Tuning Gurus Please Step In
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
Tuning Gurus Please Step In
I've got a freshly rebuild engine and tranny. Its an LT1 with iron heads and a 230/236 cam. The tranny is a 700r4 with a manual valve body and a manual tc lockup. I'm doing the tuning myself and I'm not all that experienced. I'm thinking this is a tuning issue, but I'm not sure.
I seem to get a shake through the car when I'm curising down the highway and I engage the TC. And it'll stay on as long as the tc is engaged. If I give it more gas with the TC engaged you would have though we were in an earthquake. This is in 4th, not downshifting. I tried the samething without the tc engaged and it did it as well, but ever so slightly.
Is this just too much timing? I'm running 30 degrees at cruise currently. The A/F was in the 14's accroding to the wideband. I'm running a rear mount distributor. I thought I had the timing within a degree or two of where it should be. Could the distributor have tuned?
Any help or suggestions that you guys could give would be very helpful. Thanks guys.
I seem to get a shake through the car when I'm curising down the highway and I engage the TC. And it'll stay on as long as the tc is engaged. If I give it more gas with the TC engaged you would have though we were in an earthquake. This is in 4th, not downshifting. I tried the samething without the tc engaged and it did it as well, but ever so slightly.
Is this just too much timing? I'm running 30 degrees at cruise currently. The A/F was in the 14's accroding to the wideband. I'm running a rear mount distributor. I thought I had the timing within a degree or two of where it should be. Could the distributor have tuned?
Any help or suggestions that you guys could give would be very helpful. Thanks guys.
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
Try more like 35-42 degrees in a cruize.
Also usually high load situations like this are great for finding a burnt plug wire or ignition problem. I've seen plug wires act the way your describing
Also usually high load situations like this are great for finding a burnt plug wire or ignition problem. I've seen plug wires act the way your describing
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
The kpa doesn't change a whole lot when I switch to TC on, but ti does change slightly on my vac gauge. I'll have to check the numbers exactly.
My big concern is if I'm doing something that might hurt the engine. I'm getting 14.6 mpg cruising about 60mph so I'm pretty sure that I'm running too low of timing but I never sure about this stuff.
My big concern is if I'm doing something that might hurt the engine. I'm getting 14.6 mpg cruising about 60mph so I'm pretty sure that I'm running too low of timing but I never sure about this stuff.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by mn_vette
Is this just too much timing? I'm running 30 degrees at cruise currently.
Are you convinced this is a tuning problem? I'm concerned about the balance of the new engine. Regardless of the cause, locking the converter will more efficiently transmit vibrations. Do you feel it at all when you rev it in neutral?
RACE ON!!!
Safety Car
Joined: Sep 2003
Posts: 3,599
Likes: 24
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
Originally Posted by CFI-EFI
Are you convinced this is a tuning problem? I'm concerned about the balance of the new engine. Regardless of the cause, locking the converter will more efficiently transmit vibrations. Do you feel it at all when you rev it in neutral?
RACE ON!!!
RACE ON!!!
From what you have described, it sounds like it could be a balancing issue (maybe engine or driveline component). I am not familiar with automatic transmissions, so i'm not sure how the flexplate / torque converter is balanced to the engine, but I did just have a similar situation with my 383 (6 speed). I needed to have my flywheel / pressure plate assembly balanced to get rid of a vibration above 3000 rpm.Same question CFI asked - when you are in neutral and rev it up, does it rev clean, or do you experience the same symptoms?
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Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
I just tried the neutral rev up test. Once I got it into the high rpms then I could feel a very suttle shake, similar to what I felt when I was driving, but WAY less, and that was at 4k and above.
It with the TC lock up making it worse it seems to be related to the engine loading. Thanks for the comments guys, lets keep them comming. I really hope we can get this figured out.
It with the TC lock up making it worse it seems to be related to the engine loading. Thanks for the comments guys, lets keep them comming. I really hope we can get this figured out.
Drifting
Joined: Aug 2001
Posts: 1,500
Likes: 0
From: Holliston MA
Cruise-In VII Veteran
Put it on a chassis dyno and physically verify the timing is actually where you think it is - stick your head under the hood and check with a light. Be careful. With the luck that you've had lately I'd want to make sure that the DFI and distributor are actually working the way they're supposed to.
If that works out right, I'd be taking a look at the TCC system
If that works out right, I'd be taking a look at the TCC system
Last edited by SloRvette; Sep 3, 2005 at 09:22 PM.
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
AAAHHHH HHAAA!!! I found the culprate that was screwing with my car. The number 6 plugwire had for some odd reason fallen off. That would cause the pulsating, and when the TC and/or heavy throttle you'd notice it more.
It all makes sense now. Thanks for the input guys. Always back to the simple things I guess.
It all makes sense now. Thanks for the input guys. Always back to the simple things I guess.
Drives ya crazy!
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
Originally Posted by Alvin
Also usually high load situations like this are great for finding a burnt plug wire or ignition problem. I've seen plug wires act the way your describing