Bucking/Stuttering while in boost?

[Benji]

First, I am running a MAF-T/3" Maf in blow through setup. I have been running this setup for several months. This last weekend I decided to replace my intercooler couplers with better ones as well as T-bolt clamps instead of using the worm type clamps. Needless to say, I also swapped my ECU for one I had bought.

After getting the car back together I checked for boost leaks and everything seemed to be fine. I started the car and drove for about 20 miles and it ran awesome. The car sat for several hours and then was started again.

Now ever since the car will stutter/hesitate in boost. First thing I did is swapped back to my old ecu. Same thing. I have been logging and found something really strange.

The o2 Voltage cycles normal while cruising but as soon as I hit the throttle, the o2's will drop between 0.04V and 0.08V ...

This happens with both ECU's.

 

[NOSLO2PT0]

Either you are pig rich or dead lean. Or need a new o2 sensor, although I doubt that's the problem. Check for more boost leaks. Super rich condition, or big boost leak (and i mean BIG) will cause the car to stutter under boost. Also detonation will cause severe timing to be pulled, which can feel like a stuttering as well.

 

[Benji]

sorry I should have added. Timing is still decent at WOT between 17-19 Degrees. No knock at all. I logged and logged and the only thing not right that I could find was O2 voltage!

 

[eclipsegsx9797]

yep all i could say is check ever housing that are on your piping i use to have the same problem when i had my greddy fmic, i had to go out and get t clamps to hold it. now with all the new kits t clamps already come with them so if u dont have them i would go take the time and get some. good luck

 

[NOSLO2PT0]

Then you got a HUGE boost leak. Or are running the car so pig rich. What turbo/boost/injectors/pump/ MAFT settings?

 

[Benji]

Originally posted by NOSLO2PT0
Then you got a HUGE boost leak. Or are running the car so pig rich. What turbo/boost/injectors/pump/ MAFT settings?

Running stock 14B, stock 450's, 190lph pump, stock smic, maf-t blow through. Maft settings are 2,2,2,2.

Thanks for helping me out man! I still don't get why the O2's drop way low?

 

[[email protected]]

Check your grounds. I had a similar problem.

 

[Benji]

Originally posted by [email protected]
Check your grounds. I had a similar problem.

Grounds to what? I know the voltage in my car is fine. The o2's cycle fine as they should be. They only drop at WOT!

 

[eclipsegsx9797]

on your battery all the lines coming off of it

 

[Benji]

Originally posted by eclipsegsx9797
on your battery all the lines coming off of it

I know they are fine. Everything else is working fine. I know my battery voltage while cruising is 13.7V and when shutoff at 12.8V!

 

[eclipsegsx9797]

ya that sounds good, im getting just about the same volt. but u could still have dirt connector i would double check but i dont even think it is any of these things, get some t clamps im pretty sure its the piping haveing a bad leak. i had the same problem like 2 weeks ago, check that then go to some plugs and wires if that doesnt work. its what i did just the oppisite so i wasted money on new plugs and wires

 

[Benji]

Originally posted by eclipsegsx9797
ya that sounds good, im getting just about the same volt. but u could still have dirt connector i would double check but i dont even think it is any of these things, get some t clamps im pretty sure its the piping haveing a bad leak. i had the same problem like 2 weeks ago, check that then go to some plugs and wires if that doesnt work. its what i did just the oppisite so i wasted money on new plugs and wires

I already replaced my clamps and am using t-bolt clamps now! I will check for more boost leaks. But I just don't see how a boost leak can affect my o2's that much! ???

 

[BUCK]

I've had that happen - I forgot to tighten the clamp at the Throttle body like a dumbass - my guess is also huge boost leak at one of the joints you worked on... Good Luck.

 

[Benji]

Originally posted by BUCK
I've had that happen - I forgot to tighten the clamp at the Throttle body like a dumbass - my guess is also huge boost leak at one of the joints you worked on... Good Luck.

So, when you forgot to tighten the clamp at the throttle body, did you get low o2's? Or just the stuttering?

 

[BUCK]

Wild ass bucking - flames out of the exhaust - all kinds of **** - I didn't get far down the street - it would purr to just above idle - but as soon as you went from a vacuum situation to ANY kind of boost the hose would flex off & all hell would break loose like flicking a switch - somehow it didn't appear to hurt anything after I tightened the clamp it purred...