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Pete, Auto Service Technician
Category: Honda
Satisfied Customers: 27814
Experience:  Over 17 years diagnosing and repairing automobiles various makes and models with some training and certifications.
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I have a 1991 civic that someone did a dpfi to mpfi and obd0

Customer Question

I have a 1991 civic that someone did a dpfi to mpfi and obd0 to obd1 swap on, it runs terrible, bogging out mid range. I've been told the wiring was done perfect and they don't know what's wrong with it. It back fires as well.
Submitted: 11 months ago.
Category: Honda
Expert:  Pete replied 11 months ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.My info is somewhat limited on your model here but I had seen no one else has responded and would like to see if I can help here.If at any time you feel that I cannot help with this please let me know.

This can be a tough one to figure out with the conversion that was done.I would check and make sure the correct computer is installed as well as wiring and make sure everything is connected properly especially grounds to the engine,etc.If this has already been checked into and found o.k. let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 11 months ago.
I've played with the distributor wiring and been making codes but I put it back to normal, no other codes except the o2 sensor which I still need to wire in. It's running super rich. It Boggs out at 3000 rpm roughly and then it will rev right up to 7 or 8 thousand just fine. I made sure the cooling system was all bleed out. My buddy told me that the o2 sensor wouldn't do much. He's done it on his car without the o2 sensor and it run ok
Expert:  Pete replied 11 months ago.

The oxygen sensor signal missing can cause running issues after the engine has warmed up and has gone into what is called a closed loop operation.If the sensor signal is missing in some cases the engine computer can cause the engine to run rich and cause this fault here.I would install and wire this sensor in to see if this resolves the fault here first off.

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.Your 5 star rating is appreciated

Thanks Pete

Customer: replied 11 months ago.
Hey, so I wired in the sensor, no engine codes, and it doesn't smell really bad of gas. It still Boggs and misfires at idle. It sounds like it's running off of 2 cylinders. If I let it bogg at 3000 rpm it will back fire.
Expert:  Pete replied 11 months ago.

Did it back fire out of the intake or exhaust?

Customer: replied 11 months ago.
Sounded like the intake
Expert:  Pete replied 11 months ago.

Have you tested the fuel supply to see if any fuel loss issues are found.Lack of correct fuel pressure from the fuel pump,injector issues,fuel filter issues or vacuum leak.Usually the back fire through the intake is a lean running condition due to one of these faults here or an issue with a restriction in the exhaust.

Thanks Pete

Customer: replied 11 months ago.
I found out that all 4 plugs are firing.. BUT all 4 fire and pause, then fire then pause. It will rev up and then below idle and sometimes idles and missfires. It's getting enough fuel. But if the firing is not consistent
Expert:  Pete replied 10 months ago.

I apologize for the delay as I was offline the last couple of days.This is a difficult one for me to pinpoint rhe cause on here myself.

I will open your question up for others here to see if someone else can assist further on this as there may be others here that may have more info on what to check or do with this issue.I hope you can get this resolved with ease.No need to reply to my last post here unless it is a last resort as it will keep your question locked to me and others will not be able to view it.If you feel you want to continue to work with me on this feel free to reply at any time but keep in mind in some cases it can be difficult to fully diagnose or help repair this without seeing your vehicle.

Thanks Pete

Customer: replied 10 months ago.
Alright thanks anyway

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