weird missfire problem

[94RedGt]

I didn't want to make a thread but I just need to find out what the hell is going on with my car. Its basically a stocker 5.0 with the usual boltons like exhaust and gt40 intake. Well the car seems to have a slight misfire at idle, not constant but it will idle smooth then can feel the engine have a misfire and go smooth again, it feels like a kick inside the cabin. Now while cruising at around 1600 to 2200 rpm if I hold the gas in any gear the engine does the same thing, it just feels like its cutting in and out but its really fast. Now during wot, lets say im doing 70mph and I drop it into third and gun it, it just feels like cutting in and out all the way to redline. All the sparkplugs, cables, and coil are new. The pick up coil got changed not too long ago and the ignition module too. I don't know but im starting to think its my maf sensor, a lot of people have also told me that its probably the maf sensor.

 

[RichV]

Sparkplug wires is where I'd start, even tho they are new, if they are arcing, it causes this exact thing. Make sure there is no moisture in the distributor. Inspect cap for cracks or loose towers.

Did you change all the ignition parts at once? Did this problem exist before that?

 

[white95]

^^ this and perhaps the PIP module in the distributor is failing. I was gonna say TFI module but you've covered that base already.

 

[toyman]

a lot of people have also told me that its probably the maf sensor.

Have you tried cleaning the MAF?

 

[94RedGt]

Today I got a new maf, checked the cap and rotor and no problems found there, checked for arcing and none found, no vac leaks, and I tested another coil and still doing the same, the pip module is the only thing I have not physically checked cuz I have to take the dizzy out to put a new one or just buy an entire distributor. Ok so today I went to test the car and I got it on the freeway again, cruising at 70mph drop it into third and all I feel is the engine backfire like crazy, massive pinging and the cutting out problem, basically runs like shit. Now is weird cuz if I drop it into 4th gear and punch it the motor picks up fine and it slightly pings and backfires as the rpms go higher. I think I may have a timing problem, also should pump premium cuz the pinging I have always had it whenever I drive with regular.

 

[MustangChris]

have you gotten a light on it yet?

 

[CC'S95GT]

Pinging is definately a timing issue. get a light on it. don't forget to pull the spout connector.
What kind of plugs are you running?
Pull codes and run a cylinder balance test.

 

[toyman]

Before changing the timing ensure that the HB has not slipped on the outer ring. The pulley should run true and there shouldn't be any sign of rubber protruding from the hub on the engine side. I would be inclined to remove the belt to see if you can feel any movement in the HB as well. There should be absolutely none. Timing can often be advanced to about 14* BTDC without pinging using quality 87 octane gas. Spark plugs can be damaged during the install. I would check them again. Try spraying the sparkplug and wires with a fine mist of water with a bit of vinigar added. You shouldn't see any arcing but if you do that's a likely causing the miss.

 

[94RedGt]

well today I rechecked timing it was fine, checked the sparkplugs and they are fine, empty my tank and used premium. I went to test it again and it did the same thing, I just go WOT in third gear and now I noticed that the rpm gauge just jumps up instead of climbing smoothly but the motor is not climbing smooth either, anyways as im accelerating I hear loud pops coming from the engine like backfires, so its probably missing and all the unburn fuel just burns in the hot header. I think that my pip sensor is just going bad.

 

[Paul]

Swap the distributor. What you're describing is hallmark of PIP, hall effect sensor, or whatever vernacular you'd like to use to identify it. Swapping the distributor will take a few minutes, and will likely fix it right up.

If your car has anything past 100K miles on it, and it's still got the stock distributor or balancer, they're both worth swapping because if they haven't gone out, they will.

Paul.

 

[94RedGt]

The HB is brand new, got it from autozone so im not trusting it to last long but I had to get that one cuz the old one took a shit and I needed to drive the car, now the Pip sensor I did change once but I kept the same distributor and just installed the sensor in it, its a Pita and ill just buy a whole new unit this time.