Hey all
Just finished my Delphi optispark install. Everything went good until I drove it.
Basically the same symtoms before I did the opti change. Car idles very smooth. Runs like a beast for about 10 minutes then starts missing and losing power.

I ran a scan and it shows a code 12 and 26. This is a 93 LT1 M6 firehawk with headers and new spark plugs. Code 12 means normal and 26 means EGR fault.
I am not running my EGR because of the headers. Plug wires are pretty new and are not making contact or arching off the headers. I don't mind putting money into the car as it is 19 yrs old and is in excellent shape.

I am thinking ICM or coil. What do you all think it could be? Car has 132k on it.

 

ICM and coil are good places to start. Is the ECM tuned? If not, I would have that done to delete the EGR and tune for headers.

 

DTC 12 means the ECM has entered diagnostic mode. DTC 26 (Quad Driver Module #1) for a 93 - different than all other years of the LT1 - can be either:

-AIR pump relay circuit
-EGR solenoid
-EVAP solenoid

To eliminate the EGR solenoid code, if you confirm that's what the problem is, simply push the wire ends of a 2,000 ohm resistor into the harness connector pins and tape it up.

Look at things that can heat soak and cause the engine to stop running. You've already eliminated the optical cam position sensor module in the Opti, but there is still the IC module, the coil and the fuel pump.

 

Fred and 629
I am going to replaced the coil Monday and see what happens. I know its like throwing parts at the car to fix the problem but the car is old as we know.

I also removed the air pump when I installed the Mac headers. I also need to still block off the egr and all. I just got my block off plates so that is on the list to get done.

If it ends up being the fuel pump I am going to make my own access door under the carpet so I don't have to drop the tank.

Will get the car tuned soon as I get it running right.

Thanks

 

First question, did you have the codes before you intalled the opti? Second, are you 100% sure you installed the opti correctly as in made sure the cam dowel pin went into the correct slot on the opti? Not doubting your abilities I've seen this overlooked 3 times in the past few months on friends cars and also on my car a few months back when I let my friend slide the opti on. When it happened to my car it seemed to run just fine til I took it for a test drive. I got maybe half a mile then it started having random misfires.

 

96- I am pretty sure the opti is in right. It took a few times to line the spline up but once i did it popped in flush. The car idles smooth. Really gets down when you nail the gas pedal. Will break the tires loose easy for 20-30 feet in first gear rolling at 20 mph. After a few minutes she is missing and all. I did have the same codes before the opti install.

 

He's asking about a 93, unvented Opti. In his case, a drive problem would be due to mismatching the splines on the driveshaft, since it's not driven by the cam dowel pin.

The missing AIR pump should not set a DTC as long as there is a good fuse in the circuit.

 

[QUOTE=Injuneer;6857785]He's asking about a 93, unvented Opti. In his case, a drive problem would be due to mismatching the splines on the driveshaft, since it's not driven by the cam dowel pin.



Opti question- When installing the opti if the cam location is not disturbed then the timing should be right on, and the rotor would either be where it was when taken out or 180 degrees from that point, which would not make any difference in timing. The splined opti only goes on one way from what I understand unless you get a big hammer. LOL

I would say the opti install is correct as the car is behaving exactly like it did before the new opti install. Correct me if I am wrong as this is my first opti install. But I have installed at least 50 HEI's distributors over my years.

 

[QUOTE=Matts97camaro;6857791]The only go on one way until they don't. I've personally seen both types installed wrong without the use of a hammer. And neither type require the cam to be in any particular position....just line up and go.

Your point about having the same symptoms after the install that you had before is a good one and removes the opti from the equation. It doesn't eliminate anything else....the opti wire or the spark plug wires should be looked at as well as the wiring to the coil and ICM...

Good luck!

 

[QUOTE=bw_hunter;6857861]Thanks I will check it all out Monday. I'll let everyone know what I find.

 

Update- I have replaced the optispark, coil and ICM and still have a problem. Engine idles fine and smooth for a few minutes upon intial start up then as it warms up the engine shakes from a slight miss. I am now questioning the sparkplug wires. I see no arching in the dark but for peace of mind I have ordered some Taylor Over the Valve Cover 8mm sparkplug wire kit from Thunder Racing.

If that doesn't do it I will try the replacing the opti wire/plug in. Then look into fuel supply. I'll get it eventually.
Codes are 12 and 26 same as before the opti replacement.

 

Think about what happens about three minutes after you start the car - the ECM goes into closed loop, using the O2 sensors for feedback. Have you considered the possibility of a faulty O2 sensor?

Or are you sure the O2 sensors are even getting hot enough to work. 93 is the only year with unheated, 1-wire O2 sensors, and when you put headers on, particularly long tubes, the sensors can move too far from the engine to get hot enough.

 

Actually I have not thought about the O2 sensors. I have the Mac mid length headers though. As far as I know they have never been replaced. But what you are saying make alot of sense. I will check into that.

 

Update- I got my oxygen sensors from rock auto (Denso's) installed. Idle is now very smooth even after the car warms up. With a 132k on the engine it was time. Thanks Fred I still have the miss. I found the problem tonight even though I looked before and never saw anything, apparently it was not dark enough. I popped the hood and looked at the spark plugs and wires. Well there were tiny little arcs here and there bouncing off the headers and wires,but not enough to cause a miss at idle. Also found where the sparkplug boots that slide over the end of the plug there was a light show going on there. Plugs are tight also. When i bought the car 4 yrs ago the previous owner said he had just replaced the opti cap and plugwires ( but not the sparkplugs hmmm) They are 7mm wires. I have only put about 6k on the car since I bought her.

Weird thing is that after the header install and new plugs she ran great for about a month then all this happens. I have ordered the Taylor over the valve cover sparkplug wires and kit from Thunder Racing I hope this will solve the light show under the hood. I will keep you all posted.

 

Update- problem resolved. I installed Taylor OVC plug wire kit today. Car runs great. Drove it today for about 30 minutes. Thanks for everyones input.