Did you do a tune up? Could be fouled plugs and corroded plug wires.

No tune up and that was my first guess already replaced plugs gapped them and wires are brand new, also fuel pump and fliter are good, after 4k rpms it holds powet but not under that, also seems to have a hard time starting, i have to push the pedal repeatedly

What Ecu and wiring harness is in the car?

Check voltages to your upstream O2 sensor

All stock ecu and wiring to 1997 gst, basically i took the block and sohc out my 1999 2.4 and installed it to where the 2.0 turbo was. All connections nearly the same, i will double check for volts on the 02 sensor but the thing is when this engine was on the 2.4 1999 automatic spyder it would turn on 100% perfect, i have the throttle body of the 1997 on there now, thought the ecu wanted to know its vacuum hoses were there for the canister so that got rid of all my dash lights no "check engine" anymore after installing it. Thanks a lot for your time.

Lets not over look the obvious that you are
1) using a 2.4 SOHC in place of a 2.0 DOHC.
2) using the sensors and ECU from the 2.0 DOHC to try and run a larger engine with one less cam.
3) using a larger engine with sensors expecting the airflow of a smaller turbo engine.

Why did you not use the correct ECU and wiring harness?

1) yes.
2) actually all sensors are from the 2.4, i should of not let this out, have block sohc, plus* intake mani and all its sensors & injectors, except the throttle body now, alternator, oil pump, fuel pump, crank sensor, water pump.
3)all sensors of the 2.4, was thinking of putting the 2.0 ones on but i never did.

Its a project mean while i rebuild my 2.0, i just wanted this thing running and making good used of my 2.4 since the tranny broke.

The 2.0 ecu has no idea how to control that engine.
Swap in the correct ecu and it should work as expected.

German campos said:

Im new here but i know theres a lot of smart people and i would like help with this problem, Idle is fine at 800-1000rpms but when trying to accelerate it bogs like it wants to die my guess is it's running too lean but idk why???

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Change your maf sensor I have a 99 spyder with a 4g64 and the same thing happened to me it started and idle perfect but when I stepped on gas it bog and no power at all! Turned out to be a bad maf sensor!

I have the 2.4 ecu but numbers are not compatible, and my 2.0 is manual and 2.4 is auto, 2,4 ecu would not recognize the tranny or know when to shift,
I have hope this way on the set up because ive actually had idle problems with the 2.0 gst 1997 in the passed, any wires i should check for bad connection other than plugs and injectors that would affect idle, simple thing is im running too lean i don't know why. 2.0 requires more gas then the 2.4 right? So ecu would still send enough fuel and all runs well after 4krpms its just very slow on throttle response.

I will try the maf sensor asap thanks

German campos said:

I will try the maf sensor asap thanks

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Also check for a lose or a ground cable I also had a lose ground cable from engine to firewall if a cable is lose or not hooked up therefore your engine and wiring system have no good power causing all your sensors and ecu to act up!

Wait, what injectors are you running? Also your ecu does not control your transmission so the ecu doesnt need to "know" anything about what transmission your running in this case.

You need to either install the engine your Ecu is supposed to run, or install the Ecu for the 2.4.

You can check all of the sensors. Until you use the correct ECU, it will run like crap.

You can use it, manual or auto, makes no difference.

I tried the maf sensor seems to make a slight change but still low throttle response at low rpms and after 3k it just roars like everything is well and im Running stock injectors to the 2.4 engine, im just trying to make good use of this engine because it was always good but my 2.0 always had idle problems, oh yea while it was sitting at perfect idle about 800rpms i shot some b12 in the air filter and idle went up about 200-300 but i dont know if that means im not getting enough fuel tho

German campos said:

I tried the maf sensor seems to make a slight change but still low throttle response at low rpms and after 3k it just roars like everything is well and im Running stock injectors to the 2.4 engine, im just trying to make good use of this engine because it was always good but my 2.0 always had idle problems

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U said u had a 2.0 first right? Then u changed it to a 2.4? If so then check your fuel pressure cause one engine is bigger that the other so it requires diffrent fuel pressure if u kept your 2.0 stock fuel pump it has a totally diffrent fuel pressure maybe that's what's causing the low rpm bog and no power!

Stop chasing sensors and SWAP THE ECU. The 2.0 ecu still thinks the engine is a 2.0! It has no map for the 2.4

Why is this, the most obvious solution, being ignored?

Use the 2.4 ecu and wiring harness.

use the injectors and MAF from the 2.0 (injectors, and maf need to match the ECU)

it will run 'better' that way. and given enough time for the ecu to figure out what is going on. it will run 'right'ish. it is still a bigger motor but .4l isnt enough to make the ecu not be able to compensate. the worst part will be the ECU will have boost tables that go over 100%. really though that will not matter as you are going to a non turbo engine. when we go the other way, (turbo engine in a non turbo car) it causes more issues.

DarkApollo said:

Stop chasing sensors and SWAP THE ECU. The 2.0 ecu still thinks the engine is a 2.0! It has no map for the 2.4
Why is this, the most obvious solution, being ignored?

Click to expand...

thats extra work for a simple motor swap to a compatible but slightly larger motor. not necessary.

.4l is not enough to matter, you want the ECU to THINK it still has the 2.0l in the car. ALL THE SENSORS, INJECTORS, MAF, ETC. need to match the ECU. the ECU will deal with the extra .4l and no turbo over time. (it will not take long for the ECU to have the engine running good.)

It is just three bolts and a few plugs. Right in the drivers side foot well of the center console.. extra work to make sure it is the correct ecu for the engine...?

DarkApollo said:

It is just three bolts and a few plugs. Right in the drivers side foot well of the center console.. extra work to make sure it is the correct ecu for the engine...?

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he would then have to go back and swap all the sensors, injectors, (hopefully the 2.4l injectors still use the injector box or he would have that to deal with,) MAF, etc. so that again, everything matched. thats assuming that yes the ecu plugs right in and the pins line up.

i have dealt with the 2.4l in the 3rd gen and the ECU is similar but i do not remember off hand if its a direct swap. to me the easiest solution would be the original GST ECU with all the matching components for that system.

I also had a 3rd gen GS, also a 96 GST..

Did you not read the thread? Why would he need to swap the sensors if he is USING the 2.4l sensors? He basically took the 2.4 as it sits, sensors, injectors, and all, and plopped it in, plugged the 2.0 harness up to it and turned the key.

2) actually all sensors are from the 2.4, i should of not let this out, have block sohc, plus* intake mani and all its sensors & injectors, except the throttle body now, alternator, oil pump, fuel pump, crank sensor, water pump.
3)all sensors of the 2.4, was thinking of putting the 2.0 ones on but i never did.

Click to expand...

DarkApollo said:

Lets not over look the obvious that you are
1) using a 2.4 SOHC in place of a 2.0 DOHC.
2) using the sensors and ECU from the 2.0 DOHC to try and run a larger engine with one less cam.
3) using a larger engine with sensors expecting the airflow of a smaller turbo engine.

Why did you not use the correct ECU and wiring harness?

Click to expand...

i got YOU and the OP mixed up at one point.
yes if it is already completely the 2.4l electronics it would be good to get the 2.4l ECU in there.

either way what i am saying holds true, the MAF, INJECTORS, AND ECU NEED TO MATCH.