Fuel Injector problems

[BrokeTurbo]

Well, the laser had been running smoothly while I was breaking in the new engine, when at about 450 miles, It began to studder. Well, today, I took it to the mechanics shop, and he took a look at it, and when pulling the plugs out while running, the second piston from the left seemed to not be firing at all.

Well, after some tests, checking the spark plug, and checking to see if there is spark, it seems as thou the fuel injector is not sending the right amount of fuel, or any at all.

About 3 days ago, when I filled up my car with gas, I threw in some injector cleaner, to make sure everything was good. Well, I beleive that this is the thing that did it. Could the cleaner have damaged it? I am no longer putting in ANY additives in my car, beucase it seems they all are gimicks.

He quoted me a price of 185 for a rebuilt single replacement, or 450 for all replacement. :xnuts: Yeah, This car is nailing my wallet FAST. I am thinking about taking on the task of replacing them my self.

Ive got tools and time. Would I have to go and take of the whole intake manafold? Or is it just the fuel rail, and a few plugs and harnesses? I am going to read up on this, but ive got to get some sleep, im running dead.

Thanks for the help.

Gabe
92laserturboAWD

 

[turbolover2]

For $450 you could by a set of very good 550cc injectors. Installation is very easy, less than 1 hour with no experience. All you need is a few basic tools, just 3 12mm bolts for the rail, and 2 10mm bolts for the fuel line, and a clamp for the return line. Do it yourself. If you don't want to upgrade the injectors, by a used set of stock ones for about $50 off DSMTrader.com

 

[NJGSX96]

Damn, for $290 you can get a new set of 550s. Hell, for free you can have a set of 450s I have laying around. One is broken, but the other 3 are good. Pay for shipping and we'll call it even.

 

[BrokeTurbo]

Well, I just went out side and did some working, and I took off the fuel rail, and looked at all the injectors. They looked fine. I took out the "Bad" one, and swapped it with another one, and put everything back together, and started her up.

She ran great for a minute or two, then began to miss a little bit. :xnuts: While filling up with gas, I pulled the plug wire out of the piston that had the old "Bad" injector. It didnt change anything. I proceeded to do this a few more times, only 1 time did it affect the running of the car.

So, my new question is, do I really have a bad injector? I swapped the bad with a good, and its missing on the same piston again. Could it be small connector that goes onto the fuel injector it self?

Weve checked the plug wires, and the plugs, and they check out fine. Anyone with ideas let me know.

Thanks again
Gabe
92laserawdturbo

 

[markmakeitso]

you might be able to hook up some kind of light to the connector to check for firing. maybe an LED of some sort, with a resistor if it's 12 volts to the injector.

a multimeter might work too, but i don't know if it would be fast enough to register, maybe it would show whether or not there was any pulses to the injector.

 

[steve]

First I'd be sure that you don't have an ignition problem. Connect a timing light to that cyl wire and make sure it triggers or pull the plug ground the threaded end and have a friend crank the car. Make sure you have a strong spark at the plug. Make sure to do this while the engine is misfiring since it seems to be heat related.

Then I'd find a friend or shop with a oscilloscope who can tell you if your getting a good injector pulse and then backtrack to the cause if you not. The MPI circuit isn't very complicated. It's just the ECU, wires, resistor pack and injector. One side of the injector is connected to the battery via a resistor in the pack (four resistors, one per injector) and the other side is connected to the ECU that grounds the lead when it want the injector to open. The pulses are very short so you can't just hook a light and see it you need an oscilloscope to view them.

Good luck in tracking this down.

Steve

 

[steve]

Originally posted by markmakeitso
you might be able to hook up some kind of light to the connector to check for firing. maybe an LED of some sort, with a resistor if it's 12 volts to the injector.
a multimeter might work too, but i don't know if it would be fast enough to register, maybe it would show whether or not there was any pulses to the injector.

Good idea but at idle the injector pulses are the shortest at idle and even though the led can react to single digit millisecond pulses your eyes can't. Since the duty cycle (time on to time off is so short) the multimeter won't notice any sigificant voltage change but can at least tell you that battery voltage is reaching the injector from the resister pack. Both sides of the injector will look high even though one side is connected to the ECU because the voltage will be present through the injector coil. Since the problem didn't follow the injector their good and you don't have an intermittant injector coil. I'm going to look upstairs and see if Radio Shack sells an inexpensive multimeter that can capture pluses or display frequency in this range.

