LT1 Camaro spuddering/hesitating. Advice needed.

NYSpeed Automotive
1

Warning! Long post.

First off, it’s a 95 Camaro, OBD1 car. Anyone with a scanner? They seem pretty hard to come by at local stores.

The spuddering originally started a few months ago, and I only noticed it when pressing the throttle a little in 6th @ about 60mph. I changed the plugs/wires and the car ran PERFECTLY for about 20 minutes, then BAM, started hesitating at every RPM under light acceleration. I thought something came loose, so I went back under and checked all the wire connections to the plugs and Opti, but that wasn’t the problem.

Fast forward another month, and had Carnut install a new optispark distributor (thanks again, Don). That made the car slightly more driveable, but still spuddered like hell. I replaced the ignition coil a little after that, thinking that had to be the problem, but it’s still running like poo; slightly smoother poo, but poo nonetheless.

The other night I unplugged the MAF to see if it would run fine in a closed loop, but it still hesitated the same, so I’m thinking I can rule out any sensors that could be damaged?

So what else should I look for? Loose grounds, clogged fuel filter, dirty injectors, clogged cat, even?

Also, I’ve noticed the smell of fuel on the driver’s side quarter panel (where the gas cap is) when I’m outside the car. I can’t really diagnose whether it runs better when cold or warmed up, because sometimes it runs really well cold, and sometimes it’s really bad cold. Same thing when it’s warmed up.

Cliffs: Car is hesitating/spuddering under light acceleration. Changed Opti, plugs, wires, ignition coil; no luck.

Thanks for looking.

2

So what else should I look for? Loose grounds, clogged fuel filter, dirty injectors, clogged cat, even?

check em

3

VACUUM LEAK SOMEWHERE…

oops caps…

spray carb cleaner or ether around and see if your idle changes

4

clogged fuel filter = my vote

5

LS1 swap

6

Don’t know much about LT1’s but I’d check the fuel pressure regulator (if they have one), the injectors, and MAF. Also if you unplug the MAF it goes into open loop not closed loop.

7

I forgot about that one. I was kinda suspecting that a little while ago. I may have knocked one loose when my arm was twisted in 12 directions getting to the plugs on the passenger side.

I noticed that the idle changes when playing around with the intake elbow. I checked it for leaks, but it seems pretty solid.

8

lol, that’s not a bad idea, but no.

I want to fix this then sell/trade it.

9

Check your temp sensors (there are 2, one for the dash, one for the PCM); and the wires going into them.

I had a NASTY hesitation like that, and the sensor connector had a bad wire and was loosing connection when I accelerated and causing a massive rich condition and basically flooding the motor. Took me MONTHS and lots of $$ replacing everything else to find it.

10

check the fuel pressure throughout the rev range while DRIVING, tape a gauge to your windshield. See if the spuddering coincides with a dip in FP.

You can use this to rule out the pump, filter and regulator.

11

That’s about where I’m at right now.

I’ll definitely check that. The car runs a lot better when I accelerate hard; there’s no hesitation, but there’s still a noticeable “feel” (for lack of a better word) to it.

12

Wait a sec, you unplugged the maf and it ran the same? That could be your problem right there… You can probably get one for next to nothing, i imagine.

At least try swapping with someone, there’s probably a ton of broken Fbodies on the board that would lend you theirs.

13

i know what the problem is!

your car…is PURPLE.

14

lol, touche.

15

Sounds like my pathfinder lol good luck bud

16

But really, it could DEF be a maf sensor.

17

I’ll take it apart and clean it and see if the spuddering stops/reduces. Unfortunately, I’m not friends with any FBOD guys (maybe it is fortunate?), so I can’t just do a swaperoo.

18

I betting MAF as well, this is a common problem on 3S’s I know Id hear about it all the time when i was doing that thing, all the same symptoms you describe, try swapping it out.

19

Probably the sending unit…

20

:lol:

Might be far-fetched, but 2 friends of mine have had problems with Opti-spark on their LT1’s, if everything else comes back negative…