Possible fuel related problem, potentially hurting FE
 

I've got a new car that I've been driving for a couple of months. It's a 1998 Pontiac Grand Am GT. It has 105k miles, and is a 5 speed. When I first start the car, if I don't let it warm up for a decent bit of time (4 or 5 minutes at least) it will hesitate when given gas, or just not respond (almost died on me once). If I just let the car warm up, it usually will drive fine. But I don't always have time to let it warm up for that long, and it didn't do this when I first got the car about 7k miles ago. I tried running Seafoam through it, and I think that helped for a few days.

I assume it could be a number of fuel related things, so I was hoping you guys could narrow it down for me.

so if you drive off "cold" it will still "hesitate" after it is warmed up?

Or it will "hesitate" only while it is still "cold" and then acts normally?

The latter. It always runs fine once it gets warmed up, but sometimes even 5 minutes of idle isn't sufficient. Also, if I give it gas while it is warming up, it will start to idle rougher. I usually just crank it, let it sit for a bit and then go. It still requires this type of warming up, even if it's 90 degrees outside.

what is the idle speed cold vs hot?

No CEL? Sounds like the ECU may have fallen back on it's default settings, which don't adjust for the conditions (running while cold). Usually the result of a faulty sensor

My Celebrity has done the exact same thing since I bought it 7 years ago. Not as severe as yours, it only does it when the engine is stone cold and for the first 1/4 to 1/2 mile. Changing fuel tank/pump/filter didn't make a difference. Multiple spark plug/wire changes, crank sensor/ignition module replacement no difference. O2 sensor no difference. Alternator made no difference. Swap from 2.8 to 3.1 engine made no difference. Never any codes either. A coworker hooked it up to a realtime scanner and the good "128" number was about where it ran. I wasn't going to throw dollars at it trying to solve it (everything I replaced needed replacing anyway, and the 2.8 engine lost a head gasket when the radiator let out), so I just got used to dealing with it and it's just second nature now. But it never went away. All I can figure is it must be some sensor, or maybe even the ECM. I've got a hunch it might be the IAC, but unless I stumble across a free spare, I won't worry about it.

Edit: That reminds me, multiple bottles of Chevron Techron, plus this redline stuff. Also seafoam, and GM Top Engine Cleaner. Also changed the injectors with a newer used set. Tried a different TPS too once.

Would be nice to know what it is if you ever figure it out.

I would run a bottle of injector cleaner through the tank, and check for induction leaks. It isn't happy without the o2 sensors feedback (open loop when cold).

Wow, I'm sorry to hear that. I have a pretty limited knowledge of cars (i'm just a college student right now) so there's no way I could even test all of the things you did. I had a hunch that it could be any of the things you mentioned, but that's a little discouraging lol. I really hate this car. It only has 106k miles, and I just spent $400 at the repair shop having the heater core bypassed and exhaust welded back together. This was only about 1,500 miles ago. How the heater core was broken and the exhaust busted, neither me nor my mechanic could figure out. The starter solenoid was going bad on it, so I attempted to bump start it and it backfired and somehow a starter solenoid turns into hundreds in repairs. Now this with the cold starts.

I don't recall anyone having one of these cars when I used to post here more frequently. Anyone know how durable these cars are? It has great paint, no scratches or dents, and a great interior, but I have read only scathing reviews of these cars online, I have considered trading it in on a similar model Civic but those would still cost about 1 grand after trade in, AND I would be looking at a car with 140k miles or so. I've thought about just driving it until it dies, but considering the KBB of it, and what I have read online, it sounds too expensive to maintain this car until it truly "dies". Can you guys give me some feedback/insight?

First things first replace the fuel filter I would go with an acdelco one since one of the other brands has had lots issues with mileage and clogging issues (I will try and find the article).

Next if you still have the issue disconnect the MAF it should be the first electrical connector on throttle body it will have 3 wires. Start the car and see if it runs the same (the car might take a second or so to start when you do this also it might set the check engine light). If there is no change or it runs better remove the MAF and clean the little wires in the MAF with electrical contact cleaner just make sure not to bend or damage the little wires or you will need to buy a new MAF.

Being a 98 chances are the O2 sensor is lazy or bad replace this. Your car should have two of them you only need to replace the one that is pre-catalytic converter.

Actually I would check the MAF first since if cleaning it works this would be the cheapest then do both the O2 and fuel filter at the same time so you will not have to have work done twice.


Can you explain "The starter solenoid was going bad on it, so I attempted to bump start it"?

Yes. The car no longer could start by ignition because the starter solenoid had went bad. I parked it on a hill, and attempted to coast it off the hill to get it started. This worked several times when I did not have the time/means to get the car into the shop. Then, I attempted to bump start it to no avail. The engine would not turn over at 10 - 15 mph in 2nd gear. At that point, I attempted to crank it a few times more (this time by key), and the starter managed to weakly turn it over. By this point, whatever caused the exhaust manifold to break must have happened, because I could hear it (sounded like the muffler was gone). I then attempted to at least drive the car back into its parking space. At this point it backfired very loudly and died.

The best my mechanic could figure out is that when the exhaust manifold broke, it cracked the cheap plastic heater core, causing it to leak everywhere. What caused the backfire and the manifold breaking, and everything else, I have no idea. I had a rebuilt starter put on it at that point, and that starter died within 3 days. After that I got another starter put on it (i bought the delco brand, it was the most expensive aside from the OEM starter) which is still working, but now this new problem is coming up. I have no idea if they are related, but perhaps so?