How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask CarQuestionGuy Your Own Question
CarQuestionGuy, Technician
Category: Car
Satisfied Customers: 1259
Experience:  ASE Master Auto Technician for 5 years, ASE Refrigerant Handler, ASA, iATN
Type Your Car Question Here...
CarQuestionGuy is online now
A new question is answered every 9 seconds

95 isuzu trooper: Its running on 3 cylinders 2, 6, 1......5, 3, 4 it

This answer was rated:

I have a 95 isuzu trooper 3.2

Its running on 3 cylinders 2, 6, 1......5, 3, 4 it is missing. I can pull the plug wires on 5,3,4 all at the same time and it changes nothing the idle stays the same. But I'm getting good fire on 5,3,4. The 95 has 3 coil packs 1 has 2 & 4 pack 2 has 6 & 3 pack 3 has 1 & 4. What I find odd 5,3,4 is the front terminals on each coil pack and 2,6,1 is the back terminals on each coil pack. Could this be a bad Ignition Module?
Thanks for asking your question on JustAnswer. My name is XXXXX XXXXX I'll do my best to answer your question.

It might be an ignition module. There are several things I need you to do first though.
Check the resistance of the spark plug wires. Then should be less than 30,000 ohms. Also check them to see if you can find any carbon tracking. (When the engine is running do you hear any clicking noises?) While you are doing this try to switch one of the known good wires with one of the questionable ones, see if the misfire follows.

After that remove all of the spark plugs and inspect them to see if they need to be replaced. You might have already done this, but if ot you need to check them. You also might want to do a compression test at this point to rule out a problem with compression on those cylinders.

Remove the coils and see if you can see any carbon tracking or anything that looks like it might be causing a problem. Check to see if the connectors have a tight connection and make sure the spark plug boots are on tight.

Do these checks then let me know what you find. This could be a lot of things. Possibly even the electronic ignition module.
Customer: replied 5 years ago.
Thanks for helping I'll try what you said and get back to you. Its got new plugs and wires but I'll switch them out and see what happens. It just seems odd that all 3 of the front terminals 5,3 & 4 on the coil packs are the ones missing and the back ones 2,6 & 1 are working fine. I'll try switching 5,3, & 4 plugs and wires with 2,6 & 1 and see what happens. I'll let you know something soon. I'll check the compression too.
That sounds good. Just let me know.
Customer: replied 5 years ago.
Ok Steve here is what I done.

I switch out 534 plugs and wires with 261....and it did not change nothing. Still missing on 534. I also checked the compression on all the cylinders and 160 to 170 on all 6. Its got me I don't know what else to do? 534 have very good fire going to plugs and the timing is on the mark plus I put a new timing belt on a few months ago. Also I had all the fuel injectors checked and are working fine its got 42 psi on fuel pressure. Could the ignition module be throwing off the time the spark goes to the plugs on 534? Something is off with the fuel,spark and compression timing of 534.......but what is throwing it off?
So all of the spark plugs are firing? How have you verified this? Have you done any other test other than a cylinder balance test?
Customer: replied 5 years ago.
Yes all are firing. I pulled each plug and all are getting good fire. I also put a plug light on each plug it lights up good. As far as any other test please tell me. Its odd that the front terminals on all 3 coil pack is the cylinders 5 3 & 4 that missing. I can pull all 3 of the plug wires at once and the idle does not change. But if I pull anyone of the back terminals 2 6 & 1 and the engine dies.
Do you have access to a set of "noid lights". We need to verify that the injectors are working. I know you said you had them tested, but the cars computer might not be turning them on. This will verify that they are being turned on by the computer.
Customer: replied 5 years ago.
No but I will try to get a set. Could the computer just turn on injectors 2 6 &1 and not turn on 5 3 & 4?
It is possible. It is also possible that there is some other wiring issue. We need to make sure they are all being turned on.
Customer: replied 5 years ago.
Ok Steve I went an bought a set of noid lights $16 for six lights. I just finished and all six go off and on. So the computer is working. Is the injectors bad? I just paid $210 a few months ago to have to cleaned and checked. If I unplug the plug wire to one cylinder and start the engine....if the injector is working would the plug be covered in gas when I pull it? Just thought that might be away to check the injectors without having to go in and remove them. That's a good job on a trooper.
If they were just cleaned (assuming that the place that did the work was a good shop) then they should be fine. Now that we know that they are working we can move on.

