4.3gxi bad temp sensor?

happychapboater · Monday at 8:59 PM

I’ve been having issues with one of my engines in that it is stalling at idle and sounds like it’s searching. I just got the tech mate device and have been comparing between my two motors. I noticed that the good engine’s temp while it’s cold now is at 70 degrees, while the other engines sensor is saying 85. I swapped sensors between engines and re-read the tech mate and the sensors showed the same readings.

Could this be that it’s a bad temp sensor and causing the stalling?

Scott Danforth · Tuesday at 5:16 AM

doubt its the temp sender causing the issue.

did your temp follow the sender or stay with the motor, your post is not clear there.

hunting at idle is usually the IAC. what is the IAC showing on both motors.

happychapboater · Tuesday at 6:13 AM

Scott Danforth said:
doubt its the temp sender causing the issue.

did your temp follow the sender or stay with the motor, your post is not clear there.

hunting at idle is usually the IAC. what is the IAC showing on both motors.

The coolant temp followed the sensor when I swapped them. The main problem has been to get the engine to not stall after 10-15 seconds without giving it some throttle to warm up.

alldodge · Tuesday at 6:17 AM

happychapboater said:
The coolant temp followed the sensor when I swapped them. The main problem has been to get the engine to not stall after 10-15 seconds without giving it some throttle to warm up.

That sounds like the IAC as Scott mentioned

happychapboater · Tuesday at 9:02 AM

alldodge said:
That sounds like the IAC as Scott mentioned

I replaced the IAC first and that hasn’t corrected the issue unless it was a bad IAC. I also swapped IAC between the two motors and it still stalled.

alldodge · Tuesday at 1:44 PM

happychapboater said:
I replaced the IAC first and that hasn’t corrected the issue unless it was a bad IAC. I also swapped IAC between the two motors and it still stalled.

Which other sensors have you swapped?

Measure 5V reference voltage on the MAP or TPS

What voltages does Techmate show for TPS and MAP?

What is your fuel pressure at the rail?

Don't think it's the temp sensor right now

happychapboater · Tuesday at 9:32 PM

Just throttle and IAC I’ve tried swapping. IAC position is 120.

5v for both were 4.7-4.8v with engine off, key on. Tech mate shows map volts 4.23v, tps .74v.

Fuel pressure was at 50psi for high pressure and 10psi for low pressure. It has a brand new high pressure pump just put in.

Scott Danforth · Wednesday at 4:54 AM

IAC should not be open that far. usually about 40-50

the 5.0 being read at 4.23 means something is drawing down the 5.0 reference. could be a bad ground in the harness

alldodge · Wednesday at 5:41 AM

Motor of voltage for TPS looks good, MAP is a bit low, should be closer to 4.9 but 5V ref is a tad low

Once started the MAP should be around 1.4v

With IAC counts so high there is to much air for the fuel.

Might move the bad running ECM to the good motor. Don't move the good to the bad,

happychapboater · Wednesday at 6:04 AM

Scott Danforth said:
IAC should not be open that far. usually about 40-50

the 5.0 being read at 4.23 means something is drawing down the 5.0 reference. could be a bad ground in the harness

The IAC on the good motor was showing 130 for the value with key on, ignition off.

alldodge · Wednesday at 6:06 AM

happychapboater said:
The IAC on the good motor was showing 130 for the value with key on, ignition off.

Good point, have motor running

Scott Danforth · Wednesday at 8:37 AM

all readings need to be engine running. very few are KOEO

happychapboater · Wednesday at 12:33 PM

Scott Danforth said:
all readings need to be engine running. very few are KOEO

It’ll be a couple days until I can test that when it’s finished getting painted.

4.3gxi bad temp sensor?

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