Hello all, I have a 1988 Pontiac Trans Am GTA, 305 TPI (165 000km), automatic transmission with the digital dash. At a certain point, the oil pressure level is going way too low, it hits the red and I hear an alert sound coming from the dash. It does that when I drive in the city and only when I'm at a stop... When I begin to drive again the pressure goes up. Is it normal?

 

check the oil pressure sending unit, the one that goes to the dash. There are two different sending units, one that sends only to the dash and another that sends the pressure to the ecm. if the ecm one goes bad, or reads a correct pressure but it is too low, the ecm will cut the fuel pump. It sounds like you just have a bad sending unit for the dash panel. I had a similar thing going on in my 89 formula 350. I would check that first. It isn't normal for the pressure to drop that low, it is normal for the pressure to fluctulate a little bit from being at idle to being more when under load. hope this helps you some.

 

You may be thinking of the coolant temp sensors. The only oil pressure sending unit I know of is on the back of the block behind and to the left of the distributor.

 

Nope, nope...the TPI oil sending unit, one that sends to the dash is above the oil filter on the driver side. If that is a coolant sensor, then I'll be damned i've been filling up the coolant and oil in the wrong places for all my life all of my cars. This is the one for the dash mind you. The one for the ecm, i believe is by the distributor (but I don't have personal experience with replacing this one so I am unsure about the location). The coolant sensors you are talking about are a) at the front of the intake manifold or block, driver side (for 89 350 TPI) and b) just under the driver side exhaust manifold near the alternator (for 89 350 TPI).

 

The one above the oil filter near the grounding location is the oil temperature sending unit, not pressure.

 

There is no need for an oil temp on these cars, and there is not a temp guage. have you ever had one off? it is a pressure unit. On my 89, is it both the dash and the ecm unit, NOT A TEMPERATURE UNIT.

on his car, an 88 it would be 2 seperate units, the one i told him to look for, not knowing if it was the same as mine because i did know they changed things occasionally, was his pressure sending unit. They did have two on his car, one on top of the engine, which as it turns out was for the dash, and one by the oil filter, which as it turns out was for the fuel ( I do admit that I had the two mixed up for his car, but it mattered not because you attacked me before I mixed them up in a hasty reply). if you don't believe me, well then, check out some of these posts.
https://www.thirdgen.org/techbb2/sho...essure+sending

https://www.thirdgen.org/techbb2/sho...essure+sending

hope that clears it up for you....

 

First of all, chill out. I didn't attack you. I said "You may be thinking..." I didn't go off on a rant calling you stupid or anything of the such as you imply. Get off your high horse, sit down and relax. Have a midol or something before you accuse me of such things.

Secondly..... I assumed (which apparently was wrong to do) that it would be the same as the TPI system on my '87 vette with a 165 ECM and pretty much all TPI Y-bodies in the years surrounding it.

The vettes have a temperature sensor above the oil filter (which yes I have had off before) and the pressure unit mounted by the distributor. I don't understand why there would be a pressure sender by the filter. It makes no sense to me to read the pressure at the filter before it has gone through all of the bearings where it matters most. Reading it at the top of the block shows a true pressure value. The temp sender is used to notify the driver of a high oil temp condition on our dashboard which does have an oil temp readout.