Why Idle surging only after Driving?

[tsd123]

When I crank it, and let it warm up it idles great. If I only drive it up the road and back it surges for a second. If I go somewhere it wont stop surging. It's not a bad surge, but it is very irritating. I have changed tb's, but it hasn't changed. I tested the isc coils, and the tps is good on dsmlink. I'm out of ideas now.

 

[LiquidX]

Have you checked your throttle cable to make sure it's not slightly pulling open the throttle plate as it heats up?

 

[jrohner]

BISS is just set wrong?

 

[tsd123]

Now that you mention the biss. I need to change it. It might be leaking, and causing my problem. I had changed the one on my other tb. The think is, I changed the biss, and set it on my other tb. I had the same problem. How does the fiav affect idle?

Liquid, I haven't checked the throttle cable, but wouldn't the idle be more steady instead of surge?

 

[LiquidX]

It's an idea. If the plate is open slightly, the ISC is going to try to adjust to maintain the stock 750 rpm limit (or what ever you have it set at). It has an adjustment range and could be just enough to cause your issue.

If you haven't already, do a proper boost leak test.

 

[tsd123]

I'll check it out. I'm going to do a blt. I just have to find the bl tester. I'm thinking its a boost leak at this point. I adjusted the biss, and it doesn't straighten out untill its all the way in. I changed a few things a while back so I guess I'll do the leak test, and see where that goes. I adjusted the biss in after I had got back from picking my sister up at school. It was surging, and when I adjusted it all the way in it stopped. I could go a half turn out, and be fine. It was still idling around 1300, then after i let it sit for 4-5 minutes it dropped to 650-700. I tried to adjust it, but if i went higher it barely surges from 750 to 850.

 

[LiquidX]

You tested the ISC coils and adjusting the BISS you did ground the diagnostic pin (in your case check the check box on link)?

 

[tsd123]

Yes, I tested the coils with a multi meter. I checked both the boxes on link grounding the ign. timing adjuster plug, and diagnostic pin.