I have a 2005 infiniti g35 5AT, I've been messing with it for a while and I canr figure out why my car doesn't have any acceleration. The previous owner cut the cats and left out the o2 sensors, so I have 2 codes for those. I'm still hearing a screech when I let off the gas, even after I had the timing fixed. Every once in a while the slip and vdc light come on (no abs light). When I press the brakes and rev the car It will only get to just under 2k and stop. When I floor it I go from 0 to 60 in 17 seconds. Just recently when I'm driving it won't switch over into the manual mode.

I'm about all out of ideas, nothing seems to work so far,, im planning on doing the o2 sensors next, has anyone else had any of these problems??

 

Start with the obvious and install the O2 sensors so the ECM will make proper adjustments. I suspect that you will have zero cam actuation without all the sensors plugged. If you can't afford to get high flow cats then just have O2 sensor bungs welded onto the test pipes then use non-foulers to make them work.

Does the engine rev normally when in park/neutral if you stomp the throttle to the floor?

Powerbraking will limit your throttle to 2k, this is working as intended.

Manumatic mode can be a little problematic, usually the MM switches on the shifter need to be cleaned out with PLASTIC SAFE contact cleaner.

Slip/VDC lights on can be many things but it's usually just low brake fluid in the reservoir.

Describe better this "screech when you let off the gas". Make a video if possible, upload to youtube and put the link here it will automatically embed the video.

 

Sorry for the late response , so far I'm getting all the materials needed to put the o2 sensors back in place, the previous owner decided to cut and weld cheap pipes in place of the cats so I was going to change everything from headers to y pipe and do it right. It has good response when I'm in park, although my exhaust sounds different once it hits 3k.

All of my fluids are at a good level, but the vdc and slip lights still come on after I drive for a bit

And ill see if I can find a video of the noise I'm talking about, I'm not sure if its just the belt tensioner or its something worse

https://youtube.com/shorts/j6YsRc2OK4Q?feature=share

 

A few more updates
- checked all fluids again, all still full
-figure out that my air bag clock spring may be out
-ran the codes, and I get p0507, p0037, p0057, p0158
- the screech was coming from the janky exhaust
-replaced the accelerator pedal, no change
- Car started to overheat in traffic the other day, turned car off before it could even get close to hot.
-car has been idling around 750 since I got it and its just now throwing a code

Car still goes from 0 to 60 in around 17 seconds, I was planning on doing the exhaust and o2 sensors, next fuel pump, and after that **** it and get a compression test.

I'm losing hope lmao

 

I would start with the P0507 code first, if the car can't maintain idle speed control then something is wrong. Start by checking for any vacuum leaks, pay particular attention to the PCV system, there is a hose that goes from the intake pipe to the valve cover down below the throttle body, one at the front of the valve covers that connects bank 1 and 2, then one that goes from bank 1 (passenger side) that has the PCV valve up to the intake plenum.

Make sure all those hoses are tight, no cracks, and unscrew the pcv valve and shake it to make sure it rattles. You should NOT be able to rotate any of those hoses by hand with the clamp installed.

There is also the line for the brake booster, attaches to the plenum on the right (passenger) side and goes into the battery box, then it's a hard line across the cowl and transitions back to flex again at the brake booster.

Also check the intake tube for any cracks, make sure all the clamps are secure.

Before diving into a fuel pump replacement you should just check the strainer baggy on the existing pump to see if it's full of debris.

You can also test fuel pressure but you will need a sandwich adapter like this one from Z1

https://www.z1motorsports.com/z1-pro...rt-p-9160.html

 

In my last exploration, I changed the spark plugs and replaced some ignition coils ( found some oil in 2 of the tubes, from before I did the valve cover gaskets)

- changed the accelerator pedal, just in case.
-fixed the high idle code (back to o2 sensor codes only)
- didn't find any cracks or leaks in any of the vacuum lines.
- found that I have a little too much brake fluid
-found that my exhaust is making a ton of noise (started after my car started to over heat once)
-bad wheel bearing
car does sounds a little weaker when it starts now though, or at least it does to me

Still happy there's currently no oil leaks, the only thing left is the acceleration, last night I was messing around and decided to try and time it again, I got 16 seconds 0 to 60. I don't have bad fuel economy, the car doesn't shut off on me or anything, doesn't shake at all.

Also I found a neat little button in my glove box that'll lock the trunk (thats pretty fancy for me)

 

If you have an android phone check out the app Torque Pro (costs like $5) and a bluetooth OBD2 adapter, the BAFX one on Amazon works the best.

Then you can check realtime data for things like ignition timing advance, I have a feeling that something is preventing advance, possibly the knock sensor or sometthing?

Is the car throwing any codes?

 

I still only have the 2 codes for the o2 sensors, nothing has changed so far, I'm waiting on the y pipe and I'll be able to put the headers test pipes and y pipe all together

Edit: I went back through with a better scanner and I found I have a code for a knock sensor, but will that affect the performance of the car or is it something mire serious

 

Bump

I've been working towards getting the ball rolling on this, tomorrow I'm getting the exhaust problem done. Since I've last posted I've fixed a couple of things

-changed the driver side wheel bearing (no more noise!)
-changed battery, and the battery terminal ( idle went back to normal)
-both valve covers, and gaskets

I'm still doing some research, I've kinda been putting together a list of problems

-knock sensor
-clock spring
-steering angle sensor
-new rattle towards rear of the car (started after accidently bottoming out)
-possile fuel pump problem?
and when I let off the gas It sounds like it's blowing out air kinda like a turbo, I don't know if it's actually air, but I'll find out when I get it fixed, someone had said it was the idler pulley, which I've been having trouble finding the right one.

Lmk if anyone can help give ideas, or anything that'll help me diagnose some of these

 

-Knock sensor issues are usually the sub harness which is NOTORIOUS for the insulation cracking off the wires. There are aftermarket replacements available though which use better quality wire. It's "technically" possible to replace the sub-harness using a coat hanger and some contortionist shenanigans but it's so much easier to just remove the upper/lower/intake plenums since all the gaskets are reusable metal ones. If you leave the throttle body plugged in then you don't even need to reprogram anything. Plus you can wipe all the oil out of the lower plenum galley while it's open.

-Clock spring, just be sure to make a VERY ACCURATE match mark on the old one in relation to the steering shaft, the new one needs to be installed EXACTLY THE SAME or you will need to have your steering angle sensor recalibrated (angle sensor is built into the clockspring).

-Rattle on bottoming out means you probably broke a hanger, not a big deal usually, just weld it back on.

-Fuel issue, get a sandwich adapter for the fuel damper so you can actually test fuel pressure.

-Idler pulley is an easy troubleshoot, there are two, one for the primary belt and one for the AC belt. Remove the belt and spin it by hand, it should be pretty stiff and not actually spin, if it does spin and you hear anything at all then it's worn out.