engine wont fire

[4g63tsiawd]

Just got my engine put back in after I installed new rings. My problem is it wont start, if I pull all of my spark plugs and put alittle gas into each hole it will fire for a split second. Things I've done compresion check 140 across the board while engine is cold. Used my buddies ecu nothing. I've got 45psi of fuel at my fpr. I've double check all of my sensor connections. My timing marks are all alined. I'm lost any help please.

 

[blackGSX2g]

Have you checked for boost leaks? Since you said it will fire a bit if you put gas in the cylinders I'm assuming you are getting spark, but did you double check if your injectors are firing? Maybe check the MPFI fuse.

 

[4g63tsiawd]

Yeah I already checked for a boost leak it was fine, and I also checked the mpfi fuse.

 

[WhiteTsiAwd]

Ok well if it wouldnt start before you put gas into the cylinders but did when you put it there yourself, then it is probably a fuel issue. Check your pump, pump wires, fuel filter and see what your fuel pressure is if possible. I do not think that it would be compression though, but I could be wrong. Hope you get it figured out.

 

[4g63tsiawd]

I have fuel to the rail it is seeing 45psi at the gauge.

 

[4g63tsiawd]

I'm getting a code 41 injector curciut on my datalogger.

 

[WhiteTsiAwd]

That would have been my next guess. Your injectors are not firing. Check to see if all of your caps are plugged into the top of your injectors. Umm check all of your wires and connections that are associated with your injectors and or you could have a short or something in the injector harness but i highly doubt that. I dont really know a lot about the whole injector tihng so hopefully someone else who does will chime in. Good luck.

 

[WhiteTsiAwd]

Oh I forgot to mention, look up what that code means in the manual and see what it says to do about it. I would check mine but its not near me right now and im running late for school.

 

[4g63tsiawd]

In the manual the code mean injector thats it, not to discriptive

 

[WhiteTsiAwd]

I meant go to the front and look at the troubleshooting part and see what the symptoms of it are and find the one dealing w/ injectors, assuming there is one, and got to the chapter and see what it has to say. Make sense? Prob not im way to tired.

 

[4g63tsiawd]

I did another boost leak test, first i had air coming out of the oil cap, and the line that connects back into the fresh air line that goes to the turbo. Then I put the engine at top dead center and had air coming out of my exhaust. Does this mean my head is bad, I did nothing to the head will the engine was apart and like i said earlier I had 140psi across the board.

 

[4g63tsiawd]

I did another compression test just to double check and it was still 140 every cylider.

 

[whitetiger]

I have the same problem - no gas going into the motor.... I'll post a fix if I find the problem... plz do the same

 

[4g63tsiawd]

I usually do but this ones a douzie, is your tring to fire at all.

 

[steve]

Then I put the engine at top dead center and had air coming out of my exhaust. Does this mean my head is bad?

At TDC both cyl 1 and cyl 4 are at the top of their stroke. Cyl 1 just finished compressing the charge and is beginning the power stroke and has both sets of valves closed (or should have if anything interesting is going to happen). Cyl 4 on the other hand has just finished the exhaust stroke and is beginning the intake stroke and is in whats called valve overlap, where both sets of valves are open. You shouldn't pressure test at TDC since the air will go from the intake to the exhaust via cyl 4's open valves. You should test about 30 degrees before or after TDC so that no cyl has more than one set of valves open at a time.

It's also possible for air to get from the intake to the exhaust via the EGR.

There are lots of ways air can get from the intake to the crankcase/valve cover. The easiest is via a bad PCV valve, and just about ever aftermarket valve is bad new. The other ways are via the valve guides, turbo center, and past the rings.

An Injector code means the ECU didn't see voltage on the injector circuit when it was trying to fire the injector. The voltage comes from the battery via the, MPI fuse, MPI relay, injector resistor pack, injector to the ECU when it's pulled to ground when the ECU wants to open it. Plus all the wire and connectors in between. Sounds like your problem is early in the process since none of the injectors are firing. The last common point is at the power feed to the resistor pack before it gets split off to each injector.

Steve

 

[4g63tsiawd]

Steve thanks for your reply, what do you think I should check, I know the mpfi fuse is ok, I don't hear any relays clicking but I havent tested the mpfi relay. I will go and test the resistor pack and see if it is working. Oh and I took in acount for a bad pcv valve and capped it off will doing the leak test.

 

[steve]

Start by making sure the injectors have power when the ignition is on.
If your ECU turns on (you see the CEL light and then go off when you turn the ignition on) you know that the MPI fuse is good and the MPI relay is triggering.
Measure the resistance of each injector while you cleaning and reinstalling the connectors.
You should see close to battery voltage on each of the four ECU injector pins when the injector isn't firing. To see the actual firing you need a scope. A noid light at the injector just confirms that the injector has power and the ECU pulls it's side low.

If you don't have a FSM, now's the time to get one.

