I am having an issue when in power enrichment mode and it appears to be electrical. Scan tool shows 11 volts at battery and 12.7 volts at fuel pump and the actual reading at the battery is 14.2 - 14.5 volts at idle with a new CS alternator.
This is a 1227730 ECM and a 350 TPI engine. It was running great then this started happening out of the blue after I get about 40% throttle right when PE kicks in per the tune then it lays down. Other than that it starts, idles, and runs great at part throttle.
Will start checking voltage to the ECM next. I did check all grounds to the ECM.
So it appears my electric fan and water pump are causing a pretty good draw. More testing below: B1 Key on fan and wp on 11.25 Key off 12.48 Key on no fan 11.88 Key on no fan no wp 12.2
C16 Key on fan and wp on 10.75 Key off 12.44 Key on no fan 11.77 Key on no fan no wp 12.18
A6 Key on fan and wp on 11.25 Key off 0.00 Key on no fan 11.44 Key on no fan no wp 11.86
hmmm - this sounds alot like what I am dealing with. I have a 7730 swap on my 3.1, and I get stumbling on load. I just started using TunerRT to look at what the ECM is seeing, thinking I had a sensor problem, like the TPS or the MAP.
TPI are known to run out of air at about 4000-4500. Don't know if that is where you are seeing your power drop.
Is the battery in the front? Do you have a ground running directly to the engine?
There is a wire in the control cable for the alternator, that senses voltage ( S Pin). If that wire is run to the Charge terminal of the alternator, your alternator always thinks the battery is at 14V. Mine was set up like this from a PO. Once I ran the sense wire to another 12V source ( I used the Fuel Pump 12v wire), the alternator started charging much better, and I didn't see the drop in voltage that I had seen before. From another thread " I consider it crucial for good performance that you also wire up the remote voltage sensing terminal. To do this, connect the S terminal to the vehicle electrical system's main power distribution point (bus bar, main switch, fuse panel, etc.). If the S remote voltage sensing terminal is not connected, the voltage regulator will revert to internal sensing of the alternator output terminal voltage - with all the limitations that brings. You will see some alternators wired with a short jumper wire from the S terminal directly to the battery connection at the back of the alternators, but this is neither the proper method for remote voltage sensing nor necessary for internal sensing - do it properly or leave it out."
It falls flat and surges slightly anytime I am at 40%+ throttle throughout the RPM range, runs fine at part throttle. Also it ran great for about a month after it was all put back together for a head gasket change.
Battery is in the rear and I do have grounds to engine and redundant ones to engine and chassis.
I am pretty sure my S terminal is just looped to back of alternator main stud. However I am seeing 14.2-14.5 Volts at the battery would I still see this at the battery if this was an issue? Willing to try anything at this point.
Do you think a relay would help with voltage drop to the water pump? It appears to be wired/spliced to pink wire to C500 which looks to be the ignition feed, could this be causing a voltage drip at the ignition switch? I guess I'll just have to test before and after the switch .
Pyrthian: Do you have a saved log file from TunerRT? If so it should show both battery and fuel pump voltage.
Just tested voltage with engine running at idle with coolant fan and water pump disconnected and B1 and C16 are both getting 14.3 volts and A6 is at 13.8 volts.
Voltage with engine running at idle with coolant fan disconnected and water pump connected and B1 and C16 are both getting 14.2 volts and A6 is at 13.3 volts.
Voltage with engine running at idle with coolant fan and water pump connected and B1 and C16 are both getting 13.8 volts and A6 is at 12.8.
Not sure why TunerProRT is showing 10.9 to 11.5 Volts.
I think I have this figured out. I did a voltage drop test on the grounds and I am getting 1.15 to 1.5 voltage drop on all ECM grounds except one is about 760mV.
Since you have Tunerpro RT available, take a look at your BLM, INT, Spark Advance, Spark Retard and knock counts. I've been following these on mine chasing some issues I have. It may help you see what is happening real time. My timing was maxing out, and then getting pulled back via retard, plus high knock counts.
What is your initial timing set - 6 Degrees BTDC?
As for the "S" wire, try splicing it into any hot wire that has a constant draw on it ( Fuel Pump, Water Pump, etc). May not help your issue, but you will get better charging performance that may save a battery. I was going through a battery every couple of years ( Optima) before I found this issue.
