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Discussion Starter #1
tuned by Alex R (PCM Performance). Just installed engine today due to cam going belly up. Fired it up and it ran like it was missing, but eventually cleared up. Initially, left 02 wasn't swinging like it should and BLMs were pegged. Car idled ok in closed loop, but once open loop hit, RPM's climbed a bit and BLMs crept up to 160 and stayed there. Changed out left 02. Restared car.

02's were not moving like they should, then it tossed out the following codes (eeHack)
ERR84(1-4 CONTROL CIRCUIT)
ERR83(REVERSE INHIBIT CIRCUIT)
ERR26(CCP ELECTRICAL FAULT )
ERR48(MASS AIR FLOW SYSTEM FAILURE)

Changed MAF since that was easy, and the error persisted. Changed PCM's - no change, so it's definitely in the car. Checked all the wires thinking that something got pinched and everything is clear. Pulled off the covers off of half the harness and everything looks ok, but something is obviously not. Car will NOT go into closed loop.

Looking at the codes, I am wondering if the harness that leads to the trans controls was somehow mangled in the install. I checked power on the pink lead at the MAF and it's very low. I checked resistance on that lead to ground and it shows 1.2k, so its definitely bleeding off voltage to ground somewhere.

Anyway, anyone got any ideas other than what I have laid out above? About ready to toss a match into this thing...

Thanks in-advance
 

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Dealing with compromised wiring somewhere in harness is no fun.After eliminating the possibility of damage/wear at the connector(s)... I'm not above running a brand new wire from end,to end complete with new terminal pins. If successful....I cut the old terminals of old wire,and tape end to the new wire for ID purposes in the future. Having spare harness from salvage yard can be helpful in providing extremely long repair pigtails that can extend well past suspected damaged area,and to a place where wires can be more easily spliced together.

 

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How about Fuse 4 (10 amp) under the hood?
It feeds power to the MAF, and both Oxygen sensors.
Also make sure there is power there with the key on. It could be a power issue from the ignition switch. That same power source feeds fuses 4, 5, and 6 in "run", "bulb test", and "start".

One last thing that can make things goofy on these cars: the ground strap from the engine to the firewall.

EDIT: Fuse 4 also feeds The EVAP canister, which would trigger DTC code 26.
 

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Crushed wires between engine and bell housing?

Jacked bell housing up while putting in engine and cut wires on firewall to floor flange ?

Just guesses

Next time you re&re the engine, may I suggest leaving the harness on the engine ,
 

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Discussion Starter #6
Thanks for the suggestions all. I will start the detective work tonight, and post up the results.

Next time you re&re the engine, may I suggest leaving the harness on the engine ,
I had no idea this was even a thing. I will look into it. Thx
 

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I checked resistance on that lead to ground and it shows 1.2k,
so its definitely bleeding off voltage to ground somewhere.
A circuit won't bleed off voltage to ground.
If any part of the circuit touches ground, it will pop fuse.
The only way to bleed voltage is to use current at another connection on that circuit.

Nab
 

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Discussion Starter #9 (Edited)
Looking back on it now, there were a few things that pointed me to a wiring issue. When I first put the key in the ignition and turned it to on (not start) to check tps volts and function (its new) - I pressed the pedal and it went to 100% and then instantly back to 4% and stayed there. I thought that was weird. Turned off the car, unplugged the sensor and plugged it back in and all was well. Now I think it was telling me something..
@HuSSker Fuse was popped - thanks for that suggestion - never thought of looking there. Replaced fuse, started car. Same issues persisted: Initial start, 02s voltage looks normal. As it approaches open-loop, bank 1 starts slowing down. Open loop hits and bank 1 02 starts acting lazy or not moving at all, MAF readings slowly increase, car pegs BLMs. Shut car down and started pulling the harness before I popped another fuse because something is 100% jacked up.

Checked the bellhousing transmission/02 harness and it's a-ok. Could not find any damage anywhere. I will start ohm'ing all the leads to be sure. Pulled everything from the pass-side head forward and couldn't find anything obvious. That means the mess that is attached to the backside of the pass. head to the underhood fuse block has to come out. I'm not sure how I am going to do that so if anyone has any ideas - please post them up

Out of curiosity, I checked continuity between a ground and the pink (+) on the MAF and there's continuity. @Blue Wail, I get what you're saying - but what do you make of this? (This is key-on, btw. If I switch it to test volts - it'll read 12'ish...) This is what I see on the power-lead when testing resistance to ground:



The other devices that threw the DTC's also show some continuity to ground. None of the other random pinks I tested do.
 

