350 5.7 TBI Timing/Fuel Issue

**fastacton** · 10-30-2015

I delete the oil pressure switch connector on every harness I build and I've built a couple of hundred without any issues. Whoever you talked to at Painless has no idea what they're talking about (I also have one of their harnesses and it works fine with out it as well). The switch is wired in parallel with the fuel pump relay, so as long as the relay is working properly, the switch has no effect. I wouldn't even waste your time on it. If you really want to test the difference, just jumper the switch connector (make sure you can disconnect quickly as you don't want the fuel pump to keep running if there are problems).

**Fast355** · 10-30-2015

Originally Posted by fastacton

I delete the oil pressure switch connector on every harness I build and I've built a couple of hundred without any issues. Whoever you talked to at Painless has no idea what they're talking about (I also have one of their harnesses and it works fine with out it as well). The switch is wired in parallel with the fuel pump relay, so as long as the relay is working properly, the switch has no effect. I wouldn't even waste your time on it. If you really want to test the difference, just jumper the switch connector (make sure you can disconnect quickly as you don't want the fuel pump to keep running if there are problems).

I prefer to keep the oil pressure switch. The engine only NEEDS one or the other but the 2nd is redundancy.

**1project2many** · 10-30-2015

Called Painless since I have their harness and he swears I NEED it.

I certainly understand wanting to remove all the variables but the switch is not necessary. If you NEEDED the switch then the vehicle would not run without it. It does not provide any signal to the ecm. It's a switch to power the pump in addition to the relay. There is some argument that the relay contacts can bounce while driving and eventually the contacts can become pitted due to the current through the pump. The argument is that when it happens the pump can stop working and the engine will stall, or the relay will stick "on" and the pump will run after the engine is off. This, I've been told, is part of the reason GM included the oil pressure switch. I don't disagree with having a redundant switch, but it doesn't seem as necessary when you consider there are no other redundant components on the engine. When I built my harness I used only the relay but ran a wire to the battery with a connector. If the relay ever fails I can connect the pump manually.

**Jeepcrazed** · 10-31-2015

I agree, the switch is not going to make a difference. I threw it on anyway and swapped out my fuel pump back to the carter p5001 tbi pump. Adjusted my fuel pressure up (he recommended 20 psi - seems way to high!). I cleared the codes and warmed up the motor. I can still hear that it doesn't run smooth. Anyway, I hooked up my scan tool. These are the codes it's throwing:

13, 14, 23, 25, 33, 43, 51

I have a new A1-Cardone ECM 122747, new ASDU prom and new cal-pak 16060836 (these are all the items painless wants you to run with this harness) I'm leaning toward I have a bad ECM but concerned that because I have a manual, should I use a different PROM? Even at idle, I can tell it's not running right and throwing all these codes even before I try and drive it down the road.

I tried to drive it in the neighborhood today. Still no power, backfires between gears (when I let it get to 2500 or so between shifts). Still seems like computer isn't communicating with the sensors correctly. Anyone have any ideas? All I have is an OBD1 port.

I did re-test the MAP sensor again today. It checks out fine. Vacuum good to map sensor as well. I'm about to buy an A/C Delco computer and see if there's a difference.

**1project2many** · 10-31-2015

There's a pretty significant issue if you're seeing all those codes. 13 is O2 sensor insufficient activity. 14 is CTS high. 23 is manifold air temp sensor low. In most applications the 7747 is not equipped with a manifold air temp sensor. 25 is manifold air temp sensor high. Very uncommon to see both high and low sensor codes in the same application, but worse yet, the 7747 application (as mentioned) does not usually get paired with MAT sensor. 33 is a MAP sensor code, MAP voltage high. This code can be set if the IAC is all the way open trying to keep the engine running. 43 is knock signal present when it should't be, or not present when it's expected. 51 is a prom error. That's the bad one.

Ultimately you have a list of codes that really shouldn't be present. First, you need to ensure the large ASDU chip is installed correctly and none of the legs are bent. If its been installed backward it could be no good as the older TTL chips don't put up with reversal. They also don't tolerate shocks from static electricity. Ask me how I know. The simple test to check whether or not the ecm thinks the chip is good is to turn the key off for 30 seconds or more, turn the key on, and watch the check engine light. The light should illuminate for a few seconds, go out for a few seconds, then turn on and stay on. Any other behavior like a rapidly flashing light or the light turning on immediately and staying on indicates a problem. This test is only accurate after they key has been off for at least 30 seconds. There is absolutely no sense in chasing any other issues until the ecm and memcal play nice together and code 51 is not present.

The eprom has a notch in the end. The eprom holder has a notch in the end. The notches must line up. Confirm alignment and condition of the legs. If all is well then you will either need another ecm or another chip, or both. Do you still have the original ecm and matching chip? You could plug the ecm into the harness and check for codes as a diagnostic tool. You can also get codes by jumpering pins A and B in the ALDL connector and watching the check engine light, just to confirm the scantool is reading codes accurately.

**buddrow** · 10-31-2015

Start with the really simple stuff and verify the grounds are hooked up. Poor or missing sensor grounds can cause all sorts of issues.

Buddrow

**Jeepcrazed** · 11-02-2015

I appreciate the comments/suggestions! I swapped out to another new computer (gotta love warranty coverage). Power is back!!

**1project2many** · 11-03-2015

Excellent news! Now are you going to attempt your own tuning?

**Jeepcrazed** · 11-03-2015

I've got several other things to work on first to get ready for a ride in a few weeks in Knoxville. I may come back to it and see what improvements can be made.

**Jeepcrazed** · 12-28-2015

Jeep did great on the ride in Knoxville. Funny thing is, when I hook up my scan tool to check for codes, I'm still seeing several codes (O2, map, IAC, ECM, etc...) but it's running just fine and not turning on the warning light. I'm going to pull the plugs and see what they tell me.

**1project2many** · 12-29-2015

Does the light work? I've seen them burn out before.

**jim_in_dorris** · 12-29-2015

High and low voltage codes for the same sensor makes me think there is a ground problem. Perhaps a big 3 upgrade is in order. It is amazing what it did for my truck.

**Jeepcrazed** · 12-29-2015

Light is good. Just a reminder, this is a brand new painless harness. I have the battery grounded to the engine. The engine is grounded to the frame and the frame is grounded to the tub. Alternator has large gauge wire straight to battery. I appreciate the input, keep those ideas coming! Forgot to mention, pulled the plugs. Too much carbon build up. Appears to be running rich.

**jim_in_dorris** · 12-29-2015

All the error codes are most likely the reason for rich running. I know the sensors are new. I also understand the wiring harness is new. There are 4 reasons (generally) that sensor error codes are set. 1. Sensor bad. Even new ones can be bad, but not usually all at the same time. 2. The reference voltage is too high or to low. 3 the ground is not zero volts. And 4. The sensors are all good, your voltages are correct, and your motor has a serious problem. A TunerproRT log file will show what is going on.

**1project2many** · 12-30-2015

Originally Posted by Jeepcrazed

Light is good. Just a reminder, this is a brand new painless harness. I have the battery grounded to the engine. The engine is grounded to the frame and the frame is grounded to the tub. Alternator has large gauge wire straight to battery. I appreciate the input, keep those ideas coming! Forgot to mention, pulled the plugs. Too much carbon build up. Appears to be running rich.

Then the codes are most likely from history and not current. Clear them and see what comes back.