Flowmaster 40s catalytic converter delete and o2 sensor replacement on 87 k5 blazer

[K5Blazerboy87]

So my exhaust system is bone stock. I dont need any more emmisions and i got a small hole in my muffler and its stock im going to take catalytic converter off and putting 02 sensor new one new pipe tail pipe. Will taking converter off make effect tbi or o2 sensor or anything? But ive been having issues when im driving after warms up im driving it jerks hessitates mechanic checked tranny wasn't that checked fuel pressure that was fine so figured its electrical needs to be on a diagnostic machine. But before hesitation jerking it started to be weird not start right away normally it does being a tbi but i did tuneup changed roter cap plugs coil egr valve replaced vaccum line to egr valve cause it was cracked. Then ran great and then day later it did this jerking hesitating thing while driving .

 

[1987 GMC Jimmy]

No, deleting the cat won't affect anything. It sounds like you've covered the fuel pressure. I would like to know what that number was, but I'll give your guy the benefit of the doubt. Was the filter replaced at that time? It sounds like you've covered ignition pretty well. Maybe vacuum leaks? I'd inspect all the lines per the emissions diagram, and I'd spray starter fluid around the TBI base to see if the idle changes and a vacuum leak is present. I'd be looking to sensors, too, but I imagine you'd be getting SES lights if it was sensor related. Have you been? My go to sensors there are TPS and MAP sensor. If you're running rich and haven't replaced the CTS in a while, I'd throw a new one on for good measure.

 

[K5Blazerboy87]

No my check engine light not coming on but ive never replaced o2 sensor on it will it create that hesitation jerking ?driving it starts jerking after 2nd gear like when im going 25mph to 35 and up so

 

[1987 GMC Jimmy]

Does your SES light illuminate when you first turn the key? It's just important to make sure that it's working, and if not that the bulb, two fuses, and ECM are all in working order. In my experience, the O2 sensor is not as critical as say the TPS, but it might be worth replacing. The reason I say that is because your troubles sound like they're occuring in closed loop operation whenever the sensor is supposed to start working, and when the truck's in open loop, it runs fine. Also, have you checked your timing lately? That might be worth adjusting. 8* initial is a good eightfold setting, and I'd see how that treats you.

 

[wagonman]

Pull dist cap and check if dist is worn out. No side play at all please. Did many @ the dealer. First place I would look with a no SES lite drivability issue.

 

[1987 GMC Jimmy]

You're talking about play side to side? What about rotational play?

 

[K5Blazerboy87]

my check engine does not turn on when I turn the key just fast seat belts light i recently put new circuit board on it to i wanna put led dash lights but not all lights wanna come on i think I fliped floped by accident putting 4 wheel drive into service engine cause whn ever i put it in 4 wheel drive it turns on when i take it out it goes off.

 

[1987 GMC Jimmy]

I'd check to make sure the bulb isn't burned and the ECM A and B fuses are good before you replace them.