Car Shudders at 4000 rpm

[Turbo Talon DL]

I recently got my TRE transmission installed by a local mechanic located in the same town where I go to school Lets just say he sucked and I told him. He left a bunch of my ground cables disconnected that I built for extra grounding. Well, the only thing that was done to the car was the TRE trans installation. Now the car hesitates at 4000 rpm WOT at 9 psi on an evo III. It feels pretty normal until 4000 rpm, then it just feels like all the timing is being pulled. I tried decarbonizing the engine with a can of seafoam, still no luck. I dont have a logger right now coy: shame on me, thats the next purchase ). If anybody has any suggestions, please, im wide open for them!

What influences open loop operation? 4000 rpm seems to be the magic number for my car because the a/f ratio stops bouncing back and forth and just reads rich.

 

[slipstream808]

Open loop operation is influenced by throttle position, usually. Other than that if there is an O2 sensor failure, then it will go open loop to be safe.

Off the top of my head i'm not sure about RPM's and WOT, but I believe you are right there.

 

[Turbo Talon DL]

Open loop operation is influenced by throttle position, usually. Other than that if there is an O2 sensor failure, then it will go open loop to be safe.

Off the top of my head i'm not sure about RPM's and WOT, but I believe you are right there.

The O2 sensor seems to be working properly. My A/F lightshow gauge cycles back and forth like it always has. Its a Bosch O2 sensor, $75.00, I doubt its going bad. I have no CELs either, i'm good at making those go away.

 

[brute]

Do you have any type of fuel control? Check your plugs and wires. Plug color and gap will be good. On the plugs, where the long part goes down into the head, look on that thing for little holes. This will be the spark arcing from the plug to the side of the head, which will cause studder. Just check plugs and wires. I nearly guarantee there inlies your problem.

 

[Turbo Talon DL]

The mechanics left my grounding cables for my Nology Hotwires disconnected. I had it so that it routed to the starter negative, to the shock tower bolts, to the firewall, then finally to the negative terminal on the battery. The porcelin insulators on the plugs are fine. My plugs dont leak and the electrodes are a dark reddish color. I havent looked at it yet today. I had to fix the clutch adjustment because the TOB was making noise.

 

[Turbo Talon DL]

I'm posting in this thread again just to help try and keep it alive. I reattached the ground cables they left off, and it still did not make much of a difference. I dont understand why my car would pull timing at 9 psi and 4000 rpm. I could try replacing the PCV and that vac hose. I hope somebody else here has better ideas than me.

 

[pneumo]

You might be onto something when you said it might have something to do with going into open loop at 4K. I think you should double check the intercooler hoses and connections. To remove a trans your mechanic had to remove the uicp, since he sucks he might have messed it up and created a big boost leak.