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Topic: 1985 3.8 engine Q's (Read 4085 times) previous topic - next topic

1985 3.8 engine Q's

Reply #30 –
Codes?

Also, it is std. procedure to replace the O2 sensors when you do the head gaskets as the antifreeze can corrupt them.

1985 3.8 engine Q's

Reply #31 –
Yes, rerun codes.

Are you sure you got the TPS installed correctly?  It should not be at .5V either.  AFAIK it should be ~.9V like every other EEC4 system.
Long live the 4-eyes!  - '83 Tbird Turbo - '85 Marquis LTS - '86 LTD Wagon

1985 3.8 engine Q's

Reply #32 –
TPS should be about .94 - .98V when idleing, warmed up, and in park.

Just out of curiosity, was this '85 a Canadian bought car?  As far as I always knew 3.8L were carbed in Canada untill 1987.  My first car a 1986 T-Bird was carbed. 

Also a broken FPR creating too much fuel pressure will cause a cfi to run rich only at idle.  I don;t remember the correct pressure numbers.

1985 3.8 engine Q's

Reply #33 –
How would I check for a broken regulator? I turned the tps down to .5 to try and get it running a bit leaner, still way rich as is.

The problem is mainly when you first get going or at low RPM's, you gotta be real easy on the petal but once its up past say 200rpm you can floor it and go.

Now that you mentioned it it does sound like it could be the fpr..
1980 birds X 3, 1982 bird, 1984 XR7, 1988 TC

1985 3.8 engine Q's

Reply #34 –
Got a fuel pressure gauge?  Check the pressure.

Have you run codes again?

Adjusting down the TPS is not going to help.  Set it to the correct voltage.
Long live the 4-eyes!  - '83 Tbird Turbo - '85 Marquis LTS - '86 LTD Wagon

1985 3.8 engine Q's

Reply #35 –
Quote from: merccougar50;106320
TPS should be about .94 - .98V when idleing, warmed up, and in park.


Not correct for this engine.

The KOEO tests check for the correct TPS voltage with the ISC motor fully retracted and the throttle linkage against the throttle stop adjusting screw.
The engine temp. has no affect on this. With the engine running the EEC is going to extend the ISC motor.

If the TPS voltage is out of specs it will give a code 23.

I can't believe they would design something that is mechanicaly operated to require a operating range of a couple of hundreths of a volt.

I took some TPS voltage readings on my 3.8L '84 T-Bird with various shims between the throttle stop screw and the linkage.

.75v code 23    .80v ok  1.02v ok  1.07v ok  1.14v ok  1.23v ok  1.33v code 23

1985 3.8 engine Q's

Reply #36 –
Did you change your coolant sensor?  That is what was killing my 83, I know they have different computers but it would cause the same problem.
One 88

1985 3.8 engine Q's

Reply #37 –
Quote from: softtouch;106561
Not correct for this engine.
I actually got some help on another forum and git it correctly adjusted. put it in test mode, unplug the ISC, take out of test mode and start it up, turn idle adjust screw till car just runs and set the tps there... just incase anyone else needs to do it.

Quote from: CougarSE;106572
Did you change your coolant sensor?

nooo, the tep gauge works fine.. does it use a different sensor? also the wire for what I think is a temp sensor has all the insulation burnt of.... havnt gotten around to fixing those yet though..

Thanks for all the help guys, once I finnish my curent mission i'll get back on to the stang and try to get it sorted out.

Scott
1980 birds X 3, 1982 bird, 1984 XR7, 1988 TC

1985 3.8 engine Q's

Reply #38 –
Quote from: tbirdscott;106616
I actually got some help on another forum and git it correctly adjusted. put it in test mode, unplug the ISC, take out of test mode and start it up, turn idle adjust screw till car just runs and set the tps there... just incase anyone else needs to do it.

Actually, that is the incorrect way to set the ISC. softtouch gave you the correct way in post #19.
Quote
nooo, the tep gauge works fine.. does it use a different sensor? also the wire for what I think is a temp sensor has all the insulation burnt of.... havnt gotten around to fixing those yet though..

Yes, the EEC uses the ACT (2 wires) and the cluster uses a 1-wire sensor.

1985 3.8 engine Q's

Reply #39 –
Quote from: JeremyB;106625
Actually, that is the incorrect way to set the ISC. softtouch gave you the correct way in post #19.

Thats how you set the tps :raspberry And yes I followed softtouch's instructions to set the IAC there after.

So the wire for my temp gauge is the one thats fried, the wires for the other look fine, this car is deathly original though i'm sure it should be replaced.
1980 birds X 3, 1982 bird, 1984 XR7, 1988 TC

1985 3.8 engine Q's

Reply #40 –
Quote from: softtouch;106561
Not correct for this engine.