Steve

 

[jw]

I would like to see a multimeter with waveform capturing capability. Do you know of a brand?

If you just get a multiple that tell frequency, it's not going to work because the DC is not 50-50.

 

[BrokeTurbo]

The shop that I had take a look at it, had an oscilloscope and he didnt find anything wrong. Correct me if im wrong, but an oscilloscope is a hearing device that is like a stethascope, used to hear whats going on inside of an engine/part. Correct?

The shop owner cranked the car over with the plug wire and plug out of the piston, and there was good spark. We even switched a plug with another to see if that would help. Same problems occur.

I am going to look into what I can, but if I did swap the injector with one that works, and the same old piston is not fireing, I am beleiving that its not an injector problem, but a electrical/ignition problem

Thanks
Gabe
92laserturboawd

 

[talonted_one]

your plug wire could be bad that was a poblem when i put my car back together.

 

[talonted_one]

oh an oscilloscope is a machine that takes voltage wave forms and displays them on a monitor. it doesnt "hear" anything. at the least it will tell you if there is a voltage present.

 

[jw]

No, an oscilloscope is a electronic device that can capture and view electrical signals.

[edit]Opps, you get to it first[/edit]

 

[steve]

Originally posted by jw
I would like to see a multimeter with waveform capturing capability. Do you know of a brand?

I have an HP Logic Dart here ($1500) and a nice old dual trace 75mhz oscilloscope. RatShack offers several waveform measuring multimeters ranging from $60 up. All the major companies like Fluke have one or more now.

If you just get a multiple that tell frequency, it's not going to work because the DC is not 50-50.

This statement is wrong in several ways. First the various meters that just offer a frequency range will usually measure the frequency of a DC pulse rate or an AC frequency. Second there's no requirement that either AC or DC signals be of equal duty cycle to have a frequency but in the AC case your talking something more complex than a sinewave.

Anyway this is off topic to solving the problem. Based on the information provided I wouldn't rule out a bad plug wire but I've given at least one simple check to verify that you have power reaching the injector. It should be close to whatever voltage you find at the positive battery post when your testing. That will help rule out some wireing or resistor pack problems. Resistor packs have failed and since these are high wattage resistors it's possible for them to fail after getting warm but work cold.

Steve

 

[jw]

My company has a few fluke multimeter models but non of them are capable of capturing waveform. And I doubt $60 from RadioShack can get something capable of doing it either. If you have a more exact model and make, I will like to check it out because oscillopscopes are expensive. No seriously, if they are $60 and can capture/view waveform, I will buy one right now for my own use.

I dont know why you said my statement is wrong because I am talking about multimeter that is capable of telling displaying frequencies only. Not viewing waveforms. If you hook it up to say a 10khz clock, it will tell you 10khz and nothing else, so how am I wrong that it's not capable of showing the IPW because the DC is not 50-50?
Say for instance at 3krpm 10% ON cycle is 4ms and 100% is 40ms (neglecting injectors dead time to avoid complexity), then you will get 4ms of ON time and another 36ms of OFF time. This is not 50-50. How does frequency be helpful in this case? Keep in mind I am not talking about those capable of looking at waveforms but just a plain frequency value.

Oh, btw, when I said DC, I meant Duty Cycle

Originally posted by steve
I have an HP Logic Dart here ($1500) and a nice old dual trace 75mhz oscilloscope. RatShack offers several waveform measuring multimeters ranging from $60 up. All the major companies like Fluke have one or more now.
This statement is wrong in several ways. First the various meters that just offer a frequency range will usually measure the frequency of a DC pulse rate or an AC frequency. Second there's no requirement that either AC or DC signals be of equal duty cycle to have a frequency but in the AC case your talking something more complex than a sinewave.

 

[steve]

JW, if you want to discuss I'll be happy to explain offline since we are trying to help broketurbo trouble shoot. Since all he needs to know is that he has a injector pulse. A cheap multimeter that will measure frequency will tell him what he can't see otherwise, that the ECU is pulsing the injectors by pulling one side to ground. He doesn't need to measure the injector pulse width just verify he has one. Since everything else you ask relates to you let's do it somewhere else. It's more information than he needs to know right now.