Steve

 

[4g63tsiawd]

I measured the resistance for each injector and it was good 2.5ohm, but when I tried the injector wires only the #one injector wire read and it was like 66.58 it should be between 2-3 ohms. Also I have no idea what a noid light is or a fsm is. I measured the volts at each injector plug with the ignition on and heres what I got
#1 cylider +wire side was 11.76v - wire side was 11.85v
#2 +wire side was 11.76v - wire side was .003v
#3 and #4 same as # 2

I also checked the volts at the ecu for pin # 50,51,60, and 61 which is all for injector wires and they read 11.76v. My battery is low so that why the v or so low. Why would the #1 injector wire read volts on both wires but not 2-4 only on the + wire.

 

[steve]

when I tried the injector wires only the #one injector wire read and it was like 66.58 it should be between 2-3 ohms.

Not sure what you were measuring here.

Also I have no idea what a noid light is or a fsm is.

Noid light is a tester that goes inplace of the injector so you can see if the wiring and ECU work. FSM = Factory Service Manual.

I measured the volts at each injector plug with the ignition on and heres what I got
#1 cylider +wire side was 11.76v - wire side was 11.85v
#2 +wire side was 11.76v - wire side was .003v
#3 and #4 same as # 2

I also checked the volts at the ecu for pin # 50,51,60, and 61 which is all for injector wires and they read 11.76v. My battery is low so that why the v or so low. Why would the #1 injector wire read volts on both wires but not 2-4 only on the + wire.

Something changed while you were measuring. Both pins on the injector should read close to battery voltage unless some is grounding one of the pins like the ECU does when it wants to open the injector. The fact that you saw battery voltage at the ECU pin would imply that you have that voltage as well at the injector. Unless there is a short or the connector wasn't making good connections, you can't have .003v at the injector and almost 12v at the ECU.

I'm not sure if the wire colors changed from the manual on a '90 but the power (+) wires to the injectors are black with a colored stripe and the ECU side are yellow and Light green without/with stripes.
ECU pin 51 goes to injector 1 pin 2 Yellow w blue stripe
ECU pin 52 goes to injector 2 pin 2 Yellow w black stripe
ECU pin 60 goes to injector 3 pin 2 Light green
ECU pin 61 goes to injector 4 pin 2 Light Green w white stripe

Steve

 

[4g63tsiawd]

So both injector wires should read what the battery is putting out? The # 1 injector wire is right and 2-4 are wrong cause they were reading .003v on the - wire. Also I think the wire changes its color from the injector to the ecu. Should I trace the wire from the injector and see if there is a short or a cut somewhere. Oh and I have a cd manual

 

[rodwa4]

hey i had the same problem. it was the fround. it looked fine but wasn't. just hook the negative clamp of a set of jumper cables to the negative battery pole, and the other negative jumper clamp to the engine block. hope this helps.

 

[steve]

Except when the ECU pulls the one side low, the injector winding is just another resistor between you and the battery but with no current flowing both sides will be close to battery voltage. Once the circuit is completed by the ECU you have a bunch of series resistors and each will have a voltage drop. The pin to the ECU will be very close to 0v and the other side close to battery voltage. It's a voltage divider at DC.

You'll want to recheck your measurments while wiggling the wires around and measure the wires with the ECU disconnected, first with nothing attached, then grounded at the ECU side. Checking to make sure they are shorted to ground or to each other as well as having good continuity.

The injector wire and connectors are in a hight heat enviroment, I would be surprised if they've gone bad. You can buy new 2G style MSD connectors from Summit for a couple of buck each if you don't mind getting 8 at a time.

Steve

 

[4g63tsiawd]

Well I did wat rowda4 said it didn't work but will the jumper cables was conected I re tested the wires for the injectors and now they are saying the proper volts on each one.

 

[whitetiger]

how was it that you got your voltage to be 12v+ on all injector wires??? just grounding the block to the battery??? this didn't work for me...


my thread is very closely related to this... I don't want to hijack this thread so here's a link

http://www.dsmtuners.com/forums/showthread.php?p=1442183#post1442183

 

[4g63tsiawd]

Heres the update, I've checked and rechecked all of my wire harnesses and they are all on. Here are some things that I have noticed, Steve mentioned earlier that when you turn your key to the on position you should get a cel light and then it should go off, I get no light. Next I removed my injectors and soaked them in alcohal and seafoam over night and reinstalled them and it did nothin. I let my battery charge with jumper cables for about a hour, went to get something to eat and left my key in the on position(not on purpose), when I got back and noticed that the key was on I felt the power transistor and it was I don't want to say hot to the touch but you could defiantly feel it got warm. Went to start the car and I fired but did not run, kinda like a crank crank fire crank crank fire ect. Also if I turn the key to the on position the afc powers up, then when I go to crank the car the afc resest and re powers up, and I know the wire that the afc manual says to tap into is the power to the mpfi relay. Let it sit overnight and when I got home from work I tried to start it and it ran for about 1 second and dies, like the injectors put more fuel in the combustion chamber while it was sitting, now that the fuel was burnt on the first fire it is now back to crank crank fire crank crank fire.