My car is a 98 LE, so has the plastic intake, ECU mounted on the back of the engine, with MAF inside the TB. Sort of a half-way-house between engine revisions.
Sure, here's my throttle body, the 3 pin connector to the right is the MAF sensor:
https://i.imgur.com/Sg5lGkO.jpg
I'm running a GSR setup off the throttle body, so all the stock gubbins have been removed:
https://i.imgur.com/NTvnoDv.jpg
Alrighty, so I've spent the morning running checks over the car and creating some graphs using
mes. Here's what I found....
Everything connected (car running rough)
Engine temp sensor voltage - Ranges from 1.365v to 1.460v
Engine temp sensor reading (degrees) - 73 to 75
Lambda sensor voltage - 0.2 to 0.3
Airflow meter voltage - 1.725 to 1.570
When the car hunts/misfires, the lambda sensor drops to 0.2 and airflow increase to 1.725. I'm thinking that this is indicative of the car sensing is going very lean, and trying enrich the mixture by increasing airflow.
Temp sensor disconnected (car running fine)
Engine temp sensor voltage - Steady 4.875
Engine temp sensor reading (degrees) - A very quick dip to -38 then increase to 31, with gradual increase in 1 degrees per 6 seconds
Lambda sensor voltage - Steady 0.3
Airflow meter voltage - 1.690 to 1.745
Temp sensor disconnected (car running rough)
Engine temp sensor voltage - Steady 4.875
Engine temp sensor reading (degrees) - 60, with increase of 1 degrees per 6 seconds
Lambda sensor voltage - Steady 0.2
Airflow meter voltage - 1.585 to 1.700
Temp sensor disconnected & intake covered by around 80% (car running fine)
Engine temp sensor voltage - Steady 4.875
Engine temp sensor reading (degrees) - Steady 80 degrees
Lambda sensor voltage - 0.8 to 0.1
Airflow meter voltage - 1.5 to 1.656
Temp sensor connected and intake covered by around 80% (car running fine)
Engine temp sensor voltage - Steady 1.045
Engine temp sensor reading (degrees) - Steady 86
Lambda sensor voltage - 0.8 to 0.1
Airflow meter voltage - 1.5 to 1.656
OK so what I think this means is that:
1) When the cars temp sensor is disconnected, the ECU goes to -38 and then attempts to estimate the engine temp and simulates increasing temp until it reaches operating temp of 80 degrees. It would be amazing if someone could confirm this behaviour with their car!!!
2) The lambda sensor is operating correctly, as when the intake is covered it bounces bewteen lean and rich, which is expected (from what I've read, please correct me if I'm wrong!)
3) I do still think its an electrical issue, because the car ran fine for around 160 seconds once the coolant temp sensor was disconnected. If the fuel pressure is fine (60 psi mentioned by DTR during testing, both when the car is running fine and when it isnt, measured inline by the fuel pipe running past the coolant resevouir), then something is telling the injectors to have a reduced flow, which is being detected by the lambda. If it was a mechnical issue with say the fuel rail being partially blocked, the issue would not be intermittent.
I'm going to go outside again and run some tests with the injectors....back soon!