moisture issue

[Naison]

Has anyone experienced problems with their J30 when it rains?I keep having problems. The car gets somehow wet, it start shorting and it's not working.So I take all of the spark plugs out,crank the engine to dry it (with the fuel pump fuse out) and then spray a lot of the starting fluid and after about an hour or two trying I barely start the engine cranking it with foot on the gas pedal all the way down.Every time this happens, it ends up with burned injector.Last time I used the dremel method but now another 2 cilinders don't work.One of the injectors shows about 140 Ω which is way higher than the range (10-14Ω) so I'm assuming that is shot, the other one shows normal range but the cylinder still doesn't work.So now the car is running on 4 cylinders only.I sprayed WD40 on the harnesess I'll see if it will make any difference with at lease one of them.Coils are fine and spark plugs also.I don't know what is it whit this car. Anybody having the same problems?

[GerryO]

When one of my injectors started acting up, the first Google search I did turned up something about wetness in the area of the ECM, which turned out NOT to be my problem. I finally tracked the problem down to a failed injector (infinite resistance), and chose to pull the plenum to replace all six injectors (175k miles) and do a lot of plenum-off related clean-up work.

I didn't remove, disassemble and clean the IAC/AAC valve though (I've posted links to the instructions here several times) and wish I had, as even now if I don't start the car every two or three weeks something occasionaly seems to stick and warming it up it takes a while for the miss to go away. The damp, foggy and cold coastal climate seems to affect things too. I re-assembled things putting dielectric grease on every connection I could, with the exception of those for the O2 sensors.

One loose wire or poor connection is all it takes.

[swimshark]

why did you spray wd40 on the harnesses? they have electronic cleaner at the store. also you can put dielectric grease in your plugs for the motor like GerryO said. keeps moisture out. however DO NOT PUT DIELECTRIC GREASE IN O2 PLUGS! there are online threads that will say the same. it will cause your ECU to not read them correctly and throw a check engine light.

GerryO ive done a lot to my plenum. throttle body coolant bypass, full egr delete (plates and exhaust plug), prvr and egr brackets removed. did a full plenum pull in 25 min last time.

[Naison]

Thanks for the reply. About the two cylinders that don't work, I'm positive that for one of them the injector is shot.The other one I don't know.I measure the injector and is normal range.Coil and spark plug are good.Could the injector be just plugged or maybe the ECU doesn't send a signal to it? Is there anything else you can check to determine why the cylinder doesn't work? Thanks

[1994 infiniti j30 190+]

it could be plugged but make sure your getting spark by pulling the coil off the plug while its running and see if you hear a spark. or take the coil and plug out and touch the plug to the intake manifold and have someone else tap the key and see if you have spark. if not use a coil from a known good cylinder and try it then. befor i did my injectors i had some that would misfire on and off when i ohm checked it, it was good but when it misfired and i unplugged it, it was one that was tested good so you could have one like that if so you need to put new ones in.

[swimshark]

May give you some ideas

http://s95014253.onlinehome.us/63104/159859.html

I know there is also a way to check the PTU. ill see what i can find. there are threads on 3zc.com for 300zx guys that go through these issues also.

[Naison]

Thanks for the reply.Yesterday I replaced the two injectors and now it does the same thing.With the engine running I unplug each one of the coil harness and again on these two cylinders there is no change in the RPM. I did check for spark and it looks alright.So what is it then.The whole ECU???

[yodawill2000]

Change Spark Plugs ?Hear the new injectors Clicking ??The less than 5 buck mechanics stethoscope at Harbor Freight is a must have !!

[jdurrty]

GerryO ive done a lot to my plenum. throttle body coolant bypass, full egr delete (plates and exhaust plug), prvr and egr brackets removed. did a full plenum pull in 25 min last time.

Tell me about the egr delete! The check engine light has been on since i bought the car because of "egr flow malfunction" fml.

[Naison]

Thanks for the reply.I used the mechanics stethoscope and I couldn't hear very well clicking on these two cylinders.So this time I measured directly the harness that connects to the injector ( the one with the two prongs) with the engine running so it reads only about 1-1.5V compare to the others where is 12.5-13V. Only these two are giving me that reading on the voltmeter.So I know that the problem is somewhere between the ECU and these two harnesses.I just took the ECU out now and I'll try to read some codes.So I'm assuming it's either bad connection somewhere or the whole ECU.Which it makes me wonder how it'll give 12V to the rest of the cylinders and only 1V to these that are bad 2.
Modified by Naison at 12:52 PM 3/23/2010

[Naison]

It shows 53.Which is EGR Temperature Sensor (LH). Where is it located and what's it look like?If I replace it, would it solve my problem?

[1994 infiniti j30 190+]

its next to the egr valve on the back of the engine its on the drivers side tube that goes into the intake. its hard to get to and you have to use a wrench. when i did my egr vavle with my intake off it was easy to get to, but with the intake on you might have alot of trouble getting to it.

[Naison]

That doesn't sound like it would fix my problem does it? May be because the car works only on 4 cylinders it reads different level of exhaust gas than it supposed to. Is this related to the voltage that feeds the injectors?

[1994 infiniti j30 190+]

which 2 cylinders are not firing? two on the drivers side or passenger or one on both because the egr only uses the drivers side exhaust. i would try replacing the sensor or cleaning it and see what happens then figure out why its not firing on those cylinders.

[GerryO]

That doesn't sound like it would fix my problem does it? May be because the car works only on 4 cylinders it reads different level of exhaust gas than it supposed to. Is this related to the voltage that feeds the injectors?

Don't believe it's causing your problems. Always thought there was only one EGR temperature sensor (top left in this photo), and even though there are two outlet tubes.

[GerryO]

GerryO ive done a lot to my plenum. throttle body coolant bypass, full egr delete (plates and exhaust plug), prvr and egr brackets removed. did a full plenum pull in 25 min last time.

Nice work! I did the TBCBP and replaced the EGR valve, and still need to re-install that length of coolant related tubing that heats the AAC valve in order to pull the cold idle speed down as the engine warms up with the car moving. I'll remove and clean-up the IAC and AAC valves at the same time.

[Naison]

The two cylinders that are not firing are on each side of the engine. I can't figure what could it be the problem.I though that maybe somebody happened to have the same issue and share the solution.

[1994 infiniti j30 190+]

your wiring harness for the plugs and injectors could be bad and may need to be replaced. if that doesnt do it then maybe your ecu.

[GerryO]

The two cylinders that are not firing are on each side of the engine. I can't figure what could it be the problem.I though that maybe somebody happened to have the same issue and share the solution.

It's all a matter of inputs and outputs. The ECM receives a signal from the CPS that it's time to open an injector to supply a cylinder with fuel and then close it, and a then signal from the CPS indicating that the pistion and valves are in position for firing; intake (air and fuel)/compression/power (ignition/spark)/exhaust, over and over again.

Confirm that the ECM is out-putting the correct voltages/currents to the coil packs and injectors (4/6 are working properly, so the ECM is probably OK).

Confirm that the wiring and connections between the ECM, and the injectors (noid lamp and multi-meter), coil packs/spark plugs are good.

Confirm that the injectors (ohm test), coil packs (easy to swap) and spark plugs are good. In my experience injectors don't clog, unless you are running without a fuel filter.

Compression test.

[Naison]

Thanks a lot about the info.It seems that the ECM isn't out-putting the correct voltage to these two specific cylinders. I may have to buy another one and try again.It is out-putting 1-1.5V.