will unproperly adjusted lifters cause a car to buck and jump around when driving at speed?I adjusted the valves before installing the new engine but the lifters weren't pumped up obviously they were dry,I just don't know if that possibly caysed me to tighten them to much causing my issue.Thank you..I'm thinking about doing the old adjust while its running technique.The car is a '91 trans am Tpi 305 T-5 car...also it was a crate engine I installed and was wondering if possibly the cam could be one gear off causing my issue....I'm about to sell the darn thing if I can't figure it out because it's just sitting in my garage...thanks for any help guys,david

 

I would check the distributor first. Make sure you bring the #1 to tdc, check position of rotor to the #1 position on the dist. It should be pretty close. If not, reset the dist.

 

So how much did you turn past "0" lash? Did you adjust them in the proper sequence? Is your distributor lined up right, and are your wires on right? Is your timing correct? Also, what do you mean by bucking and jumping?

 

well not that it means much but the dizzy is a brand new one,I did install the distributor with the rotor pointing at #1 at tdc and the wires are on correctly.I've checked this multiple times with no change.

I turned 1/2 turn past zero lash in the sequence that the shop manual showed.

by bucking and jumping I mean it idles fine,I mean like perfect.I take it down the road and around 45-50 mph at steady throttle it'll start acting like it's missing and literally jerking vigorously,I can accelerate and It'll stop and run fine till I hit that steady speed again.also when I pull back into the garage I can open the throttle by hand to a just over idle position and itll like start stalling and sometimes it'll even backfire pretty loud.

I have replaced all sensors,I have checked the tps voltage and it is perfect within specs of the shop manual.I have also checked the fuel pressure while idling and while driving with the issue happening and it is spot on also...maybe this will help explain a little better.Thanks for the help you guys i really appreciate it

 

Does the car throw any codes? If it runs fine before and after 45-50, you cam and valves should be okay. Maybe a vacuum leak?

 

yeah no codes,I almost wish it was so I'd be able to start tracking it down.I will mention that I blocked off the egr and removed all the vacuum ports to it.all my vacuum lines are new and I've done the whole spray carb cleaner at vacuum connections to see if the car revs up too.I've replaced 90 percent of the vacuum lines,any that looked stressed or were flaking and crumbling....This is what I'm talking about dude I'm at a complete loss here!!

 

Some times if you remove the egr you need to get the prom reflashed. Some have had luck without reprogramming too, but then that would throw a egr code. I'm just asking here, but are the runner gaskets on correct? they are easily mismatched. It's hard to diagnose a problem over the web, but don't get discouraged yet, there are some sharp guy's on here.

 

I actually have a reflashed prom and the stock one,I've tried both ways it runs better with the reflashed one but still has the same issue(even replaced the ecm with a new one).I did check the gaskets and replace them once again already since the fresh engine install when I thought it could be an injector(which it wasnt) I know it's difficult over the web and I wish there was a good shop or mechanic here to take it to just to diagnose but the good ones are hard to come by these days...The guys here have helped me so much in the past and thats why I keep on coming back,TGO is the go to for thirdgen experts.I'm gonna try to not give up but its hard when everything is brand new it still jacked up.

 

okay,I still need help with this same issue..I'm looking into possible internal issues now.I was thinking that the only two things that I changed when I put the crate motor in was I deleted the EGR and removed all the stuff with it including the A.I.R tubes and the egr relay or valve-whatever that thing called that the vacuum lines are connected to..haha .I have checked for vacuum leaks vigorously and replaced lines and blocked off all unnecessary vacuum ports.
I say all that to say the second difference is I used the cam that come with the crate engine.The motor is an 87-93 5.0L 8cyl according to the tag that come with it.I don't know if the cam is a tbi cam or if there is even a difference.When I run the numbers on the block it come back to be a later model vortec engine,probably a truck one but I don't know.I cant find any info on the freaking cam though that makes sense to me anyway as compared to a stock tpi cam.I will post a couple pix of the numbers on the cam that come in the short block that and see if you guys maybe can help me out...if all it is is the cam thats an easy fix though I'll hate myself for not changing it out on the rebuild...Thanks for any help guys