tutorial, so no link here. Perhaps Daedalus can email it to you. If the dealer read them bad with his Consult, they're bad. I'd recommend you suck it up and replace all of them. I just did that and mine runs perfectly and will continue to do so.

[kman2k1]

There's no way I can afford to replace all of them. 6 I can replace myself, but removing or loosening the manifold to where I can get to 8 intimidates me. I hear there are a few fragile hoses under there and I don't want to risk breaking any. 2 injectors should cost me around 300 online, and service maybe 200. Geesh, those technicians make more in an hour than I do in a day.

[Chally]

Yeah, but we don't keep it all! Sometimes we end up with LESS than the wage earner

[911/Q45]

You might get #8 without pulling the plenum, but no way to get #6. Those hoses need replacement as badly as the injectors, so it will end up being more expensive to take the bandaid approach. You aren't too far from Jerry Tucker, check with him for the best package deal.

[QShip]

You might get #8 without pulling the plenum, but no way to get #6. Those hoses need replacement as badly as the injectors, so it will end up being more expensive to take the bandaid approach. You aren't too far from Jerry Tucker, check with him for the best package deal.

Agreed.

[kman2k1]

I guess I got 6 and 8 mixed up. I'll organize a road trip to San Diego with some college buddies. Is Jerry Tucker a NICO member?

He even has a coupon. http://www.sdreader.com/php/qs...UCKER