I have been watching all the data on TunerPrort and AutoXray 6000 and nothing obviously wrong from the data.
So just tie (T or splice) the S wire off the CS alternator into the existing power to water pump, fuel pump, etc...? Thinking water pump would be easiest here as it is very close to alternator.
[This message has been edited by T4Turtle (edited 09-20-2018).]
just loaded my log file, and my battery voltage runs about 13.9 +/- and fuel pump voltage is 13.2 +/-
seems pretty close. I did have ground issues, and did alot to make solid grounding.
I thought I had pretty good grounds as well, even added a redundant ground. Checked ECM grounds for resistance and all looked great. Also the new ECM is seeing better voltage at about 12.5 now, but still low so this may vary depending on what the grounds are doing while running. Worth a quick check to do a ground voltage drop test while running.
Went through and cleaned and tested all grounds in the engine area and still having the same voltage drop. So I am looking at going through the ground wires and started taking apart the bulkhead connector at the firewall. I have it split apart about half way but the side with the side clips is not coming apart easily.
Any tricks here or is it just difficult because of all the silicone inside?
[This message has been edited by T4Turtle (edited 09-22-2018).]
It's the glue inside. A heat gun on low will take care of loosening it up, but do it carefully. Hair dryer might work too.
Thank you.
It is called a hardshell grommet in the manual so I take it the wires are just straight through with no terminals is this correct? I am going to run new ECM ground wires through it.
Started testing all of the original ground wires in DMM mode with my scope and I am seeing .3 Ohms on all of them from one end to the other, then from battery negative to ECM I get the same .3 Ohms. So I decided to try my regular DMM and I get 0 Ohms testing with it. Previously I had 4 ohms with the scope but this was with the battery positive lead connected so I decided to pull the battery positive lead and test again with my regular DMM I get 1.8 Ohms on all grounds with the positive lead connected.
So I am getting more resistance on the ECM ground leads with the battery positive lead connected when testing from ECM ground to battery ground.
I was going to change all ECM ground wires tonight but I do not see much of a problem with the original ones.
Voltage drop test looks a lot better with my regular DMM.
DMM reading 20.8 mV on ECM ground A12 versus scope showed 1.49 Volts. Ground D1 reading 23 mV on DMM versus 760mv on scope. Ground D6 reading 1.2 to 2.6 mV moving around a lot versus 1.14 Volts on scope. Ground D7 reading .1 to 3.3 mV moving around a lot versus 1.21 mV on scope.
I am moving onto checking power supply wires from C500 to ECM. Does anyone know where C501 connector and S510 splice are at within the harness? I do have a manual but it does not show where they are at.
Also I noticed the PO did not have the alternator wired direct to the C500 they had two fusible links going from starter to alternator.
This may not be relevant to your situation but my stock 2m4 shows 11.2 V on the ECM reading in tunerpro but 13.4 V on Aldl Droid. I think it may have to do with the ADX files. I don't have any problems with battery charging or any accessories
This may not be relevant to your situation but my stock 2m4 shows 11.2 V on the ECM reading in tunerpro but 13.4 V on Aldl Droid. I think it may have to do with the ADX files. I don't have any problems with battery charging or any accessories
That is interesting I do get full voltage when testing at ECM pins while running but not in TunerPro or with AutoXray 6000 scan tool.
Running the wire from alternator to C500 helped a lot I am now up to 13.5 volts in TunerPro and AutoXray live data. It does feel better but still not 100%. Maybe it will be stronger if I start leaning it out as I am around 10:1 at WOT now.
My issue is solved. I did not have enough base timing. I was advancing the distributor to try to get more power and decided to check where I was at with a timing light and was reading over 20 degrees base which is not likely possible to turn the engine over without kick back here and the starter spun the motor fast with no kick back. Either my old timing light with dial advance is off or I messed up the TDC procedure when I relocated my timing marks. Instead of and going through a checking this I decided to set timing based off maximum vacuum this went from 14 hg to 18 hg and I must have twisted the distributor about 1.5 inches. Runs a lot better, some slight knock sensor retard here and there but I can change the timing table to adjust for this.
