HELP!!! Nissan QG18DE – HARD START, ROUGH IDLE etc

[Kylie]

Hi All,

I have an Australian 2001 Nissan Pulsar Q 1.8L sedan (QG18DE) with an automatic transmission and about 192,500kms (120,000mi).
It is doing my head in. It has been to three mechanics and an auto electrician over the last few months and aside from throwing parts at it, they don’t know what to do.

The symptoms are:
-Hard to start 9 out of 10 times – will take a while to crank over – most often when cold but will struggle on occasion when warm i.e recently driven.
-The rpms vary at start up – sometimes they will be at 300 and climb up to 600, at other times the rpms will jump right up to 1100 and either stay there or creep down to around 800 and at other times it will idle normally at about 700-750.
-During this time it idles rough, the whole car shakes, the engine visibly rocks in the engine bay, it will feel like it is going to die and makes a sort of chugging sound.
-Usually feathering the accelerator will encourage the idle to even out.
-If I try to drive before this “tantrum” has passed the whole car continues to shake and struggles to get the revs any higher than 1500. Prior to the spark plugs being replaced the car was even harder to start and when I came to a stop, like at a stop light, the car would sometimes shudder, drop revs right down to about 300 and try to die out, when I feathered the accelerator to keep it from dying or if the light changed and I had to drive again, the revs would not get above 1500rpms do this chugging and shuddering thing and then it would “snap out of it” and drive okay.
-There is a strong fuel smell.
-I have noticed a decline in fuel mileage.
-The oil, oil filter and spark plugs where all changed within the past month and are already dirty and oil of gasoline/burnt. The air filter has also been changed within the past month and the fuel filter was changed about 3 months ago.
-The car feels like it drives okay…I think. To me it runs rough at times. And I think that it may miss or something while driving but I am not be entirely sure. I can feel an inconsistency. It is really hard for me to describe because I don’t know what word to use or what exactly it is that is happening.
-I have not noticed any smoke from the exhaust although there is a fair bit of carbon there – but I couldn’t tell you the last time that I cleaned the tail pipe so not really something to go by.
-There is no CEL.
-The last (3rd) mechanic I took it to noted that the timing was behaving erratically and was not advancing like it should – replaced the cam angle sensor and more recently, the crank angle sensor.
-The 3rd mechanic noted that my fuel pressure was a little sluggish but didn’t think that this could be or was enough to be the cause of my problem.
-I tested the compression but I don’t think I did the test entirely properly and I only did a dry test. My readings are: cyl #1 165psi, cyl #2 135psi, cyl #3 125psi, cyl #4 150psi.
Redid the compression test:
DRY TEST
FP – Final
CYL #1 75 – 165
CYL #2 70 – 145
CYL #3 60 – 135
CYL #4 75 – 155
WET TEST
FP – Final
CYL #1 80 – 175
CYL #2 75 – 185
CYL #3 70 – 150
CYL #4 75 – 175

The things I have done so far (not necessarily in this order):

-New fuel filter, NGK spark plugs, oil and oil filter and new air filter – spark plugs were the only thing to show any sign of improvement
-New battery – no improvement/no change.
-New cam sensor – no improvement/no change.
-New crank sensor – feels smoother but issue not solved.
-Swapped out coil packs – showed no improvement so put original packs back in.
-Various injector cleaners – no improvement/no change.
-Replaced engine coolant temp sensor – no improvement/no change.
-Cleaned EGR valve, PCV valve (replaced rubber grommet), cleaned MAF sensor – did improve the overall running of the car to a degree.
-Cleaned throttle body whilst still attached to intake – did improve the overall running of the car to a degree.
-Checked TPS, IACV, FPR and fuel pump – no improvement/no change.
-Replaced all 8mm (approx.) dia. vacuum lines as they were disintegrating – no improvement/no change.
-Tested all fuses with a test light – all okay.
-Checked all wiring connections – all okay.
-Checked for vacuum leaks – at home smoke test and carb cleaner methods.
-Injectors all seem to be getting power and clicking.
-I can hear the fuel pump cycle at start up – looked clean when I pulled it out of the tank. However the o-ring
-Coil packs all seem to be getting power.
-Also I have tried to “prime” the fuel lines after it has been sitting for a few hours or overnight before starting the car – no improvement/no change.

