'03 DTC PO171, 301-304 and brake issue

[1800ES]

Just replaced a motor (1ZZ-FE) that had been siezed up I(thrown rod) with a used long block. Having two issues, which may or may not be related. (Car sat since last Nov.) Getting a rough idle after car warms up, check engine light on, with trouble codes 171 (lean) and 301-304 (misfire). Have searched for vacuum leaks (none found), swapped coil packs, removed and sealed intake manifold, swapped the oxygen sensor on exhaust, made sure all connections intact, both electrical and hoses. It also appears the car is without power brakes. Related?

Totally perplexed. Help would be appreciated as niece needs this car.

[fishexpo101]

Possibly related - power brakes gone and lean CEL with misfires point at a huge vacuum leak somewhere.

I assume all connections to the throttlebody assembly/intake manifold are made? All it takes is a missing vacuum hose. Since you don't have power brakes - I'd start there and work back to the engine - might find something that way. Could be anything from a missing/cracked hose, broken fitting, to a bad check valve.

How does the car run when cold? Better than after it warms up? How did you check for vacuum leaks initially - just a visual inspection or did you do more there?

[1800ES]

Thanks for your reply. In checking for vacuum leaks we looked the motor over repeatedly and checked all the hoses. We used propane to see if that would identify any areas leaking. Removed the intake manifold and sealed the gasket just to be sure.

The car runs better when cold but as soon as it comes up to operating temperature the idel deteriorates. We've cleared the trouble codes to turn of the check engine light. After running and warming up the check engine light and identical trouble codes reappear.

[fishexpo101]

I'd double check the MAF sensor in the air box, make sure it is clean - also double check the throttlebody for any obstructions, wiring issues, vacuum issues.

Could be a ECT sensor issue too - sort of a long shot, but a bad ECT can cause ECM headaches. Have you reset the ECM? Clearing the codes should be enough - but sometimes, you need to completely pull power from the system and have it relearn fuel trims.

Since it seems to run OK in open loop - and starts to degrade in closed loop mode - could be a combination of vacuum leak (intake and exhaust leaks are possible) and/or electrical issue (sensors).

[1800ES]

Can you tell me what the ECT sensor is and where it is located, please?

[fishexpo101]

ECT is the Engine Coolant Temperature sensor. The ECM uses the temperature reading to determine if the engine has reached operating temp or not. Has a strong influence on driveability - if sensor runs too cold, transmission will not shift into overdrive and the engine will not go into closed loop mode. ECT sensor is on the cylinder head - should be right side of engine (looking straight at the engine), right by the airbox and throttle body, above the transaxle. Has a wire leading to it - can be easy to miss with all the other tubes and wiring running in that area. You'll know that you found the sensor because it will have a pretty good sized hex base on it, the electrical connection is dead-center above that base.