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When I first put the key in the ignition and turned it to on (not start) to check tps volts and function (its new) - I pressed the pedal and it went to 100% and then instantly back to 4% and stayed there. I thought that was weird. Turned off the car, unplugged the sensor and plugged it back in and all was well. Now I think it was telling me something..
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Dan. Did you meter VDC for the TPS??

no sure what "%" value means you note unless some scan tool reading.

VDC should be .67vdc (+/-) closed and 4.5 vdc full open. As you open the TB blades vdc should increase steady and smooth, no spikes.

Might want to jiggle wires leading to TPS while metering its vdc...maybe something "intermittent" in that wiring based on the 1st try testing it

While not the "typical" symptoms....if you have a spare ICM try that. I found a failing ICM played havoc on my 02 and STFT readings. Again your issues do not point to ICM but if you have a spare, try it
 

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Discussion Starter #11
Dan. Did you meter VDC for the TPS?? VDC should be .67vdc (+/-) closed and 4.5 vdc full open. As you open the TB blades vdc should increase steady and smooth, no spikes.
Yeah, sorry - it was VDC. Set to .67. Scan94/95 & eehack also have a percentage-open, so that's what I was referring to. I was testing/checking because it is a new TPS on a new throttle body and wanted to make sure it was ok before I turned the key and started fighting a bad setting.

Update: I went out to measure resistance on the wires to the fuse block. Positive leads on the MAF and CCV both have over 400 ohms of resistance, so there's problem #1. Checked resistance to ground on the positive leads and the MAF was as shown in the earlier pic. Went to test the CCV connector and it initially was the same, then went to infitity. Jumped back to the MAF + and it also had gone to infinity. So something I did in wiggling wires temporarily addressed that. There's problem #2.
 

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Y it is a new TPS on a new throttle body and wanted to make sure it was ok before I turned the key and started fighting a bad setting.

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"new TB..", is it a stock 48??

...after you get the wiring issues sorted you may find a aftermarket, larger, TB will need some adjustments if idle becomes a issue. Typically due to pegged IAC counts so you would need scan ability to read IAC counts if you do have a issue

take a close look at the pins of your PCM and the 4 connectors for any bent or contaminated pin
 

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Discussion Starter #13
Update: So I think I've found at least part of the problem. I took out as much of the harness as I could and removed the loom. The bit behind the passenger head is all that's left in there because the #(@)! trans dipstick tube makes getting the harness out damn near impossible. Anyway, the wires themselves all look great. No nicks or breaks that I could find; visually or with the meter. In looking at which errors popped, and then went away, (CCP, Opti low-res, 2 different transmission errors, 02's being lazy, MAF, and a blown #4 fuse) as well as digging into the FSM schematics, I noticed that the errors were not confined to one PCM plug as I suspected, but instead across 3 of the four.

I took out the PCM and battery and dug into the individual plugs and everything looked and tested OK. Checked the ground at the rear of the engine to the body and it was ok. Removed the 4 ring terminals at the driver's head, and that's where things went weird. On the stud, I was getting wildly sporadic ground readings holding the meter to the bare stud (going into the raw aluminum head). Holding the leads perfectly still, the meter would swing from infinity to .## ohms of resistance. Moving the lead to the other bolt holding the coil and ICM and the reading would be dead-steady at .02 ohms. Move it back to the stud and it would swing from 400 ohms to infinity, to .03. It swung around so much I had to turn off the audible alarm on my meter. Switched to alligator clamps on the leads and the issue persisted - so its something in that stud that is causing loads of inconsistency in the ground.

It's the same damn stud that was in there before, so I've no idea what is going on, nor do I really care. I'll swap it out with a new bolt and see what happens.

Question: would that have caused the #4 fuse to blow or should I keep digging?
 

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I'd be tempted to use a length of (12ga) wire with a ring terminal,and run to a nearby point on the block itself. Splice,solder,shrink-wrap those individual grounds together to the single stronger wire. Mysterious electrical problems often have problematic grounds as a source.
 

