Hi,

I've had this problem for awhile, but it seems to be worse lately. It used to happen only when the car was cold, but now it's more often.

I have a ScanGauge OBDII thingy, which displays ignition timing, IAT, etc. At partial throttle, in any gear, but particularly in the higher gears, such as on the hwy, the car will studder, timing will go negative, and the car will fall flat. Boost building sounds different as well and I can smell exhaust if the windows are open, even on the hwy. Boost gauge will still show normal boost. I have to back out of the throttle. Sometimes backing out and giving more throttle (60%+) will eliminate the problem. Sometimes I just back out of the throttle and ease in a few times before it will go away...

It could be knock, but again this is light load with partial throttle. Maybe it's the tranny noises being detected as knock?? With the different sound and smell, it's probably a leak though, right? Could a boost leak or exhaust leak cause the car to pull timing like that?

Car has ~101K miles, so I'm now trying to go through and replace old stuff anyway. A few months ago had an AMS IC and full IC piping installed. I just ordered a mil.spec HF cat to replace the Random Tech that I've had for several years. I'm also planning to install a mil.spec tb. If the TB seals are bad, could it be the culprit? I'll have a boost leak test to confirm, but looking for any other ideas.

Thanks,

FB

 

To bump and also add info, the issue is intermittent, which is why I wasn't sure how the leak would cause it? Would a leak in the TB be intermittent and possibly worse at partial throttle? Just say yes so I can justify the purchase of a mil.spec tb to my wife...

 

if you can hear something that sounds like a boost leak, or a funky noise under boost, when its pulling the timing it sounds like you are having the same issues as me. we need to keep in touch to solve these issues, cuz i spent olot of cash alrezdy trying to fix it.

but i unplugged my mivec oil control valve solenoid, and the car runs perfect. i think something is making this chatter causing the car to pull all timing...

keep in touch

 

adding to that, i def do not have a boost leak. its something electrical making false knock causing the knock sensor to pull the timing

 

Hey,

Just an update, went through and tightened my IC piping couplers. I found that my cone filter was pretty loose (it's a simple MAF adapter setup). Tightened it up and I've driven to work once. I think I still have a leak in the exhaust and maybe around the TB, but it didn't pull timing like crazy like it usually does on the hwy.

A couple of times, timing did go slightly negative, but the car didn't fall flat and make the "weird" noise while building boost...

Have a new mil.spec HF cat, 65 mm TB, and a Map 02Elim dp on order to address the leaks, but hopefully this other problem is mostly solved for now? We'll see how it holds up.

 

Did you guys ever find out the issue?

 

Also curious if you ever diagnosed this problem. From my past experiences, i would bet on either a phantom knock from other engine components, or a decent leak in the intake system. Knock would obviously pull the ignition (Check your scanner to see if its tracking knock? See if it goes buck crazy under load when it normally backs your ignition off). It could be a sensor going bad too, the older they get, the more sensitive it seems they become, picking up vibrations from outside of the block. With 100k+ its probably a good idea to start replacing some of those key parts. Hope this helps, let me know if you figured this one out.