ckdudlmq

Hi guys new here! Looking to get some insight on my 93 t/a. I haven't had the car very long but have done a lot of research to figure out all the small stuff but this time I'm stumped. It is almost stock engine just bolt ons. It has long tube headers. The engine wasn't going into closed loop so I changed to 3 wire O2 sensors which solved the problem. The problem I have now is that the car surges on acell idles rough at times and has a ses light for being lean on bank 1. I hooked it up to my lap top and the data shows rich on bank 1 and lean on bank two. All other sensors seem to read correct. Fuel pressure was checked and is about 42 lbs driving or koeo. There is not a maf since it is a 93. I went through and did the spray check on the intake and also checked for vacuum leaks and still have no answer. Any idea?

v8vette84

I'll kick this off...

ckdudlmq

Nice!

v8vette84

Seriously though..... THIS MAN NEEDS HELP!

superspirit

Check for a vacuum or an exhaust leak on the lean bank. do a search for split BLM's there is a lot of info in those threads.

hrcslam

Check TPS % at idle. Also check to make sure the throttle blades are closing all the way. I'd start there.

Does the BLM split (that's what you have) go away as you increase rpms?

Octavarium

iTrader: (4)

I had the same issue with my car and it ended up being the optispark. The reluctor ring warped and would miss an injector pulse on one side of the engine. On the 93s the engine is batch fired so each bank fires all 4 injectors at the same time.

ckdudlmq

Thanks guys. I'll check that stuff out tomorrow. I do know tps % is 0 at idle and .69 volts. Voltage seemed correct wasn't sure about that percentage. Seems like there should have been something. Also forgot to mention its a new opti about 2k miles ago.



Here is a snap shot of the data

hrcslam

Could be the opti, what brand did you go with? Does the split go away with rpms?

Did you try swapping sides with the O2s?

Also, did you verify the throttle blades are actually fully closed at 0% TPS?

ckdudlmq

Hello guys I have a follow up to your suggestions. I checked the throttle body blades and verified they are completely closing. I logged some data while driving and under light throttle the fuel trim gap closes. The lean bank ends up adding about 15 percent long term and the rich side quits pulling 15 percent and actually ends up adding about five percent. The opti is in fact a cheapo from advance because it was bad when I got the car and the previous owner said it was under warranty there so I got it warrantied. The old one had antifreeze in it. One thing I just noticed is that koeo the lean bank O2 voltage drops to almost zero before the car is even started. How does it know the car is lean if it isn't running? I will try to switch the sensors and see what happens

ckdudlmq

Might have solved the problem. I switched the oxygen sensors and sure enough it thinks the other bank is lean. This is the second sensor in two weeks. They are Bosch. I'm going to change to a denso and see what happens

v8vette84

So you already replaced the "bad" one and it also already crapped or was already crap? Thats pretty shitty of Bosch.... I have used them with good results myself but who knows. That was quite awhile ago, they are built in China i'll bet.... Junk! I wonder if one brand is the same as the others now... I read on some forum that sombody bought an AC Delco O2 and it ended up being a Bosch unit in the box... Could have gotten ripped off or Bosch makes Delco's O2 sensors. What vehicle did you look up to get the 3 wire O2?

ckdudlmq

yeah Bosch is made in Mexico. But yes it seems as though I have gotten two bad oxygen sensors. I will update when I get a new one in. I had to order it

obinderwer

The reluctor ring warped and would miss an injector pulse on one side of the engine.

ckdudlmq

Well guys looks like I got it figured out and did indeed get two bad Bosch oxygen sensors. I went with ntk this time and all is well for now. Thanks for all of the suggestions!