Engine Idles fine, enters Closed Loop and Dies

[AntMan]

Engine: 87 BGN 3.8 Turbo

As the title states, any suggestions?

Changed the following: O2 Sensor, Crank Angle Sensor and TPS......the MAF, computer and chip all original (stock).

 

[TurboBob]

how do you know its going into closed loop? i.e. what other data might you have?

unplug the o2 sensor and see if the symptom changes

Bob

 

[AntMan]

will try your suggestion.

Here's what happens, the electric fan kicks on, reading at the TSP went up from .42 - .46 volts, engine then immediately cut-out and would not restart. However, after letting the engine cool for 30-45 minutes it does start up again.

 

[TurboBob]

well, the fan and closed loop are 2 different events.

tighten the grounds on the back of the passenger side head, and make sure the wires are not corroded back inside the insulation.

Stock ECM I assume?

Bob

 

[AntMan]

Yes stock ECM. So does the fan kick on after or before the engine goes into Closed Loop?

I'll check the Ground wires, when I installed the wire harness the wires all looked good but I will recheck.

 

[TurboBob]

closed loop usually happens around 125 degrees, the fan much hotter than that.

which wiring harness did you install.....?

B

 

[AntMan]

well I purchased the engine wire harness off this site (Used) but had no clue there there are variations, what are the differences that I should look for?

I need to mention I converted over my 85 BGN to an 87 BGN stock engine.

I appreciate your input.

 

[87geeinn]

Back up a little bit. So after some clarification, you are saying the car dies once the fans kick on, right? As Bob mentioned earlier, closed loop is programmed in the chip to activate once the car hits a particular temperature. In similar fashion, the fan(s) will kick on once the engine temperature reaches what is set in the chip, which will be a different temperature.

Would be helpful to know what chip you are running. Are there any modifications to the fan wiring from the stock configuration (i.e., is the fan resistor bypassed? Do the fan relays have jumper/bypass wires on them? What condition are the fan relays?) If I had to guess, I would venture to say that when the fan kicks on, the fans are drawing enough amperage that the voltage drops way down to a point that the ECM is going bonkers. I can't remember the threshold but I think if the ECM sees something like less than 10v, things will act up and can possibly shut the car down since the ECM can't operate properly. I suggest starting the car up and watching your voltage, paying particular attention to the voltage the moment the fan turns on.

Pics can speak volumes sometimes, so snap a few of the fan relays and the fan wiring if possible.

 

[AntMan]

Basically the car is stock in almost every regard (Wire Harness, Fan, ECM, Chip etc....). I'll check to see my voltage drop to the ECM when the fan kicks on.
It seems likely after reading the input from you both, that the car has an electrical issue (ground or otherwise) which is something I have not looked at closely. Thanks for the great advice, will follow up with what I discover.

 

[87geeinn]

It's not a good idea to still be running the stock chip...but that's been covered umpteen times in numerous other threads. Just do a search and read up.