92 Lumina Euro 3.1 FI idle & start problems

[RedWolf92]

Changed PCV valve & MAP sensor just for giggles... no fix.

Next step will be the mechanic, but I think I'll go car shopping this weekend as well.

[xjoeharperx]

Your problem is the ecu is bad..i have run into this problem many times before..the ecu is sensing that the voltage is 25 volts causing the car to flood and sputter..causing a loss of power and stalling...

here is the last post from it...this was the fix for the car
http://www.automotiveforums.com/vbul...d.php?t=184210

[PartsMaster]

Remove the IAC Valve located by where the air intake hose is located, spray the inside of the chamber and the IAC Valve with carb. cleaner.
When the IAC and chamber gets carboned up the car will not function properly or will not start. Just ran across this problem this last week.

[Kooterskkar]

Vaccum leaks, check for vaccum leaks.
Also, pull off the intake plenum (part on top that says 3.1MPFI) and go to town on it with a bottle brush and a can of carb cleaner. Get all the carbon out of it. Clean out the throttle body as well. And when you get done with that, and get it all put back together with new plenum and tb gaskets, get a can of seafoam and run it in through a vacum line. A good one is the one for the cruise control balloon by the battery. Theres a t-fitting there that is good for this. Follow the instructions on the back of the can of Seafoam.
If the plenum is extremely carboned up, you might have an EGR valve stuck open. Those can cause problems like this. Try that and see if it helps.
PCV valve on a 3.1 is on the back valve cover. On the right side if your lookin at it from above. Its got a funny shaped rubber hose that you have to get from a dealer if you break it. You can do that while the plenum is off and it will be easier to get to.

[web923]

I have a 93 Lumina v-6 3.1 and the pcv valve is located on the valve cover that is close to the firewall just below the map sensor. Must tilt the engine to gain access. I had to remove the map sensor. The hose runs from the pcv valve to the underside of the intake manifold. When I attempted to change the pcv (the hose being brittle) busted off near where it connects to the underside of the intake, which is impossible to reach. Be gentle!

[ibjammin]

where is the knock sensor on a 3.1 located , and what does it look like?

[jeffcoslacker]

I doubt the knock sensor has anything to do with it. If it is coding for that, it probably relates to excessive knock, which can be caused by too much air (lean), poor fuel delivery (lean again) or excessive engine temp. I forget, have you checked fuel pressure, or changed the fuel pressure regulator?

[lumina1]

I had the same problem and come to find out it was just a cracked spark plug! Check your plugs and plug wires!

[bigblack89]

I am having a similar problem with my 92 Lumina 3.1. I am assuming all of my problems started with a cracked spark plug. I bought the car and removed a spark plug from the front. Low and behold brand new bosch platinum 2's were already installed. So i left it at that.
About 5 months later, as I am driving home from work, my car starts to misfire, backfire, sputter, and attempt to stall. I stopped let it cool for a moment that restarted the car. The same problem kept happening. Pulled ther code and nit was a bad ICM. Replaced it, and my car began to run again.
After the ICM replacement, I noticed my car did not idle while driving down the road, or coming to a stop.I checked vacuum lines, replaced my IAC, TPS, cleaned my EGR spotless, but the same thing kept happening. During this time I probably retrained my idle 15 times.
I call my brother, who is going to automotive school, and ask his opinion. He thinks i have a bad coil. I checked all resistanced when replacing ICM, and all coils checked out ok, but he insisted i check them when i am having a problem. Still all Resistances check out. Next i pulled plugs off coils 1 at a time while idling, to check spark, and notice a possible miss, or week spark on 1 post, of each of 2 coils.
In decide to replace all wires and spark plugs as well. While removing my sparkplugs found out that the cylinder #1 spark plug's ceramic is cracked in half... Here is my problem. Changed all plugs and wires, plus the coil attached to that spark plug, relearn idle, and go for a drive. Low and behold the same issue is happening again. Obviously this spark plug has caused a huge problem, so I tap test my ECM and the car stalls out.
Before my new ECM could arrive, the old one completely failed, and left me stranded, needeing to be towed home. After installing the new ECM and PROM the car starts right up, better than before. After relearning the idle, I go for a test drive, and i have still the same problem. Throughout this time i have noticed the problem occurs only when the accelerator is not depressed, and the car is in motion. The problem becomes amplified when driving on less maintained roads.
Now my theory is that this spark plug basically caused almost, if not every, component of my computer controlled ignition system to get damaged. I spent hours pouring over manuals and learning every detail the computer takes into account when controlling spark and fuel/air mixture. Then in a wiring diagram i found my next most likely culprit.
Obviously my 3x crank position sensor is working, at least somewhat, because the car has no problem starting, and has loads of power. There is a posibility of some faulty piece ofnit cause faulty readings, leading to the stalling issue, when it is not receiving a positive increase in crank speed. However; this is not the only crank position sensor GM put on these vehicles.
GM also put in a 24x Crank position sensor. Per the manual This sensor is responsible for relaying information to the ECM about crank position, to improve engine idle, and low rpm driveability. This to me matches the exact problem described above, and as to what i am having. I will be testing this sensor soon, as well as the 3x crank sensor. I will also be testing my MAP, Canister purge valve, IAT sensor, CTS, Knock sensor, and O2 Sensors, since these are all connected to the Electronic Spark Timing system.

