Car runs worse after dark ?

[turbotaone]

My TTA is not running to good and I think that it may be
something in the electrical system. It seems to run worse
after dark when I have the headlights on. I drove it today when
it was about 75 degrees and sunny outside and it ran pretty
decent unless I tried to floor it, than it would stumble and surge
and then smooth out and pull strong. If I slowly gave it gas it
would pull smooth clear up to red line(18lbs.boost)and ran fine.
The scanmaster numbers all look good,except the 02,s are a little
high(mid 800,s)which I know the car runs rich. Here is the part
that I don't understand, since the car is rich it should run better
when the weather is cooler, right ? Well I took the car out tonight
and the temperature was about 60 degrees and the car ran really
bad. It ran good if I was just cruising around with no boost,but if
I tried to give it gas and build some boost it would start missing
real bad and it felt like it was loading up and a couple of times it
did take off,but I could feel it surging really bad as it exelerated.
The only thing that I did different between today and tonight was
turn the headlights on. Could this be an electrical problem causing
this ? Could it be a bad ingition module ? I already replaced the
coil pack,02 sensor,and maf sensor. What do you guys think ?

Thanks James

 

[gofastr]

gremlins usually only show their cowardly faces at night. If I were you, I would contact an exorcist to get rid of those demons.

 

[Hawaiian Turbo]

Check the volts with the lights on then off. Could be the regulator not keeping up with the voltage needs. That will cause problems. HTH

 

[Buick Beginner]

Idea

Another idea is to find a well lit area that you can drive on at night and not run your lights. Maybe a road with tons of street lights. Then you would have at least another piece of good info. for your trouble shooting, becareful though. - BB

 

[Lee_Burough]

When you said the scanmaster numbers were good, I assume you meant that the battery voltage was steady under acceleration and with the headlights on....right?

If yes, you might need that exorcism

I suggest you post all your scantool numbers for the experts to evaluate and make some suggestions. I'm wondering if your MAF is pegging out at 255 or some other smaller number (does it pass the "tap" test?). BLM's and other PCM values would give us a look at the bigger picture.

I'll go ahead and humbly state the obvious here: Do not overlook some basic things like plugs and wires....I had a very similar problem with my 87 TR LTD (with normal scan tool numbers and passing the "tap" test), it ended up being bad plug wires and that discovery was after a lot of wasted energy and money....Those wires looked great too

good luck