KA24DE idle problems after loading the motor.

[KA24DET3/T4]

Hey guys, I have a 91 s13 SE 5spd. with 200k miles. Lately the #4 injector has been acting up, but the past 2 weeks it's been fine.

Now more recently, my idle seems to be fluctuating really bad. If I load the motor by driving in any gear, speed up to any mph, and then push the clutch in to bring the motor back to idle, my rpm drops all the way down to 100-200 rpm and then back to 600, then down to 100-200, then back up. The only way I've avoided this issue is to turn the Fan to 1-4 to bring the idle up.

Any ideas?

Also, I've been trying to pass smog in CA, but I have high NOx levels. 15 mph is 595 (max)/ 1132 (my level) and 25mph is 592 (max) / 563 (my level)

any ideas?

Thanks in advance,

Thomas.

[Evaprototype]

Thomas, it sounds like a vac leak or possibly a bad Idle Air Control Valve. I had the same exact problem and had an enormous hole in the hose between the EGR and EGRC-BPT.

[KA24DET3/T4]

@Evaprototype, funny story. When I first bought the car, I felt that 90 degree hose and alas it had a hole in it. so I bought an OEM one from a local nissan dealership. Right after the install of the new 90 degree hose, I cranked her over. It started fine, but about 30 seconds into the idle it started doing the weird fluctuating idle thing. Now mind you this was 2-3 months ago, and it hasn't done it since that day.

Now it's doing it again. Is there any easy to check for a vac leak?

Thanks,

Thomas.

[Evaprototype]

Thomas, the simplest way to check for a vac leak is to grab a can of brake kleen and start spraying around the engine bay, listening for idle changes (it can bog or rev). Make sure to check along the mating surfaces of the IM/head and lower IM to upper IM, sometimes the gaskets crap out and cause fun leaks. Don't forget the PCV system hoses under the IM...I've had the one larger collector hose dry out and crack as well. Good luck!

[KA24DET3/T4]

checked for vac leak... nothing so far... IM/ head is good.... PCV hasn't been checked because it's a PITA to get to.... (any simple way to get to it?)

still a fluctuating idle after I load the motor..... if I'm at a stand still and rev. the motor with no load (A/C and fan off) it doesn't do the fluctuating idle. However, when I drive in gear and put the clutch in and keep it in to coast it does the fluctuating idle really bad (usually stalls)

[rivera01]

Besides vacuum leaks you could be experiencing a stuck open egr valve, especially since it went away for awhile and came back (vacuum leaks would very rarely do that). Bad egr will make nox go way high.

Check the egr valve is working correcly.

[KA24DET3/T4]

will do. it's in the shop getting checked out... EGR is being replaced. Spark plugs, and some other misc. stuff.

I'll keep you guys filled in.