I installed a racingbeat header and a rebuilt tranny this past weekend, After putting the tranny and header in my car has developed a stutter. The stutter occurs after 3800 rpm only . I can make it accelerate smoothly if I rev it slowly. I thought it may have been the actuators for the 5&6 ports because I had to take them off to get to the header bolts. I checked them today and re-installed them with high temp gasket maker because I had ripped the paper gasket. I still have the same problem. The only other thing that I've changed is the o2 sensor. I had to pull one out of a parts car that I had. The o2 sensor was brand new but I'm afraid it could be the cause of my problem. The stutter quickly becomes a bucking at the higher RPM's. Does anyone have any suggestions as to where to start checking to solve this problem? whats the best method to see if the o2 sensors good?

 

i dont think it is your O2 sensor at all. Hell, when my car was running i didnt even have one hooked up bc i broke the wire and never got around to fixing it. I would look to see if you maybe knocked the wire on your secondary injectors or something about that. 3800-4000RPMs is when the secondarys kick in UNDER LOAD. So, if you are sitting still or are in nutral and you hit the gas, it may rev past the 3800 bc its not under load. i would check to see if your secondarys are firing and if you are getting a signal from the ECU to them as well. Also, look around for vac leaks and check and reset your TPS, you never know, my freind had a 2500 stumble and it was due to a bad TPS, though not likly your problem i would check it. Good luck and hope this helps.

Edit:Try un hooking your O2 sensor temporarily and driving it to see if that helps. It might run a lil rich but it should run "fine".

 

My 88 tII stumbles at 3800 due to secondary injectors

 

This is not just the normal 3800 stumble. I was driving last night in third gear trying to find exactly where the bucking was and its more like 4800 to 5000. As far as the o2 sensor, when mine was'nt hooked up I couldnt rev it above 3000 rpm. I did notice that i left 2 wires disconnected from the tranny job. What does the sensor in the bell housing of the tranny do?

 

Mine did that when I was missing the orifice (pill) in the boost sensor line. If you hadn't messed with the boost sensor I wouldn't think that would be it though. Maybe a ground wire problem. Did you forget to reconnect one of the grounding straps when installing the trans?

Make sure there are no leaks in you boost sensor vac line as well. Never know.

 

What systems does the tachometer deal with. I've noticed that sometimes around 5000 RPM after a couple of violent bucks...The tach will drop to zero and so will my super AFR. When the tach drops out I have perfect acceleration, nice and smooth. This lasts for as long as the tach is out and it instantly starts to run shitty again when the tach kicks back in and gives me a reading. Anybody know what systems to start checking?