ignition timing and problems...

Hello

I have a few questions here but first an explanation...

I have a 93 Olds Silhouette. No this is NOT the OLDS section but there is more activity in here AND I need this van fixed before deployment to somewhere with allot of sand...

The van is missing. NOT a steady miss. It accelerates fine and fast like it should but there is a "put" "put" that you feel. The r.p.m. gauge shows the sputters too. Reverse is worse. Also when you hold your foot steady on the gas pedal while driving it lopes or surges.

What has been replaced..

The trans (rebuilt), plugs, wires, O2 sensor, cap, rotor, fuel pump, (all new)TBI (rebuilt and injectors have great spray pattern no dripping), timing chain (new) tested TPS with a multimeter and it shows good.

What I did so far...

Took timing light and put it on all the plug wires to see if they are sending signal normally (they are)
changed MAP sensor with another I had lying around (no difference) changed coil with another I had lying around (no difference)
changed module with another I had lying around (no difference)
checked ALL plastic hoses for cracks (none found)

I also need to know the timing procedure. The chiltons says there is a tan, blk wire I need to disconnect but I cant find it.

<<<<NO CHECK ENGINE LIGHT EITHER. >>>>

I do have codes that are for the O2 sensor, MAP sensor but these only showed when I disconnected the particular part. The light then went back off when the part was reconnected. There is no current light however.

How do I check the ECM? Does this sound like am ECM problem? Could the timing wire already be disconnected and the engine running off of the default, (without the ECM)???


Thanks

Make sure all the coil packs have tight and clean connections to the ICM. Also take the coil packs to autozone and have them all tested.

3.1 dont have coil packs.
my fault since I didnt mention it
Hence the new cap and rotor...

thanks though...

Drive that thing into a dark garage, have someone torque it up in gear while you watch for arcing in the ignition system. If you don't see anything, use a spray bottle of water and see if you can get it to stumble or die by wetting the coil, cap, wires, etc. You said you swapped the module out, I was gonna suggest that might be bad, do you know for sure that the other one is good? Also the HEI ignitions were notorious for blowing pinholes through the rotor so spark could jump to the shaft under it if there was high resistance in the secondary path at any point. Sometime they would hole a brand new rotor right away. Take the rotor off and look hard at it for evidence (black pinholes, halos). It is kind of puzzling to me that you said it seems worse in reverse. The only thing I can make of that, if it is a misfire caused by arcing (of a bad plug wire, for example) the way the engine torques the opposite way in reverse might somehow cause physical movement of the affected part that puts it closer to its' misdirected arc path. Also, I thought I remember that wire coming off the back (distributor end) of the motor and heading to the ECM. I remember that on 2.8 S Blazers and like that, don't remember ever working on a non-DIS 3.1 V6, but it has been a while. I'll try to think of more....

That also sounds kind of typical of a cracked insulator on a plug. When I was first starting out in the shop, sometimes I'd crack one on installation, and it would behave similar. But the interesting thing that I just realized, you said the drop out can be seen in the tach. Is it subtle (coresponding to engine speed) or actually dropping out as if the signal is lost (dropping lower than actual engine speed and recovering)?

I too thought about the possiblity of a cracked insulator on a plug, however, last time that happened to me on my '90, the SES light came on.

its not a steady miss. Its doesnt seem like the same cylinder. Sometimes it misses pretty good and other times not much.

Do any of you think it could be the ECM??

93 Silhouette has a cap and rotor?

yeah...

3.1 dont have coil packs.
my fault since I didnt mention it
Hence the new cap and rotor...

The oldsmobiles always had to have something different...

Early Lumina vans had rotors, didn't they? Seems like I remember one coming in at one point, but then agian, they all look the same...

I've got transmission surging in OD, when I shift into Drive it goes away. You've probably got the same thing I do as far as that's concerned...but I've got the foggiest clue as to what I've got. Something with the TCC solenoid, you may want to start there.

Check all your wires going to the distributor, not just the plug wires. Timing is almost completely ruled out if its not a steady miss, just make sure your points are set right.

there is no points...

Its an HEI distributor. Has a pickup and module. Has a cap and rotor...

The ECM uses the coolant sensor, map, O2, IAC and prolly something else to determine fuel flow spark curves.

I've been to the junkyard many many times and seen 93 Luminas with the same setup. When I say Lumina I am talking about the minivan. NOT THE CAR.

TIA!!!