Odd Voltage drop issue

[700+SL2]

95 SW2 5-spd
I've only had this SW since the summer. Whenever I had a cold start and start off driving in 1st gear, when I hit around 2000 rpm the engine would bog right down and struggle to get to around 3000 rpm then runs fine. It would do that only once. Runs normal after that until the next cold start.
I found out that when I start off if I shift out of 1st just under 2K into second, it doesn't do it.
So now that it's dark out I see that at that 2K spot the lights dim for 1/2 a sec. so 1st up to 1800ish and shift. As I'm shifting the light dim then I'm in 2nd and good to go.
I've swapped plugs, wires, coils, throttle body w/sensors, map, maf, ects, fuel filter, regulator, rail, injectors.
Also, at one point I found my ABS wire scraping in the CV boot so I pushed it out. Well the wire was shorting out and aside from braking issues, at that 2K spot the ABS pump would kick over.
it does it no matter how long I let it run before driving
It doesn't matter if I rev it up over 2K before driving.
The CEL is disabled so I don't know of any codes.
It's a 95 but an earlier vacuum EGR. So no EGR plugged in.
Any ideas?

[billr]

Re-activate the CEL so we can get some clue about what is happening; post the codes.

[700+SL2]

Ok. That was fun getting in there to insert the light.
Codes 15. 26. 32. 35
So what I see in my book is
15 - coolant sensor low voltage
26 - quad driver output fault
32 - EGR
35 - Idle Air Control-rpm out of range.

I can get an EGR valve and plug it in to get rid of 32.

[billr]

Ignore the 32 and 35 for now. I think the 15 actually means the temperature is out-of-range low, not the sensor voltage (the voltage is actually out-of-range high). Disconnect the ECT sensor (the 2-wire one) and jumper the sockets in the harness connector with a 1/4W resistor of about 300 ohms; see if that gets rid of the code 15 (and maybe change other symptoms). Don't use a resistor with large diameter leads, you don't want to stretch the sockets on the harness connector. Obviously, if you corrosion in that connector let us know, that can also be the problem.

[OldNuc]

The 26+32 is a bad EGR solenoid, or disconnected. The 35 is a dead IAC as the RPM is out of range of the PCM desired and it can not correct.
15 is a near open circuit on the ECTS. Probably a bad connector. Use a 200 ohm resistor.

[700+SL2]

Should I be disconnecting the battery to clear the codes as I try this?
Picking up the resistor tonight. I'll plug it in and I'll plug in an EGR valve since I have one tomorrow morning

[OldNuc]

Just pull the PCM B fuse, it is easier and will clear all codes. Yes, do reset-clear codes.

[Saturn Night]

ECTS and wiring are likely your culprit.

Code 26 is QDM A, which controls the ECTS, Cooling Fan Relay, EGR, and something else.

26 + 15 indicates the obvious: a cracked ECTS and potential wiring damage
32 is coming on because the fuel mixture is not changing when the EGR circuit is commanded "ON"/"OFF" by the PCM, and hence why you are bogging down over 2,000 rpm(which IF the ported-vacuum EGR is functional it is opening too much and probably at the wrong time). Code 32 will set no matter what, because the wrong EGR system is being used with your PCM.

As throttle opens at low engine speeds, your vacuum signal decreases. As the engine revs up, the vacuum signal increases.

A vacuum EGR is easy to test. At idle, push the plunger upward, and you should hear your rpm drop, probably get some stumbling and misfire(thanks to extra exhaust gas entering the chambers).

[OldNuc]

You need to spend some time getting familiar with a S-Series.

The 26+32 is a bad EGR solenoid. Bad solenoid means valve not open means fail test.

The QDM has no interaction with the ECTS circuit in any way. The code 15 is a excessively high resistance in the ECTS circuit. That can be a rather long list of possibilities.

This is an S-Series forum and what happens with other makes is not really directly applicable in most cases.

[700+SL2]

Thanks.
So for today's test I grabbed an EGR valve and plugged it in the connector. The vacuum EGR is non-functional.
I pulled the ects connector and did look a bit corroded. I stabbed in a 220 ohm resistor (no 200 or 300s) and pumped PCM B fuse.
Wouldn't start. 1 fire and then crank.
Pulled the resistor and plugged it back into the ects and it fired up but the idle lingered in the 1000-1500rpm range. Road test was great. Ran smoother through the 2000s in 1st and seemed to feel better in that range the rest of the 5 min trip but the idle would float high and then settle down. Does it need to relearn? No CEL light
Home I checked codes and all 4 showed up again (I didn't think to double check before road test)
Now that engine is warm I replaced the resistor into the ects connector and cleared codes (double checked they cleared) and did a quick 1 min test and it started and drove as good as previous test but idled normally. No codes showed up.

[700+SL2]

[billr]

As you found out, a cold engine may not start (easily) with that resistor because the resistor "sets" engine temp at about 180F. The PCM then sets fueling too lean for a cold start.

Both the resistor test and the picture of the harness connector indicate the ECT sensor is suspect, should be removed and inspected, at least; and, the harness sockets need to be well-cleaned or the connector replaced.

[Saturn Night]

Originally Posted by OldNuc

You need to spend some time getting familiar with a S-Series.

The 26+32 is a bad EGR solenoid. Bad solenoid means valve not open means fail test.

The QDM has no interaction with the ECTS circuit in any way. The code 15 is a excessively high resistance in the ECTS circuit. That can be a rather long list of possibilities.

