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

[roushstage2]

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

A TPS or IACV would not set a lean code.

No, but may account for the rough/low idle. Still probably needs to be cleaned.

Alex- it may not be coming out of the hole, but there definitely wouldn't be ignition in that cylinder, which on a hard acceleration, can definitely cause a problem similar to yours.

[03mach1]

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

Thanks tyler I will pull out each plug and check them.
I will keep you guys updated on what I find out.
Alexander

[roushstage2]

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

Any updates Alex?

[03mach1]

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

I pulled the plug wires off but did not pull the plugs. just by looking down where the plugs are they look bad. one had rust. and one wire I checked was not snapped on. on these new cars the spark plug wires have to kind of pop on and one was not poped on wich may have solved the problem. I drove the car yesterday and it did not do it. I will drive it again for a little longer to see if the longer the car runs the issue will get worse. The only obsticle that is getting in my way is that I have to pull off my strut tower brace and air intake to get to cylinder 2,3,4. I hope to get to my car tommorow. I have been buisy the past couple of days and I hope tommorw I can get to it. I will take pics. I filled the car up with some medium grade shell gas. Also I have to re clay my car there was road construction and some loose asphalt got onto my car and it won't come off in a wash.My day looks open tommorow so it looks like it would be the best day to do anything.
Alexander

[roushstage2]

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

Which cylinder was the wire loose on? All plug wires should "snap" on.

If you replace the plugs, sounds like a new set of wires would be best too, along with some Di-Electric Grease.

[03mach1]

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

Cylinder #5. It was not snaped all the way on. so I have been looking at kragen online and a new set of plug wires are ranging to 40 to 50 dollars. and a set of spark plugs are 30 to 40 dollars.

[roushstage2]

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

IIRC, Cyl. 5 would be bank 1, so that may explain that code. Has the CEL gone off? The code you gave though indicates your upstream O2 sensor isn't working/reading properly/the proper amount. Maybe it was because of the plug?

If you really want to replace the plugs and wires, let me know. I will see what prices I can get on a quality (perhaps even Ford Racing) sets of each.

[03mach1]

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

That could be it. I just got in from working on it I got far to getting the strut brace off and pulled a couple of wires off one at a time. I just started working on it because I got my Yoshimura RS3 bolt on pipe for my bike and I put that on today. took about a half an hour. I will get my camera out and take pics of the pipe and the cars plugs and wires.
Alexander

[03mach1]

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


I know the pic is bad but that is cylinder #5 spark plug. it is very light almost white which is very lean. How would I richen the car up. This is just one cylinder but I guess the rest of them are the same. Would I take the car to the dealer to richen the car up using the comp? I am now wondering if the guy who put this motor in was drunk or blind because there are so many issues with the motor that i am uncovering.

[03mach1]

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

Well I have bad news. I will have to take the intake manifold off to get to bank two saprk plugs . Unbelievable . This is why I love my T-Bird over my mustang.I will take pics to decscribe what is up. But anyways I just got off the phone with my dad and he said to me not to touch the car anymore and let a proffesional to loo at it. Other wise we are considering to trade this car in. I would fix what I can do then take it to a dealer and get a used mustang. And if I get my new job I can possibly get my favorite car the 08 bullitt mustang. I tride to convice my parents in letting me get a old mustang 67 through 70 any model over getting a new car because of future fixing costs and comlexity of fixing a new car.

[Sal329]

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

Stang97 are you on any of the mustang boards? Check out www.Corral.net www.stangnet.com

[03mach1]

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

I am registered to mustang forums but the site server never works I will give one of those sites a try.

[roushstage2]

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

Well I have bad news. I will have to take the intake manifold off to get to bank two saprk plugs .

That doesn't sound right...

[roushstage2]

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

The MAF sensor and the TPS (those things I mentioned earlier) both contribute to the determination of the A/F Ratio. A lean condition is of course caused by too much oxygen in the mix. With the amount of miles on the engine (higher IIRC), I would not rule those out. A can of CRC MAF cleaner is only about $5. If you do need a new TPS, they run about $30-$40. I would just give the MAF and the IAC a cleaning first, then check to see that the Bank 1 HO2S 1 is working properly. That can be done with a voltmeter. Also, couldn't hurt to check your timing while you are at it, should be 10deg BC.

The code that you pulled (P1131) is telling you that the HO2S (Driver side, before cat) is not working properly, and that can and will likely cause a lean condition. Newer cars are actually easier to fix than older ones because OBD-II will tell you exactly what the problem is, unlike an older carburated engine. Just take a look above at the code, that is the main problem. There are just other contributing factors if they need to be cleaned or are not working either...

FWIW- When I put my O/R X-Pipe on, the after-cat HO2 Sensors freaked out because the readings were off (no cats), and my CEL came on and my car ran lean.

Sounds like the car just needs a larger tune-up...

[03mach1]

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

I have a new intake manifold on the car and I cannot get the socket down the hole to get the spark plug. The manifold is covering up a 10th of the hole and the socket just won't fit.