1989 sho bucks and jerks violently,but hard accell ok?

[shoclown]

all right my 89 sho bucks and jerks really bad only once in a while, i also have no tach.
i first changed the crank sensor thinking this would fix it,nothing no help.
i checked the tps sensor with a gmm/dso and patterns are good no glitches were found( i thought it seemed to do it only at cruise,so i thought maybe bad tps)
i have looked at the patternfrom the cam sensor and pattern is good on dso/gmm.
i have swapped out the ign module with a old one that was on a e-bay intake and same problem is still there ( i know nothing about the donor ign module could also have the same problem) but i checked it useing my snap on vantage and modis gmm/dso and could not find anything that was out of specs.
any ideas? it does it hit and miss sometimes with a week in between, others all the way to work?
the car is bone stock right now except for an oil catch can for pcv system ( it just passed smog with flying colors also??????any ideas?

 

[shonuffmine]

Check all your grounds first,especially the 2 bolts that hold the crossover tube on the intake ,or fab a bround wire to one of the 4 bolts on the DIS module! Are you gettin a check eng light?what are the codes

 

[shoclown]

no codes no check engine light??

 

[St Louis SHO]

Possibly a PCM. I had an 89 with the exact symptoms. Replaced PCM, all was well.

 

[LOUDSHO92]

Just becasue you have no check engine light doesnt mean you dont have codes.

Might be a bad or dirty IAB. Maybe clean it out.

 

[shobote]

Might try removing MAF and cleaning the filament with electronics cleaner.

 

[shonuffmine]

Pull your codes and go from there,here,s a link how http://www.shotimes.com/php-bin/mod...cle&mode=thread&order=0&thold=0&sid=83.Always good to clean the MAF and IAB out too

 

[oneqwicksho]

Is the car acting like its only running on 3 cylinders? If you give it gas does it struggle to move? And if you down shift and get in the gas is the problem more noticeable? If so I would say faulty crank sensor. I had the same problem, changed the crank sensor still had the problem changed it again (thinking I had a bad one) and bingo after that ran great no problems, if its under warranty and you have the time I would change it, and make sure you reset the clearance between vane and sensor to 0.8mm (0.03-inch)

 

[Frisbeeguy]

My 89 does this as well. Only on occasion and at any time w/o warning. It's happened at least 10 times in the past 18 months. (I've done a complete 60k service, H2O pump & CPS in the last 6,000 miles)
It'll buck wildly and not go anywhere while accelerating - tach doesn't work properly yet the engine seems to idle O.K. when depressing the clutch or coasting in neutral. It does seems to idle just a bit "off" during these episodes while parked at the side of the road.
I wriggled wires & found the culprit!
It's one of the wires in a bundle that is located in the back left of the intake near the firewall. (sorry I don't know the actual name of all the parts)
When I slightly move the wire it immediately smooths the idle & drives perfectly! I have not ever "fixed" it but did wrap the bundle together w/ black electrical tape to support the "loose" wire. It has only happened once since wrapping the bundle a couple months ago. (this is a daily driver)

 

[SuperHO]

lemme guess...when you checked voltage on your cam sensor, the car wasn't in the middle of throwing a tantrum, was it? change your cam sensor and wave byebye to this particular set of problems.

 

[Geek SHO]

My blue '95 has been having this exact same symptom, and I have changed crank, cam, and throttle sensors. I've also changed PCMs, DIS's and MAFs. The best I could figure was the wiring itself was damaged, and never got around to rewiring the TPS (which is where all my troubleshooting was pointing at) before giving it to my Dad before moving to Texas.