OK so my friend put a ls1 in his 3rd gen rx7.. Everything is together and the car runs fine as long as its cold.. WHat happens when it warms up is it starts hesitating and running like crap like its missing but its not a spark or ignition miss.. mY formula(LT1) did this when my front o2s were bad, but im not sure if you guys have any other ideas because his o2 sensors are brand new. The car tries to die also while in closed loop you have to keep on the gas to keep it running, but in open loop its completely fine and idles at 800 just like it should. BTW motor is a stock ls1 out of a 99 TA.. If you guys have any ideas let me know.. tHanks in advance oh and no I havent scanned the car yet were waiting on a friend to bring over autotap

 

02 Sensors switched

 

mass air sensor?????

 

damn, I'd want to say o2 sensors too...they are the only thing that "closes" the loop aren't they? I thought MAF still had a function in open loop operation. You could try unplugging the MAF which would force the engine into SD and see if you still have troubles once closed loop kicks in....that would be easy enough to track that part down

 

Well the maf is new, but i just realized that he used bosch o2 sensors and that they dont work correctly so ewre gonna try some delco ones and see if that helps

 

Let us know what happens with the new o2 sensors. I got the exact same issue going on right now and I have bosch o2's as well.

 

If it runs like crap in closed loop, but runs fine in open loop, leave it in open loop I did, but I'm weird like that...got tired of paying for O2 sensors that kept dying.

 

If it's a stock LS1, chances are it's mechanical...not in the tune. I'd start with the O2's. If they're not the problem, then I'd re-check all of the wiring to make sure everything is going to where it's supposed to. If it were the MAF, it would run like crap all of the time. If it only runs like crap once it hits closed loop (ECT reaches 92*F), then it's more than likely O2 related....either the sensors themselves or the wiring back to the PCM. That's my $0.02...

As stated above, if you all are tuning these cars yourselves...get a wideband and ditch the O2's. Run open loop and keep an eye on the AFR. That's what I do for the same reasons mentioned above. $140 for a pair of O2's is not what I want to be spending mod money on annually.

 

it was a lt1 car and it was a bad new gm opti

 

Did you replace the o2's first and then move to the opti or how did you figure that one out? If it is running good now I'm jealous.

 

It started hesitating in open loop too so I knew it wasn't o2 sensors and I literally replaced everything else that effects ignition since it was a new opti and then just tried my friends used opti and it ran 100 times better so I knew it

 

You gotta love the opti's. You would think you could check that off the list when you put a new one on.

 

They must the be worlds worst distributor.
My old '93 Z28 chewed a few too!

 

mine ate 5 until I switched to a dynaspark