Stupid 240

[chrispaugh]

So I will admit I am a bit of a newb when it comes to 240 game. I own a 1989 240sx with a s13 sr20det redtop. Car has a walbro 255, front mount intercooler, a t28 s14 turbo, and a exhaust.. other then that the car is stock.. Recently I have been running into a problem.. will drive great at first but After awhile of driving the car it just feels really doggish.. It still runs and drives but it feel like it lost all power still revs all the way to redline just feels like a huge loss of power.. It also did this when i had the old t25 on there, The turbo started to smoke and get shaft play so i made the upgrade to the t28.. Last night we started trouble shooting.. Fuel pressure was 39-40psi (which is normal), checked the maf looked brand new no gunk on the reader and was plugged in, checked ignition timing was at the right mark, replaced the coolant temp sensor, Did a boost leak test did find a coupler was ripped replaced that. drove it for a bit and it came back..

Now here Is the kicker.. The o2 sensor was wired in before when it started doing this one the old turbo.. So with my luck when i put the new turbo in it broke a wire so i just left it unhooked.. But my thinking was since it is a obd1 or obd0 the o2 sensor really doesnt do anything i understand it sends a rich lean rich lean signal.. but i didnt thing they were that depndent on it..
Any insight?

[jr_ss]

Check your TPS and MAF voltages. Do a compression check and check for boost/vac leaks. You said it went away when you fixed the last one, doesn't mean you can't have another one.

[chrispaugh]

Well the problem is it is so interminttent I drove it to work this morning and it drove perfect, Drove it to lunch and again ran great.

[cotbu]

There are no stupid 240's! Ugly yes, but not stupid! The owner's of 240's are becoming more stupid!

[chrispaugh]

I'm more Stumped then Stupid.

[jr_ss]

Well the problem is it is so interminttent I drove it to work this morning and it drove perfect, Drove it to lunch and again ran great.

Regardless, check over everything...

There are no stupid 240's! Ugly yes, but not stupid! The owner's of 240's are becoming more stupid!

Unfortunately, this is becoming more and more a reality.

[ultimateirving]

Knock sensor and harness. Check them. Sounds like it could be retarding timing based on knock input.

[chrispaugh]

Knock sensor and harness. Check them. Sounds like it could be retarding timing based on knock input.

Thats what ive been thinking because even the pitch of the exhaust changes but i didnt think they fail often

[cotbu]

Get an FSM, search how to pull codes, post codes, then fix problem.
The knock sensor will throw a code if faulty, or unplugged. (34)

[OnTheChip]

I have seen an old fuel filter cause those issues.

[chrispaugh]

Pulled codes this weekend and double checked for boost leask and no boost leak and no codes :( pulled a 55 no malfunction