1995 Stumble After LT Headers
Melting Slicks
Joined: Jul 2005
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On the top image, are the white zones where the BLM enable is becoming disabled? As in falling out of closed loop? What kind of O2 sensors are on a 95? Single wire or 3-wire heated?
Also, yeah it seems like something going on with the right side... bad injector perhaps?
Also, yeah it seems like something going on with the right side... bad injector perhaps?
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From: Indiana
1995 has 3 wire I believe. All three sensors I plugged in were not single wire, I know that for sure.
EEHack has the ability for me to cut cylinders and check cylinder power. Could this help diagnose a bad injector without pulling the fuel rail?
Would it be possible only one bank is lean after header install? The right bank post-cat O2 is actually on the left bank, opposite of stock. This is because the Hooker headers I put on had it switched, so I pigtailed it over the transmission.
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From: Indiana
White zones are where BLM is disabled yes, but it never fell out of closed loop during this time. Based on these graphs, it only falls out of block learn when I’m on deceleration or power enrichment.
1995 has 3 wire I believe. All three sensors I plugged in were not single wire, I know that for sure.
EEHack has the ability for me to cut cylinders and check cylinder power. Could this help diagnose a bad injector without pulling the fuel rail?
Would it be possible only one bank is lean after header install? The right bank post-cat O2 is actually on the left bank, opposite of stock. This is because the Hooker headers I put on had it switched, so I pigtailed it over the transmission.
1995 has 3 wire I believe. All three sensors I plugged in were not single wire, I know that for sure.
EEHack has the ability for me to cut cylinders and check cylinder power. Could this help diagnose a bad injector without pulling the fuel rail?
Would it be possible only one bank is lean after header install? The right bank post-cat O2 is actually on the left bank, opposite of stock. This is because the Hooker headers I put on had it switched, so I pigtailed it over the transmission.
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Posts: 93
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From: Indiana
Right bank is way lean. LTermBLM is pegged at 160, with some fluctuation. STerm BLM stayed at 128 during idle, but when I started driving it was jumping all over the place. I think I pinpointed my stumble events when it jumps way high, STerm over 190 when engine RPM is sitting around 2000RPM.
Brain blast though after talking it through with someone. I was running through the install again thinking of what could be causing the issue, and I noticed that my pre cat is installed on primary 7 for the right bank, and my post cat is installed in the collector. On my left bank, the O2 is installed in the collector. In my mind this would cause readings to be way off since it's just reading cylinder 7 and not the entire bank. Does this theory have any substance? Or am I dreaming here of a simple fix...?
Brain blast though after talking it through with someone. I was running through the install again thinking of what could be causing the issue, and I noticed that my pre cat is installed on primary 7 for the right bank, and my post cat is installed in the collector. On my left bank, the O2 is installed in the collector. In my mind this would cause readings to be way off since it's just reading cylinder 7 and not the entire bank. Does this theory have any substance? Or am I dreaming here of a simple fix...?
Melting Slicks
Joined: Jul 2005
Posts: 2,207
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Oh, yeah definitely that's a problem IMO...
You don't want the entire engine bank to be represented by just one cylinder's worth of sampling on the O2 sensor. If you can move that sensor into the collector, that would be a far better approach.
You don't want the entire engine bank to be represented by just one cylinder's worth of sampling on the O2 sensor. If you can move that sensor into the collector, that would be a far better approach.
Melting Slicks
Joined: Jul 2005
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Double check your spark plug wires... make sure one hasn't been burned by the headers or something like that.
High BLM's will result from misfires due to a bad wire (lots of unburnt O2 being dumped into the exhaust stream).
High BLM's will result from misfires due to a bad wire (lots of unburnt O2 being dumped into the exhaust stream).
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From: Indiana
This is definitely a problem with the right bank itself though. I swapped the O2 sensors around from left to right and it had no change.
I’m still confused though and new to this. If the BLM is running high at 160, does that mean it’s seeing too much gas or too much air?
Melting Slicks
Joined: Jul 2005
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160 means the O2 sensor is seeing way too much unburnt oxygen in the exhaust. Could be a number of things..
Faulty fuel injector(s) not delivering enough fuel (could potentially swap all four injectors side to side and see if the problem moves to the other side)
Bad ignition component (plug or wire) not burning the A/F mixture thereby releasing all of that oxygen into the exhaust.
Exhaust leak introducing oxygen into the exhaust after the fact
Bad O2 sensor on that side (which you ruled out by swapping O2 sensors)
Faulty fuel injector(s) not delivering enough fuel (could potentially swap all four injectors side to side and see if the problem moves to the other side)
Bad ignition component (plug or wire) not burning the A/F mixture thereby releasing all of that oxygen into the exhaust.
Exhaust leak introducing oxygen into the exhaust after the fact
Bad O2 sensor on that side (which you ruled out by swapping O2 sensors)
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From: Indiana
AH HA! My sensors were swapped! I had my left and right banks confused, so the issue was on the passenger side. Google AI told me the drivers side was the right bank, on my car at least, this isn’t true.
In the end I had my right bank pre-cat O2 hooked into Primary 7 on the left bank. My dummy post-cat hooked into the right bank collector, and then of course the left bank pre-cat in the left bank collector. Swapped my connections around and no more BLM at 160! Now they’re sitting at 135-136 balanced at cruising. No more stumble! One new issue that’s small, but that’s for another thread.
Thanks for all the help here guys!
In the end I had my right bank pre-cat O2 hooked into Primary 7 on the left bank. My dummy post-cat hooked into the right bank collector, and then of course the left bank pre-cat in the left bank collector. Swapped my connections around and no more BLM at 160! Now they’re sitting at 135-136 balanced at cruising. No more stumble! One new issue that’s small, but that’s for another thread.
Thanks for all the help here guys!
