injector leak (code 45). knock sensor(code 34)

[mike7401]

Hi all, I was away for awhile. I changed spark plugs,fuel pump,fuel filter,pcv valve,cleaned egr valve, (and port to plenum), cleaned throttle camber, aac valve,fan blade,struts front & rears with bushings, trans filter internal & external, pulled codes got 34 &45 ( ks & injector leak, reset a few times but comes back. First 43 no check enigne light just code, then 45 with check engine light. Start fine but when warm on restart, rpm hunts almost turning off(sometimes it does)Then fines it self and settle to line above half way 1000- 500 Also doe not pull on top end like it should ( feels sluggish)

[maxnix]

KS & harness ohm test? Where did you set IAC screw?

Check all vacuum lines? Inspect FPCU & MAF connections?

[mike7401]

I can't seem to get a right reading on ks, mass sensor cleaned, connector seems ok, no change when moved. Did not change fpcu. Iacv is about 1.5-2 turns out from front seat. Doesn't seem like vacum leak alone, did check though

[Denver90Q]

Did codes first show up after all the work was completed? OEM parts? What ohm readings are you getting on injectors and KS? Does check engine light remain on while running? How many miles on engine?

[goody90q45]

.....I can't seem to get a right reading on ks, mass sensor cleaned, connector seems ok, no change when moved.......

I just got finished with a month of having to look at the CEL on the 90Q because of code 45. All the injectors were ohming good and the gas mileage hadn't dropped so I knew the injectors were probably OK. I did add 2 bottles of Redline injector cleaner since I hadn't done it since buying the Q 5 months ago but the CEL didn't go away.

What did clear it was cleaning the MAF and CAS pins and their connectors. I also cleaned the connectors for VTC soleniods, EGR solenoids and injectors 1,2 and 8. All had some level of green corrosion. I use cotton swabs and toothbrushes with electrical parts cleaner then coat with dielectric grease. Tighten the pins in the connectors with a small nail to look like the pin in the middle in the pic.

I can't seem to get a right reading on ks....

See if this helps to ohm your KS and fuel injectors.

[mike7401]

Wil try, car has 129000 miles. Gas mileage seem low about 250 to a tank 75-80 miles on the first 1/4. Check engine light turns on after about 45 miles of driving, on restart it is ok. Had a 92Q that pulled like crazy especialy on top end. ON this car top end seems light, does not like full throttle kick down. Seems better with throttle right before kickdown

[goody90q45]

I mentioned the Redline injector cleaner because even though it didn't work immediately it may have helped clear the CEL for the long term. I noticed a change about 2 weeks and 2 tanks of gas after pouring it in. If your Q had been sitting unused for weeks or months before you bought it it's easy to see how the injector internals could start to gum up. My last 90Q had a junkyard fuel rail put in by a previous owner. Two of the injectors were completely plugged.

You'lll see a big difference in power when you get all the connectors clean and tight. There's 5 more injector connectors that can be cleaned next time the plenum is off.

[mike7401]

I used bg44 and 4 bottle of techron before. Just thinking how is it getting its reading to know code 45 injector leak, what sensor. Plugs were very black and egr port was plugged shut. Was able to clear with small wire.

[mike7401]

I check fuel line by engine, found fuel lines loose, return and supply and by filter tighten car runs alot better ( I. must of forgot to tightened it) Still stumble alittle at warm start up sometimes. Will continue to check.

[mike7401]

The Q felt so much better I rode it into work( N.Y.C.) 88 miles one way, tank was filled before I left,after trip,gauge is slighty above 3/4. Before I could barely get 75 miles on the first 1/4 . When I got to NY check codes again still got code 34 knock sensor. She is feeling like a Q again. Will replacing knock sensor make top end even better or is computer retarding timing too much on top end already? NO more code 45 (injector leak) I hope.

[goody90q45]

Don't replace the KS until you ohm them to verify they're still working. If you get a reading of about 550k ohms there's nothing wrong with them.

[mike7401]

I can't get a right reading, will get my other tester. The Q feels so much better. I wonder if I should even change it, if it shows bad. Will the pickup be alot better and mileage, when changed.

[maxnix]

If you are over 120K, have no record of replacing the under plenum hoses, spark plugs or VC gaskets, you need to start researching and planning.

[goody90q45]

I can't get a right reading, will get my other tester. The Q feels so much better.

On the 95Q you may have to turn the ignition to the ON position to get a reading. If you clear the codes does the KS code come back right away?

