Greetings! I am new here, and now the new owner of a v6 85 Firebird auto, that I already love despite it being a major project, and still giving me troubles.

So the good news is the car seems to run great after its been warmed up and moving around for awhile. Despite some vibration/rattles, it really does handle great.

The bad news is, when you first start the car, it behaves strangely it seems.
Initial start will idle at around 1100 rpm's, with a oil pressure of around 60ish?
Any initial driving will have hesitation and hard(seems like delayed as well)shifting up until past 37 or so (3rd gear?) temperature wise we will climb until around 220-230.

After a few minutes of driving like this (5-8 minutes probably) things change drastically. Idle becomes stays around 600, oil pressure drops down to about 30, hesitation seems to go away, and shifting smooths out quite a bit. The car then drives fine, until I turn it off again.

I have put new plugs/wires/kn air filter/pcv valve into the car, I mean to replace rotor/cap(cant get the back screw out so far) , and the fuel filter. I also plan on cleaning the IAC, and adjusting it and TPS if needed.

I have made a data cable to do logging, but haven't been able to get it to work so far. So that and the fuel filter are my current priorities, I'm hoping that the data logging will tell me the general status of the TPS and so forth.

I'm also noticing what seems like below par fuel mileage if the 23 mpg range is accurate.

Just looking for advise on what could be going on (my fear is ECM problems) and saying hi, since ill be around here alot probally.

 

WELCOME to TGO.
you did not list your location in your member info, where abouts are you?

well, on to the tech:
RE: oil pressure. BOTH of my cars do the same thing. my 2.8 and my 5.7. my 5.7 does this with a NEW sending unit. so far as i can tell it is normal for the Oil Pressure to read high until the car is warm. someone correct me if i am wrong.

RE: temperature. unfortunately this is "normal" as well. when i say "normal" i mean they left the factory with the intent to run that hot. many people feel this is TOO hot for an engine to run, and there is some debate to that, but for the most part cooling modifications are in order. if your car is indeed fuel injected the fan is controlled by a sensor in your cylander head. and IF you have air conditioning there is also an air conditioning pressure switch that tells the ECM to turn the fan on when the air conditioning is on.

1st and cheapest. a toggle switch.
on your fan relay (located on your firewall on the relay bracket next to your brake booster) there will be a green w/white striped wire. this wire is grounded by the ECM or sensor when your fan is to come on. YOU can ground the wire whenever you want and the relay will engage the fan. so all you need to do is solder or splice a wire on to that one, run it to a switch in the passenger cabin and flip it when ever you think the fan ought to come on. if you wanted it to be real low key you could trace the wire to the ECM and splice it near the ECM connector, this way you keep wire mess out of your engine bay. you could also splice this into the plug on your air conditioning where the green white wire is.

2nd. a head/block coolant sensor switch.
your cylinder head has a sensor in it (rear of passenger side head IIRC). it grounds the relay @ 233*F from the factory. you can go to NAPA and purchase one for a different application (same thread size) and get one that comes on as early as 200*F. (probably a marine application)

3rd. radiator coolant sensor switch
same as above, but you put a plug in between your radiator fins. not as factory looking. and a little more expensive, but easy.

RE: 6-8 minutes and then things change.
when you first start a computer controlled car, be it a TPI 350 or a CCC 2.8 it starts off in "open loop". in this mode the engine IGNORES the o2 sensor and just does it's thing. it knows what it needs to do to run the engine as long as nothing is screwed with (IE idle adjustment screws on carbs or TBs). after the engine warms up it enters "closed loop" and begins listening to the O2 sensor to adjust fuel accordingly. if your car runs rough at first and then runs fine once it enters closed loop this means it is NOT a problem with your o2 sensor.

RE: high initial idle.
more then likely someone has tinkered with the idle set screw instead of adjusting minimum air in the proper way. do you know how to set your IAC minimum air? here is a link to the tech article URL="https://www.thirdgen.org/tpimod2"]TPS/IAC tech article[/URL]
doing this should fix your high idle issue. but be sure you do it when the car is cold.

People who know more then me: did i mix up the open/closed names? i know i got the descriptions right. (as right as i understand it anyway.)

 

Well, you kind of got the descriptions right. During Open loop, the only sensor that is "ignored" is the O2. All the other sensor (MAF/MAP, IAT, ECT, TPS) are still used for load sensing and fuel delivery.

The idle thing is normal. It's actually programmed in to idle high on start up for 2 reasons. 1: It helps a little with idle quality when it's cold. 2: It sounds silly, but with the FI engines, it's not needed and it's there because this was a transition from carburation. With Carbs and chokes, the idle was higher on start up, this FI "fake" fast idle helped people make the transition to FI easier with fewer complaints, people don't like change that they can see.

Warm temp is good for the car...to a point. Warmer engines have better combustion with less emissions and better milage, but not as much power. 220-230 is normal, any higher than that and I would start to worry.

Running well after a few minutes can indicate a problem with TPS, ECT, IAT or MAF/MAP. Typically, a temp related problem will be an issue with the ECT or the IAT. The ECT is the more likely culprit since it has more affect on fuel delivery than the IAT.

Somewhere on this site there are testing instructions and sensor range specs for all the sensors. for them and you'll learn how to diag your car the right way.

Welcome and Good Luck

 

Thanks for the replies, I updated my profile information, I'm located in rainy Portland.

I'm glad to hear the oil pressure seems to be normal.
Yes the car is fuel injected(MPFI) and also has AC, I've been reading, and theres been mention of air dams being under the care to bring up air intake? Is this suppose to be present on a 85? What does this look like as well, I don't believe mine has one. My trashy Haynes Manual also makes no mention of this that I can find.

I will do a search for the sensor information post, I have never heard of ECT sensor, nor does the generally worthless haynes manual mention it that I can find.

Thanks for the welcome guys.

 

WOW! I'm in Hillsboro. if you ever need any help or tools just let me know. i am also a member over at www.cascadecrew.org message boards. we are a local NW carclub with many members in portland, and we are always willing to give beginners a hand with cars. check us out.

2.8boy. thanks for the more specific info, I'll edit my post to remove the incorrect information.