Steve

 

[jw]

How can what I said is off topic? You started by recommending to broketurbo how he can troubleshoot using a oscilloscope and then didnt give enough details on how to do it right. It's just the same thing as someone said his car is bogging/stuttering at higher rpm, I'd suggest him to do an intake leak test. Someone come and ask how/where to get an intake leak tester. I would be glad to tell him how/where to find one. Should I tell him off and said contact me offline as we are trying to help the first guy? This is just the same senario. You mentioned something and I want to know where to find it. How can it be only for my personal information only? How do you know broketurbo is not interested in getting the multimeter with waveform capturing capability if it only cost $60 and do it himself instead of paying the mechanics?

All the information is for the archive as someday, someone will read this post and interested in doing the test himself will find it helpful, so why do we have to take it offline? I am sorry but I disagree with what it was said, how can you said IPW is not necessary for debugging if the ECU is sending in the right signal? Since broketurbo himself said the problem seems to be electrical, so this is ON topic. Reading a frequency does not tell much, just like what I have first said. Frequency with DC not equal to 50/50 is not helping. It may just happen to be noise that the multimeter picked up giving your false readings and you will be back to square one.

 

[NJGSX96]

Gabe... I got your PM, but after reading this thread some more, do you still need that injector?

 

[BrokeTurbo]

Yes, I still Would like the injector. Email me off line. Your private message box is full.

Ok, I did some more testing, and it seems that the injector is not getting any eletrical pulse telling it to flow fuel. I took the connector off, and hooked up a voltameter to it, and it showed 0.02-0-0.04 while the others showed 2.99-3.46. Im not really sure where to go from here, but I do suspect a bad wire/harness or something to that state. Anyone know what might be wrong?

Im going to look around in some books, and ask some people and see what they say.

Thanks again

Gabe
[email protected]

 

[BrokeTurbo]

Ok, Ive been batteling a fuel injection problem, with the number 3 injector not getting a pulse from the electrical side. I've taken the ECU out of the car, and off the harnesses, and inspected both the harness at the ecu, and at the injector. Both look fine. I also opened up the ECU, and nothing is looking bad. I've heard of problems with compasitors leaking, but I guess Im fine, beucase nothings on anything. All is clean.

Where should I go from here?

I was thinking about putting the ECU back in, take a little bit of rubber of the light green wire right where the harness connects into the ECu, and seeing if it has voltage. If it does, I must have a cut line between there and the injector. I will also recheck the voltage at the injector harness. I will also get that small light (Noid) i beleive and see what that does too.

Anyone have any ideas let me know. Thanks

This was reposted becuase of prior help. Thanks

 

[BrokeTurbo]

Ok, Ive been batteling a fuel injection problem, with the number 3 injector not getting a pulse from the electrical side. I've taken the ECU out of the car, and off the harnesses, and inspected both the harness at the ecu, and at the injector. Both look fine. I also opened up the ECU, and nothing is looking bad. I've heard of problems with compasitors leaking, but I guess Im fine, beucase nothings on anything. All is clean.

Where should I go from here?

I was thinking about putting the ECU back in, take a little bit of rubber of the light green wire right where the harness connects into the ECu, and seeing if it has voltage. If it does, I must have a cut line between there and the injector. I will also recheck the voltage at the injector harness. I will also get that small light (Noid) i beleive and see what that does too.

Anyone have any ideas let me know. Thanks

This was reposted becuase of prior help. Thanks

 

[jw]

You can do a continuity test to check if the wire got cut along the way. Also check the resistance of the wires and compare them. I would also suggest to test with a working ECU and see if the problem persist. The ECU may visually look fine but it may not work. I have one right here that look perfect but will not the car will not start.

 

[BrokeTurbo]

Well, last night, I told everyone how I took the ECU out and examined it. Well, I wanted to see some readings of voltage and what not, so I put it back in the car, started it up, and wala. The injector is now firing again. I have no idea what when on, but its working.

So, I guess ive got it solved, but i really didnt do anything. Ill look into it some more, and see what I can find. Thanks for everyones help.