MadZ420

Ok guys thanks for taking the time to look at my problem. I recently rebuilt my engine and repalced the stock turbos. My ECU is flashed, stock turbos, greddy boost controler. I'm miss firing on the number 4 cyclinder. I know this cause I can remove the coil pack connector and there is no RPM drop likie all the other ones and the car wont go anywhere fast and shakes ALOT.

I tested the coil adn plug they work. I did the injector test in the FSM by taking the crank angle sensor off and turning it to hear them click one by one. I don't have an Ohm tester, that's why i did this test for them. They all work too. I also did a compression test on the cyclinder and it came back around 125.

The ecu threw out codes for

Engine temp
fuel temp
knock (which the sensor melted to the block and isn't connected)
throttle sensor.

My questions are will this combo of things cause a missfire?

If I can get my hands on a volt meter how would I test these sensors to see if they are bad?

Please help guys it's been a year and a half since I've gotten to drive my car for waiting for new turbos.

ZLover4Life

Once I got here...

... I stopped reading. Go to Sears or Radio Shack and get a Multimeter - they're probably less than $15 for a basic one. Test the resistance across the leads and then come back. A firing injector doesn't not mean it's a well-firing injector. If the resistance is too low, it'll fire for too long and dump too much fuel to ignite. If the resistance is too high, it'll fire for too short and not provide enough fuel to ignite. There's a reason nobody in the Z32 world uses that FSM's method for "testing" injectors - it's too fallible.

Edit: After a quick scan of the rest of the post, yes, a combination of some those things can cause a misfire, but I'd say you still need to *actually* test the injector. And since you need a multimeter to do all the work anyway, you may as well.

91zxtt

I agree with zLover. Test the fuel injector as that is your most likely cuplrit. Once you get that fixed, then it sounds like 4 more things to work on (knock senser, temp sensor, fuel temp sensor and throttle sensor.

PooFlinginMonke

Sounds to me like an engine ground is not attached.

When you get codes for multiple devices and have done major engine work, check any ground points on the far.

You might find that all the codes reference devices that share the same sensor ground.

snwbrderphat540

all great suggestions, but anyone else concerned about the 125 psi reading on that cylinder? seems a bit low even for a turbo motor no?

MadZ420

OK thnks guys. I got my dad's multimeter and the thing must suck cause it reads 0 ohms for everything, ha ha. So I got to go get a differnt one. I'll check my grounds again too.

Thanks for your time guys. I'll post when I can actually read the fuel injector.

Wouldn't the compression be a lil low cause the rings haven't fully seated and sealed yet?

snwbrderphat540

its possible, still a bit low i think, i neglected to catch the rebuilt motor part haha. sorry aboot that.

PooFlinginMonke

You will get low compression in a cylinder that has not fired recently because fuel has washed down the cylinder walls removing the oil film which helps along compression.

ZLover4Life

Yes, but fuel shouldn't be washing down the cylinder walls unless it's not firing for some reason. If the cylinder is firing, compression should be quite acceptable and it would NOT contribute to a misfire. Something else is wrong.

PooFlinginMonke

The cylinder with the low compression is the one that is not firing.

Now if he unplugs the injector on that cylinder and runs the car for a bit, he can get a more accurate reading on the compression.........assuming that it is firing the injector in the first place.

ZLover4Life

125psi is enough compression fire, and my Z is a testament to that fact... I don't even know why we're discussing this. The low compression is not the cause of the problems, it could be a symptom. We're trying to figure out why it's not firing, and then we can worry about compression once it is.

napoleonzheking

it's either the injector (he needs to test it with a multi), the coil pack, or the harness is fubar... it isn't hard.... it's the number 4, it's not 5 or 6 in the back which can be a pita to mess with with... what needs to happen is madz needs to test it and get back to us...

MadZ420

Ok sorry guys I just got another multimeter. I'm going to go test it out now. I know the coil is good. I got spark when I pulled the coil and layed down touching a ground and ran the car. I could see spark. The fuel injector harness plug gets voltage to it. I'll repost in a few with the ohm reading.

and Thanks again guys for your help

MadZ420

ok the injector tested out to be 11.6 ohms.