I have plans to replace the thermostat, just because I think that is something that I ought to do as a maintenance/preventative thing, I have had the car for 4 years and I don’t recall any of these parts being replaced.
In the 4 years of having it I have had it serviced regularly without any major complaints other than the power windows flogging out on me which I had fixed and the remote central locking not working and a “gremlin” living in my doors. The most major work I have had done is the front brake discs and the struts.

Also, when I took the tubing off of the throttle body, I noticed that the throttle plate has a line of greenish-white residue that looks as though it has been exposed to water or something. Can you tell me what this is about?

Well, that is all I can think of right now and I am sorry for the epic saga but…you know.

Thanks very much,
Kylie

Topic

[Its me]

Have you put a vacuum guage on it? Possibly a restricted exhaust… Eric has a video for this. .. Also, you can try to disconnect the exhaust from the manifold and see if it revs easier…

[college man]

according to the compression chart for that engine. The
compression you have is to low. 192 psi is the standard
and the minimum is 168 psi Redo the compression test.

http://www.nicoclub.com/FSM/Sentra/2001_Sentra/em.pdf

[Kylie]

Thanks College Man,I will redo the test and see if anything changes.

And thanks also ToyotaKarl, I will try the vacuum test also.

🙂

[Trent “Teddy” Martin]

I’m going with MAF haha will randomly fuck up one day and cause you shit loads of issues including over fueling

[Rudy Wilmoth]

🙂 I am sorry that this is a problem. I’ve been reading about the Pulsar on the Aussie websites and there may something you may have missed. When you said you replaced the cam angle sensor, Did you change the crank angle sensor also ? There are two sensors, the cam angle and the crank angle sensor that work together, if you changes only one, the other may be the culprit. You may also have a bad fuel pressure regulator that may causing this problem. I know you have done a lot of different things to fix your problem, but it can be fixed. This appears to happen to a lot of Pulsars in Australia. Good Luck.

[Kylie]

Hi slotcar,
Indeed. The next thing I am replacing is the crank sensor. The symptoms I have read about do sound a lot like what I am experiencing. In saying that though I have had the crank angle sensor go on my previous car and it was quite different to what I am experiencing now…but there is only one way to find out.

I have also had a good look at the FPR and checked for the typical signs of it malfunctioning such as fuel coming through the vacuum line and I have to say that I saw nor smelled any evidence of that. The fuel pump also seems to be in working order. I thought the fuel check valve but as I mentioned in my initial post, I have tried priming the fuel lines before attempting to crank it over but it made no difference.

The MAF sensor may still be the culprit but I’ve done as much as I can do with that short of just replacing the thing. I am really trying to avoid simply throwing parts at it. The parts that I have replaced have either been cheap or in need of doing anyway or my mechanic has recommended that I try that.

My biggest concern is that it is something more sinister i.e. burned valves or along those lines. Something big. But for know I guess I’ll just keep hunting. 🙁

[Kylie]

[quote=”college man” post=87829]
according to the compression chart for that engine. The
compression you have is to low. 192 psi is the standard
and the minimum is 168 psi Redo the compression test.

http://www.nicoclub.com/FSM/Sentra/2001_Sentra/em.pdf%5B/quote%5D

OK. I have retested the engine’s compression. (FP = first puff)
DRY TEST
FP – Final
CYL #1 75 – 165
CYL #2 70 – 145
CYL #3 60 – 135
CYL #4 75 – 155
WET TEST
FP – Final
CYL #1 80 – 175
CYL #2 75 – 185
CYL #3 70 – 150
CYL #4 75 – 175

Also, when I was testing cylinder #4 on the wet test I noticed smoke coming out of cylinder #3 but none others.
It occurred to me after the fact that I should have taken a photo of the spark plugs while I had them out but they are filthy! You really would not guess that these were replaced about 1 and a half months ago. Especially #3 spark plug.

