: Surging/shaking through first gear???
06-06-05, 10:40 PM
My '93 has done this for a WHILE and it was something I thought had gone away or at least been improved by a recent transmission fluid and filter change, but not so.
It goes like this--unless you accelerate from a stop (i.e. a redlight) SO slowly and feather the pedal so much that you just about get run over, there's a moderate shaking sensation that increases in severity the harder you push it. Only does it all through first gear, and then all is smooth as silk and flawless after 2nd gear hits and speed builds.
Always felt like the car has to struggle to pull itself away from a dead stop, but, in reality, it has quite a bit of power and I still easily chirp the tires most of the time. And, like I said, once at 2nd and above and up to speed, it shifts flawlessly like a brand new Caddy.
My father thinks it might be a "sensor/electronics" related thing, but I really don't see how that could cause such a clearly felt surging sensation.
Any ideas on what might be causing the 1st gear shakes???
That is wheel hop from the awesome power!
Does it do it in reverse as well?
Does it do it in a second gear start (come off of a stop in second, does it start from second like my 94 does)?
Have you adjusted the TV cable recently? It should be adjusted around ever 6 months to ensure cable stretch is taken care of.
06-06-05, 11:08 PM
NO--to the first and last question, and maybe, for the comment about 2nd gear. I do think, now that you mention it, it may also very faintly do the same thing when I slow pretty far down and then get back on it.
But, for the most part, it's from a dead stop, going forward and through first gear. Once you hit second, it pretty much evaporates and the car sounds and feels like a freaking turbine on warpspeed power.... :)
Bothers me a lot though, because the car, even though not an LT1, is still amazingly strong and smooth, but hard to "launch" at anymore than a crawl because of the slight shaking. I mean, I can do it, and often do push it to get away from redlights before anyone else, but I keep wondering if something is really wrong and/or if I'm causing any undo harm by making it jump so often?
This car is still babied and driven lightly for the most part, but this is one issue that keeps me wondering...
First, and always, keep the TV cable adjusted. It controls line pressure in the trans and is very important to keep set proper. Even bumped up one notch can't hurt, but often at WOT it will reset itself. BBob has some posts on setting it on the HT4100/4500/4.9L and the FWD forums.
Does it feel like it is binding? Like a u-joint or flywheel problem? I had one very similar to your symptoms that no one could figure out and it was the trans to engine bolts were loose. I didn't tighten them as tight as a should have when I dropped in the 455 and the torque worked them loose. Check engine to trans and torque converter to flywheel bolts. They are odd to troubleshoot.
06-07-05, 07:51 PM
More interesting points to consider....thanks!
It's something I really only notice most when doing my usual "shoot off the line" starts, but even then, I don't see why I have to put up with it shaking....it's like the car is trying to pull a massive trailor or something and just doesn't have the guts to get it rolling at first--but it's just me and my relatively light self in the car.
It isn't some sort of lean engine problem causing a shake is it?
06-08-05, 07:11 PM
Not sure. Drove it all over today, in insane 95-97 degree heat and humidity with the A/C on maximum blast, and the hesitation/shaking through first gear was barely noticeable.
Really not a big issue, but was still curious to see if anyone else had a similar problem and knew whether or not something really was wrong. As is, I think it's fine, but it still strikes me as odd....
Surf over to fullsizechevy.com, I found some descriptions under "hesistation" as a search there that were similar to yours, one nearly identical. The 93 FW I think uses the same engine as the 91-95 Full Size Chevy trucks. So much would apply.
They seemed to come up with fuel pressure being an issue.
Here is some of what I found that I was going to send to someone else with a similar problem: