Low speed miss

[fgordon]

I have an engine miss that comes in around 1800-2000RPM under acceleration. This only happens when the outside temperature is approaching 90 degrees and the engine is at or above 180 degrees. I have replaced the IAT sensor, MAF, air filter, coil pack, ignition module, injectors, and chip. I checked the TPS voltages and the are within the range. All the replacement parts were new or known good parts from other cars that were operating normally. The car runs all day at 180-190 degrees so there is no overheating issues.

Does anyone have any ideas?

 

[fgordon]

Anyone?

Please PM me if you don't want to post. I'm fresh out of ideas.

 

[buickin87]

There is several possibilities:

-coolant temperature sensor malfunction in the temperature area in question
-cam sensor failure
-ECM
-TPS problem
- maybe O2- sensor
Anyway, the problem seems to appear after the engine has moved from open to closed loop(if you don´t drive with open loop all the time).

 

[TurboBuRick]

There is several possibilities:

-coolant temperature sensor malfunction in the temperature area in question
-cam sensor failure
-ECM
-TPS problem
- maybe O2- sensor
Anyway, the problem seems to appear after the engine has moved from open to closed loop(if you don´t drive with open loop all the time).

Good advice.

Also might have a loose balancer or a misaligned crank sensor. Are you still running the factory sensor and bracket? Is the motor stock?

 

[fgordon]

Thanks for the info. The motor is stock and everything is factory except the chip and injectors.(it does the same thing with the stock chip and injectors) I'm going to try replacing the TPS with a new one I have on the shelf and follow that with a new ECM. I don't understand why the problem is specific to the outside temperature. When the outside air temp is in the low to mid 80's, the problem doesn't appear even when the water temp exceeds 180.