The KOEO tests check for the correct TPS voltage with the ISP motor fully retracted and the throttle linkage against the throttle stop adjusting screw.
The engine temp. has no affect on this. With the engine running the EEC is going to extend the ISP motor.

If the TPS voltage is out of specs it will give a code 23.

I can't believe they would design something that is mechanicaly operated to require a operating range of a couple of hundreths of a volt.

I took some TPS voltage readings on my 3.8L '84 T-Bird with various shims between the throttle stop screw and the linkage.

.75v code 23    .80v ok  1.02v ok  1.07v ok  1.14v ok  1.23v ok  1.33v code 23



Sorry:sorry: . My bad.  That whole previous post of mine was wrong.  I was thinking of my SEFI 5.0L where hundreths of a volt DO matter on the TPS.  For anyone else reading this SEFI also should be checked key on engine off measuring the voltage between both outside wires in the three wire connector.

1985 3.8 engine Q's

Reply #41 –
I guess ill chime in,,,,,,,,,,,

As always with the 3.8 cfi, and i say ALWAYS and FOREVER,,,,, the first thing that hampers engine perfromance is the EGR base plate and trottle body base carbon build up. When the gold vac elbow fitting on the rear driver side of the CFI can not get proper vac becasue of carbon, the egr is not able to actuate properly.  When it can  not move or is carbon'd up as well, the EVP sensor can not chime in to its common buddy the Map, then the engine can not determine proper idle speed and the tps voltage range becomes more and more out of range.

Rule of thumb,, with CFI's,, always remove the CFI (4 nuts) and the egr base plate and chip away at anything that does not belong then reinstall.

The TPS was at one time adjustable as the mounting holes were at one time sort of oblong shaped.  I brought this up not and then but no one seems to remember.  Anyway, to make it adjustable,, just use a 7/32 chainsaw file and make the holes oblong yourself.  Then you can pretty much dial in the voltage you need. 

As far as the injectors,, ill bet you experience a slight hesitation before the actual power kicks in.  The fix,,,, remove the injector screens  and either replace them ore just leave em out.  I dont run screens in mine.

As for your idle control motor,,, sounds like you have a hard to find working unit,, if you decide to run without one,, you will quickly notice what its primary job is,,, it slowly allows the engine rpm's to decrease when you let off the gas instead of a sudden drop in trottle plate movement from open to close.  Makes for a smoother feel when letting off the gas.

I guess from what you said,, it was fairly virgin under the hood and if so, i would have never hampered with the tps or the isc until i removed the CFI and got rid of the carbon.  Call my bluff on the carbon thing but you will be amazed if you take a moment to look.

1985 3.8 engine Q's

Reply #42 –
Quote from: tbirdscott;106616
I actually got some help on another forum and git it correctly adjusted. put it in test mode, unplug the ISC, take out of test mode and start it up, turn idle adjust screw till car just runs and set the tps there... just incase anyone else needs to do it.Scott


The shop manual proceedure for setting the throttle stop adjustment screw starts with a new screw.

With the throttle plates closed, turn the screw inward until there is a .005 inch gap between the screw tip and the throttle lever surface which it contacts.

Turn the screw inward an additional 1 & 1/2 turns.

1985 3.8 engine Q's

Reply #43 –
Quote from: jcassity;106781
Rule of thumb,, with CFI's,, always remove the CFI (4 nuts) and the egr base plate and chip away at anything that does not belong then reinstall.
Well when I replaced the TPS (it was shot) I had to remove the cfi and the egr got cleaned out, and the tps holes ovaled out (I remembered that one ;) ) the egr valve is fairly new. Just tested the fuel pressure and its right at 39 where its supposed to be, ignition off and running.

Quote from: jcassity;106781
As far as the injectors,, ill bet you experience a slight hesitation before the actual power kicks in.  The fix,,,, remove the injector screens  and either replace them ore just leave em out.  I dont run screens in mine.
How do you remove them?

Quote from: jcassity;106781
As for your idle control motor,,,Makes for a smoother feel when letting off the gas.
so it doesnt really matter then? it will just feel like a standard? I hate the idea of a computer controlling my throttle anyway...

Quote from: jcassity;106781
I guess from what you said,, it was fairly virgin under the hood
In my experience thats never a good thing... and yeah, the egr had some pretty big chunks of  in there.

Thanks
Scott
1980 birds X 3, 1982 bird, 1984 XR7, 1988 TC

1985 3.8 engine Q's

Reply #44 –
ttt
1980 birds X 3, 1982 bird, 1984 XR7, 1988 TC