Misfiring

**Dropped GP GT** · 11-02-2009

I have a 97 GT and the number one cylinder is misfiring. I swapped injectors, swapped spark plugs, tested to see if it has spark when it is missing and it is, checked for vacuum leaks and everything. I bought a code scanner and got these codes. p0301- cylinder no. 1 misfire, p1200 fuel injector control circuit, p0441 emission purge solenoid. Ok so i replaced the purge solenoid and nothing. Whats weird is the car ran fine 2 weeks ago, i started it yesterday for the first time and the number one cylinder will not fire. can anyone tell me where the fuel injector control cicuit is and how to fix it?

thank you for your response and time to review this

**mikedinthecity** · 11-04-2009

very interesting, i always thought the injectors were ran off the computer...i never heard of that code, did u check compression? i would start there. maybe a cam sensor? also i have had 3800 codes come up for lets say misfire number 3 but i know it was misfiring on more than just 3.... is your car for sure misfiring just on number 1?

**blueguy** · 11-04-2009

Check the plug wires...change them...then check the coils...as for the injector...not sure...maybe check the connectors

**Dropped GP GT** · 11-05-2009

well when i have the car running i went through every cylinder pulling the injector plugs, any the engine rpms and everything changes on all the cylinders but the No 1 cylinder. I just bought the plug wires and spark tested every cylinder and no problems there. Whats really wierd is all the injectors read the same voltage when i tested them. Could my computer be bad? and the code p1200 is a manufacturer specific code, what ever the hell that means, lol. i'm just getting so frustrated cause everything is checking out to be ok.

understanding the DTC codes:
First character stands for the system type...
P= POWERTRAIN
B= BODY
C= CHASSIS
U= NETWORK

Second character stands for sub-systems....
0= GENERIC
1= MANUFACTURER SPECIFIC
2= GENERIC
3= GENERIC/MANUFACTURER SPECIFIC

Third character stands for sub-systems...
1= FUEL AND AIR METERING
2= FUEL AND AIR METERING (INJECTOR CIRCUIT MALFUNCTION ONLY)
3= IGNITION SYSTEM OR MISFIRE
4= AUXILARY EMISSION CONTROL SYSTEM
5= VEHICLE SPEED CONTROL AND IDLE CONTROL SYSTEM
6= COMPUTER OUTPUT CIRCUITS
7= TRANSMISSION
8= TRANSMISSION

Fourth and fifth characters...
THE FOURTH AND FIFTH CHARACTERS DEFINE THE MALFUNCTION THAT HAS TRIGGERED THE DTC.

some research i found about defining trouble codes, thought it might help everyone out if they ever needed to diagnose a problem.....

**Dropped GP GT** · 11-06-2009

Ok, I am at a total lose here. I checked the coil packs, spark plug and wire, fuel injector and even the computer and still don't know why my number one cylinder is misfiring. i scanned it and came back with the same codes as in my first post in here. i unplugged my MAP sensor and started it and no change. What else is there to check that would only cause that cylinder to misfire??? PLEASE SOMEONE HELP!!!!!!!!

**Dropped GP GT** · 11-06-2009

i know its on the number one for sure cause when i pull the other wires while its running the engine bogs down and there is no change when i pull the number one wire.

**GPSims39** · 11-08-2009

hows the coolant level? may be a long shot but i had a misfire for a little while then my HG blew, ended up coolant was slowly leaking into the cyl causing the misfire, just a thought.

**Dropped GP GT** · 11-09-2009

Ok i'm at a complete loss. I can't figure this damn car out. I test the compression, good there, test the camshaft position sensor and the crankshaft position sensor, both good, tested the wiring to the injector, no problems there. what the hell is going on with this thing? i see people reading this postings and no one has any ideas. please i am at my wits end.

**cerick08GP** · 11-09-2009

Well I spent a few years as an electrician trouble shooting break downs. And finding intermittent and multipoint failures can get be challenging to say the least. Most people can easily find a single component that has completely failed. Anyway there comes a time you just need to start replacing stuff, or as we affectionately called it “Easter egg” the problem. I would replace the injector, even though it “tested” fine.

And since you mentioned wiring in your last post I have a good one for you. I would burn headlights out on an old car of mine about once a month. This went on for a couple years, it got to be expensive! I attempted many times to find the cause, came up empty. Until the faithful day when enough was enough, I was going to find the problem if it killed me. So I ended up stripping back the wire harness about 4 feet, and found the wires had been cut and reconnected without insulation.

Then I checked the other side, it had the same deal! Nearest I could figure some jack a$$ ripped out a security system without properly addressing the wires. With any used car it is amazing the stuff you can come across.

**GPSims39** · 11-10-2009

Bro i gave you my experience, check your coolant, make sure its not slowly drinking any cause i will tell you what, you will be in for a HUGE supprise if im right.

**Dropped GP GT** · 11-12-2009

i think i may have found the problem. theres no pulse at the injectors, or at the computer terminal. so i think my computer went out. any ideas on it? please let me know.

**Dropped GP GT** · 11-13-2009

well i fixed the problem. it WAS the computer. zzp and everyone else i talked to said it wasn't. got a new computer and runs like a new car. Thanks everyone for some of your ideas and stopping to check out my post. HAVE A GREAT NIGHT EVERYONE

**Liquifire** · 11-13-2009

by the way, asking zzp for advice often times = fail

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