08 Vibe Intake Manifold Gasket then no more pickup

[nanookofnj]

Hello. Last Friday the check engine light came on. I had it run at a local Auto Parts store and the diagnostics said bad Intake Manifold Gasket. Looking online this was common with 1.8 L Toyota engines so I dropped it off at the shop and told them to please confirm my findings and then replace the gasket. The code was P0171.

I just got it back from the shop where they replaced the gasket, but now on the ride home, I have zero pickup. I mean I can stand on the accelerator and nada. It eventually gets to running speed, but there's no power anymore, and there used to be.

Any ideas? 101K 2008 Vibe. Thanks!

[vibrologist]

In reality there is no code for the IM gasket. The code says "lean condition". Typically that is caused by a vacuum leak somewhere between the MAF sensor and the intake. Let's hope it was nothing but a bad IM gasket.
Maybe the shop disturbed the Throttle body in some way. This is a drive by wire throttle. This is just a guess. I suggest taking it back tot he shop and showing them the issue.
Another thing you could do is disconnecting the battery negative cable and then stepping on the brake pedal for a few seconds. This should reset the computer. Reconnect the battery and see if something has changed.

[sideshowalan]

If they did replace the intake manifold gasket, there are a handful of vacuum hoses that must be disconnected, one in particular is very easy to miss when hooking it back up, they probably just forgot to plug it back in.

[vibrologist]

Sideshowalan reminds me of something. Do you have a lot of misfire and horrible brakes? If so they forgot the brake booster hose.

viewtopic.php?f=30&t=43476#p508663

[nanookofnj]

Thank you all for responding.

No mis-fires and breaks are good. The accelerator felt like it was already depressed when driving, I'm leaning toward the throttle cable or possibly them forgetting to re-attach a hose, as you both mentioned, or not knowing that one of the hoses is leaking. No engine light on after replacing the intake gasket though, despite not being able to hit 2000 RPM last night on the way back to the shop.

More to come. The mechanic who tested it this morning stated "the gas pedal seemed like it was stuck in the depressed position". Will report back once I get her back. Thank you all again.

[vibrologist]

You don't have a throttle cable. It is an electronically controlled throttle.

[nanookofnj]

The Service Manager called me before lunch. There are apparently 2 screws that connect the gas pedal, one was gone and the other had worked its way out. Unreal. At least it was an easy fix! Thanks again all for the info.

[lannvouivre]

They should not touch the gas pedal for a lean condition. I think what they probably meant was that the two bolts for the throttle body (the other two are nuts on studs) weren't tightened correctly. Again, the gas pedal is basically like a remote inside your car. It's connected to the engine computer via electrical wires, and the computer is connected to the throttle body with more electrical wires.

A lean condition, P0171, is caused by a leak in the intake system of the engine sucking in air that's not getting measured. The MAF, mass air flow sensor, measures the air going into the engine. A crack, bad gasket, or loose component after the MAF, can cause extra air to be sucked in. This means the computer is telling the engine to put in the wrong amount of gas for it to run optimally. The O2 sensor (or in your case, a wideband air/fuel ratio sensor) then tells the engine computer, via exhaust gas analysis, "oh crud! We're not adding enough gasoline!"

All your gas pedal does is control the movement of the throttle body. The throttle body comes after the MAF and controls how much air the engine gets. The engine computer looks at the throttle position and the gas pedal position, plus data from the O2 or wideband sensor, to decide how much fuel it needs to use for the car to both run correctly and obey your commands.

In a rich condition, the engine adds too much gasoline (usually due to a bad fuel injector or plugged air filter).

Does this help you better understand what's going on?