Vibration In Engine! (will Post For Help!)

[Philhawtin]

Hey All I Have A 93 SC400 Pearl White and a stock engine. for about 2 months i have had a vibration in my engine when say the car is park or neutral, i hold steady RPM's at pretty much any range. i usually go for about 2k rpm's and a vibe. will start about 3 seconds, then go away and then all is perfectly smooth, then another 3-4 seconds later, it comes back. its repetitive and a nuescence it does it while driving down the road too. but just as an example.

i took it to my old work place, (automotive diesel, ) and hooked up our snap-on modis, (Scanner) and found 2 codes yet no check engine light, and both codes were for air flow sensors, meters, or what ever. well my buddy was cheking each channel of the MAF wiring harness, 4 wires and the modis was placed on the driver side of the car and the wires were stretched over to the mass air flow center. and he could not get readings cause when he had the cords close to the engine he was getting too much interference from the engine, so maybe i though it might be bad wires somewhere???

oh and p.s., i checked all vacuume hoses

thanks all help would be appreciated!

Phil

[SuperCoupe400]

Check your motor mounts. It's probably time for them (and the tranny mount) to be swapped. Even if this is not what's causing the specific vibration you're getting, if you've got more than 100k on the original mounts, it's definately time for new ones. btw, the engine's got two mounts, and tranny just one.

[92Lex]

I've never had communication problems with the MODIS. The paper clips the tech used probably didn't make solid contact to the MAF wire. The reason the MIL didn't light up is because those are "soft" faults...MIL will light up on "hard" faults or second trip failures.

[mccube]

it happened to my 93 sc4 as well, when the car wasnt moving it had some kind of vibration that comes and goes away in between 3 - 4 secs, so i decided to change the plugs first and noticed that the one of the spark plug cable were broken inside so i had to changed it too, and the problem went away, hope this can help you. :)

[Philhawtin]

I Appreciate all your help with this, and yes i am 99 % sure i micht have a broken plug wire.. thanks again everyone