Brian47p

i got a 91 5.0 lx with a weird engine skip. the car starts out running perfect, and once the car gets to running temp. it starts to idle rough and skips randomly. i think my catalytic converters are going/gone. Could this be the problem? i have had it veiwed by 5 mechanics, top to bottom from timing to fuel to air to electrical and its none of those. The only thing i can think of is maybe my cats are backed up and the back pressure gets too high wen the exhaust starts to flow and get hot after about 15 minutes. i am no mechanic and was wondering if this is a possible cause to my very annoying problem. I also checked IAC and throttle position switch, cleaned them out and also cleaned out my intake. they were very backed up but never changed the skip. please someone help me the car is almost undrivable because it is so annoying to look like you are bucking your transmission when you are driving down the road.

Riceinator

I have a similar problem. I've been told to change the TFI module. I haven't done it yet, and I;m not sure when I'll get it done, but if it's soon I'll let you know if it makes a difference.

PRO50SC

Skip, as in miss? OK, 5 mechanics have looked at it and none of them can diagnose it? These guys work out of their back yards?[&:]

Bad converters will not cause an engine miss. Lack of power yes, but not a miss.Sounds like a secondary ignition problem. Does it do this under load, at idle or both?

Brian47p

i will start the car up, drive it fine until about 10 minutes in, ill come to a red light, and the idle will drop to about 500 oro 400 rpms. then it will be a sort of buck/choke type feeling when i am starting to accelerate. i get very little power and if i step on it , the car does not go it does a buck, go buck go buck go sort of motion. its hard to explain but i look like i cant drive the thing, even tho it has nothing to do with my shifting.

Brian47p

also, when idleing, the car is very rough and does not haev a constant idle, its a hover from about 400 to 600 rpms up and down, liek it is struggleing to stay on.

PRO50SC

So while the car is cold, it runs problem free? Something is getting hot and causing the problem. Like I said, it could be secondary ignition, mass air meter, lots of things.

nitrous_bob

try this..... unplug the iac and reset the idle

if you cannot reset the idle there is a vac or mechanical problem, i'd look at vac

after you reset the idle you need to reset tps, and then i'd reset the computer too

if the idle bounces too much to set and stalls, look for vac issues like i said

also.....maybe b4 you do anything...reset the computer and see how it runs/doesn't run

if it doesn't want to stay running, just drive it hard, it will "learn" to idle again, but that indicates there is a problem

by resetting the puter your clearing the lean/phat condition it was making up for

hope that helped.....i actually have a milder version of that problem myself, havn't bothered replacing much though so i can't say what helped, i did however find a chewed vac line that runs behind the dizzy and made a little diff. the hard plastic ones are notorious for breaking too

white93pony

im having a similar prob at low rpm mine feels like it has no power till i hit about 3 grand and it clears up fine sometimes below 3 grand it kinda pop back fires outta the exhaust changed sensors timing comp ignition nothing has helped yet!?

dillon1340

check to see if there are any stored codes that might point you in the right direction. i agree with above, a skip is usually ignition. i had a bad skip on my 89 today after working on it. turned out a spark plug was cracked.

SweetLou

I am having the same problem as well. I have replaced the distributor cap and rotor, the coil, the ignition modual, and was going to replace the pip today (the pickup inside the distributor) but couldn't get the shaft apart. I may go into the erg and the erg control box next. I need to get mine to a mechanic first though to see what they say, as i haven't brought it to one yet.