Motor is bogging...again *rips hair*

Th0r · 11-03-2009, 09:42 AM

So that wonderful issue of my car bogging down at low RPMs is back again. And again, no codes. I've inspected and replaced every vacuum line I could find, gone through 2 cans of throttle body checking for leaks, and have been romping on the car while monitoring AFRs, temps, and spark with a tech2 (also found out my blower is only pushing 4psi...boo!). Everything, even at the exact moment it stumbles, reads normal.

I give. Last time this happened I screwed with it for two weeks and then it disappeared. This morning I had to neutral drop my car to get it out of a declined parking space since it would stumble and die every time I gave it gas. If I were to start shot-gunning part replacements what should I start with?

leroBob · 11-03-2009, 09:46 AM

Bet it would be nice to have a few of those $600 back to your car to the shop! jk

Th0r · 11-03-2009, 09:59 AM

Haha, I have 13 technicians at my disposal, and that's not helping! The guys that have looked at it are just as lost as me about now.

I should also note that this is not an RPM jump, but a drop. It randomly drops to about 300rpm when idling or going from cruise to WOT.

[ion] C2 · 11-03-2009, 11:02 AM

Wideband gauge or you're talking about just looking at the upstream O2 sensor's output?

Th0r · 11-03-2009, 11:36 AM

Where ever the Tech2 gets its data from. It's 14.1-5 at idle and steadily gets richer till I hit 11.7 at WOT

jayson_waltz · 11-03-2009, 12:03 PM

whats your fuel pressure reading when it stumbles? pump going out maybe?

AlbinoMonkeyRat · 11-03-2009, 12:44 PM

what's your mileage? I'm thinking a possible clogged cat...

Th0r · 11-03-2009, 01:19 PM

Oooo....I never thought of that...could that also cause an intermittent and faint "glub" noise I hear out of the exhaust after it heats up?

[ion] C2 · 11-03-2009, 03:40 PM

It would prevent you from going anywhere faster than like 25mph. It would also cause you to read more boost because of all the pressure in the exhaust. My cat clogged with 45 mins to go to reach ASS '08. And then I drove it to Midas. Massive loss of power.

clutch1 · 11-03-2009, 04:43 PM

You're boosted... time for a whole new exhaust anyways!!

undersc0re · 11-03-2009, 07:38 PM

Low rpm miss or bog would have me look towards a spark leak to ground somehow maybe through a coil housing or boot, or even bad plug. The computer may not even pick up a miss when that happens. Other than that maybe valves or injectors which is less likely.

Th0r · 11-04-2009, 08:04 AM

Injectors are new, plugs are new, coils/housing are new.