Idles fine, falls on its face in gear
 

My 88 suburban has the 350 tbi in it and I've been having issues where I barely have any throttle in gear. It'll idle fine, bogs down occasionally but I tap the gas and it evens back out. When it's in gear no matter if the engine is hot or cold, I have almost no throttle, it'll get enough to taxi it down the driveway but that's it. The driveway being about 70-80 feet. I've already tried a new tps, map sensor, o2 sensor, new fuel pressure regulator, and have gotten nowhere. It's got codes 33 and 34 showing up so I'm wondering if it ain't the actual wires going to it. Any ideas or possible suggestions would be greatly appreciated.
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Re: Idles fine, falls on its face in gear
 

I don't know about the codes but just for good measure, check all the fuel lines for damage and replace any inline fuel filter if you haven't.
Best of luck, hopefully the someone here can help with the codes.

Re: Idles fine, falls on its face in gear
 

Put a new fuel filter in, still having the same problem, tracked the lines from the engine bay all the way back to the pump, there was an area that had crud and felt wet, along with the smell of gas, It wasn't actively leaking but I'm wondering if that could be a contributing factor, I forgot to mention in the original post but in park or neutral I can rev it up no problem, there's also a smell of fuel from the exhaust along with blue smoke. I'm looking into replacement lines now but I've also googled the codes, code 33 said low voltage to the map sensor, and code 34 is high voltage to the map sensor, along with code 45 which was oxygen sensor rich. A buddy of mine said it could possibly be the fuel pump? Which I guess just doesn't make sense to me because it'll still rev up fine, but who knows. Thank you, for your time and the suggestion, I'll be looking into new lines today.

Re: Idles fine, falls on its face in gear
 

Do you have any vacuum leaks?

Is the EGR valve stuck open?

Re: Idles fine, falls on its face in gear
 

Replaced all the vacuum lines I could see about 3 months ago, I'll double check that and figure out how to check the Egr, then I'll report back

Re: Idles fine, falls on its face in gear
 

Link: https://troubleshootmyvehicle.com/gm...gr-valve-tests

TEST 1: Continuous Vacuum To EGR Valve
EGR Valve Stuck Open. Diagnosing A Stuck Open EGR Valve (GM 4.3L, 5.0L, 5.7L)
The fuel injection computer is the one that regulates the opening and closing of the EGR valve thru' the application and release of vacuum (through a vacuum solenoid).

One side of the EGR vacuum solenoid (the one that has only one vacuum inlet port) connects to the vacuum port labeled with the letter J on the throttle body.
Ezoic

In case you're wondering, the letter J is embossed above the vacuum port on the throttle body.

The other side of the EGR vacuum solenoid has 2 ports. One is a vent port (that vents vacuum to the atmosphere) when the engine is idling. The other port connects to the EGR valve and should only have vacuum when the PCM commands the solenoid to activate.

So, the first thing we'll do is to make sure that vacuum is not being applied to the EGR valve when the engine is just idling.



These are the test steps:

1
Disconnect the vacuum hose that connects to the EGR valve vacuum port. Leave the other end that connects to the EGR vacuum solenoid connected to it.

2
Connect a vacuum gauge to the vacuum hose you just disconnected from the EGR valve.

NOTE: If you don't have a vacuum gauge, don't panic. You can still check to see if vacuum is present in the vacuum hose.

3
Start the engine and let it idle and check to see if the vacuum hose has vacuum.

The vacuum hose that connects to the EGR valve should not have vacuum.

Let's take a look at what your test results mean:

CASE 1: Vacuum WAS NOT present. This is the correct and expected test result since manifold vacuum should NOT be present when the engine is idling.

The next step is to remove the EGR valve from its place on the intake manifold and make sure it's valve pintle is not stuck open. For this test, go to: TEST 2: EGR Valve Pintle Stuck Open.

CASE 2: Vacuum was present. This is a problem, since vacuum should not be present when the engine is idling.

This could be caused by one of two possibilities, either the EGR solenoid is defective or the vacuum hose is attached to the wrong port on the EGR solenoid.

Resolving this ‘continuous vacuum to the EGR valve at idle’ problem will solve the EGR valve and rough idle issue.

Re: Idles fine, falls on its face in gear
 

The Egr had no vacuum, replaced all the weathered vacuum lines and have since gained more throttle, went from having barely any to roughly half throttle before it bogs down and stalls, disconnected the battery to reset codes and the only one that came back up was code 33. Also, another thing I feel is worth mentioning is before it stalls there's a pop sound from the engine bay. Possibly backfire maybe? But nothing from the exhaust.