J30 sputters above 3600 RPM

[edgartheace]

Hey Guys, My car just recently strated sputtering at about 3600 RPM's. It doesn't matter how hard I mash on the gas it just won't go above this but drives and shifs fine as long as I stay below this. No check engine light, and the ECU reads codes 13 engine coolant sensor, and 33 oxygen sensor. I already cleaned the MAF and checked for vac leaks. Does anyone know what might be causing the issue.

[1994 infiniti j30 190+]

fixing those two codes might fix it. even just the o2 sensor could be why its sputtering. getting the wrong air fuel ratio causing it to run bad.

[Infinitiguy19]

Replace the fuel filter and run a fuel pressure test..

[edgartheace]

I'll try the fuel filter and check the fuel line pressure. One more bit of info it won't rev past 3600 both under load while driving and while parked with no load on the engine.

[driverdriver]

I would replace the 02 sensors (there are 2). The fault codes indicate this.

[Infinitiguy19]

The O2 and coolant sensors wouldn't cause the engine not to rev above 3600 RPM's. But replacing those two will help.

[edgartheace]

Hey guys, last night a new problem crept up. As my wife and I were getting ready to leave the dog park, the car started up just fine but then shut off after about 10 sec. I restarted it waited for 30 sec. then put it in reverse only to have the car die again. I restarted several time only to have it die within 10 sec. Finally when I when to start it for the 10th time the started made grinding sound and wouldn't start anymore. So obviously the engined siezed, or the flywheel had some teeth break off. I think one of my injectors might be leaking fuel into the cylinder causing it to flood and hydrolock the engine with gas. What do you guys think, and I'll let you know what else i find when I get home today and take a good look at the car.

[1994 infiniti j30 190+]

probabely killed the battery trying to start it so much. should fix whatever codes you have first then go from there. trying to figure out whats wrong with existing problems wont make getting it running any quicker. if you want to take out the fuel injector fuse and take out the spark plugs and see if the engine cranks. but only tap the key so that way if the cylinders are flooded with fuel it will just purge out instead of all over the place. i had to do this when i did my injectors when i had the intake on and it flooded the cylinder and thats what i had to do to get the fuel out of the cylinder. i eventually had to do all six so the plenum trick for me was useless. thats my advice on your issue and what i would do.

[edgartheace]

Hey guys finally got some time to put some work in on the problem. First the starter was acting up because the bottom bolt had fallen out and the starter had shifted from its correct place, bolt replaced amd were good here.. Ok I replaced the sensors as well as the fuel filter but it still did not fix my issue. I checked the fuel line pressure and it is within spec. 34 psi at idle with Vac line attached and 42 without it. The preesure rises as the engine revs up. But at 3600 rpms it stills acts like its starving for fuel. Could my ECU be toast because I'm stumped as to what it could be. Any help would be appreciated guys.

[GerryO]

The engine coolant temperature sensor code is probably more significant than the O2 sensor code, but new O2 sensors will improve gas mileage.
What does the FSM trouble-shooting guide suggest?
Check timing?
Ohm check the injectors?
Check the coil packs and spark plugs (OEM are best)?
Check the EGR valve and tubes for clogging?
Catalytic converter?
Open/stuck thermostat?
Try the 300ZX forum, as the Z32/VG30DE engine is common to both vehicles?

Think simple; the ECM is probably OK. How many miles on the engine and what sort of service history does the car have? How does the engine idle?

Good J30 maintenance is mostly about prevention, keeping things clean and in good working order.

[edgartheace]

Ok Guys I got my hands on a 300zx ECU my brother had. Put it on the J and the car reves all the way to redline now the CEL on and slight hesitation at about 5600 but pulls hard after. Looked up the codes causing the CEL and it spat out code 34, Knock Sensor. Could this be the reason my Car has been acting funny.

[GerryO]

Ok Guys I got my hands on a 300zx ECU my brother had. Put it on the J and the car reves all the way to redline now the CEL on and slight hesitation at about 5600 but pulls hard after. Looked up the codes causing the CEL and it spat out code 34, Knock Sensor. Could this be the reason my Car has been acting funny.

Glad to hear about the improved results using a different ECU. Always thought that the KS code doesn't cause the CEL to come ON, but a bad KS does alter the engine timing. Recall one time that my car had two issues/codes and that the second only appeared immediately after I'd fixed the first. Could still be the TS that's triggering the CEL? My failing O2 sensor didn't trigger the CEL, until I slowed down after driving about 100 non-stop freeway miles.

[yodawill2000]

Knock sensor will not trigger the CEL and is ignored over 3k RPM.

[edgartheace]

Guys It started doing the same thing again after it spent the week fine. Does anyone have any idea what could be causing it.

[GerryO]

Another possiblity to consider:

http://www.auto-facts.org/throttle-position-sensor.html

http://www.wellsve.com/sft503/counterp_v2_i1_1998.pdf

[edgartheace]

Hey Guys finally had some time to work on the J. The problem ended up being the CAS sensor. I toom it apart and cleaned out some metal shavings the would block the sensor. Car works fine now with no problems.

[yodawill2000]

Good Job !!!!!

[GerryO]

Very nice work and thank you for the "things are again good to go" report. So many failure modes...

Did the CAS sealed bearings feel rough/dry or loose, and do you figure that at least one of them was coming apart?