94 N/A crank, but won't start

[Z Prime]

Hello. So I have a 94 na 5 speed. The car was showing no problems or anything I go to leave work and it won't start. Try to turn over but wont. Now I did have the battery tested it is 100%. I have seen alot about the ptu being the problem. I am wondering if that is where I need to start? A few months ago, my car wouldn't start for a second, then I pumped the throttle and it started right up. The injectors are only a few years old, and the fuel pump is loud when I switch to the on position (which seems to be normal). So any suggestions? That is all the info I could think of at the moment. Sorry it is so long.

[Z Prime]

Okay. So I got it started. Had alot of white smoke coming from the exhaust when rpms would get to about 6k. Kept revving it until there was no smoke.

[evildky]

Uh oh! Large amounts of smoke generally means a blown HG. You should never free rev your engine to 6k, ever.

[Z Prime]

There is no other sign of a blown head gasket. Nothing wrong with the oil, no oil mixed with the coolant either. Could it be anything else? I am about to just drop a f&@^ING grenade in the car. I put seafoam in the engine (due to a sticky lifter) and gum out in the gas tank and then my car just died while driving after I put them in my car. I also seem to be losing power. I seen on a different thread that I need to check the connections on my ptu, and cas. What about spark plugs? I hope this doesn't cost me an arm and a leg.

[nissanfreak12]

If you flooded the engine, it could have puffed out white/bluish smoke for a short time. Normally black smoke if an rich condition, but a flooded engine could cause a white smoke like you described. Pressing the throttle to get started is a classic flooded issue. Seafoam will do the same thing.

If you are losing power, check ecu for codes first, don't rely on the check engine light. Then check the injectors to make sure the ohm between 10-14, balance test, connectors for corrosion. Does it lose power when hot or warming up? CTS will cause a rich condition if it thinks its still cold when its actually warm. Will also flood an engine. Cats will cause running issues when hot, not so much when cold.

[z.Leinbach]

The gum out stuff is crap doesn't do what it says. Better stuff would be royal purple Max clean, or Lukas would be better for cleaning, for the gas tank,

[evildky]

You cant fix a physical problem with a chemical. Carbon buildup is not likely to cause any driveability issues, the only thing any of these additives can fix that would cause a drivability issue is a clogged dirty or sticking fuel injector otherwise they clean some internal parts that aren't causing whatever inspired you to pour the crap in.

When a PTU fails if usually only fails on one or 2 "channels". Each coil pack receives it's trigger signal from the ptu, each coil pack is triggered by a different wire leading to a different "channel" on the ptu.

If you have a miss the first thing to do is isolate which cylinder(s) is/are not firing. The easiest way to do this si with the car idling, unplug each cop one at a time, if the engine stumbles or the rpm drops that cylinder is working, plug it back in and move to the next until you have identified the problem cylinder(s).

Now swap the cop and spark plug from the known bad cylinder(s) to a known good cylinder and repeat the test. If the problem moves to where you moved the suspect plug and cop then one or the other is the likely suspect, move the cop back and see if the problem moves to determine if it's the plug or the cop. If this initial moving of parts does not move the problem then it could be the ptu, cas or even ecu but first you need to check for fuel.

You can ohm the injectors and should find out pretty quickly if the injector is the issue. If the fuel injectors ohm good, moving cop's and plugs had no effect it's time to check the ptu and compression.

To check the ptu, take all the plugs and cop's out, place the plugs in the cop's and lay them on the plenum, pull out the cas (marke it's location first), then while holding the body of the cas to a ground rotate the cas, you should see each spark plug fire one at a time, if one of them does not fire that "channel" is likely dead in the ptu but again could still be the wiring. If all the plugs fire as they should , it's time for a compression test.

[Z Prime]

Alright, I will check all of those as soon as I can. Thank you all so much for your help so far! It is greatly appreciated!

[evildky]

If you have a logic probe you can check the input and output signals at each channel of the ptu as well as the cop's, just quicker and better when you have the right tools.

[rmlamp]

Definitely check for codes, my Z wouldn't restart after I drove it for awhile. Mine ended up having a bad coolant temp sensor and it didnt have the CEL on but it was throwing a code. So as nissanfreak12 said, don't trust the CEL. If it restarts when it finally cools down completely, it could be the coolant sensor. Check for codes and let us know what you find.

[evildky]

bad CTS and bad O2 present the same, when they go bad the run crazy rich causing fuel fowl, letting the car sit long enough to get cold and for the wet plugs to dry out it starts fine but warm restarts are an issue.

[Z Prime]

So I changed out all the plugs, and 2 coil packs. 1 was really corroded. So I took it for a test drive today, it died on me on the road, so I had to turn around and start it back up. Died on me 3 times within a mile. The engine was making a loud rattling sign and i had loat significant power. The last time it did I couldn't get it to start or crank over. It just clicks. The starter isnt that old. I don't know if I've blown the engine or what. This is really frustrating!!!

[z.Leinbach]

If a ptu is causing a dead cylinder condition, will it cause a super rough idle (acting like a lopey idle feeling). An if so replace the harness or the ptu it's self

[edgewise]

You might to check the crank /cam position sensors and the ignition control module also. Not sure about the setup on your 94 Z is the similar to my 87 Max, but my CPS died with a one sputter and then a no-start. It did not throw a code. I still have problems blowing ICMs and they can partially fail with symptoms like you describe. On my Max it usually throws a code 21 for the ICM.

[Z Prime]

So I got the sub harness with 4 connectors on it and only 2 connectors that go into the ptu. so what do I do with that? It won't plug into the harness on the car, so what are they even for? I mean the only thing I can think to do is cut the old connectors off the original harness and as well as the new. And just Re wire the new connectors to the old harness. I read something about soldering, but I don't have a soldering gun. I would post pics but I don't know how to on these forums.

[Z Prime]

Okay, so I am at a loss... I changed the ptu, cas, starter and starter relay. It only clicks when I try to start it. Nothing else happens. Just clicks once. So is there anything else it could be? I'm about to just sell the thing and cut my losses.

[evildky]

If You only get a click you either have a bad battery, bad starter or bad connection. The fact that you get the click indicates your relay and ignition switch are working. the fact that you only get a click indicates the starter is bad or not getting adequate voltage. check the cables.