BRAINS TRUST. help needed

[robkeith]

hi, im running an ecotec with the 808 ecu. previous motor ran very well no issues, this replacement motor??

!/ ecotec with vp loom and sensors.

Runs well when cold, performance is great, BUT, after reaches operating temperature power drops dramatically?

at no time does it misfire or bad idle etc just down on power! feels like retarded ignition??

have changed the following:-

1/ ECU
2/ Plugs & leads
3/ DFI plate and coils
4/ oxygen sensor


today i disconnected the following, again with no difference in performance, still NO misfires or idle problems??

In order.

1/ Knock sensor
2/ oxygen sensor
3/ coolant temp sensor

I noted that the ECU didnt immediately throw codes for the knock sensor or oxygen sensor when they were removed and was slow to throw a CEL after is disconnected the temp sensor.

Im at a loss where to go next??

 

[Immortality]

Where is your MAT sensor mounted?

If it's temperature dependent maybe the ECT sensor isn't working properly and giving false readings.

 

[Lex]

Where is your MAT sensor mounted?

If it's temperature dependent maybe the ECT sensor isn't working properly and giving false readings.

Sounds like he has the Buick pcm? Wouldn't he need the ecotec pcm?

 

[Immortality]

Nope, just a tune to suit and the appropriate sensors fitted (primarily the MAT sensor in the plenum somewhere).

Which reminds me, I'm not sure if the 3800 V6 and Ecotec use the same ECT sensor, it might pay to fit the sensor from the old engine to the new one.

 

[woteva]

Had to drill and tap a hole in the back of the plenum in my VR Ecotec for the MAT sensor. Was easy to connect the MAP sensor and the VR ecu coolant temp sensor was different and required drill and tap under the thermostat.
Runs great on the VR ecu with an old greenfoam racing memcal.

 

[Not_An_Abba_Fan]

Something has obviously changed, if something is not connected you will have a spare plug. VP loom will not have a knock sensor so I don't know how you have that connected. Maybe you have the MAT plug connect to it and no MAT sensor in the new engine?

 

[Immortality]

I thought the 3800 V6 does have a knock sensor? Just the one, and the ecotec has 2?

It's the Holden 304's (VN-VS) that don't have a knock sensor fitted from the factory except HSV models.

 

[Comcal76]

I thought the 3800 V6 does have a knock sensor? Just the one, and the ecotec has 2?

It's the Holden 304's (VN-VS) that don't have a knock sensor fitted from the factory except HSV models.

Yes the VP V6 has a knock sensor.

 

[Not_An_Abba_Fan]

My bad, I didn't think pre-ecotec had them.

 

[losh1971]

Mine has a knock sensor.