Hi all, I recently took a job in a neighboring city, so have done alot of commuting on the highway over the past few months. Well recently while cruising on the highway at around 2K RPM, I noticed what seemed to me to be a sporradic "miss", which is sometimes like a hesitation or a "bucking". The tach doesn't jump, I can just slightly feel it.

Also last night I went and got in my car and started my engine just fine but I forgot something in my apt so I killed it and went inside to grab it. Well when I went back downstairs to start it again, it started but BARELY idled and sounded like a sick goat and started spitting out smoke. It also sounded like I could hear a huge sucking sound from the engine bay, like the throttle was stuck open or something. I killed it again and waited a moment and restarted it and it was fine.

Any ideas guys?

P.S. Also the I put in a new IAC controller a few years ago, so it's not the old stock one. And I completely cleaned out the throttle body passages at the same time.

 

I HAVE THE SAME PROBLEM WITH MY '88 IROC-Z. I STILL HAVEN'T FOUND OUT WHAT THE DEAL IS.

 

Possibly a clogged Cat? (If you have one)
That hissing sound could be your Cat. It'll make your car hesitate.

I bought one of those cheap Catco cats from summit, and the honeycomb looking thing inside actually broke apart and stuck sideways in my exhaust. Pulled the flange back, punched the rest of the crap out, and fired the car up and blew that crap out. Legal looking straight pipe!

 

ACTUALLY, THE CAR WAS BOUGHT WITH THE CATS ALREADY REMOVED.
SO I KNOW THAT AINT IT. I'M DOWN TO THE FOLLOWING IDEAS.
INJECTORS
FUEL PUMP
OR SPARK PLUGS.

 

Sucking noise + barely idle is usually a vacuum leak.

 

Ok this problem seems to be getting worse and worse. It has gone from a slight miss at highway speeds to full on rough choppy acceleration at any speed. It barely runs sometimes. Anyone suggest where to start to diagnose this problem?

Also sometimes when I come to a light and it starts getting so rough that it seems that it is about to die, I kill the engine and wait a second and restart it and it is ok again for a little while...

 

Well I thought I'd start with changing the spark plugs, which I haven't done in a while. I put in 8 new AC Delco R44TS plugs which is what the old ones were also. All the old ones were nice and tan except for the #5 cylinder which was completely fouled.

So changing the spark plugs didn't help my drivability at all. It is still running terribly. Anyone know what causes just a single plug to foul? Could this be what is causing my car to run so poorly?

 

i had the same problem in my iroc turned out it was a melted plug wire on the number one plug. id check all your wires its easiest at night though so you can see the spark jump, or in the day pull them off one by one and visually inspect them all.

good luck

 

I had this same problem a couple of months ago. The cause for my problem was the button that sticks out of the bottom of the distributor cap and contacts the rotor, it had fallen out!! The sucking noise you mentioned could be a vacuum leak or it could just be the IAC valve opening fully to try to maintain idle on an engine that isn't running right. In any case, start with the basics, inspect all of your intake piping (MAF?) or vacuum hoses and also pull your distributor cap and rotor and inspect them. You should also look at your engine at night while it is running to see if any of your spark plug wires are shorting to ground. If you have already ruled out these things it could possibly be your TPS or MAF, these two things have a tendency to intermittantly act up when they fail. If you have a MAP sensor instead of an MAF sensor, the same thing applies.

 

Whoops, I didn't read everything! Sounds like your #5 injector may be bad. You could pull your fuel rail while leaving it hooked up and have a friend turn the key on to see if any of the injectors are stuck open. Also, for safety, unplug the two connectors on your coil before you do this. Be aware that some engines will pulse the injectors once when the ignition is turned on.

 

im having the same prob here as well with my 87 trans am. I changed the spark plug wires, and spark plugs. i did an oil change which i dont hink it had anything to do with it. all the plugs seemed fine to me and the wires i just changed them cause they were really old and i just bought the car and didnt look like anyone changed them before after i did that it started bogging i thought maybe a wire wasnt in all the way but it s all checked so im clueless.

 

Well I think I found part of my problem. I went ahead and waited until nighttime last night and went out there and popped the hood and started it up to look at the wires and my engine bay lit up like a christmas tree!

Sure enough, the #5 wire was arcing in two places, onto the firewall and near the brake booster. It also looked to be arcing near the spark plug boot. I also saw on the other side that # 4, 6, and 8 were glowing at the boot (spark plug side) as well. I am definitely replacing the wires because of #5 but what does the glowing at/in the boot mean?

I am running Accel 8.8 mm wires which are a few years old and probably won't get them again after seeing how quickly they deteriorated. Anyone got any recommendations?

 

well i found my problem as well one wires wasnt plugged in at all so as soon i did idle was perfect. all that s left now is A/C. The guy i bought it from said he filled it, but it s still blowing hot air. any ideas i also have a 91 firebird v6 is it possible to take anything like the compressor to fix my car or no. 91 is TBI, and my car is 87 TPI. also need i guesss a new battery cause it has a hard time starting. lookin at a yellow top optima battery

 

Well I went to Advance and put on some new Autolite Pro 8mm wires for now, because I didn't want to have to order some better ones and wait for them to come in, and to do some more research on a good wire / sleeve combination in the meantime.

Did the night time test, no leaks anywhere. It runs 100 % better now. Thanks for the input everyone...

 

I took my car on the highway last night and after driving smooth for about 10 miles, the bucking came back.

This time it is much more violent and noticable. It feels like the engine dies for a brief instant just enough to jerk the car forward and then kicks back in.

It got pretty bad, almost to the point of me thinking about pulling over and checking things out.

Any ideas?

 

Try replacing your fuel filter and consider the pick-up coil to be the culprit. Once they start to go, all kind of crap starts to happen.

 

Yeah I'm thinking it's something in the distributor too. I got a new one I'm going to put in soon.

About the fuel filter, what is the lifespan on these? It's probably been about four years since I changed mine. I'm somewhat hesitant to do it again because last time I had a hell of a time getting it to seal tight. I was under the car five or six times re-tightening the connections because it kept dripping fuel when I pressurized the lines. Is there any kind of thread sealer for this?

 

Im having the same problem, my cars wants to die and chugs. I repalced the fuel pump already. Im thinking its the spark plugs, fuel filter, coil, or distributer, or clogged cat, or clogged muffler, their is a whole in my exhaust by the muffler. This problem started to happen right after I changed the oil. I bought new valve cover gaskets b/c when the car starts up the smoke comes out of the valve cover gaskets. My 8th cylinder ring is going out from what the last 2 techs told me. so I dont know if I should start replacing a bunch of stuff or get the ring fixed ???? How much would it be for the ring to be replaced, or should I just find another 305 TPI and drop it in. Salvage yards around madison wi want like $750 for a tpi motor with 100,000 miles on them NEED ADVICE thanks

 

Hey SVELTE, you should be using an in-line fuel filter, thus you should not be losing any kind of fuel if placed properly. The filter is threaded. And you should check for any cross-threading.

 

Hey BLUEZ28, If you are to replace one set of rings, you may as well rebuild the whole motor. Hell, you got it practically apart anyways.
All I'm saying is that for the little effort to change just one cylinder compression may not be worth that. Go for the rebuild, even for just a quick honing, new pistons, rings, and bearings. Might as well throw in a high-volume oil pump.