Car Hesitating when stopped in traffic

Hi all, thanks for reading my post. I have a 1998 Pontiac Sunfire. I keep up on her engine and have only experienced this issue one other time back in the fall or winter. Like that day, today I started the car and drove off without letting the engine warm up a little because I was in a hurry. It was fine on my way to my destination but on the way home (about 5 miles from my house) I hit a lot of traffic an pretty much caught every red light. About 1/4 of the way home, every time I stopped the car started acting like it was going to stall out. The best way to describe it, would be if cars breathed like we do and she was out of breath panting. She had no trouble accelerating and there seemed to be no problem when continuously moving, it was only when stopped. Like I said, she only did this once before on a cold night and I was stopping and going after driving without warming it. She hasn’t had a tune up or new spark plugs in a long time and she’s due for an oil change. My feeling is that it is fuel related? I dunno. To top it off, my dad is looking under the hood checking the fluids right now and he just informed me that someone must’ve hit my car because there is now a dent and scrape on the fender, I had NO idea this was there so I am just really annoyed. Anyway, back to the topic, I have a lot to do this weekend and kinda afraid to go back out now in fears of it stalling out and being stranded.

The problem might be with a faulty Idle Air Control valve.

The IAC valve controls the engine idle speed whenever the accelerator is released.

These valves can have problems as they heat up. So as you were stuck in stop and go traffic, the temperature under the hood increased to where it started effecting the IAC valve.


The IAC is a definite possibility.
When was the last time you gave it a tuneup?

Another idea, since it happened during stop and go traffic, maybe the electric radiator fan isn’t coming on like it should when the coolant heats up, and the engine is overheating a little in that kind of traffic. That wouldn’t happen on the freeway as the airflow from the car moving is enough that the radiator fan isn’t needed. Suggest to ask your mechanic to check it.

I presume the check engine light is not on. If it is, ask your shop to determine the diagnostic codes. That might provide a clue.

If the problem persists and the diagnosis remains elusive, it probably makes sense to bring all the routine maintenance suggested in the owner’s manual up to date first. Otherwise you may be paying a mechanic to diagnose a problem that wouldn’t be there if the routine maintenance was done. Since you have to do it anyway, no sense being double billed.

Oh my goodness, at least three or four years with the tune-up, maybe longer. My mechanic kept telling me it wasn’t needed yet every time I asked but I know it is now.

If the vehicle needed a tune-up, the Check Engine light would be on with a misfire code.

If the Check Engine light isn’t on with a misfire code, then a tune-up probably won’t help.

However, the IAC valve can be faulty and never turn the Check Engine light on because it’s not an emissions control device. It’s an engine control device.


Totally agree with @tester on this. Try the IAC first. Sometimes cleaning them may help but they usually have to be replaced.

Well for whatever it’s worth, the check engine light has been coming on a lot lately. It happens to be off now but until the other day it was on for a week or two.

The problem I have is knowing where to take the car. The last mechanic I would go to really never seemed to do very much or tell me very much about what’s wrong when I had a problem. I started taking it to someone else but a pattern started that I’d go back to get something done that I couldn’t afford to do the time before and he’d have a whole new list of things he said “his guy” found. I am not sure how much I can trust this, I have no way of knowing for sure if he’s making crap up just to get more money outta me, If I take my car to him, he’ll come back with like an $800 list of new things. As for testing the IAC, I really don’t know how to do that although I’d love to be able to. Am out of work right now and can’t afford to do much, catch 22, need my wheels so if I find a job I can get there. Pretty important to keep her running well.

So far today she seems to be normal.

When working with auto repair shops, you as a customer need some leverage. One way to get leverage is just to use the same shop over and over again. They’ll have incentive to do a good job for you this time, to get your business the next time. But if you don’t have a shop you like yet, the best way to find a good one is via your friends co-workers, fellow church-goers, anybody you have a personal relationship with. Ask who they use, then from among that list choose a shop that specializes on Pontiacs, or at least American-branded cars.

Here’s the critical part: Make sure the first time you visit the shop, speak to the owner or manager, and tell them who it was that recommended them to you. This gives you some leverage, b/c they’ll know if they don’t do right by you, try to overcharge or make up work that doesn’t need doing, or something similar, you’ll be telling their other customer, and they’ll not loose your business, but your friend’s business too.

One more bit of advice when working with shops. Make sure they are aware early in the conversation if your finances are such you can only afford a certain amount at the present time. No need to be embarrassed, if you don’t have it, you can’t pay it. It might annoy the manager somewhat to tell him this, but not nearly as much as if his staff does the work, then you can’t pay the bill. So ask them to prioritize what needs doing so the most important can be done now and the not-as-important can be done later when you have the funds. And if you defer recommended work that later causes even more expenses, don’t complain to the shop about that. That isn’t the shop’s problem. The goal is this: Both your and the shop are just doing the best you can given your available resources.