Cars acting REALLY funny

[Lupo222]

So I haven't driven the car much the last month or so, but tonight I took it out for a 5 mile trip to the movies. When I left, it ran fine. About a mile into the trip, it stalled at a light and was lunging and surging real bad. I pulled over into a plaza and turned it off. Started it back up and it was fine. Drove about another mile and it started doing it again. Pulled over, reloaded my tune and it ran ok all the way to theatre.

When I left, it drove good about another mile or two and started doing it again. This time, it felt like vibrations coming from the car as well. I limped home (about 1/2 a mile) and parked it.

Tomorrow I'm gonna pop the hood and check all the vacuum lines and intake, TB plugs, everything. Reload the tune and run it again.

Any ideas??? Sounds almost like its a computer/tune issue, but also may be a cam issue...gonna datalog and send it off to Lito to see what he thinks if I can't resolve this...

 

[IHVOCD]

Try putting the stock tune back in, but don't start it. Then put Lito's tune back in and see if that helps.

 

[Lupo222]

i'll give that a shot .... im almost positive its the tune, just the way it was acting...

if that don't work, time to datalog

 

[Lupo222]

i wonder if temperature can affect that...air temp...when i tuned, it was about 100 degrees here. maybe 90 in the shade. now, its 50 or so

 

[Swarzkopf]

Sounds a lot like a vacuum line popped off.

It could be the MAF table being way off, but I doubt it would show up so quickly- drivability would probably slowly deteriorate with the falling temperature, not just all of a sudden be totally hosed one day.

 

[Mike K]

Dirty maf sensor? Or as stated a vacuum line?

 

[stkjock]

tunes don't change

check the battery voltage and alternator output as well.

 

[Hatchman]

1. Check TB, clean if dirty, could be throwing off the TPS
2. Vacuum line check
3. Clean MAF
4. No codes/check engine light?
5. Check battery voltage, off and running, if you get a bad cell, it'll be around 10volts when off and could do what you are saying.
6. Tell car this is not funny, and to act serious.

Temp shouldn't make it run like that, as MAF/IAT/PCM/sensors should compensate.

 

[Swarzkopf]

The MAF usually needs a little help from the front 02 sensors in keeping fueling accurate across a variety of conditions- while the MAF is able to compensate a lot, a dramatic change in temperature/air density does throw the MAF transfer off by a bit. At most throttle conditions, this is resolved by the front O2 sensors reporting actual fueling vs predicted fueling (via MAF values) and the change is applied via fuel trims to keep fueling accurate.

I've seen cases where the MAF may appear to be spot on in 80* weather but way off in 20* weather...and fuel trims can only do so much.

All that said, I still suspect that in the OP's case it's something else- probably a vacuum line that popped off.

 

[Jefro]

How old is the gas? Maybe try fresh gas first

 

[Lupo222]

gas is pretty fresh...a month maybe, but the tank before that sat for 7 months while i was in afghanistan...maybe 1/4 tank. I couldn't run it all the way down before i left.

also, the other day i had a dead battery. this is the first time i drove it since i put in the new one...maybe thats the problem? alternator? thats kinda weird though...this ALMOST felt mechanical <gasp>

 

[retfr8flyr]

It sounds like you may have water in the gas from it sitting so long.


Earl

 

[Lupo222]

think i should buy an additive to clean it out? any recommendations?

 

[Hatchman]

Bad battery will give all kinds of problems, lights turning on and off, engine sputtering. A quick trip to Advance/Autozone will get it checked out if you don't have a cheap voltmeter.

 

[Lupo222]

Bad battery will give all kinds of problems, lights turning on and off, engine sputtering. A quick trip to Advance/Autozone will get it checked out if you don't have a cheap voltmeter.

Ya I just bought a new one. That one was 5 years old

Any advice on a fuel additive for bad gas (water?)

 

[retfr8flyr]

I have had good luck with a product called Dry Gas. I don't remember who makes it but you should be able to get it at Auto Zone or similar places.



Earl

 

[Lupo222]

I went to autozone and got it. Ran the car about 10 miles or so. Started out slow to make sure it's ok. When it didn't act up, I slowly got more aggressive until I could do some WOT pulls. Then ran it a while after and all seems well. A little hesitation in first barely noticeable...but everything else is great. Let's hope it stays that way

 

[char259]

Hope it stays that way for you. What pullies are you running for the 12psi

 

[Swarzkopf]

FYI, that fuel additive is probably reducing your octane by a little bit. I'd not go WOT until you're next tank of gas.

 

[Lupo222]

thanks...i smelt it and it smelt like something flammable lol...can't imagine it drops it much, especially since my tank is full. But when I get about 1/2 way, I'll top off and continue doing so for a couple of times here.

I have the 3.2 on there now...going 2.8 soon