ka24de, engine shakes very bad during idle <<noobie>>

[link180sx]

Today my ka24de 93 240sx coupe started to shake when I started it up. The engine shakes very badly when it's idling. When I rev the engine 1,500+ rpm the engine is normal but when it gets below 1500 it begins to shake. The car is drivable to a certain extent and I can smell gas coming out of the exhaust. I have two MAF and thought it was the problem but wasn't.

The engine had a knocking sound coming from the timing chain before this had happened. Any help is much appreciated.

[AZhitman]

Hmmmm.

My first thought would be MAF connector coming loose.

The sound from the TC leads me to believe perhaps a TC guide has broken and caused the TC to jump a tooth (throwing off the timing).

Now is a good time to pull the valve cover and front cover (pretty easy) and remove the TC guides (there was a factory TSB advising removal).

Reset timing, hopefully no damage has been done.

There's a step-by-step guide for this job here somewhere... Can someone help find it?

[180fan]

My guess would be MAFS plug or injectors. Wiggle around the MAFS plug and see if that improves the idle. If not, wiggle around the injector plugs and see if that improves idle. If that doesn't do anything, try pulling injector plugs one at a time and see if it really stumbles or not. If it doesn't stumble with an injector plug off, you've got a shot injector. Give those a try before grasping at the timing job.

[link180sx]

Thanks for the fast reply guys. I've tried wiggling the maf, the injectors. Haven't tried pulling the injector plugs one at a time. But I doubtt it's that. So this weekend I'm going to pull the valve cover and do my timing. Hopefully I can find that step by step guide that AZhitman mentioned.

[Ramius83]

When I had that KA in my 240, I experienced the same problem. It was simply a loose spark plug wire, and that was it. I found out which one it was by disconnecting each injector at a time. When I got to the third cylinder, nothing changed. Then I knew it was that cylinder. Checked the power and pulsing going to the injector harness and it was good. Checked the spark plug wire and found it to be loose at the distributor. Simple fix....

[link180sx]

Sorry for being such a noob but engine running while disconnecting each injector at a time right?

[dkdeleon68]

yes disconnect one at a time untill you find the one that doesnt change the performance of the motor. the injectors that are working will make the motor shake even more when u unplug them.i would check #4 injector first i bet it will be the bad one.

[link180sx]

Hey 180fan you were right =)

Today I unplugged one injector at a time and guss what... unplugged injector #1 and there was no change the motor still shakes, injector #2 the motor shakes even more, injector # 3 the mortor shakes even more, but injector #4 when I unplugged that one the motor wasn't shaking any more? So what should I do? Do I just go and buy new injectors to replaced injector #1 and #4 or just #4?

[Chezedik]

have it flow tested, and check the harness, if it fails replace it, if not, check harness, ecm, injector pulse (You can do this by putting the key in the run position, taking out the distributor, and turning it by hand). Just because you found that does not make it a fuel problem. If you still get no where, then check spark and compression.

[jmacnissan]

hey you guys i have the same poblem, when u say check injectors are you meaning fuel injectors or spark plugs