PhenixTAGT

So a few months ago I posted about a rough idle and surging issue at low rpms. I did a datalog and its showing the car is running very lean at WOT but rich at idle. I've checked for the usual suspects and there is no vac leak or exhaust leak. The car is still pulling hard and has power but its surging in the 1500 to 1800 rpm range but at WOT it isn't shuddering or anything that would suggest a lean issue. Since it is only lean on one bank I assume I can rule out a fuel pump issue since that would be equal on both sides not just one. I have checked the forums and can't find an answer. If anyone here has had the same issue and figured it out,any input would be great!

whytryz28

iTrader: (28)

Checked the IAC?

great421

iTrader: (1)

One bank = an O2 sensor issue.

The IAC motor could be at fault for your idle (FYI - it was for mine), but so could alot of stuff. So, before you start throwing expenisve parts at it (as you've indicated above) start with inspecting / cleaning the IAC motor.

Also, make sure the engine is clean (Seafoam), and the plugs and wires are OK too. Lean up high could be your O2 sensors, but it also could be as simple as a dirty air filter or dirty MAF.

Good luck!

96capricemgr

iTrader: (1)

Signature?
Link back to original thread that might contain pertinent details?

PhenixTAGT

Yea I realized the way I worded it that it looked like I've been throwing parts at it. The engine is rebuilt and has only had 5k miles on it tops since the rebuild. I had to replace the opti after the waterpump leaked from the weaphole and fried it. The wires are new after the previous set began to melt,through the heat wrap. The iac has been in the back of my mind but the local dealer reminded me that it would most likely not effect the performance through the ranges. And that's where their knowledge stopped. It really sucks being stuck in an area that specializes in fox body rustangs! As far as the o2s, I guess I will pull them again and check them. They are bosch so Lord knows they're probably part of the issue.

PhenixTAGT

Update on issue. After a few days of rain I did a log, found the map sensor kpas are way up there. Looking at an issue with a possible egr problem. Guess I shoudlve deleted it in the tune