Bxlt1

Hello everyone. Just did an opti change after it died while driving monday:mad just in time for the weekend lol it's not running at all, it starts stumbles and dies for no more than 3 seconds.ive done many optis timing seals water pumps on my car friends and family so this is routine for me and easy if I dare say. I did the harness test 11.8 at pink and 5 volt at white even tho I do have a p100 code the 20 amp fuse is good. The maf is clean no breaks in the resistor inside,I swapped 2 good maf on my car it still doesn't run. It runs with the maf off while using the map sensor but runs horrible and motor shakes violently sputters and idles at 500 I never had this problem before as Ive done this so many times.my plug wires are correct opti is lined up perfectly all my electrical connections are correct,no vacuum leaks fuel pump and pressure are perfect. As of now it's only starting and barely idling in speed density mode. Any help I would appreciate it.sorry for long rant I will shorten my response with any questions you guys have. Ps 96 z bolt ons tune etc... Nothing fancy just or was a good running z28

shoebox

Since you say everything else is perfect, consider that it could be a bad opti (not sure what brand you installed).

Bxlt1

I did think that shbox even Delphi are crap but I think and hope it isnt.its weird to describe without seeing it. It starts stumbles and dies immediately,After all the normal checks and rechecking I still don't know why it runs in speed density and not maf. Btw it idles bad 500 rpm motor bounces all around like a huge vacuum leak or if it's on 5 or less cylinders. This is in speed density mode. Maf start cough cough cuts out in 3 seconds

Bxlt1

For bout 2 weeks I was having opti symptoms but brushed it off because I really don't drive it that much 5-7 k a year but knew I had to change or check it out,even tho no codes came up. When disassembling I found out why the lower fresh vacuum hose was off and we know the rest dirt moisture etc...that opti and the one I put on was from the parts lady new unopened.prior never had a problem pissed cause this opti had bout 20k and perfect
,but **** happens lol

Injuneer

Did you actually determine the Opti is the problem, or are you just assuming because the vacuum line was off it must be the source of the problem?

What year is your car - A SIGNATURE WILL HELP YOU GET HELP?

https://www.camaroz28.com/forums/lt1...nature-879835/

We have no idea whether your engine is stock or modified, what trans it runs (determines the correct idle speed), etc.

The reason this is important is the P0100 - that indicates as you have already figured out, the MAF problem. But in the 1997 models, it isn't unusual for the pink wire that supplies 12V to the MAF sensor to break inside the harness. Key on, engine off, check for 12V between the pink wire at the MAF sensor and the black/white ground wire.

Bxlt1

Sorry bout that injuneer I'm on my s5 while on my car.basically stock,m6 free mods tune and bolt ons.its a well maintained car IMO.as of now it runs and it was the opti now I have a p0303 code which I'm trying to figure out why, will keep all posted thanks again guys.

Bxlt1

It's a 96 and I took apart all wiring and found nothing unusual on how I put it all back together,I did all normal checks including voltage at maf and so forth. I knew it was the opti off the bat because how it was running and starting the last two weeks just went this Monday. Like I said it runs and starts perfect just gonna get this misfire p0303 fixed

Bxlt1

Pm I couldn't get my signature going ?? 96 z bolt ons free mods tune cat back. I still have misfire p0303 it goes away when I scan but comes back checked everything again plug wire connections injector harness etc didn't do a voltage test yet,all this happend after opti change.it starts runs no problem has a shake at idle but a blip of throttle it smoothes out. But goes back to shaking a bit. Driving the car cause of misfire it's down on power and acceleration,you can feel it stumbling and running like crap.any thoughts next besides test injector. Thanks again everyone

moparman

P0303 indicates a misfire with number 3 cylinder. Have you pulled the plug?

Bxlt1

A.m mopar man.yes pulled plug all good color gap so forth.im gonna swap plugs and injector harness than ohm test the wire and check voltage at injector.after that ??????? I had misfires before but easily fixed burnt plug wire,loose plug etc but not like this.

Bxlt1

Ok as of now the car runs so bad,it starts and idles but driving is so bad.the car barely moves I'm getting p0305 p0307 also p0303 and sometimes p0306 don't know why it's going to pass. Side now. Also I have a real bad raw exhaust smell on driver side I'm thinking now blown manifold gaskets ? Or bad 02 even tho no code comes up. Btw it only has the first 2 no rear,but long since tuned out. All the headache and b.s came after a simple opti change never had this mess before in 9 years. Most if not all of shoebox tests and so forth all checked out normal from maf to ohm test on wires. Need help please any more suggestions.

DocJhn

I don't know if it was coincidence or not but the Z's Opti was replaced a couple weeks ago. New Coil and new Maf also. It would start stumble and die. An excessive amount of Seafoam in TB was thought to be the problem, but after getting it to run for a while and still croaking, that was discounted as it should have all passed through. I told my Wrench to ck the air filter, sure enough was dirty. Cleaned it she fired right up and has now done a 100 miles no probs. Acc to 100mph smooth and sweet! Just a thought. Good luck!

1996LT1Z28

I'd make sure that the plug wires are going to the right plugs. I changed my opti and put the plug wires in the wrong places.

I learned real quick on that one.

Bxlt1

Hello everyone quick update still running like crap it starts idles fine but drives like its a 4 cylinder it has no power at all in all gears. Every time it starts and I drive immediately all these misfire codes pop up 303 305 307 sometimes 306.now the majority of the codes are driverside obviously and I do have a strong exhaust smell so I'm leaning toward blown manifold gasket,I checked all injector o rings all fine,voltage on all are 120v plus I did spark test and noid test checked plugs, wires for cracks tares etc. honestly it ran better with the opti that was going out,I had power and the low mid torque we all love bout these engines. Now it barely accelerates. All else is good from maf icm coil fuel pump fuel press. Etc I'm leaning towards the mani fold gasket or could bad 02do this even tho no code shows up. I have the first 2 only the rest tuned out. Like I said before this was always a great running car gave me little to no problems but after this opti change something went bad??????

ACE1252

So.....why not put the old opti back on it and see if it gets better? I'm not sure how you get to saying the problem is a manifold leak when it was running much better before the new opti swap.

Simple logic would say that something is screwed up from doing the opti change....now what that might be could range from wiring harness issues, spark plug wires, to other electrical/mechanical issues.

I have read of some opti's being bad out of the box, but generally it's not the GM or Delphi ones.

Which brand opti did you get and who did you buy it from?

Are you absolutely certain that you clocked/installed the opti correctly? You can install the 95+ opti units in the wrong position. This will usually damage the unit as it puts excessive stress on the rotor assembly. Did the opti seat to the block easily(by hand) or did you have to pull it to the block with the screws?