MawneeC5

iTrader: (12)

I'm stumped. The car runs perfect when its cold, idle and cruising. But as soon as it warms up past 170F coolant temp it wont idle(surging and failing). And on the road it bucks and sputters like its on 1 cylinder at anything below WOT.

For backround I just removed my procharger. And I'm starting with a stock tune for a 98. It still has all the other mods in my sig. What baffles me though is that when I put the cam in two years ago it was fine with the stock tune. I drove the damn thing around and even took it to the track with the cam in it and no tune for over 9 months.

I'm tuning with EFIlive, I'm not looking for optimal performance here..just want the thing to be drivable. Any ideas ?

macca_779

There are quite a lot of ECT/fueling tables that should be adjusted when you start running your motor cooler. Have a look around in your tune.

MawneeC5

iTrader: (12)

You misunderstand. It wont run once it warms up

My90Iroc

iTrader: (26)

The idle airflow table is based around ECT so there's a good place to start with the idle. As far as the sputtering you may need to adjust the throttle follower. That'll help smooth things out when moving from a stop.

That's not a huge cam you're running so it shouldn't need a whole lot of change from stock.

Are you using a completely stock 98 tune or just some tables copied from a stock 98 tune?

MawneeC5

iTrader: (12)

Stock 98 tune from the EFIlive database.

I've since tried to work around the problem by removing my thermostat and setting my fans to keep the coolant at 150. Problem still shows up its not directly linked to the coolant temp.

1320FEVER

iTrader: (9)

Do you think maybe its when your engine is going into "closed loop" mode, this might be happening? At what temperature is you "closed loop enable" set at?

MawneeC5

iTrader: (12)

Thats exactly what it was. I forced it into open loop tonight and it ran perfect. So now to figure out why closed loop isnt functioning right.

Once it kicks into closed loop my O2s(all 4) are bouncing all over the place and my LTFTs are bouncing from -1% to -18%.

My90Iroc

iTrader: (26)

That's not uncommon. Once you start getting cams with some overlap they can pass unburned fuel dropplets through and onto the O2 sensors. Naturally this prohibits the sensor from doing its job properly and will mess with the fuel trims.
I've been running open loop for the last year and a half with no problems at all. The maf can adjust for weather and altitude so if your ve tune is right you shouldn't see any ill effects from running open loop all the time.
Also don't forget to reset your LTFTs otherwise the car will be using the stored values in there and you'll be tuning around that.

1320FEVER

iTrader: (9)

Yeah, I've got a open loop tune on mine for the same reason.