Another KA with a bad idle! Video included

[big_tuna]

I'm trying to bring my 240 back from the dead. The car is a 1993 convertible with the ka24de that was 5 speed swapped by the previous owner. Since I bought the car, it has not idled properly. So far i've swapped in a 5-speed ecu, put in a new temp sensor, put in new intake gaskets, cleaned the iacv and replaced the gasket, cleaned the throttle body, replaced the maf, fixed the vacuum leaks, blocked the egr, and cleaned up a couple ground wires that were visible. I'm kinda out of ideas now. I had it idleing smooth at 700rpm earlier today for about 10 minutes. I thought i fixed it then it started doing its song and dance again! In the video i did not hit the throttle at all to keep it running, even where it comes close to cutting out. I wanted to show exactly how it behaves without any assistance!
Any help would be much appreciated!

http://youtu.be/WUdy4pGkUmo

[majgoldfish]

Have you looked at the following?

Get a timing gun, and watch the timing marks on your crank pulley. Couple times in the video looked like it was staying at around 1000 RPMs for a few seconds... See if the timing kicks up or down (most likely will be retarding timing) -- My car was having a lopey idle and the timing was going all over the place due to a misfire. My misfire issue had all sorts of sources I had to go through to get it to purr. I needed new plugs, wires, cap n rotor, fix vacuum line leaks, replace intake manifold gasket, and also the knock sensor.

Speaking of knock sensors... have you inspected yours? Get a multimeter and check the resistance of it. you should be able to test it while it's on the car, just attach the probes to your harness. However, it is possible that your knock harness could be AFU and the sensor fine. I'd recommend buying a 'cheap' replacement at the very least. (Nissan KA24DE 2 4L SR20DE 2 0L VQ30DE 3 0L Knock Sensor | eBay (http://www.ebay.com/itm/NISSAN-KA24DE-2-4L-SR20DE-2-0L-VQ30DE-3-0L-Knock-Sensor-/330673419924?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item4cfdabf694))
I bought a knock sensor from this guy, reluctantly... I'm not generally in the habit of buying sensors that aren't OEM. But at one point I was grasping at straws to fix things on the car, and wanted a cheap test.

Disconnect your MAF and see if it still is doing this. If idles smoother, by a lot... you may have a faulty MAF. Did you get the MAF from autozone? Or is it a nissan part? Reason I ask is, everyone I know who has used an autozone/oreilly's MAF has had issues with them.

Hope some of that helps.

-fish

[big_tuna]

Hi thanks for the reply! I haven't checked the timing or the knock sensor yet, I better do that. I just bought a multimeter to check the tps so I will check the knock sensor too while i'm at it. Did your idle improve when you tested it with the ebay knock sensor?

The maf I bought was a used Nissan part. The car runs like garbage with the original maf and the used one I bought, both are clean as a whistle. The idle does smooth out when they are unplugged. However yesterday i did a coolant flush and idled the car with the maf unplugged, the rpms were still jumping around. Yesterday was the first time it has done that with the maf not connected.

I changed the plugs last year but not the wires or cap and rotor. Guess I better add them to the list! Thanks a lot for all of your suggestions, that definitely helps me!

[majgoldfish]

The knock sensor helped, however... my main issue was a blown intake manifold gasket. The previous owner either himself, or paid someone to do a crappy job. The manifold was missing a bolt and blew out in between cylinder 1 and 2. I had to tear down the intake manifold side and replace a ton of stuff.

Practically anything that was rubber needed replacing. All of my PCV lines were AFU.

When you say you fixed the vacuum leaks, are you sure? I had NUMEROUS vacuum leaks. And NONE of them were detectable by spraying carb cleaner while engine was running (RPMs on engine should have increased whilst spraying).

I would very much recommend going to town and thoroughly inspecting the intake manifold. There are tons of places for potential leaks on it.

-fish