My nephew 94 Accord with a H22 swap on chrome with Crower cams and internals with Injectors (I can find out) on stock fuel pump. He was running a STR 68mm throttle body with no issues. He swap out to a 70mm throttle body with no issue (calibrate) so he swapped it back down to the 68mm. Now he has issues when idling at 2k rpm. He adjust the idle screw on the throttle body and fixed his idling issue but now the car is running to lean that the motor will buckle. He said he adjusted the TPS to the correct voltage or ohms

The only things that came to my mind was
- Not enough fuel. He does not have a fuel gauge on the filter or fuel rail and no FPR to adjust the fuel.
- TB gasket (Nephew don't think it is)
- Vacuum Leak (Nephew claim none)
- Tuning software on chrome (Nephew said he did not touch the tuning)
- Distributor been changed along with plugs & plug wires
- MAF Sensor?
- Map Sensor?

If you can think of anything else please let me know so I can have my nephew resolve this issue.

Thank You.

 

Are you sure it's running lean, what are the AFR's you are seeing while the engine stumbles and at what RPM range?

Where it has a chipped and tuned ECU you have an advantage. Do you have a wideband O2 sensor that you can actually monitor your AFRs? If you have access to Crome and a laptop you can hook up to the ECU and monitor all of the sensors and see what might be happening. If you do not have access to a tuning laptop then you will have to check the sensors with a volt meter and make sure they are functioning properly. First things first, you need to verify that it is a lean condition.

With all the parts changes and going back and forth with the throttle body, pulling and pushing wiring harnesses around in the engine bay. You never can tell what might have come loose. You should check all of the vacuum hoses, wires and connectors. Pull the spark plugs and see what condition they are in. If they are white and chalky then it is running lean. if they are black and wet and smell of fuel then it is running rich. Ether of these conditions and you should check the ignition and fuel systems and/or the tune.

 

The motor wants to shut off while idling (not enough fuel).

Wideband O2 sensor busted from being low (bottom out).
I will give him a call to see how the spark plugs look but he said before there dry.
Nephew checked all vacuum hose/lines there fine.

After talking to some of my friends
Tuning software and or IACV (Idle air adjustment).

I think the best thing to do is for him to check the IACV. If not take it back to his tuner. I don't know when the next time I be able to fly out there.

 

Update
Got off the phone with my nephew last night. He fixed his wideband. We both agree some how his tuned got screwed up (dyno tuned). He is going to have his tuner take a look at it. I'm not sure if the burn chip or the ECU itself is acting up.

By the way the Injectors or 310cc

 

Final update.
It's confirm the chip went bad.