No power after swapping in 3400-Removed AIR

[TazMan]

So I've been working on a 2001 lumina in my spare time and I finally got up to turning over the 3400 I swapped in place of the old 3100 it came with. It starts and idles just fine but it doesn't even have enough power to pull itself up the hill I live on past 30mph. I removed the air injection system with the intention of changing the computer but haven't gotten it just yet. Would that cause the problem I'm having or should I be looking elsewhere?

[1QUICKHATCH]

Any codes? Sounds like the transmission may be stuck in 3rd gear/ limp mode

[TazMan]

I have two codes for the air. I can't remember what they were, but they were both for the air injection. No others so far. Transmission is starting from first gear and shifting through the gears. If I hit it, it will down shift just fine, but the engine just has no power to push it. Just downshifts and very slowly picks up speed. I honestly wasn't too familiar with how the air injection works, but after a lot of searching here, it seems my problem has nothing to do with the AIR at all. No codes really pointing me anywhere. All sensors are new A/C Delco. I changed the exhaust before I pulled the old motor so CAT, Muffler, etc should be good. Only reused the ICM which was fine when I pulled the old motor. Not sure where to go from here. I'll swap out the ICM For another one I have lying around somewhere but I really haven't found anything to point me in any direction yet. I'm really stumped right now.

[1QUICKHATCH]

Hmm the first thing I thought was cat until you said that it is new, how long was it down for? No animal nests in the air box?

Did you have a crank relearn done at all?

[TazMan]

No, no nests anywhere. I cleaned all that out b4 I turned it over but there was nothing like that. I'm not hearing any misfiring or anything like that. It idles smooth and starts up immediately. I don't have a scanner that can do a case relearn. I think maybe I'm going to have to pull the valve covers and make sure none of the rocker arms came loose or anything like that. I thought something like that would be loud enough that it would be obvious but with the crappy aluminum threads in these heads, it's the only thing I can think of to check at this point.

[GhostGALA1]

Should see if you can borrow a scanner that can view live data before you go ripping into the engine. At least that way you can see what the engine is doing. Check the fuel trims and ignition timing. These kinds of conditions don't always cause detonation or misfires. Not to mention you would be able to look at all the other sensors that can effect power, throttle position sensor, engine coolant temp sensor or even the EGR system.

Just out of curiosity, what ECU/PCM are you running with the 3400?

[TazMan]

Right now using the stock 3100 ECU. The upper and lower intake manifolds are ported and there's a 65mm throttle body on it. The computer is the next step, but the car is so weak right now I can't even get it past 25mph driving up the hill I live on. I know the stock 3100 computer isn't ideal but it wouldn't cause the 3400 to fall on its face like that would it?

[GhostGALA1]

I wouldn't think it would be that sluggish. I'm pretty sure the two engines use the same fuel injectors. However, I am not 100% on the fuel pressure or fuel maps though. I am relatively new to the 3100/3400 GM tuning game. I am in the midst of getting used to using HPTuner, just using it to monitor how everything is working on a stock engine for now. This is where a scan tool or someone with a tuner would come in handy for you.

Could pull the spark plugs and see if they give you any signs, wet with fuel or black = rich and chalky white = lean.

Did you have a compression test done on the 3400?

[TazMan]

I didn't have a compression test done. I heard the engine run in the car it came out of but the car was wrecked in the back and not drive able. It supposedly had 74K on it. I used the complete block and bolted on a pair of rebuilt heads I had. I was actually just telling my brother in law the same thing about pulling the plugs not 5 minutes before I read your post. If I get home early enough I'm going to do that tomorrow and see what I find.

[AleroB888]

I have had a bad TPS cause that symptom. And I have had a new replacement TPS be defective out of the box...... Can you verify that it reads zero degrees rotation when throttle is closed?

[GhostGALA1]

I have had a bad TPS cause that symptom. And I have had a new replacement TPS be defective out of the box...... Can you verify that it reads zero degrees rotation when throttle is closed?

^x2, and if your scan tool does not show TPS % you can back probe the TPS sensor at the connector and verify the voltage for CT and WOT.

With the ignition on and the engine off, check the voltage at the sensor.
Power wire should read 5v
Ground should see battery voltage 11-12v approx. and
At closed throttle the TPS signal wire should read approx. 0.5 - 0.9v.
At wide open throttle is should read approx. 4.5v.

If your voltages are out of range slightly you might be able to loosen the two mounting bolts and adjust the TPS until you get your voltage in the ball park. You should also check to see that you have a nice smooth rise and fall in voltage as you open and close the throttle slowly and as smooth as possible. If you see any sort of stumble, hesitation or jump in voltage, the TPS is more than likely bad.

[Purple pit]

This car has a MAF right? I have no real idea about what is going on, but it would seem that there is a good size jump in air flow vs stock. Can he unplug the MAF and try to see if it will run in SD mode?

[GhostGALA1]

The 2001 3100 and 3400 both show the same GM Part number for the MAF sensor. It should be good to go, as long as it is working properly. Could still try unplugging it to see if it would make a difference. Anything is worth a try.

[TazMan]

I've been pretty busy and haven't had much time to do too a lot. I've tried swapping out the MAF, ICM, MAP, and TPS Sensors for known good ones. I tried driving once with the TPS disconnect and once with the cam sensor disconncted. All produced pretty much the same results as I've been getting. That's all I've had time to do so far. I won't have a chance to work on it again till Sunday or Monday so any ideas for when I get back to it are greatly appreciated and thank you everyone for all your suggestions.

[Purple pit]

Not to be too basic, but have you rechecked the firing order? Totally sure the injectors are fine?