90 240sx KA24E Woes.. please help

[rocksteady_racer]

Ok so I rewired the MAF and I replaced the tps. Still having the same problem. here's the symptoms: Running too rich - up to 3000 it's rough but once you pass 4k it's definately running way too rich cause it smokes gas out (thick black smoke at around 3000 to 5000 rpm). But it does hit 5000 rpm now just hard to get there. So that's why I figure I can rule out the MAF. The only thing I can think of is that the Fuel Pressure Regulator blew out from the Walbro 255. but everyone usually says that doesn't cause a problem normally or maybe an intake manifold leak or something ridiculous. Also I checked the compression on the block and it looks fine to me. . I just swapped the coolant temp sensor like 5000 miles ago not even. I even used a nissan one. I'm running stock injectors right now thus my confusion of how it can run so rich LoL. I was just wondering if anyone else has had similiar problems because every mechanic I go to is like I have no idea LoL. And it's not running rich in one cylinder it's runnning rich across the whole board cause I just swapped my spark plugs and they were black and I get maybe 6 mpg. Could it be something stupid like the distributor is going bad? Or maybe.... I just got a new ignition coil not too long ago from advance auto so maybe that's causing all of this, like it broke already cause it's 120$ piece of junk LoL? Or maybe just direct wiring it straight thru might fix it (with the relay to the battery thing)? Please Help I'm totally lost at this point LoL.

[JNM240]

Or it could be your coolant temp sensor is bad, making the ECU dump way too much fuel, causing black smoke, fouled plugs, 6mpg, ect....

[rocksteady_racer]

Really? i heard someone say that on another board and I just replaced it about 5000-10000 miles ago I figured it wouldn't have broken so fast since I got a factory nissan one unless it was defective. But I'll try a new one since that's what I've heard twice LoL.

[sloweighty]

Or it could be your coolant temp sensor is bad, making the ECU dump way too much fuel, causing black smoke, fouled plugs, 6mpg, ect....

if it was the temp. sensor then wouldnt there be times when you cannot start the car and times when you could start the car because that was my experience with the temp sensor

[rocksteady_racer]

Then I remembered that my radiator had a little rust in it so it probably fouled up the new sensor that's probably why it's not as bad as above but still annoying to drive. So I'm going to swap in my new radiator and new sensor and if see if that fixes everything. Anybody recommend any good flushing liquid that will get some of the rust out of the engine before I install the new radiator?

[rocksteady_racer]

Ok so it wasn't the coolant temp sensor. Does anyone know where I can find the sensor electrical specifications so I can check all of them with my multi meter? In particular I want to check my MAF sensor and my ignition coil the most because I think it's one of those two and the coolant temp sensor wiring. Any help would be greatly appreciated

[rocksteady_racer]

So if anybody could tell me where to find those and I check all of those and it's not any of them I'm pretty sure I need the head rebuilt because it's making a horrific tapping sound.

[blacksrjdm]

So, ok, tapping sound on a KAT with a smoking problem.

Is it tuned?What was the compression?How is the idle?Is it overheating?Have you tried swapping ecu's with someone?Is your check engine on?How many miles on engine?What kind of turbo?

A HORRIFIC TAPPING sound is normally what I would go after first. Unless that is just the chain guide. But, if it isnt the chain guide, then the horrific tapping noise, just might be the issue. I would remove the valve cover and see if you can see anything loose, broken or otherwise. I dont think at all that this is an electical issue. Also, could be leaking injectors. Not unheard of to have all four go bad. But, not likely. Could even be that the turbo is shot. But I would start at the tapping and go from there. Tapping is never good.

[Wc240]

have you ran the factory test to see if your ECU is in fuel control? if not, i would suggest doing that first

[rocksteady_racer]

What's the factory test for ecu fuel control? I'm probably going to take the valve cover again to take a look. I tried pulling the ecu to check the codes and it came back with 55 (no errors) on the check. I then unplugged the MAF to see if that changed anything and it didn't so I figured maybe the ecu is screwed up and that's the whole problem. I'm going to take the valve cover off and take a look to see if anything is broken. It's not boosted yet. It's just NA. Also I unplugged the tps sensor and it didn't change anything. It ran exactly the same. But the tps sensor is the same as before and it's brand new also it ran the same with it unplugged. so I'm pretty sure it's either an ecu problem or head problem. My mechanic friend also said the tapping might be from one of the injectors so I haven't ruled that out yet but I don't know how to check them with my multimeter.
Modified by rocksteady_racer at 5:16 PM 5/16/2009

[rocksteady_racer]

I just drove it and it seems a little better now since i played with a bunch of stuff. But now it seems to be stutter stepping randomly. Could it be a crank shaft sensor or something or the head maybe?IIt still won't rev past 5500 for some reason and it struggles up to it. It can't be a vehicle speed sensor doing this right?
Modified by rocksteady_racer at 11:02 PM 5/16/2009

[rocksteady_racer]

I fixed one of the injectors - it was reading 0 ohms. So I put the new one and now the motor is running alot better. However, it won't rev past 5500 rpms. Is that a vehicle speed sensor on the transmission or something? Or an ecu problem? Mind you it's all stock. The only other thing I could think of is I have to replace the timing chain or something?