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Ummm, what the hell, fast one day then slow the next day!!!??

1.6K views 12 replies 8 participants last post by  Otis  
#1 ·
Ok I have been having this problem for the past few months.
One day the car will just scream like a bat out of hell and then the very next day the car feals slow as shit, then a few days later it's fast again on the same tank of gas.
Like for example last night I was tunning the afc on my 93 talon tsi and the car would just sream like hell, I loved it. Then today I havent touched a thing on the afc and now the car feals slow as hell, like the boost is getting choked up, but it's the same boost level.
Just this past month I have installed denso 660cc injectors and a super afc along with a centerforce DF clutch.
Does anybody know what could be causing this? It's not a boost leak at all, Ive checked it.
Oh ya and the exhause sounds different from day to day, like last night it sounded deep and smooth, and today it sounds loud and crappy, WTF!!!!!!!!!!!!! HELP!!!!!!!
Could I be doing some thing wrong on the afc?
.90-91v on the o2 readings......
 
#2 ·
I always say "invest in a TMO Datalogger". This way you can find these annoying "gremlins" much easier. Mine had symptoms like yours, and it turned out to be a hyperactive knock sensor. Sounds like your timing is being pulled back for some reason or another.

http://www.tmo.com/ for the logger, best $300 you can spend. You can also get the pocketlogger for less, IF you have a palm pilot.
 
#3 ·
Bad battery

Well after all this time it ended up being my battery, it's got a dead cell in it, so it would not charge up enough.
So therefor the reason it was running great the night before is cause the temp out side was like 47 degrees, and then the next day in the day time it was like 72 degrees.
Anyways during the day the radiator fan would come on every stop light I came to, putting a load on the motor and the volts would drop really bad. At night the fans wouldnt kick on as much as during the day. It's fixed now that I have a better battery in it, see when the battery would drop in volts It would mess with the injectors causeing it to stumble and do weird stuff.
But with the new battery I have notice a pretty big differenc in performance:) cant beleive it was somthing so easy, dumb me hehe;)
 
#6 ·
Re: What mods?

kid-tsi said:
Evil,
What mods do you have?
I am all so a FWD I am just curious what mod you have.
Kid
Here is the current mods that I have done...
removed air can & silencer
k&n filter
joe p manual boost controller
2" upper & lower I/C piping
blitz super sound blow off valve
fuel pump rewire mod
wallbro 255 lph high flow fuel pump
3" cat back
tighter shift mod
2nd generation throttle body elbow
starion front mount I/C
3" ABS intake
modified maf
denso 660cc injectors
apexi super AFC
center force DF clutch
auto meter a/f mixture gauge & pro shift light
Auto meter boost gauge
blitz turbo timer
greddy upper strut tower bar
intrax lowering spring

Now when I ran that 13.17 @105mph last year this is what I had.
removed air can & silencer
k&n filter
homemade manual boost controller (set at 17-18psi)
2" upper I/C piping
blitz super sound blow off valve
35$ blue thunder plug wires
fuel pump rewire mod
wallbro 255 lph high flow fuel pump
3" cat back and every thing else was stock:)

So the tracks open here on march 31st, and I should be able to run high to mid 12's with no problem, and the boost set at 22 psi on race gas:)




[Edited by evil_eagle on 03-21-2001 at 12:46 PM]
 
#9 ·
hey evil are you still on the stock 14b?? If so what is it ported??? Damn impressive times
 
#10 ·
My car does that sometimes, especially when my boost levels are on the border of fuel cut. I think its the timing being pulled, and after some easier driving it seems to advance it again. You may not actually be getting knock, your knock sensor may just be a little anxious. Id bet thats your problem.
 
#11 ·
BlkGost said:
hey evil are you still on the stock 14b?? If so what is it ported??? Damn impressive times
LOL thanks man, yes it is the stock 14b, NO it isnt ported at all, I thought the same thing when I first got it and went from 15.0 flat bone stock to 13.17 @105mph within like 3 months with only 450 dollars put into it:)
And the most reason is that I have great compression, I tested it just last month and this was the result with 110k miles on it
#1-160
#2-160
#3-155
#4-153

So really the motor is in GREAT shape:) Thats the main reson it is so fast with very little mods;)
But ya hopefully I'll beable to show some more impresive times this season, I'm pretty sure that it will run 12's this year:) Wish me luck....
 
#12 ·
About the slow one day fast the next thing, my car does that really badly too. How did a dead battery cause this? When the car is running it doesn't even use the battery, it runs off the alternator. I'm just curious because I would love to fix the problem too, yes I know, a Pocketlogger will be bought eventually, $$$.
 
#13 ·
The power from the alternator still has to go through the battery. Think of it as a filter for the electricity. It cleans it up somewhat. Plus if more of a strain is placed on trying to charge the battery...you kinda see where im coming from. At least that is the way i see it.