240sx shaking engine at idle

[S13DatsunRicer]

I own a 1991 Nissan 240sx 5 speed with 135k. I just got the timing chain replaced and the car now has a slight Shake/Bounce at idle and when driving, its not bad or noticable when moving though. If you look at the motor when running, you can see it bounce to either side almost 2 inches. Before the enigne would not move/bounce at all side to side. If you are in the car you can watch the shifter shake from side to side too with the car. The car seems to shake worse under 900 rmp but at about 1,000 rmp its almost not that bad. I do not belive that it is the engine or transmission mounts.My mechanic told me I should replace the PCV and put in new plugs. Any help or info would be greatly valued.

[Turb0wned]

i had the same problem but mine was because it was idleing low i put up the idle to and its find now but you dont seem to have the problem it could be a vacume leak maybe.... or while the cars running take out a spark plug wire and it should wanna die if it does put it back and do the same thing to the next 3 (1 at a time make sure u put the one u take out back in first before takin out the next one) if it doesnt look like the engine struggles when u take one out then one of your not getting any spark for that one

[S13DatsunRicer]

Thanks for the reply

[TampaDriver]

Do a tuneup and check the timing. Also might wonna check the vacume as mentioned above. Might want to change the gas filter as well.

[Guffed]

Leak in your intake manifold?

[O0ooAJoo0O]

have you removed the AIV? that will help alot. fixed my idle probs. also, might check your mounts. mine are shot.

[GTS4-R]

Could just be motor mounts

[TachyonS14]

I have a vibration problem too, and I took out my old mounts to put in new ones to find out my old ones were just fine! And the shaking still goes.. ARHGHEGH

[GTS4-R]

hey i like ur little movie there

[lbrowne]

I took out my AIV setup and it helped quite a bit.

My shake was coming from a fluctuating idle. Now I still get it if I brake quickly but if the car is left idling it stays right around 650 rpms...so i don't know if I got to adjust my idle for that or not.

Take out the AIV though, won't do any harm..

[S13DatsunRicer]

Thanks for everybody who took time to reply and help. I think that the engine is misfiring because when I listen to the exhaust pipe, the flow/sound is not constant, it cuts out about every second or so when the car shakes/bounces. The sound use to be a constant. The bouncing is only really noticeable when idleing or at low rpms. The car just seems to bounce every second or so when idling and you can see it in the shift nob. I just bought a multi-meter and are going to start testing connection throught the motor, any usefull info would be great. :thinker

[O0ooAJoo0O]

dude, take out the AIV, im telling you, thats the same thing my car did. i got new plugs, 8.8mm wires and checked everything, its the AIV. its a good idea to remove it anyway. i thought mine was misfiring, it shook really low about every second, then would bounce. its the AIV.

[TachyonS14]

S14's don't have AIV, correct?

[S13DatsunRicer]

I need to go through emissions soon and I might not pass without the AIV. The more I read, the more I think its the timing. The car does not accelerate like it used to and is not as smooth. I looked today and found a missing bolt on the distibutor were you adjust the angle. I will look into it very soon. I also took out all of my plugs today and correctly gapped and cleaned them, they were at .56 instead of .41. I plan to buy new NGK plugs when some money comes in. The car did idle smoother after but it still did not fix the problem. I am about to start using 10-40 oil becuase of the miledge instead of 10-30 as the past owner. I have a repair manual and are trying to make it drive like it did before my new timing chain. It will be hopefully soon runing good once again.

I will start doing some of the recomendation in past postings.

[O0ooAJoo0O]

good idea for inspections. i didnt realize you had to go throught that. also, i use 20-w50 on my ka, its a little thicker so i dont leak anymore. and the NGK iridium IX plugs are awesome. helped me out alot.

[chickentendah]

HEY! my redtop sr20det does the SAME EXACT thing your car does man!!!

do redtops have an AIV???

[S13DatsunRicer]

Today I brought my car to my freinds auto-school. The timing was off over 5 deg so I adjusted it with the help of a timing gun and a cool shop hand. I also put in a new fuel filter. The car gained all of its lost power and runs fast once again. This however helped the idle but did not stop the shaking/bounce while idling. It did idle smoother then before though but it still had that idle shake to her. I Also pluged the plugs for a second one at a time while the engine was running to see if one was the culprit but they all did the same thing when pulled. I tested the O2 sensor with a multimeter and it read fine. I wiggeled almost every wire and connection to see if it had any affect on the engine idle but nothing came up. I checked some lines with a vacume gauge and I found no leakes. I want to spend more time with the vacume gauge and the multi-meter though. I think I have now figured that it is not the timing or ignition causing the problem. Any other ideas on what else should I look for?