Mis fire in all cylinders on Bank 1

[Saleen405]

This car must be jinxed. It's one problem after another. The car has been back together for some time now but still on jack stands. Now the problem is I have a TON on misfires on Bank 1 only. The car had a chip in it before I did all the work to the car (build thread in sig). I removed the chip from the PCM a while ago and just yesterday I was looking around the area by the PCM and came across this. Im not sure what it is/does, if its still part of the chip, if that's what's causing my issues or what. I unplugged it and started the car and it ran even rougher so its definitely doing something. It's spliced into the harness for the computer. Any ideas on what it is?

 

[Stanger00]

I googled maf xtender and it pops on on the first page of images. It looks to be a old school maf xtender and it could be jacking up the tuners MAF transfer function.

Remove it and tell your tuner that it may be a MAF transfer problem now and to revert back to its original scaling.

http://cart.grcperformance.com/oscommerce/index.php?cPath=52&osCsid=a17c5bb438e0edd9...

 

[Saleen405]

Thanks for the reply man! Helped out alot! I'm going to call my tuner now and let him know. Thanks again!:beer:

 

[Stanger00]

No problem man. A lot of us want to see your car back on the road. When I first seen that thing I didnt know what it was. With the close up it started to make sense that it could be a maf xtender.

 

[Saleen405]

Well I removed the extension, as the problem is still there. I've checked every possible thing over and over. Starting to think its a PCM problem and may swap that out next. Just seems weird that the misfires are on one side of the motor only.

 

[DarkAffinity]

If it was a problem with the MAF, both of the banks would be experiencing the problem. Usually when it's related to one side only, it has to do with a faulty Oxygen Sensor, that is sending false information to the PCM. In which case, the PCM would attempt to add or remove fuel in attempt to correct the Rich/Lean condition that the O2 sensor is lying about.

 

[Saleen405]

I changed out both front O2's and nothing changed. The mis is still there. I pulled both valve covers yesterday to make sure the cams were timed the same, and that checked out. I also pulled the whole harness and I am going to run through that today and check for a cut wire. The passenger O2 isn't switching like it should so something is off. When I first got the car back together, I popped for PCM fuse under the hood for whatever reason and I am thinking it took out something in the PCM, so I also ordered a new one yesterday too. Compression checked out, everything is there.

 

[DarkAffinity]

The passenger O2 isn't switching? Are we talking about Sensor 1 or Sensor 2 on the passenger side?

Your passenger side of the vehicle is also Bank 1 of the engine, so if your Bank 1 Sensor 1 O2 isn't switching, that right there is the cause of the misfire. Depending at what voltage the sensor is stuck at or if it's just not sending any signal back your PCM is going to use that input and attempt to correct it.

Low voltage or no voltage = excessively lean
In this case the PCM would try to correct it by adding fuel, until it reaches a set percentage of fuel added. I believe with Ford vehicles it is between 20-30%. Once this percentage is reached you will get a code around the lines of Fuel Trim Limit Reached, Rich or Lean.

High Voltage would signify a Rich mixture, which would cause the PCM to to remove fuel from the Cylinder Bank affected. Even if the bank A/F mixture is perfect, the PCM will take in the Sensor's faulty data and attempt to correct the situation.

In most cases, the wires leading to the sensor become damaged or get severed due to road debris. So I would check those first. Then check that the connectors are in good condition and show no signs of corrosion or damage. I would also perform a "Wiggle" test on the connectors while someone checks the voltage output with a Scan tool or Digital Volt/Ohm Meter. If you have to do this use a lift since you have to be under the car while it's on and the exhaust is hot enough for the vehicle to be in closed loop.

Hope this helps!

 

[Saleen405]

Thanks for the info man! It is bank #1 sensor #1. I have the rears turned off. I pulled the harness out of the car so I can really inspect it, and I am going to go over it one more time before throwing it back in. I also ordered another PCM because I popped the fuse for it a while back and may have messed it up. I replaced both front sensors and still getting a low voltage reading. This is the only thing holding me back, and then the car should be good to go.

 

[slowassgt]

Did you swap coil and plug with another cylinder? Also if you do that and the miss is still there swap the injector next.

 

[Saleen405]

Swapped coils and plugs yesterday from side to side. Still missing on the same side. I'm going to swap the injectors right now.

 

[Saleen405]

Swapped injectors. No luck because bank 1 is still missing. So plugs and coils are good. Next step is to pull it back apart.