1993 Q45 engine runs better when ambient temperature is above 70*F

[Infinitiguy19]

Interesting maybe I should just stick attempting to advise my year.

No big deal so you messed up its not the end of the world. And you tried to help, Rather than say "Get a 1994 Q45"

Consult program? Is it free?

You have to buy a Consult cable that hooks up the the laptop. Then there are free softwares like: Calumsult, OBD Scan tech Nissan and ECU Talk and more but those are the ones I use.

But when I turn off each injector I notice no real difference. But this stumble is very mild and not nearly as bad as a bad injector. Its like it has a pattern or rhythm or something, Because it stumbles once every second or something.

[goody90q45]

I think one of your injectors is plugged. Why don't you send in your spare fuel rail to Deatschwerks and have the injectors serviced?

[Q45tech]

With an accurate electronic pressure sensor you can see the ~ 0.3>1.0 psi drop [at the input of rail] as an injector opens at idle or cruising. A clogged injector will obviously not have the drop.

Without accurate test equipment trouble shooting is very difficult.

[Infinitiguy19]

Do you mind showing me one because the ones I find only give two digits and no decimal points?

[silkysmoothyjud]

My pute went down for a while, but to finally have some closure on this subject, just drive the car, the Q will either fix it's issue or it will fail completely and make it easier to find the problem.I sent some old injectors to D-works to get "cleaned" (rookie mistake), not niqole's fault, I NEVER would have found those misfing SOBs had I not did it myself....
Modified by silkysmoothyjud at 4:12 PM 11/6/2009

[Infinitiguy19]

Just to add the motor and transmission mounts were replaced in 200X. Yet the motor has some movement to it and when driving ~40 MPH I get some shaking.

I know the exhaust needs some work for sure...

I will take a video of engine tomorrow

But I am comparing my engine mounts to:http://www.youtube.com/watch?v=V_kCcZl8 ... eiblkess5I

Computers as so much easier.

[silkysmoothyjud]

The injectors keep this car 8 pieces away from perfection....

[Q45tech]

Amazes me that so many whine and blame injectors, when the culprit has always been the fuel and your congressmen and senators who voted for the change....that caused the problem, not the innocent injectors.

After all the injectors didn't change they just sat where they were first installed.................what changed the fuel ...duh.

Be careful they are proposing E15 and E20 to create more problems for America.

Guess who is suffering injector failures now BMW and MB - check their boards.

[Infinitiguy19]

Amazes me that so many whine and blame injectors, when the culprit has always been the fuel and your congressmen and senators who voted for the change....that caused the problem, not the innocent injectors.

After all the injectors didn't change they just sat where they were first installed.................what changed the fuel ...duh.

Be careful they are proposing E15 and E20 to create more problems for America.

Guess who is suffering injector failures now BMW and MB - check their boards.

So true, luckily I found a place that offers 110 octane fuel WITHOUT E10!!!

But could a bad HLA or more cause a idle problem then disappear above 1700 RPM's?

I ask because after I did the oil change the idle has gotten a tiny tiny bit better, I am very sensitive and a perfectionist. But I did half a can of BG Quick Clean then put in new oil with a filter and added BG MOA. HLA tap is still there in the morning or when ever the car is cool. The HLA noise seems to be coming from the right valve cover (The one with the throttle body, EGR...), I found out using a Mechanics Stethoscope.

There is also a strong idle fluctuation because sometimes its close to 1000 RPM's other times is closer to 700 RPM's. But this is taken from the dash tach.

To be fair though the temperature today was 25*F.

[silkysmoothyjud]

Those injectors are sensitive to the weather. I am getting a little stumble that goes away after about 20 minutes. I only have one injector left to change so its a no brainer.....

[Q45tech]

Anything with copper wire inside is sensative to temperature changes.Injectors, solenoids, sensors, etc.

Why ecu has broad wide powers to try to maintain preprogrammed idle speed.

The CAS creates 360 pulse per engine rev and 660 rpm [11 revs per second] creates 3960 pulse per second AND ECU constantly COUNTS EACH ONE as this is ecu's master clock which is compared to a precision quartz crystal oscillator.

