So this happened once before but I did a bunch of work to the car and it seemed to get better, now it's back.

Car idles almost like it has a miss or a lumpy cam, which I'm sure it doesn't. When idling the car will be jumpy just sitting still. Normally when driving the car seems to pull fine, but once before it had an issue where it would get really choppy and hesitant as the rpm's go past 2400 or so. Instead of pulling smoothly it would just get choppy and sputter. Now it's doing it again.

Any idea what could cause this? First I figured the idle was IAC but would that effect the overall performance too? The car was running perfect all day and then out of nowhere it started acting up.

I replaced the following...
plugs, wires, cap, rotor, pcv, fuel filter, air filters...

 

And whatever it is why does it only do this sometimes, and the rest of the time it's fine?

I'm getting no codes at all, no cel, nada. Just runs like ***.

 

And now...no start.

 

It's been a while since I've done any drivability trouble shooting, but try the Control module in the distributor or the Electronic Spark Control Module.

 

So I went to check for spark and the bastard started right up. This is the one thing I DIDN'T want to happen!!!

Now how the hell do I find out what's going on?! At least if it stayed dead I could trace it back to whatever's not working.

Any ideas??

 

Right now i have the same issues on my 305 tpi. Good luck i will follow this thread. i can tell you right i have done in a pm if you like

 

Again, I don’t want to lead you down the wrong path with my drivability diagnosis, but if your issue happens mostly when the engine is hot, then goes away after it cools off, then I would replace the control module inside the distributor. The last time I had anything like this happen was about 10 years ago with an 83 Oldsmobile 442 that I built a 403 for. Car ran sporadically and would just die for no reason when it got hot. Let it cool off and it started right up. I replaced the control module and the thing ran like a completely different car!

 

HA!! Must be a thing with the 403 olds motors. The 87 442 I'm selling has a worked 403 and it had a similar issue. It seemed to be just the coil going bad on that one.

Distributor module was actually my 1st guess too, but now that it's running right again I don't know what to do. My friend at work said just drive it til it acts up again and start checking for spark & fuel immediately. I'm debating just doing the module and seeing where it gets me. I figure it's got to be either fuel related or ignition related. 1st guess was distributor module followed by the coil.

My friend's next guesses were fuel pump or vapor lock due to the gas tank not venting. I'm more leaning towards ignition components though. It was hot both times it did this, if that helps. And the car does seem to be running rich at times. If it were fuel related and the pump was going wouldn't it lean it out?

 

Well, the only time I ever had issues with fuel starvation was with a friend’s 88 Blazer (of course nothing on it was stock, it had a wicked 383 stroker and it had an electric fuel pump), my 76 F-250 4x4 and a customer’s 98 S-10 pickup. The Blazer’s fuel pump died and it just quit running until I figured out it was a fuel pump issue. My F-250 would idle, but it wouldn’t go any faster than about 25 MPH before it would stumble and die. It would re-start but it went back to the same old thing. When it finally quit starting I was able to get it to check out for spark, so I went to the fuel system and finally discovered that my mechanical fuel pump was bad. The 98 S-10 stumped me for a long time (spark checked and fuel pressure was always good), until another mechanic put the fuel line from the tank on a flow tester. Turns out the pump was creating enough pressure (good enough for a gauge check) but couldn’t create enough flow at that pressure. Replaced the pump and the S-10 was back in business.
It’s been 9 years since I worked as a mechanic (and even then I didn’t do the drivability issues, I was the heavy mechanic) so I don’t want to steer you wrong, but I think your issue will be resolved from within your ignition system. Somewhere in your car there’s an electrical gremlin laughing at you every time you open the hood. If it were me, I’d replace the module (about $40.00) and see where that gets you. Worst case scenario is that you’re out $40.00 and the problems still there (but at least you’ll know it’s not the module).

 

I agree with replacing the ignition module. If it's going bad it can cause intermittent problems like you are describing.

 

Replaced the module and coil just for the hell of it...doesn't seem to be working. Still breaks up at higher rpm. This is ridiculous. It still gets choppy and just feels like it's out of breath.

 

Have you put a gauge on your fuel rail yet?

 

That's the next step. Have to get the nitrous line off the fuel rail. Where's the test port on these supposed to be? They hooked the nitrous line up towards the back of the passenger fuel rail on the top of the line but it looks almost like they added the fitting. It also has no schrader valve in it, so I have to source one.

 

It sounds like they put a fitting on the schrader valve for nitrous. There is supposed to be a schrader valve toward the back of the fuel rail on the passengers side.

 

So it finally quit starting on me at work, THANK GOD!! Checked spark, fine. Checked fuel pressure, 40psi. Still wouldn't start.

All that bullshit...just to find out it's the damn VATS system!!! When you'd wiggle the key just right the car would crank and thats it. Do it again and it starts right up. Apparently it screws with the injector pulse when the car's running too...hence the choppy stuttery acceleration.

All I'm going to say is thank god my boss is a madskills GENIOUS!!! I don't think I'd have gotten this one on my own. Now I just have to get a new tumbler & some keys and FIX IT! I'll update the thread after it's done to verify this is the problem.

 

Back to square one. This is pissing me off beyond all damn beleif!!!!! WHAT THE **** IS GOING ON?!?!

The starting issue & the choppy bs issue were apparently totally unrelated. Car's still running like ****. It idles shitty CONSTANTLY now and still breaks up in higher rpm's when accelerating. It pulls hard til about 4k +/- and then gets choppy and loses power. Checked spark, seems fine, checked fuel pressure, fine, checked for vacuum leaks, nothing. The one thing we did notice was when we put a noid light on the injector plug the light was somewhat dimmer than usual...

Ideas??

 

So it's got weak injector pulse. It did before too, but it was enough to run the car, now it's not enough to start it. Seems to be getting fuel pressure to the rails though....