The car just started hesitating a lot under load on the way home from work yesterday. It kinda feals like the opti but whenever I had a problem with them before they always throw a code. Has anyone ever had a bad opti that didnt throw a code?

I had headers put on about a month ago and I checked in there in the dark for arching/burnt wires and didnt see anything.

Any advice would help

-Thanks

 

I may be wrong but I don't think it will necessarily throw a code ... someone else wanna chime in???

 

my old car didnt throw a code when it went out.you may want to check your plugs though first,if you havent already

 

Ok so it may be the opti even with no code. I thought the computer was really sensitive to it going out but thats what I wanted to hear is if anyone has had them go without codes.

I will pull the plugs that I can easily get to and check them later today hopefully. But they are brand new TR55's and went in with the headers.

Has anyone had plugs foul that quickly? Probaly less than 2500 miles on them?

 

Hesitation can be many things. Anything from your fuel pump to damaged spark plug wires.
First thing you need to do is check your fuel pressure. If that is good then you need to examine EACH of your plug wires CLOSELY.
There are many posts on how to check for both. Do a search and you should be pointed in the right direction.
Have you done any mods lately? A detailed mods list would be helpful.

 

I had an opti go bad without throwing codes but the car would randomly shut off. As others have said I would look elsewhere first. Fuel and ignition first. I've replaced my opti about 5 times, 4 out of the five times it threw a code. When I first put in my headers I burnt 3 wires in the first month. Took three burnt wires to finally get them routed right without them burning. Zip ties are your friends lol

 

Thats a good point I hadent event thought of a weak fuel pump untill you guys mentioned it. I always think of fuel pumps just dying and not working at all when they go.

Z28LT1_JUST_NASTY
How did you determine you burnt wires? I tried looking in there in the dark while it is running looking for arching but didnt see any.

Mod list is simple:
AS&M Headers
Mufflex Cat back
Wires in stock location with NGK TR55's
SLP Cold Air Intake

Thanks for the input guys.

 

You might want set up a "signature" and add the year of your car, model , eng, trans and major mods. That way people can answer your questions more accurately.

For example, the code lists are different between OBD-I and OBD-II, so how the PCM detects a faulty Opti is somewhat "year" related. Both OBD-I and OBD-II set codes for a faulty optical sensor section of the Opti, but no direct codes for the high voltage section (cap & rotor). But OBD-II adds the ability to count misfires, by individual cylinders, so high voltage problems may show up there.

 

Dont own a camaro but a lt1 caprice and threw no code when opti was on its way out

 

I had a similar situation after I installed my headers. it was the o2 sensors. I had plenty of power when I first started the car, but after a few minutes of driving I got a bad hesitation.

 

I dont mean to hijack the thread but I am having a hesitation under a load and thought it was the opti, so I got one but havent installed it yet. Mine has been doing this for some time now and I just now logged a run this morning. It showed knock at all times (during the hesitation) all the way up to 15 degrees. The fuel psi is good and the wideband stays around 14. As far as a dark test for underhood lightning, there is none. I have made no new mods since it started this. Can a bad set, or just one, knock sensor cause this? I have no codes coming up.

 

Test everything:

Check fuel pressure - http://shbox.com/1/4th_gen_tech2.htm...essure_testing
Swap fuel filter
Check for burn wires
Check for fouled plugs
Test coil - http://shbox.com/1/coil_testing.jpg
Test icm - AZ can test it
Test opti - http://shbox.com/1/4th_gen_tech2.html#opti_test
Check pre-cat o2's

As for the question about knock sensor...I don't know, but heres how to test it - http://shbox.com/1/4th_gen_tech2.html#knock_sensor

 

I physically took all the wires out and laid them out on the ground to look for burns. I know it sucks to do but it's really the only way to get a good look at them without the possibility of missing one.

 

^^^Yep. You can't get a good look at every inch of the wires until they are right in front of your face. I thought for sure my wires were good once, until #7 was out.

 

Sorry about never specifying the year. Its a 94 OBDI

I did the opti test and everything was ok. After looking at it further with my firend I am prety sure its a burnt wire on the pasenger side. Most likely that #7.

Ill test the fuel pressure before I pull the wires but It "feals" like a down cylinder on the pasanger side. I was hoping that I wouldnt have to go in there untill I needed to change pulgs but looks like that isnt so.

Looking foward to seeing how the heck to get to that #5 plug.

And thanks for all the replies guys.