jph46

Hi everyone...been chasing a ruff idle in gear miss on a stock 93 LT1, auto trans. I have a H64 set which is lean condition bank 2 right. O2 sensors Bosch, were changed less than 800 miles ago, within 6 months. Also FIC Bosch III injectors about the same time.
Question: would a swap of O2 sensors from side to side help find a bad O2 if I get a DTC 65 after swap?
I have an appointment to do a diagnostic test next week that I can cancel if I find the cause of this miss. Also after reading some posts about Bosch O2's, I have 2 AC Delco on the way just to be sure.
Thanks for looking.

bjankuski

Swapping the O2 would confirm if they were bad if the code switched sides, my guess is the O2 are fine and you have an ignition miss. The miss will show up as a lean mixture.

jph46

My thinking was also the ignition side, the ICM, Coil, plugs and plug wires all have been changed. No codes have ever been set till today on the H64 thus the hope it is just the O2's and not the opti. Would be nice to find it is the O2 sensors before I spend $100 for a diagnostic check. Try to load datamaster on my Windows 10 laptop and got no where with that!
Thanks for the response!
Will follow up with a post if I find anything?

Kevova

What are the INT BLN and cross counts? A ignition miss should be rich, unburnt fuel A lean miss egr, injector(s), vacuum leak possibly carbon. I would look for vacuum leak. Make sure intake bolts are tight. Run BG44K best fuel system cleaner I know of. Since since it an intermittent code at this time. If there is no drivability problem just the light popping on occasionally. I would wait before spending money on diagnosis of a condition that may or may not be present when I take it in remember to use anti seize when swapping O2's

antfarmer2

Look at the o2 wire might be melted or worn by miss routing.

cardo0

A scan would helpful here to look at O2's and see what the injectors and ECM are doing. An O2 swap will verify a good/bad O2 sensor but w/new sensors I don't expect it will be that simple.

jph46

I've been trying to install datamaster, but my computer is Windows 10. Need to go back to Windows 7.
My first thought on this idle in drive issue was the opti, before I replace it with a Petris unit I wanted to make sure the opti was on the way out. I checked the codes via paper lip method and found the H64 code. Swapping the O2 I hoped would give me an indication if I had a bad O2, so far no codes since the swap.
Each time I start the Vette the idle miss has gotten worse, it went from every 10-15 seconds to a more constant miss and even feel like it wants to stall.
I don't mind spending the money to have my local shop do a diagnostic, right now I have a great looking low mileage Vette that I can't trust to get me across town. I've located 2 different vacuum leaks that didn't change a thing once fixed.
I have the FSM but I can't scan to verify anything, the test lights and multi meter only tell part of the story.
I really appreciate everyone's advice, my appointment is this Thursday at the shop unless I stumble on what's causing the miss.
Have a great 4th of July.
Cheers

cardo0

So are we chasing a problem the car had before the O2's were replaced or after? Before the injectors were replaced or after? Why did you replace them - O2's and injectors both?
U need to change the tune for injectors with different specs.

jph46

Everything was changed before the issue started. Replaced stock injectors ohms reading was off, WITH FIC BOSCH III's, O2's ,plugs and wires all original, changed EGR was not holding vacuum and was getting ready for smog check. Car ran great passed with flying colors. A few months later started to have a slight miss, car quit running, found bad ICM, replaced and coil. Since the miss started a few months ago I decided to change the fuel pump, filters and fuel pressure regulator, no change in miss. I've checked and rechecked for vacuum leaks, checked intake bolts everything checked good. Recently I pulled the opti out to check on rotor screws, found one loose, applied blue locktight. While the opti was out found an oil leak at the opti shaft, replaced seal.
Only code I've had was in the last few starts that was the H65. Never had check engine light on.
Just went out and started the Vette, put it in reverse and it felt like it was going to stall, idle was ruff. I know a scan will tell me a lot and hopefully tell me if I need a new opti or not.
Kills me to see her on the easy lift for the last few weeks and not able to enjoy the ride.
Thanks.

jph46

FIC said these are the same as stock, Vette ran great with Bosch III, miss started after ICM & Coil installed. Both O2's and injectors installed months before miss started.

jph46

How do these plugs look? Removed about a week ago with about 900 miles on them? Plugs, O2's, plug wires and Bosch III injectors all all at about same time.
Thanks

antfarmer2

Did you use the proper thermal grease when you did the ICM? New parts can be bad out of the box. I would have the ICM and coil tested.

Kevova

#8 appears fouled they all but #4 look like engine is running rich. Of course misfires can cause over fueling. I would clean or replace plugs and check firing order to be sure wires fully seated at both ends and not crossed. It is possible to use oscilloscope to check ignition operation.

jph46

I did ?
Thanks

jph46

After removing plugs cleaned, checked gap and re-installed. Had the opti exposed so double checked the plug wire locations.
I'm taking the Vette into local shop this Thursday, asked them to do an oscilloscope.
Thanks

antfarmer2

Did all the plug wires click twice?

jph46

Sure did!
Just went out to the garage, started her up, put it in gear and the RPM's went from about 800 down to below 500 and sounded like it wanted to stall. As this miss has gotten worse in the past few weeks I'm thinking it's maybe the opti going south.

cardo0

I wanted to follow up on this as i can read u have a lot of effort with this problem.

Well your plugs look like the end cyls/plugs are a little sooty and i believe the '93 cars were batch fire where all the injectors fire at the same time so my guess here is the fueling is ok and the end cyls just arent firing for some reason - at least not as well at the middle cyls.

Yea i would look some where in the ign controls and the dealer maybe good for this check as they have more diagnostic tools/equip. One thing u could try is power down the ECM - lift the batt pos or pull the fuse and step on the brake for 10 sec. Then see if the car starts and relearns its start/stop and driving settings. Or u may not want to try this and just wait for the dealer to look at it. Well i think your due for a diagnose and see what the dealer says as you've spent a lot of money already. One thing for sure is u have a degrading problem and ive never had an opti get sick on me but more like it would kill the engine then sometimes start again but continue to kill the engine more often. Kinda like the opti(s) would just pass out for a period or for good rather than keep getting worse sick. A degrading ign reads more like a dying ECM but thats only my guess.

Good luck and let us know what u find.

jph46

Just wanted to follow up on this post, replaced the opti with a Petris, idle as smooth as a baby's butt. Thanks for all your advice.

cardo0

Thx for the feedback, it helps us all.