LoudestNinja

I've had this car for about a month. I can tell the previous owner was trying to troubleshoot this problem and gave up. new distributor, new plugs, new wires, all plastic connectors are new. Tested maf, tested and adjusted tps. It appears the previous owner removed a/c compressor and heater core. Car runs and drives, won't idle by itself until warmed up. Checked timing.. Seems to be on point. Very confused. Read about power transistor unit. Can't seem to locate it anywhere though. Any insight or advice would be appreciated. I noticed that plugs are ngk and oem plugs are auto lite copper resistors. Could the pre gapped ngk plugs be my issue?

rogerz

plugs are not your problem. Who told you oem plugs were auto lite. disregard any information you got from that source because head up syndrome. Did you test the maf with a vom per the fsm? are you sure the intake system doesn't have a mouse nest in it. check the fuel pressure with a gage inserted twixt the fuel filter and the fpr. open the cover on the ecu and be sure no fried components therein. check (or even better replace the engine temp sensor (ALSO referred to as the coolant temp sensor. Probably not the o2 sensor but you could disconnect it and see what happens. put a vacuum gage on the system. if you got big leaks it confuses the ecu and it can't give you the correct fuel. are all you connections tight and corrosion free.? Get your battery load tested. Be sure you have clean, tight corrosion free terminals on both ends of your battery cables. Be sure the ground (negative) cable goes to a bolt into the frame before going to the starter. grounding through the starter is not a reliable connection. Z's don't like low voltage. causes the electronics to act funny. it is possible to have enough amps to crank but not enough voltage to run the electronics. If you have one size fit all cheapo clamp on terminals they are a problem waiting to happen. Usually on a rainy night around Oh Dark Thirty. previous owner obviously thought the Z was a 49 ford which had no electronics but did what his daddy did and replaced everything without doing any diagnostics. You could do the diagnostic tests on the ecu outlined in the fsm. takes two people to do properly one counting lights and the other driving safely while watching what is ahead. I caution you to take the readings you get as a big maybe because I have almost never gotten the answer to the problem after doing the test.

my guess massive vacuum leak or the fuel pressure is way low because you got fire and air or it wouldn't drive right. When you say no power under low how fast can you go? The N/A 300 is not very fast to start with. Any kid in a honda with a big pipe can blow your doors off.

86tcoupe

A completely cold compression test ,a good idea when you replace the plugs to tell you about the mechanical cond of the engine
the idle may be gummed up idle solenoid ,passages
what is the 0 to 60 time ?
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LoudestNinja

Okay, sorry for the delay in response. I've been working as much as possible to afford any necessary parts or tools.

I should have time to mess with the car today.
I will re test the maf today per fsm instructions.
I've done the ecu diagnostics without driving the car. It gave me codes for tps and no load on a/c.
I adjusted the tps per fsm instruction and the code went away.

I will make sure my grounds are good. Maybe clean the connections to the ecu. Inspect the intake and ensure no leaks or blockages.

There's just no power on take off. I can floor it and still no real low end acceleration. Once up to speed the car will shift and drive fairly normal.

I'm comparing performance to my daily driver right now. 2002 focus zx3 130hp
Both cars are automatic.

LoudestNinja

O-60 is significantly worse than stock focus zx3

86tcoupe

Is the kickdown swt. on the A/T adjusted right? also there is the TPS switch
We found drilling the heads of the rivets on the back lets you remove the cover to adjust the 2 contacts correctly forward is idle the back power or full throttle there should be a slight gap from 1 to the other
but a 2L very light zx3 should take a plus 1k lb n/a z31.
With the smaller ring gear .that is designed to have more pull power at high speed

LoudestNinja

I haven't checked the transmission other than driving and feeling the shifts.

When you power brake the car it revs to 3k maybe 4k rpms and stops. Doesn't spin tires. I removed oil cap while it was running. No change in idle or anything.

What exactly does the ptu do and where is it located?

rogerz

you can tell if it is the kickdown switch by pulling it into low range and see if you get the same result. Had that problem on my turbo 81 it was a real dog til it got going then zoom. for grins I pulled into low range and whoa bessie she took off. give complete info when you post:
if you would really like answers that would help you and avoid flames give the following info when you post: year of car, n/a or turbo engine, stick or slushbox, digital or analog dash. Most of us can tell by the year what model you have ie 85T is a turbo z31. Z cars come in many flavors and they are all different. example 84,85,86 Z31's pretty comparable. there were changes in 87,88,89. in addition 300ZX can refer to two completly different cars the Z31 and the Z32. No mindreaders here the more info you can post the more likely you get a cogent useful answer. The cars with L engine (straight six) changed almost yearly from their introduction. A 240Z and and a 280Z have similarities but they can also have wide variance.