So I made the mistake of buying a car sight unseen.
I ended up with a B16A in a 97 Coupe.Since purchase it was idling sporadically. I cleaned the throttle body and it idles better now, but still around 1300 rpm. Between 1500-2000 RPM the engine surges. It's as if there's a limiter there. When more gas is applied the engine runs fine above that rpm range. I took it up and down the street after cleaning the throttle body to see if it solved the problem. It's practically undriveable in its current state as it yanks you back and forth in the seat very hard.
This engine is running a Skunk2 Pro Intake Manifold.

I've checked the PCV Valve and it's fine.
When I put my hand over the throttle body it lowers rpm but does not kill the engine.

Should I check my IACV and clean it?


Any thoughts would be appreciated.
Thank you!

 

Is it surging at cold idle or warm or both? Yeah retreading the FITV is defenitelty a start. Clean the IACV as well.

 

It's surging at both warm and cold.

 

clean your iacv

 

I cleaned the IACV, detected and fixed the vacuum leak causing sporadic idle.
No more Idle problems.

Still have the surge between 1500-2000rpm

 

^You have a massive intake air leak.

Replace the TB and IM gaskets, and torque the nuts and bolts to spec.

 

I just found an issue with my b16a2, where the previous owner used a b18b throttle body but kept the b16a2 gasket, which caused a massive vacuum leak, since it didn't seal around the fitv.

If I was you, I would either perform a smoke test - go on YouTube and you can find diy vids - or get a can of brake cleaner/starter fluid and use it to test for leaks.

 

https://youtu.be/8aTAwO-2-6k

You need to seal the intake opening - I put a small plastic over the throttle and place the intake pipe around it - and "T" off of any vacuum line on the manifold.

Pump smoke into the engine and see where it leaks out from. You will get some out of the exhaust, which is normal, but none should leak from anywhere else.

 

I've fixed the leak. Idle is fine and where it should be doesn't surge at all.

Still surges at 1500-2000 rpm.
Don't know what to do about this. Thinking it might be ecu related. This is running a p28 that's been chipped. I thought it may be the "2step" but it's set at 5250

 

You completely contradict yourself in one post.

 

I meant the idle surge is now gone. But that I still have the issue at those rpm. I apologize , I've been at this all day and am getting tired.

 

This^ is a surge, as you even state.

1500-2000 is your idle speed, right?

 

Do you mean it's bogging when you drive at those rpms? Try the idle relearn procedure

 

My idle speed is 800rpm and doesn't move. Only when its revved up to 1500-2000 does it surge. I don't know if surge is the right word for it but it pretty much feels like I'm hitting a record limiter until a lot more gas is applied.

For example I could be rolling away starting to apply gas and it will surge in that rpm range. Yanking me and the car back and forth.

It does it any time it gets in that range whether it's in gear driving, downshifting or standing in neutral.

Above this range everything is wonderful and problem free.

 

What B16A engine?

What ECU?

What CEL codes are thrown?

 

B16A Second Generation

P28 Chipped

No CEL Codes.

 

I think your idle speed should be closer to 700 rpm, so adjust it while monitoring with an accurate tach.

Bleed the cooling.

Voltage test the TPS.

Did you already clean the IACV and FITV (if you have one)?

 

I've bled the coolant.
The IACV has been cleaned. I don't have an FITV.
Turned the idle down and it's at 700 now.

Still feels like I'm hitting a wall at 1500-2000

 

But did you do it properly?

That was fast. What idle set procedure did you use?

 

Yes I bled the system properly and let all the air escape the system.
I turned the screw on the throttle body to set the idle.
Could this issue be timing related?
The timing belt has a good amount of slack on the deflection side. Could this be a result of the belt skipping a tooth?

 

I assume it was done incorrectly due evasion of details.

This is not a proper method of idle adjustment for any OBD1 ECI that I'm aware of.