This is an S-Series forum and what happens with other makes is not really directly applicable in most cases.

Looking at his harness picture, I would say I was right about ONE of the problems. I appreciate the fact that you know tons about these cars, but you can stop discounting my "general" knowledge of OBD-I with your condescending remarks. While "what" works on ONE car may not apply to ALL cars is a true statement, the "physics" behind how an internal combustion engine, electrical systems, and hydraulic systems operate IS actually applicable to ALL cars.

Meaning that general characteristics that affect a different vehicle, can also affect our Saturns. This is twice, that a code 26 was immediately assumed to being associated with the EGR system, and we have confirmed that at least ONE of those it was not. Unplugging the EGR system will NOT cause a code 26. It WILL cause a Code 32.

Code 26 & 27 are designed to detect possible electrical spikes in the circuit or for a defective PCM.

I have only ever owned OBD-I cars, most of them GM, and hopefully I will never have to deal with OBD-II. And in this particular case, I am right about his ERG system, as well, probably because I have a 1995 1.9L DOHC Twin Cam sitting under the hood of my SC2 that is in my driveway.

[fetchitfido]

Either put the electric EGR back on it like it requires from the factory, or live with the fact that the CEL with be forever activated (on) with code 32.
If it's a '91-'94 head (pray it's '92-'94 and not a '91...lol) you'll have to find someone with the adapter, or find the guy on here that was making them for something like $80 (IIRC).

Those codes are mostly voltage related, which means the 5v reference from the PCM is suspect and depending on how the electric EGR plug was disabled may be causing all the issues. Verify that connector is corrosion free, moreso than that crappy abused looking ECTS connector.


Hmm...might be able to remove GM's hacked in electric EGR controller and wire in the vac solenoid direct to the harness, the '95 PCM expects the vac operated EGR stuff so the hacked in module makes the PCM think the electric EGR is working like the vac one. That'd save effort/time/money with trying to put the electric EGR back on it.

[OldNuc]

The OP is working on a 95 and the 26+32 are pointing at a failed conversion module or a filthy connector and as this lives close to the right end of the battery on the wiring harness I would suspect filth is the big issue. Or a failed EGR.

The ECTS plays into EGR operation so the ECTS needs fixed first. Replace the sensor Standard Motor Products TX73 or equivalent and go to JY and get that IAT sensor connector and as much wire as you can get. Replace your connector and solder and heat shrink the splices, do not use wire nuts or crimp connectors as they will not last.

[OldNuc]

Originally Posted by Saturn Night

Looking at his harness picture, I would say I was right about ONE of the problems. I appreciate the fact that you know tons about these cars, but you can stop discounting my "general" knowledge of OBD-I with your condescending remarks. While "what" works on ONE car may not apply to ALL cars is a true statement, the "physics" behind how an internal combustion engine, electrical systems, and hydraulic systems operate IS actually applicable to ALL cars.

Meaning that general characteristics that affect a different vehicle, can also affect our Saturns. This is twice, that a code 26 was immediately assumed to being associated with the EGR system, and we have confirmed that at least ONE of those it was not. Unplugging the EGR system will NOT cause a code 26. It WILL cause a Code 32.

Code 26 & 27 are designed to detect possible electrical spikes in the circuit or for a defective PCM.

I have only ever owned OBD-I cars, most of them GM, and hopefully I will never have to deal with OBD-II. And in this particular case, I am right about his ERG system, as well, probably because I have a 1995 1.9L DOHC Twin Cam sitting under the hood of my SC2 that is in my driveway.

You really need to break out the 95 FSM and read it along with look at the actual wiring diagrams. Anyone who has been here for more than a week knows the ECTS and most likely the connector must be changed before any more troubleshooting can be done, The ECTS DTC 15 is in no way related to the DTC 26. Read what I posted above re: 26+32.

[700+SL2]

I had pulled the ECTS which was brass and swapped in a sensor I bought new and had in another 1.9 for not too many miles.
The EGR connector was dangling when I got it and looked real clean like it was recently disconnected. I'm ok with keeping the non-connected vacuum valve in place with an electric valve plugged in and tie-wrapped to something. Wouldn't that be ok for the PCM?
I have a link for the replacement ECTS connector. So I'll order that and I can swap out the ECTS with another.
I didnt get a chance to drive it after this morning but I'm taking it tomorrow so I'll pull the resistor and reconnect the ECTS to start (or will it start with no resistor?)and see what codes come up.
Thanks guys.

[billr]

You may be able to get it to start by doing several "key-on/off" cycles. Each time the PCM is powered up there is a "priming" pulse of fuel delivered from the injectors. Several such cycles may put enough fuel in there to get the cold engine to fire. If you do disconnect the resistor, you probably don't need to connect the sensor to get it to start. With the sensor disconnected the PCM probably defaults to a fairly rich mixture, good enough to fire up.

[700+SL2]

Well, I think you guys nailed it.
Took it this morning, started it without the resistor and let it run for a few and inserted the resistor and headed out to the car show. After the temp was up it ran good and showed no codes.
Leaving, I plugged in the ECTS and it drove just as good home and showed no codes.
So I'll order the new ECTS and connector and hopefully that'll take care of it.
Thanks.

[OldNuc]

To get multiple prime cycles REQUIRES the key to be OFF for a minimum of 20 seconds and usually it is closer to 25.

Getting the ECTS circuit functional usualy solves many supposed unrelated problems.