Is the check engine light on right now?
What are the codes?

After I know this then we can do some more tests.
Customer: replied 5 years ago.
No check engine light is not on........the only code is 12.
Code 12 means that everything is normal (according to the computer!) so let's check a few other things.
Let's get a vacuum reading. This will help to verify that the exhaust is not plugged.
Also, lets check the MAF sensor. Just disconnect it and start the vehicle. If it runs better then the MAF might be a problem.
Have you checked for a vacuum leak? Take some carb cleaner and spray it around the engine and vacuum lines to see if the engine picks up RPM's. Also, pay special attention to the intake manifold area.

Let me know the results and we'll go from there.
Customer: replied 5 years ago.
I've already done the vacuum check when I took the injectors out to be checked. Plus I put all new gaskets back when I put the manifold back on. As far as the exhaust I opened up the exhaust in front of the converter.....its flowing free no backup. As far as MAF sensor it does not have one. Its got a MAP sensor but not a MAF sensor. I've changed the MAP sensor. Also put in a new CKS too.
OK. I think that covers all the basics and I don't see any problems so far. I think we can start isolating the problem. I think that there must be a problem with the ignition system since everything else checks out ok.
I believe this vehicle has a waste spark system. You might know what that means but if not, it means that when one cylinder is firing on compression the opposite cylinder is firing on the exhaust stroke.
I think we should have the ignition control module tested at this point. An easy way to do this is to take it to NAPA and they can test it.
Then we'll go from there.
Let me know what you find.
Customer: replied 5 years ago.
Steve we might be getting somewhere with this. I looked up what a ignition module does and several sites said this.

"an ignition control module controls the spark timing and in some cases fuel injector timing of the engine"

This sound just like what its doing! Boy I hope this is it! If not I might just run it off a cliff!

Anyway I'll let you know something soon!
I hope this is it too. You have checked a lot of the common things that can cause this problem, so hopefully we're getting close.
Customer: replied 5 years ago.
Sorry Steve...I have Widblue internet service and its been down the last 30 hours. Here is what I've done.

I took the ignition module to advance store they checked it twice and its working fine. So I went back home and took my 30 30 and finshed the trooper off. "just kidding" but felt like it!

Here something I did.......I took a stethscope and listened to the injectors while the trooper was running. The 3 cylinders that are missing.....the injectors were not making a clicking sound like the 3 cylinders thats not missing. Totally different sound. Do you know of any other test on the injectors you can do without pulling them? Or is there anything else I should look at first?
The test you did to listen to the injectors is a good one to tell if they are working. Since we know that they are getting the signal to turn on the injectors it could be that they aren't working properly.
You could switch the known good injectors with the suspect injector and see if the misfire follows.
You might have a problem with the coils as well, but I would check those injectors first I think.
CarQuestionGuy and 7 other Car Specialists are ready to help you
Customer: replied 5 years ago.
Hi Steve....Well we found the problem it was the injectors. I pulled the injector rail and left the gas line hooked up with the injectors still hook up also, I put a small cup under each injector and turned the engine over and 3, 4,& 5 injectors put zero gas in the cup.....but 1, 2 & 6 filled the bottom of the cup with gas. I switched the wires around on the injectors too but it did not make a difference. I wonder sometime about those places you take to have the injectors cleaned if they do anything at all??? Anyway I found a complete rail with all six injectors on ebay for $40. The said it come off of a trooper with a bad rod knocking. But this time before I put it back together I'm going to check it the same way I did above. If you want I'll let you know when the rail comes in and I get it its running.

Thanks Tony
That is great. This was one of the last things I wanted to check since they were supposedly just cleaned. I think some of these companies just shine them up and make them look pretty then send them back.
Please let me know how it runs when you are done. I'm glad we got this one figured out!