......I wonder if I should even change it, if it shows bad. Will the pickup be alot better and mileage, when changed.

If both KS were dead it would affect your acceleration. If only one is dead you won't notice it. If for some reason you can't get a reading from the KS harness clear the ECU codes and if the KS code doesn't come back immediately they're fine.

[mike7401]

No check engine light no more, but stumble is wost now. Especialy sometime at idle in neutral car turns off. In drive at idle engine want to turn sometimes but not as much. Then sometimes its great. Car does seems to pull stronger, but sometimes at around 4k rpm, doesn't like to rev past 4k rpm. Code for 34 (ks) comes back right away, afer reset, only code. Mileage is 120 k +. Just did front right wheel bearing today was noisy, better now. I don't understand how sometimes it drives and idles fine, then sometimes it does not.

[goody90q45]

Did you clean the MAF, CAS and TPS connectors? Tighten and lube the pins? Your symptoms sound MAF or connector related.

[Infinitiguy19]

My bet is the fuel pump and soon enough if not already a bad Fuel Pump Controller.

[mike7401]

I did clean connectors, when mass sensor plug is shook no change. I replaced fuel pump, spark plugs, fuelfilter about 5-6 months ago, factory fuel pump.I di not lube connector ,will do

[maxnix]

My bet is the fuel pump and soon enough if not already a bad Fuel Pump Controller.

Time to measure fuel pressure.

[goody90q45]

No check engine light no more, but stumble is worst now. Especialy sometime at idle in neutral car turns off. In drive at idle engine want to turn sometimes but not as much. Then sometimes its great. Car does seems to pull stronger, but sometimes at around 4k rpm, doesn't like to rev past 4k rpm. Code for 34 (ks) comes back right away, afer reset, only code. Mileage is 120 k......

Did you replace the fuel pump after it had been buzzing for many months? It may have taken out the FPCU. An easy check is to bypass the FPCU and run the fuel pump on high speed only. Remove the trim piece between the trunk and the fuel tank and unplug the FPCU. It's in the background in the pic near the PR speaker. On its connector run a jumper from the pin shown to ground. If the car runs good it's a bad FPCU.

[mike7401]

Will check, I due have a spare fpcu from a junk yard. When I replaced fuel pump, I opened fpcu to have al ook , looked good, no burned marks on board.

[goody90q45]

Try the jumpering first. It's quick, free and you'll know the results instantly. If that works then temporarily install the backup FPCU and leave it dangling in the trunk for the test drive......(Trying to save you from having to remove the back seat and rear deck more than once)

[qship96]

Dont forget to GROUND that dangling FPCU or it wont work!!!!!!!!!!!!!!

[96Qowner]

LOL, that's a VERY good reminder! I'm sure many hours have been spent scratching heads for the lack of that ground, heheh.

[mike7401]

Ok check omhed injectors, got 11.1-11.24 on 2,3,4,5,6,7,8 and 15.24 on #1 also check at the injector itselft. Got 540 M ohms on 1 knock sensor, no reading on the other one. Ordered under hose and gasket kit from Scotdale Infiniti. Ordered knock sensor on ebay $55 each came in already,Nissan package and part #.

[silkysmoothyjud]

Had the same prob. Please be sure to check your EGR hose and make sure it is fully connected to the pipes next to the O2 under the car (leaky injector code for me, Im pretty sure) KS and harness for sure, do em both, you wont want to do it again, redo the coolant hoses in the Y- shaped apparatus right above KS. Sounds like you have possible injector probs, and MAF connector probs....One way to find out is to hit the highway, get to 80mph and gun it. The car will more than likely not gain speed at all with bad KS. Good luck

[mike7401]

I did also order harness from Scotdale. Had the Q on I80 up to 95-100 mph, but as you said, it gains speed but not that much when floored seems timming is being retarded a great deal, when floored.

[silkysmoothyjud]

ks FOR SURE. You should replace the gas lines on the fuel rail and clean out the valley. Put the RTV on the y shape connector while it is fully assembled when you put it back toghether. Check Q45. org, try and save all other hoses cept for the three sided hose comming off the Aux air control on the back ot the plenum. Try and save said hose, but dont hesitate just to hack it. Order another and just tilt the plenum with the other longer hoses underneth attached. Take one screw out of injector #7's injector cover so that you can remove said injector with out plenum removal later on down the road
Modified by silkysmoothyjud at 9:24 PM 5/7/2009

[maxnix]

You really want to replace both KS at once as you don't want to repeat the job when the other one fails.

[silkysmoothyjud]