KA24E Cold Engine Issue

[Riedell]

Same post on 240sxforums.com

Start the car when its cold with no problem. Go to drive it with partial throttle and when it hits 2k RPM's the front end goes down, so I open the throttle a little more (still in 1st gear) and when it hits 3k RPM's the front end goes down. To get out of this "front end" issue or "lack of power" deal i open the throttle up to get past 4k RPM's and it has the power. It feels like a lack of power at those RPM's. When the car is warmed up, these problems do not happen. No check engine light or other light indicators.

Anyways I have good injectors, spark (plugs), compression. I'm getting fuel of course while im driving. I recently did a plug cleaning on my MAF (and cleaned the MAF), CTS, and TPS. O2 sensor is brand new, no vacuum leaks.

Any ideas?

[sx moneypit]

You could have a bad MAF sensor,have you checked for any codes?
Sounds like it is running lean.

[Riedell]

MAF sensor is good. When I cleaned it the idle was adjusted to normal. Maybe it needs another cleaning?

[sx moneypit]

Couldn't hurt to try it.

[Riedell]

Probably tomorrow I will. Earlier today I was in tampa and my fuel pump took a crap (OEM too!). I bought the original sunshade and had my pump replaced. Tomorrow morning I'll see if the problem persists when the engine is cold.

[sx moneypit]

May have been the problem all along.

[Riedell]

In conclusion to this thread, the problem could possibly be in the distributor components when it gets moisture inside of it (dew and humidity in the weather)

I have changed my TPS and has made a significant difference in my problem. Also, make sure your coolant level is good when the car is cold. Check to see if you have air pockets in the system also by loosening the bolt by the CTS (on a ka24e) while the car is running cold. When it starts to warm up coolant will come out very slowing in that hole which means hopefully no air pockets are present in the engine.

One small other issue could be the MAF and your grounds to it or for others. Check all grounds and voltage for the MAF. My problem has been solved partially/fully but I will be doing other small adjustments so this problem is cleared.

Thanks guys for the help.