HIya guys,
I've gotten great responses to my postings so far, so I figure I'll post this one a little differently.
My car vibrates in cycles. It almost feels as if it is pulsating. Going down the highway the motor should make a clean, single pitched revving noise, but it doesn't. THe engine rev's but the sound changes pitch, from deep to deeper at 50/50 intervals. The deeper pitched times cause the car to vibrate, like something isn't properly weighted or is out of balance with something else.
Going down the Pike at about 3000 RPM's is downright annoying.
Any ideas? The harmonic balancer looks to be alright from what I can see. Could it be a faulty tq. converter?
TIA

 

C'mon guys. SOmeone must have an idea.

 

I can't say this with any certainty, but my car was making some odd kinda rattleing noises a year ago or so. Turns out it was the pump in my tranny, but that isn't what I was getting at. My mechanic firend who rode with me had said something about like a pressure bypass system, or something in the exhaust system he thought could have been wrong...I suppose if there is a pressure relief system in there, and it was malfunctioning, it could cause the change in exhaust note, and vibrations....
Other than that, I'm sure you've checkted the basics, filters, consistant spark, etc. Other than that I'd say the ECM might be trying to compensate for something, and over compensating, then under compensating, etc. Does the ROM of the motor change, or just the exhaust note?

 

Hi.
THanks for responding. It actually isn't the exhaust note that changes... it's the engine sound. I'm trying to get ahold of the guys that built my block originally now to see if maybe the dowel pins that align the block with the tranny are wrong due to an align bore. The shop changed it's number and location though, so I'll try again tomorrow.
Any suggestions you have are of great help. I know everything get's good spark. Exhaust flows pretty freely. Intake creates a ton of vacuum.
Thank you

 

Check your plug wires. When i had one slip off it would make the sound chop at idleand vibrate, didnt notice it as much at higher rpms.

Andrew

 

replaced a tranny mount latley? my car does kinda does that after replacing the mount with a poly unit, gets down right annoying, how is it at high RPMS or hard acceleration?

 

The higher the RPM's, the faster the noise. It doesn't really get louder or anything, it just increases in speed.
Tranny is new and it's no longer a 700R4, so I think they had to change the mount. A stock mount wouldn't fit the TH350, right?