6-7 rpms [1% error] is more than enough to get ecu attention and start the tweaking process.

When engine get old/worn and have varying cylinder compression those weak cylinders drive ecu crazy as the ecu is constantly trying to fix those weak cylinders with fuel or ignition timing changes.

The ignition changes are easiest since they don't involve something mechanical like IAC or changing injector timing which affects 4 cylinders.

Study hystersis and feedback loops and the oscillations that can occur when you overshoot the ideal in limited time.

[Infinitiguy19]

Would it be the injectors if: Today it was 30*F and snowing and when I started the car up for the plow to clean up (Thanks neighbors) I let it warm for 2 Min because I was in a rush. But when I put it in gear (Reverse) the car started shaking worse than usual and maybe as bad a bad injector or cylinder.

That would explain a lot except sometimes when its colder than 30*F it does not shake like a bad injector/cylinder.

Well I just need to convince the local dealer to do the consult test several times in varying conditions.

[silkysmoothyjud]

absolutely,CEL (sometimes), then slight shutter, intermittent kangaroo hop, then permanent kangaroo hop. Mine have all failed in that fashion.

Also, dont forget that loud almost "rod knock" like lifter tick with no vibration. Why it does this I do not know, but it is a tell tale sign.

[Infinitiguy19]

absolutely,CEL (sometimes), then slight shutter, intermittent kangaroo hop, then permanent kangaroo hop. Mine have all failed in that fashion.

No check engine light EVER, I do have a slight shudder and intermittent kangaroo hop. Coming this Summer: Paul pulls the VH plenum and then puts it all back.

This has been going on for 1.5 years.

Did you try the BG fuel injector flush?

Man laziness and Q45 don't go together.

Also, dont forget that loud almost "rod knock" like lifter tick with no vibration. Why it does this I do not know, but it is a tell tale sign.

When does that start to happen?

[silkysmoothyjud]

That loud tick is the first thing, then the shudder, then the hop. If one is failing, others are not far behind. When you pull the plenum, do all four injectors 3-6. Leave one screw in injector #7's cover, so when that bish fails, you wont have to remove the plenum to change it. You will know what I am talking about, just look at #7's cover with the plenum on and leave the screw you cant see OFF....

[Infinitiguy19]

Lucky for me the previous owner replaced all the injectors, rails and harness with BRAND NEW OEM parts. And in the process he used hex head screws not philips head screws.

I am not into leaving screws off on injectors covers though.

Power balance tests will ensue, Sucks that my Consult connection guy flaked.

[silkysmoothyjud]

It doesnt sound like those injectors are new, but they are first generation and from what I read, need to be changed ALOT!

[Infinitiguy19]

Well they do OHM good which is half the test, the other half would be to send them off to DeatschWerks or performing a BG fuel injector flush.

First generation injectors are not full proof but neither are the second generation G50 injectors. The ones that seem to be holding up are the ones made after 10/96, Qship96 when was your car made?

[silkysmoothyjud]

I would not send the rail anywhere. I send some old beat up injectors to D-werks and they came back with a paper saying they where ok. I installed those bishes (under plenum 3 and 4) and they stumbled like crazy when the engine warmed up. No CEL either, I never would have found them if I hadnt done it myself. ohmed fine the whole nine, all my failures ohm perfectly..

[Infinitiguy19]

How can that be if you sent them to DeatschWerks, As far as i know they are a good company.

Either way I have no plans to send them anywhere but the trash if they are bad.

[silkysmoothyjud]

The injectors were trash from the gitty up. I bought a used rail off ebay when I first bought the car. Rookie mistake, but D-werks should not have approved them for real...

[Infinitiguy19]

Well I don't know if its too late but let them know over there and see what they can do.

[silkysmoothyjud]

I was done at that point, after being cheap and ignoring advice on this site, I decided to go brand new oem and have not had a prob since.

Also, removing the plenum when I was a rookie was an all day affair. I was friggin pissed!! Howeve, now I could have removed my plenem, changed all four and have it back on the road in about 2 hours....