This has been a problem ever since I first bought my car, which to this day I have not been able to determine the cause.

When you start the car up from a cold start, it is IMPERATIVE that you let it warm up by feathering the gas to 1500 - 2000RPM for at least 5 minutes, but I like to do 7 - 10, before you drive. Here is what happens if you don't. The car will run extremely rough, no power and huge hesitation in the 2000 and below RPM range, rough idle and stalling at stops.

When the car is first started, it will hold at 1500 RPM for a few seconds as normal, then start to idle down. As it idles down, you can feel and hear the engine run rougher and rougher. It will get down to about 500 RPM (If warm it holds a smooth idle at about 650 RPM), and stumble here for a tad before stalling (And setting off a SES light, always a code 44). For the first 3 - 5 minutes of warmup, when feathering the throttle there is a huge hesitation and rough condition if light enough throttle is applied to run anywhere below 2000 RPM. If you try to feather the gas, this will actually cause the engine to DECREASE RPM and stumble.

The one time I did try to drive the car (late for work) without letting it warmup was a huge mistake. No power unless moderate throttle was applied and car would stall at stops unless lightly touching the gas. Right before I realized my mistake and pulled over, the car threw a MAF code, which is the one and ONLY time it has EVER thrown a MAF code.

Also I have noticed that even after you warm it up, for the first 5 minutes of driving if you hit any stops and try to let the car idle on It's own, you have maybe a 50/50 shot whether the car will throw a 44 and immediately start the rough idle at 500RPM. When it does this, sometimes the SES light will stay on for the whole ride to work, and sometimes it will go off on It's own a few minutes later after driving around.

Once the car is warm, it runs fine like off the lot. Every once in a blue moon it will still trip a code 44 during normal driving, but this is rare.

Once the car is warm, it will run fine until allowed to completely cool off. Park the car and run into 7-11? Hey no problem turn the key drop the ratchet and go. Run into the store for about 30 minutes? Hey no biggie there just start the car blip the throttle a few times to get everything circulated and your on your way. Go into work and take my lunch break after working for 3 hours? Eh, car runs smooth when started but will still act out if not warmed for 3 - 5 minutes, but not as severe as a cold start. It's like a part or sensor somewhere needs heat to run properly, and the colder it gets the crappier the engine runs.

Things I have tried so far:

- Replaced the entire longblock (Mind you, because the last one had a rod knock)
- Replaced the CTS with a brand new sensor
- Removed the IAC and inspected, cleaned and lubricated it. Made sure it functioned properly by sticking into a coke bottle while plugged in and turning the key to ON. pintle shot out like a rocket. also cleaned IAC passage.
- Replaced the TPS with a used piece, but made sure it functioned correctly with a voltmeter and was properly calibrated in harmony with the minimum air.
- Replaced the oxygen sensor (Very important before I did this the car would ALWAYS throw a code 44 all day long. After it took care of 95% of the 44 issue but still throws one sometimes and had no effect on the cold start problem).

My next assumption, is once again the oxygen sensor. Except a different sort of approach. I read that cars with exhaust headers need heated O2 sensors. Well, my car has exhaust headers but still a 1 wire sensor. The O2 sensor is located at the END of the headers just before the Y. You even have to jack the car up to change it.

I believe this is the problem because of two things. The temperature of the engine is directly related to how bad it runs when first started, amd because of that one time it threw a MAF code. I know for a fact my MAF sensor is fine, and also I know that the MAF and O2 work together in the fact that the MAF is the first line of calculation in air/fuel mixture and the O2 is used to make minor adjustments to that calculation. If the O2 was giving a crap reading maybe this could have made the ECM think the MAF was out of whack? I also know that the metal wire in the MAF has to heat up to give an accureate reading, but I wouldn't think it would take nearly that long. 30 - 60 seconds I can swallow, but now 5 - 10 minutes. FFS the coils in my toaster turn glowing orange within the first 5 - 10 seconds!

Any ideas guys? Greatly appreciated!

 

Mine seems the same, so I have a few questions for you. Some may seem dumb, but bare with me. What are the codes meanings and MAF? I know the MAF is some sensor but that's it.

If I keep on the throttle I can usually get away with driving it without having to warm it up, but usually I try to let it sit at least 1300 for a few minutes without the fan on (I have an electric fan switch) and when I see it go up a few lines I usually go, but it still doesn't seem like it's "Warmed". Oh, does your car do any lurching motions while driving at a steady speed and set rpms?

 

When coolant temperature senders go bad they tend to error low so the ECM thinks it is EXTREMELY cold outside and the car runs extremely rich and wont idle. I dont know the range of values it should be in. But maybe check a shop manual or do some research on it and put a DMM on the CTS and what it's reporting.

Or just replace it and see if that fixes it.

I doubt that's what it is since it runs fine normally... but these electrical parts can fail in strange ways so who knows.

 

 

Did you ever find out the problem? Mine does the same thing...

 

I pretty much fixed mine, it works well enough. We adjusted my carb a bit, and we figured the non existant choke was part of the problem. Just made it run a little richer and uped the idle in the morning, roughly lunch time I just switch it around for a bit more lean.

 

Finally found the gremlin.

The MAF was bad. Car will hold a perfect idle now from a cold start. No more hesitation either.

Oh and no more code 44. The exhaust doesn't smell as potent now either.

The bad MAF sensor was throwing the fuel mixture to the rich side.

Also, something else I discovered. A MAF works by heating the platinum wire inside 212F ABOVE the incoming air temperature. So, if you IAT sensor is going bad, it could make it appear that you are having a MAF problem. Luckily this was not my case and I did not have to remove the plenum.

 

I have the exact same car as you and the exact same problem. And I know it's running rich because I have two black smog trails going up my nice white bumper

So my question is how easy is it to replace the MAF? Could I pick one up at checker or do I have to order it from somewhere?

 

Not hard at all. When you open your hood, look at the snorkel that runs from the throttlebody to the filters. About halfway, you will see what looks like part of the tube is a seperate piece held by two clamps. This is the MAF sensor. It will have a 5 wire harness plugged on the underside. Takes 5 minutes to swap.

As for the cost, depends. I got the reman from autozone which was $125 with a core charge of $80. What I would do If I were you is "rent" one from autozone or advance. They do have a return policy so don't ask to avoid suspicion. If it doesn't correct the problem, just return it and tell them you never installed it because you found another part caused the problem. They will return it as long as it hasn't been installed.

Good luck.