Danny Davenport

So my primary vehicle has taken an electrical dump, so I'm hustling to get my 1995 T/A on the road. When I back it out of the driveway and 1st gear it to the end of my street, I'm good. When I turn onto the main neighborhood loop and do a lazy pull through 3rd, response is great. Takes right off. But after that, the rest of the loop feels like limp mode. I'm thinking knock sensor, but this being my first build and time/budget unfortunately being an issue now, I was hoping you guys might have some ideas. I checked for vacuum leaks with a propane torch and didn't find any. Is there a way to check for knock without on board laptop reading? What else should I be checking?

Vehicle information :

95 LT1/T56 Trans Am
LT Headers
Corsa exhaust
Ws6 airbox

hrcslam

Try it again, but with the O2s disconnected. If that helps, look for an exhaust leak.

Tbird232ci

iTrader: (4)

Why do you think it's a knock sensor? Have you pulled codes? Checked fuel pressure?

Danny Davenport

Gonna pull codes tonight after work, but no CEL came on. Haven't gauged the fuel pressure, but the first pull is fine, and after the power loss it still idles and revs fine. That seems evidence, to me, that pressure is good, but I am a bit of a noob so I could very well be wrong. From what I've been reading, the symptoms are similar to picking up some knock. Was hoping my description would yield an obvious answer.

Danny Davenport

I'll try that this afternoon. Thanks.

Danny Davenport

I went to pull the O2s and came across this.

I see this as being the possible culprit for maybe two reasons:
1) there's maybe an 1/8th gap between exhaust and frame, about 6" downstream of the collector. Might even be touching. False knock?
2) those are fuel lines on top of the exhaust. Maybe getting some vapor lock? You guys see the same thing?

hrcslam

That's the drivers side right? If so, those are fuel lines.

Vapor Lock really isn't an issue with our fuel systems. They are a pressurized return style fuel system. So if it does vapor, the pressure from the fuel in the tank from the pump will push it out and the vapor will either be pushed through the injectors (rather quickly) or back to the tank. Vapor lock doesn't happen usually to an engine while it's running as the fuel is moving past the heat source too quickly to boil.

False knock could very well cause it. But, it should do it whether it's in open loop or closed loop. Disconnecting the O2's forces open loop. If it does it with the O2's disconnected, then it could be false knock from that Y-Pipe hitting the frame.

If you look at pacesetter Y-Pipes, you'll see that there's a flat spot in that particular area specifically to clear this section of frame. You could take the Y-Pipe off and bang if flat right there for additional clearance.

Also, I recommend you ditch the header wrap. It's probably there to keep the heat away from the fuel lines (I don't have anything there, just a flat spot for clearance and zero issues in Phoenix heat), but it's really not needed if you have good clearance. The header wrap is absorbent and likes to hold on to oil and other liquids. This causes premature corrosion and creates a fire hazard.

SS RRR

iTrader: (2)

I thought the PCM would then rely on its default fuel maps/spark curve if it had no data from the O2's? Meaning open loop?

Danny Davenport

Flattened the pipe for clearance and it still did it. Gonna disconnect O2s and see what happens will update shortly. Thanks.

Danny Davenport

Ok. First, let me just say, if you're going to unplug something and then take it for a test run, make sure you don't accidently let your car cover get dragged down the road with you. Gonna play hell cleaning all that melted **** off the exhaust. Not to mention, the panic attack that sinks in when smoke starts coming in. Christ.

Second, with the O2s unplugged, it seems to run 1000x better. Did 5 or 6 pulls without hesitation. So what's the fix? New O2s? I don't have a tuner at my disposal, so not sure where to go from here.

Danny Davenport

Sorry, should've scrolled back up. I found two pinholes yesterday at the Y-pipe couplings and fixed those. Don't seem to be any others. Header gaskets seem good, as do collector flanges.

SS RRR

iTrader: (2)

New O2s. Get quality ones. Can't remember what brand but there was a thread about it recently. A search should bring it up.

Danny Davenport

Searching through the forums, i'm seeing basically "anything but Bosch". Most are saying Delphi. I should only need 2 upstreams, since I have no cats, right? I've found a place where I can get Delphi's on closeout for like $8 a piece, but that seems too good to be true. Am I missing something?

VoyagerCamaro

It was my thread. These are the best 02's. ACDelco AFS75 GM Original Equipment Heated Oxygen Sensor https://www.amazon.com/dp/B000C9VTS6/ref=cm_sw_r_cp_api_RBZsxb5HW0B0X

VoyagerCamaro

Is the close out sale online? Send the link if so. And yes Rears are not needed if you have no cats. Unless your local inspection requires visual. I still have mine but had my tuner Solomon tune them out. So I still have the visual aspect of them. All a rear O2 is there to do is make sure your car is in functioning condition. they have nothing to do with the fueling of the car.

Danny Davenport

They're Delphi ES20317

I'll post the link after I place my order. Just want to make sure they're the right ones. Don't want the vultures buying up the remaining stock. Lol.

Danny Davenport

It's these:
Delphi Oxygen Sensors ES20317 - Free Shipping on Orders Over $99 at Summit Racing
http://m.summitracing.com/parts/dfp-es20317?seid=srese1&gclid=CjwKEAjwpqq6BRC99aKUkaSj uDsSJAC0pNTV_nbdopB-3SrXOBlHSbLtLkNtjPxQoqFwVjQK-DuFRRoCPOXw_wcB

But from somewhere else.

VoyagerCamaro

Haha smart idea.

Danny Davenport

Those seem like the right ones though, yeah?

BALLSS

IDK about the part # listed but the AC Delco 02 part # is AFS 75