New Guy Needs Help...

[NotSoSho]

Ok. I am new to the SHO. I am a mechanic and I'm having a couple of issues with my first SHO. Here's what I know about the car.
-1992 5 spd
-3.2 swap with 3.0 cams
-largest available MAF sensor
-oil pressure runs between 10-50 psi depending on rpm (is this normal?)
-temps run from 180-210 (fan doesnt cut on until 210)
-supposedly 80k miles on engine when it was installed and 60k service was done during install about 8k miles ago
-runs great most of the time but lately it has been randomly trying to stall at idle and during deceleration (never during acceleration).
-when it tries to stall the radio cuts off...

Things I would like to know
-How do I tell which computer was used?
-where is the diag port "supposed" to be?
-where is the computer?
-I know it has been swapped but is there a difference in vacuum systems or would vacuum routing remain the same?
-during these commone swaps how much of the electronics have to be altered and is there a post swap wiring diagram and vacuum diagram available?

Any input would be appreciated. I know I could look most of this stuff up at work and cross reference but I figured i would give the experts a shot first

 

[rubydist]

the pcm is in the firewall on the passenger side, above the glove box. You should find a pcm label on the connector in the engine compartment (may need to remove wire harness connector to see it) and on the back end (by flipping down the glove box and looking above it).

The diag port is in the same area as the pcm connector. Originally, the connector was clipped to the plastic cover that goes over the wiper motor, but by now that cover is likely gone, or the connector is no longer clipped in place.

The vacuum routing should be identical, and it should have the original 3.0 wiring on it.

Oil pressure sounds typical - this is a "low pressure, high volume" system, so 10 psi at idle is not unusual.

Fan operation sounds about right, maybe a tad high to kick on, but not much.

The random cutting out (with the radio cutting out too) sounds like an electrical issue. These systems are very sensitive to grounds, so I would start looking at all the grounds to make sure they are clean and not corroded (since you are in FL and water is in the air all the time). Second, I would pull and re-seat all the fuses to make sure they have good connections. Third, I would look at the key switch and the connectors on the key switch circuit.

btw, welcome aboard!

 

[SHOdded]

Welcome aboard! Second the electrical issues recommendation. Also possibly look into a new thermostat/cooler thermostat if you believe the temp issue is a cause for worry. What is the normal ambient range for where you live?

rubydist, could an ECT sensor issue cause the fan to come on at too high a temp?

 

[jimtash]

What do you mean largest available MAF sensor? If it's aftermarket or bigger than stock, make sure the PCM has also been programmed to adjust for the extra air. Otherwise the engine will run lean.

 

[rubydist]

yes, the cooling fans come on when the pcm sees the ect at certain value. that is the 2-connector ect that goes to the pcm, not the 1-connector ect that runs the gauge.

the thing is, who knows for certain that the gauge he is using that reads 210 is accurate? most aftermarket gauges are not right on the money. for example, on the F100 project that I just got running, the brand new gauge tells me that the engine runs at 205*, but when I datalog, the pcm says it is at 190*. which one would you believe?

 

[NotSoSho]

Wow thanks for the replies! Turns out it was a ground issue from the radio being swapped before I bought it. As far as the MAF goes he said it was the largest MAF without reprogramming 70mm from another model i believe. The temp is not a big issue, its steady so I guess its ok. You guys are awesome thanks for the help... beat an old Vette in a Taurus yesterday , it was a good day.

 

[itwonder]

For the random stall at idle problem, first thing is to try the idle reset procedure. Forum search will find past posts with how to.