Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wrong

[03mach1]

I was driving with my friends who was in the car ahead of me and after a stop sign I decide to give it a hard accel. At 4 grand on the RPM gauge the car started to back fire a loud continuous pop pop pop pop like a back fire and it lost power for that split second. I think it could be a spark plug issue or fuel issue. I run 89 Octane in it. I also run Lucas fuel injector cleaner. Is that bad for the car I put it in once a month not every fill up. Please if you have any suggestions that could be wrong with the motor plaese reply. And it continues through first to second and maybe third I have not tried third at 4 grand that is going really fast.

[premier.mobile1]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Could be any number of reasons. Valve timing, valve clearance, ignition timing, intake leak, vacuum leak to the head, cracked distributor allowing moisture in. Not likely that it is spark plug or fuel related. Hope this helps.

[InfiniteDetail]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

You need to pull the codes. If you don't have a code reader, Autozone will pull the codes for free.

[Sal329]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Does the check engine light come on? Could be a coil pack, wire, sparkplug, bad gas?

[03mach1]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

The did come on a two months ago. I think code p1131 lean bank one but I cleared it and it has not come on since. The motor is a 2000 GT motor. I did replace the intake manifold its a long story. I am the fith owner and I guess when the old owner blew the original up he replced it with a 2000 motor and jerry rigged a bunch of things like my thermostat my car over heated last summer turned out that the owner before me used water plumbing pipe for the thermostat out let meaning my eletric fan did not know what to do. I am running 89 octane so the gas could not be bad. I did get 91 at a safeway could that be it? The car is a front line used car so I just can't see a fuel system issue like this. I did thought at first the timing was out but how does the timeing go out on a new car like this it is not like my 62 where I need to re time every so often. It may have a cam on the car nor sure but it does idle ruff compared to most other mustangs same era. Do you guys think a valve could be sticking to the head? Not sure on really what to do. I do minor work on this car I hate messing with these new cars with the comp in it. Where should I start (Plugs, timing light?) I have never had this happen to me.
Alexander

[roushstage2]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Not likely the gas. The timing may be responsible for the rough idle, or it could be a dirty IAC, TPS, or MAFS. Let me check into it for you.

[03mach1]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Not likely the gas. The timing may be responsible for the rough idle, or it could be a dirty IAC, TPS, or MAFS. Let me check into it for you.

Thanks Tyler, What systems are those that you have stated. IAC,TPS or MAFS. I am not sure. I probably know the sytems just do not know the abriviation.
Alexander

[Mike Phillips]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Not saying this is the problem but when an engine backfires like pop corn popping at a high RPM one cause can be a burnt valve.

[03mach1]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

But how does the valve get burnt? (Running lean?) If the car is running lean why does the comp not have check light come on. I think that there are a lot of parts on this car that are jerry rigged. And I get to fix them.

[roushstage2]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Thanks Tyler, What systems are those that you have stated. IAC,TPS or MAFS. I am not sure. I probably know the sytems just do not know the abriviation.
Alexander

IAC= Idle Air Control
TPS= Throttle Position Sensor
MAFS= Mass Air Flow Sensor

The first two are on the throttle body and control the idle and the throttle position, respectively. These can be cleaned with parts cleaner.

The MAF is located right after the air filter and senses how much and the density of the air that is coming into the engine. You need a special cleaner for this because you cannot physically touch the wire without damaging it and you will also need special driver bits to get it off.

[InfiniteDetail]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Pull the codes before you start spending money or guessing at what's wrong. The computer is very good at telling you exactly what is wrong.

I've got an '88 Mustang that uses the EEC-IV computer, and learning to read the codes has saved countless hours and dollars. I believe your Mustang uses the EEC-V computer, which is similar.

You might post over on www.stangnet.com for more help. I've gotten lots of good help there.

[03mach1]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

I pulled a code off today pending code. P1131 o2s no switch lean. That is what the reader said. I cleared the code and I will see what happens. For now I am going to check all my plugs. Maybe I loaded up the plugs. So thanks everyone who helped. I will keep an update. I will be working on my car tommorow.
Alexander

[roushstage2]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Here is a reply from someone on another forum:

check the spark plugs....you might have stripped a spark plug and blown one out of the head....it will like come out in the plug wire. if so, join the club.

[Sal329]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Had a sprak plug blow out on my 4.6 DOHC I got a heli coil kit from Autozone and all fixed. Not as bad as I thought. But if you did have one blow out the car would not run right at all.
From the code I would think you need an O2 sensor. You can try cleaning the MAS. A TPS or IACV would not set a lean code.

[03mach1]

Re: Need help Mustang backfiring at 4000RPM hard Accel need suggestions of what is wr

Thanks guys I will pull the plugs tommorow. So when you mean a blown plug the threads are stipped and the A/F mixture is leaking out of the plug? Thanks guys for all the help now I just got to go do it.
Alexander