[Tech II]

Have you checked coil output with a spark tester?

[Schurkey]

Considering the work already done, throwing a fuel pressure tester on that vehicle sounds like a worthy project, too.

[bigblack89]

Its definitely worth a shot, checking the fuel pressure, when it is warm. However, the fuel pump and fuel filter were the first things that i replaced on the car. I thought they were bad because i wasnt getting any fuel. When i was installing the new one i noticed the wiring was wrong. I used my multimeter to do a continuity check to correct the wiring from the inside to outside of the fuel tank. After this the fuel pump started working.
I have an extra coil here, that i just bought. I can swap it out 1 at a time, with the 2 remaining old coils. I dont have a spark tester though.
After installing the new ECM and PROM, i have run into another issue. My instrument cluster works, except my speedometer wont read a speed. When i turn the key to the on position, the speedometer will rise a little, but stay below 0. I jacked the car up, threw some tape around a small break in the VSS connector wiring, put it in drive, and took my foot off the break to see if the speedo would work, and no dice. I did notice a small amount of fluctuation in speedo needle, but barely anything. I have also noticed while actually driving the vehicle, the shift points are a at a much higher rpm, they are rougher, and my TCC clutch isnt working correctly. To me all this points to a bad VSS.
When i took my VSS out and looked online for the part, all the manuals say i have the VSS of the 3 speed transmission. I know for a fact that I have the 4t60 transmission, it is stamped to the bottom of the oil pan. I am wondering if the reading from this VSS, and the one the manuals say i should have differ. If so could it be the new ECM is configured to read this input signal. I dont think it should matter though.
While checking the VSS i think i found the solution to my idle problem, and who knows maybe the speedo issue also. The wires from the VSS, and the Crank Position Sensor both run underneath the passenger side of the engine. This happens to be in between the Crankshaft Pulley, and vehicle frame. I know for sure i saw a break in the insulation on one of the twisted wires for my Crank Sensor. It has to be shorting out causing the stalling issue. Maybe the VSS wires are shorting out here too. I will fix the crank wire tomorrow.
Back to the VSS. I pulled it out and checked the resistance on 20k ohms and it read a steady .48. Then i put the gear in the sensor and turned it. the ohms went from .48 and varied from positive to negative. Im not sure if its supposed to do that, I will look for specs on this sensor. Volts AC were produced, and they increased with the speed i spun the gear. I could only get it up to about 1 volt. The sensor worked before i changed the ECM, and it is putting out AC voltage like it is supposed to. Tomorrow i will check continuity from the sensor wiring harness to the ECM.

[bigblack89]

Alright so i finally solved all of my problems. I fixed the breaks in the cable connection my crank position sensor, and that fixed my idling issue. As far as the speed sensor goes, the PROM that i received wasnt programmedc correctly for my speed sensor. I put my original prom in the new ECM i purchased, and the speedo began to work.