I also got an injector test kit from my bro in law. It's pretty much a light that plugs in the harness of it. With it pluged into the number 1 and 2 cyclinders it lights up and pulses. When pluged into the number 4 it does not do anything. I test the wires and the thicker wire going to the connector reads 15 volts with the car running. The skinny wire reads between .541 and .657 about. So I'm guessing the preoblem is with the skinnier wire? Can I asumme that that is the signal wire telling it when to inject? I guess now I need to know where that wire goes and what to look for. Would that wire go back to the PTU at all? Well isn't the coils what the PTU does? Then where do the injector wires go?


Just thought of someting. I found out that the injector wires go to the ECU. Before I pulled the motor most of the injector connectors turned to dust in my hands ha ha. So for a temp fix I crimped some tiny female slide on ones. When I was trying to put the number 4 connectors on with a pair of forceps I did tuch the manifold and it sparked. The car ran fine after that happened. Now since I put it back in I got new REAL connectors that I soldered on. So I thinking maybe I shorted something in the ECU maybe? I guess the sure way to test that is to borrow a buddy's ECU and plug it into my car and see if the problem is still there?

napoleonzheking

did you try disconnecting your battery for about 30 minutes to completely reset the ECU then see if it threw any codes again and ran better? did you get all the grounds hooked back up properly?

MadZ420

Ya all the grounds are back on. I even tried adding an extra one. I actuallt needed a new battery cause the other was sitting for a year and a half. It being disconnected made no differance.


Well just went down to pull the ECU out and sounded like it had a lot of sand in it. So I opened it up and there was so much ROAH poop. Now I keep my car so clean, I have no idea how one would even get in the car let alone my ECU. So I'm going to clean it up and throw it back in and see if it helps any. God that's so nasty!!

MadZ420

Ok well put in my buddy's spare NA ECU. And guess what...... the cyclinder fires. So guess some how my ECU got shot. Now I've already bought a flashed one, so now I have to buy another one? THIS SUCKS!!! Any one got one for sale?

napoleonzheking

I have an NA ECU for sale possibly.

MadZ420

Well if you read my first post . . . I had been waiting so long to drive my car cause I had to save up for new turbos. So the NA ECU wont help. I have a JWT flashed ECU that needs to be replaced. The NA ECU I have was to test the injector. The injector works with a different ECU . . . which is the NA one. I need a flashed turbo one. But thanks.

But I still need to know how to test those sensors to see if they are bad. Even though the cyclinder fires with the NA ECU, it doesn't want to go anywhere at all with any gas. The car idles fine though.

Ok well I assume the NA ECU can't see the TT PTU, cause it throws out a 21 code and pretty much wont run.

So now I don't care if it's flashed or not I just need a TT ECU PLEASE!! Any one know how much they go for?

napoleonzheking

I have a stock TT Ecu, 92, MT, fed as well.

MadZ420

Well how much do you want for it? It will be a lil shile before I can scrounge up the cash for it.

I had a bad idea to try. I know it's bad, but it is the injector thats not firing. So I want to know some thoughts on this before I try it.

I was thinking of taking the injector signal wire of the cyclinder that fires right before the 4th one and jumping to the 4th injector. The ignition timing will be right, just the fuel will be in there a little bit early. I know it's a bad idea but any thoughts on it?

napoleonzheking

i wouldn't do that. you'll be dumping in fuel on the exhaust cycle...i'm sure will some will make it out, and you'll run lean on that stroke. well depending which injector you jump from, you could bring in fuel on compression cycle, which would be even worse.

if the fuel gets there early your going to lose some on the exhaust cycle, and run lean that stroke.
if it gets there late, your bringing it in on the compression cycle.....

MadZ420

Ya I know ha ha, like I said it's a bad idea. But how much you want for that ECU?

I am very intrested in that ECU. But do you or anyone else know if they make a completely stand alone ECU for our car?

snwbrderphat540

a stand alone is for any car, you have to make it adapt to yours. aem ems is probably the most popular

MadZ420

Ya I was reading up on them. No they claim you can just plug you stock harness right into them. But I gave z1 a call and they said they can sell me a stock ECU and put my existing chip in it for a total of $350. That AEM is still $1,200. So I guess I'm better off going through z1. Depending on how much knight wants for his TT ECU.

Ya the number 2 injector is about to go too, def need a new ECU!