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I’d be looking @ grounds. Especially since engine was out & you did cleanup & painting.
I'd be tempted to use a length of (12ga) wire with a ring terminal,and run to a nearby point on the block itself. Splice,solder,shrink-wrap those individual grounds together to the single stronger wire. Mysterious electrical problems often have problematic grounds as a source.
x2
Very often grounds are the source of electrical issues. People throw all kinds of parts @ cars, only to have the problem(s) stick around.
When grounds are missing from a circuit, the voltage attempts to find a path, and weirdness a plenty occurs.
 

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I'd be tempted to use a length of (12ga) wire with a ring terminal,and run to a nearby point on the block itself. Splice,solder,shrink-wrap those individual grounds together to the single stronger wire. Mysterious electrical problems often have problematic grounds as a source.
I have been thinking about doing something like this since I am upgrading my large electrical cables.

I think I will run a 10 or 8ga from the negative battery cable on the block to the head stud. That particular ground regularly seems to be a problem.

Initially, left 02 wasn't swinging like it should and BLMs were pegged. Car idled ok in closed loop, but once open loop hit, RPM's climbed a bit and BLMs crept up to 160 and stayed there. Changed out left 02.

02's were not moving like they should,

@HuSSker Fuse was popped(#4) - thanks for that suggestion - never thought of looking there. Replaced fuse, started car. Same issues persisted: Initial start, 02s voltage looks normal. As it approaches open-loop, bank 1 starts slowing down. Open loop hits and bank 1 02 starts acting lazy or not moving at all,

Question: would that have caused the #4 fuse to blow or should I keep digging?
Usually a fuse blowing means a short to ground so you may still have a problem. From your O2 issues it may still be in this area. As I am not a mechanic I get Bank# vs Left/Right mixed up. Are you sure you are on the correct side?

ERR84(1-4 CONTROL CIRCUIT)
ERR83(REVERSE INHIBIT CIRCUIT)
ERR26(CCP ELECTRICAL FAULT )
ERR48(MASS AIR FLOW SYSTEM FAILURE)
I would clear these codes and try running the motor again. I expect they will not come back if you are right about the ground problem.

When I first put the key in the ignition and turned it to on (not start) to check tps volts and function (its new) - I pressed the pedal and it went to 100% and then instantly back to 4% and stayed there. I thought that was weird. Turned off the car, unplugged the sensor and plugged it back in and all was well. Now I think it was telling me something..
Have you done the TPS recalibration? It may be hitting 100% before it is really 100% open. (separate issue from your current ones)
 

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I installed multiple redundant grounds from motor to frame. Also ground straps to/from body to the frame,in addition to the motor. Dual post batteries also help,allowing heavy gauge cable(s) to be used...
 

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Discussion Starter #18
Usually a fuse blowing means a short to ground so you may still have a problem. From your O2 issues it may still be in this area.
Yeah, I am thinking I am not out of the woods yet. That blown fuse is a bad sign.

As I am not a mechanic I get Bank# vs Left/Right mixed up. Are you sure you are on the correct side?
Yes. On the harness, its pretty hard to screw them up. One side is married to the oil-level sensor plug. The other side is married to the trans fluid pressure sensor.

I would clear these codes and try running the motor again. I expect they will not come back if you are right about the ground problem.
That's the plan. Just gotta get it all back in there and hooked back up. I'm not going to dress any of the wires until I am sure the issue has been fixed.

Have you done the TPS recalibration? It may be hitting 100% before it is really 100% open. (separate issue from your current ones)
I don't think the TPS on these needs to be calibrated. I believe the PCM does it each time the car is started. Correct me if I am wrong, please. I have set the TPS for correct voltage, though.
 

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I don't think the TPS on these needs to be calibrated. I believe the PCM does it each time the car is started. Correct me if I am wrong, please. I have set the TPS for correct voltage, though.
You are correct.The PCM sets the closed position every cycle. I was thinking of another system. Some require a max min setting But the LT1 is automatically calibrated .

tuned by Alex R (PCM Performance). Just installed engine today due to cam going belly up. Fired it up and it ran like it was missing, but eventually cleared up.
.

The IAC may benefit from a reset. Also may be what I confused the TPS calibration with as I would have done it when I switched TB several times.
 
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