That isn’t good, is it??? 🙁

I checked the vacuum also. That is fine.
I thought that a restricted exhaust would cause it to run lean whereas mine is running rich.

CHeers,

KW

[Kylie]

OK. So…I have changed the crank angle sensor, what a bitch of a job that was.
Thanks Nissan for thinking of us all by putting the sensor not only right at the back of the engine and wedged in under the starter motor, but also only really accessible from under the car and not leaving much of a gap at all to get your hand AND a tool in the space.
So far it STILL has a hard start/idles rough and has hunting RPMs (now more evident).
I am going to pull out the IACV tomorrow and give it a clean, see how that works out. I couldn’t undo the bolts holding in the IACV last time I tried. They are Philips head screws. SO I got an impact screwdriver and hoping that works to remove the IACV.

*SIGH*

Could my compression be causing this problem? Or is it acceptable enough and all of this trouble is being caused by something else?

🙁

[EricTheCarGuy]

Have you tried a power balance test? In my experience Nissans are famous for injector issues. I usually find a bad injector by doing a power balance test. Just because they ‘click’, that doesn’t mean that they’re good. Since you state you have a rich condition, this might be worth looking into.

Also, are you sure you’re performing the compression test correctly? Those dry numbers look awful low. You need to be sure to hold the throttle open when you crank the engine, this is something that’s commonly overlooked.

More info on solving issues like this can be found here.

http://www.ericthecarguy.com/faq/solving-automotive-performance-issues

Keep us posted on your progress.

[Kylie]

Hi Eric,

The injectors has been my suspicion from the start! The mechanics that I have been to have been of the belief that this could not be the issue.
I have done a power balance test as far as unplugging the injectors while the car is running. The engine seems to struggle at equal amounts with each on I pulled.
But yes, that is definitely something that I will look into further.

The first time I did a compression test I did not have the throttle open, I did the test by myself and even still the numbers were not all that far off the second lot of readings.
With the second lot I had a friend help me and this time the throttle definitely was open each and every time.

[Kylie]

After speaking with my mechanic to retouch on the idea of leaking injectors to which he still didn’t think was “it” but said we could give that a go, he thought though that it is more of an air flow issue.
Aaaaaand then I told him of my compression test results… he thinks that this could be the issue. Said he will do a bit of research and let me know what he finds out.

So, yay.

[college man]

[quote=”Munkee85″ post=88213]After speaking with my mechanic to retouch on the idea of leaking injectors to which he still didn’t think was “it” but said we could give that a go, he thought though that it is more of an air flow issue.
Aaaaaand then I told him of my compression test results… he thinks that this could be the issue. Said he will do a bit of research and let me know what he finds out.

So, yay.[/quote]

keep us posted on your progress. 🙂

[EricTheCarGuy]

I agree, if you did the compression test correctly, those readings don’t look good. If you’re engine has mechanical issues, such as low compression, there’s very little point in looking to other causes.

Keep us posted.

[Kylie]

Yea. Pretty much.
I will probably still poke around with a couple of things. I just really want to keep it running for a bit longer. I don’t want to spend a large sum of money on a new car just yet.
But really, there isn’t much point in going to the effort and spending the money to repair it i.e rings and such or a new engine the car is old and not in great condition anyway.

Thank you very much everyone for your time and advice. I really do appreciate it.

Kylie 🙂

[Lincoln Whyte]

Hey i may be late and as eric says nissans do have issues with injectors from time to time, a good way to test it is to up the fuel using a scan tool to the car and see if it revs out cleanly if it does then you do need to check em injectors….

however it is very possible that the strainers from the injector might have broken off and find its self between the plunger in the injector…..

but while u at it though is it possible for you to get a screenshot of the data that the engine is showing? while its running?

you said the cam and crank angle sensors was changed, was the circuit checked for continuity and were u able to scope them to see the patterns?

[Author]

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