when i go to start up my baby it stalls out if i don't tap the gas before it dies. It even does it after the 3k warm up. could this be a dirty fuel system? or poor spark?

 

Hey Alex, its David from KCRX7club.com, and I have the same problem. I think I have narrowed it down to a few things. I have the '3800 stumble', so I think it could be the grounding. I also am running very rich, and haven't solved that problem, but I think the problems are linked. I thik that my secondary injectors are stuck open, which would explain why I have terrible mileage even when I shift at 2500 all day long. Now if my secondaries were stuck open, thenm when I start up the car it woudl almost flood and bog when the car tried to rev to 3000 like it wants to, since the secondaries kick in at 3800 - 4000. ( I think, I don;t know for sure if thats true)

I don't know if my hypothesis is right, so somebody correct me if im wrong.
The reason I think I may be wrong is that I have the '3800 stumble' which, I believe, means that there is a problem with grounding, resulting in the secondaries not working right. (whether they don't put enough fuel or put in too much I don't know, I don't really understand the stumble that well.) I would guess that its a too rich stumble, as a too lean stumble should cause detonation. Again I don't know nearly as much about my engine as id like too, but I am starting to understand it, and I kno wjust enough to get more confused than if I knew nothing sometimes lol

I hate to be the guy who post bad infoa nd then gets flamed for it, so I made sure I said that this is what I think is happening, and not to take my word for it.

 

i belive you are correct in your thinking on the 3800 stumble. i have that too, but it stops once the motor has reached operating temperature. i have been getting bad milage as well. but mine will rev to 3k but once it dies off it bogs and dies if i dont hit the gas.

its good hearing from someone close by

 

oh and one more thing, get a volt meter and check your TPS (throttle position sensor) it should not read more than 5.5 at WOT (wide open throttle). If thats bad, then it will cause bad gas mileage, and cause your engine to run funny and do wierd stuff. Again, if anything ive said is wrong, then let me know, my word does not have years of expirience behind it like teds, so take my info for what its worth.

David

 

Masao - Just out of curiosity, have you actually disconnected your secondary injectors to check your theory? They do turn on @ 3800 on a stock S4 setup. Try disconnecting them and run the car (keep it below 3500), see what happens. If everything is the same, that's not your problem. I don't think it is, but you might be right with the running rich thing. It might be time to adjust your idle fuel mixture, using the little adjustment screw they provide. It's mounted to the passenger shock tower, on a black diamond-shaped thing with "R" and "L" on it. Turn it to R, your idle mixture goes richer, L goes Leaner. you can figure it out, go as lean as you can while maintaining a stable idle. If you do a search for 3800 hesitation or things like that, you'll find LOTS of threads about it, and a bunch of fixes.. There's also a few good links in the archives about it.

Alex6969 - It can be a fuel system clog, or a spark issue.. start with the basics: When did the problem start? Have you checked/changed your plugs/wires, fuel filter (both the one on the line, and inside the tank?) and air filter lately? It's possible that you have a minor vacuum leak as well, so if you have changed your filters and plugs recently, try spraying some start fluid around, underneath your throttle body, while your car is idleing. If it bumps up or down, then you have hit a spot where you have a vacuum leak.

 

Ok I am going to go try and adjust the idle fuel mixture right now. How will I know if I get too lean, besides idle being rough? I don't want to detonate and cause serious problems, as I have heard that can be the end to a 13B. I don't know if that is a realist thing to worry about while just messing with that screw.

 

Oh and I will be pm-ing you about megasquirting, I don't want to clutter this thread with stuff that doesn't pertain to the problem it was started to fix.

 

Got the PM, I'lll respond a bit later.. I should be working

The screw only affects your idle mixture. It will not have any affect as soon as the engine notices load in any way, shape or form.

 

OK, good deal. I will do it now. Oh and I had previously read all the archived threads about the '3800 stumble' and this weekend when I get som etime I will try to check the ground on my ecu, and see if that is the problem, as that the most common cause, form what I have heard.

Oh and by the way I don't know if I've told you, but those green flames are sweet.

 

i noticed it about a month ago after i took my emissions **** off. i had to remove the intake(filter, maf, and intake pipe thing) could i have nocked something loose like a vaccum hose or wire? nothing else comes to mind.

 

hey wanko, take the bra off and let the ******* hang out!

 

you definately could have messed something up. But it should be easy to figure out. It's not your MAF, or else it either wouldn't start at all, or it woudl start, and die within 3 seconds. I'd look for cracks/leaks in your intake piping, all the way back to the throttle body. Don't forget about the tube running off it. And check around there, to make sure you didn't jar any vacuum lines around the throttle body inlet that the pipe attaches to. It's possible that if you bumped one, it cracked due to age, so inspect them closely.

Nah, you don't want to see what's under there.. Tis a messed up bumper under that bra.. It'll be taken care of this winter, with a nice body kit and some other goodies.

As you already know by now, I responded to your PM. And thanks again for the compliment, I'm rather fond of them

 

alllrighty i'll start snooping around and find the culprit