Once my car starts to warm up (just above cold) it backfires and idles/runs bad. The backfire is coming from under the hood, the intake I'm guessing? Once the temp gets to normal, the car runs fine. Any ideas?

The car runs great when cold and when running a normal tempt. It's just that period where the cars temp starts to rise.

Thanks in advace...............Mike

 

Little more info on the car..........


It's a 92 LX 5.0, 181,000 miles. It has new plugs and wires. The ONLY thing replaced under the hood was the alternator (just replaced), the thing lasted 180,000 miles..........dang!! The water pump was replaced also. Everything else is original, including the MAF and all other sensors.

Thanks again..........Mike

 

my car had poor idle and bucking under acceleration problems, I replaced the O2 sensors and it fixed everything

 

Thanx for the feedback, was thinking that, or the maf sensor. How many 02 sensors do we have, 4? Any idea how much they cost?

 

two O2 sensors, I bought Bosch brand at a NAPA store and they were 40 bucks a piece, they might be a little cheaper at Advance Auto or Auto Zone, sometimes they run sales on 'em too

 

Take the MAF off and spray the **** out of the thermistors with electronics contact cleaner. Bet it fixes it.

 

Yeah, just got done doing that. Figured I'd try that b4 the O2 sensors.
I did notice the car runs pretty much the same with the MAF unplugged.
Sound like the MAF is shot?

Mike

 

Almost sounds like a leaky ignition coil. Has that ever been done? Sometime they rupture and arc out under load. At 180,000 you can't go wrong by replacing anyway.

 

Never replaced the coil, so true on the ''can't go wrong by replacing''. I'm shocked it ran so good for so long with everything original in it. Once I get a little more money, I''l throw some parts at it. Think I'm gonna start with the O2 sensors than maybe the coil. Thanks for all the feedback guys.

Mike

 

180,000 miles on original O2 sensors? I'm shocked it runs at all honestly, get some new O2s in there and even if it doesn't fix your problem, it will help.

 

181,547 to be exact More than likely I'll be changing them out this week end. Valentino, they just screw in? Looks like they come with some sort of greese, or is that like a thread lock?.................Thanks man

 

yeah they are just threaded in, it will be a lot easier and quicker if you buy one of those special O2 sensor sockets from the parts store. the sensors come with anti-sieze on the threads

 

OK, I had the same problem with my 87 Gt, I am the Original Owner and one day it started stumbling, it ran better when warm but finally was getting so bad it was ****ing me off!! replaced the standard tune up stuff, tps and finally after all that I replaced the FUEL INJECTORS. Now she runs like brand new with 185,000 miles. The injectors where so bad the were breaking appart when I took them out, they were junk, I can't imagine how bad they were flowing and not cooling the cylinder walls at all. The Mustang runs cooler and has the power back!!!

 

This may seem trivial, but when you changed the plug wires you didn't follow the firing order and use the chevy bank sequence (1357 - 2468)???