Bogging on hard shift

Shiroelex · Mar 27, 2007

This one is really puzzling me. It's been doing this real bad ever since I brought my car out of hibernation. It was doing the same thing, but to a much smaller degree, and much less often, before I parked it last fall.

What happens is, when I take off fast from a stop and shift into 2nd hard, the engine bogs down like if you tried to do a burnout with traction control on. The engine bogs for one second right as I hit the gas once I'm in 2nd, and then it's fine. It's to the point now where I almost can't even squawk second gear. All of my COPs are new, I have fresh plugs in, JUST did the fuel filter, and my maf is spotless. I'm totally lost on this one.

I did get on it pretty hard a little while ago, and when I was cruising along slowly afterwards, it smelled pretty rich, like when I accidentally left a big vaccum line off of my plenum once. I checked all of my lines, and even did the propane test, and everything seems good.

BurningRubber · Mar 27, 2007

Old, worn clutch? Maybe its slipping just a little on the hard shifts.

40th GT · Mar 27, 2007

The only thing I can think of is that you have a bad batch of gas in your tank. And the hibernation added to the problem-the gas in the car lost its 'freshness' and now you're down on power.

Did you use fuel stabilizer before the hibernation?

shhak · Mar 27, 2007

I don't know much about the N/A 4.6's but I currently have almost the same problem right now with my 03 cobra. It runs and drives fine if I'm just cruising but when I lean on it a little, it acts as if the traction control is on. It bogs and sputters until I let out of it. It even made my "Service Engine Soon" light come on. I found out it is the FRPS. (Fuel Rail Pressure Sensor) Ask Uncle Meat if it could be the same thing. He's the one who tipped me off to the problem. If it ruptures the diapram inside of it, it will suck raw fuel thru the vacuum lines and into the oil. Smell your oil and see if it's got a gas smell. Did your engine light come on?

Kilgore Trout · Mar 27, 2007

I think it is either fuel or spark related. Change your plugs make sure you gap the new ones perfect. For your car I would suggest somewhere between .050 and .054 for the gap. I would suggest Motorcraft AGSF-32C plugs. Also change your fuel filter. Plus might as well change the oil and SeaFoam all three ways. After doing all that reset the PCM and let the car relearn the idle properly according to your owner's manual.

It should run a lot better after all that

If it still does not run better after all that it could be the fuel pump or bad coils.

Also, when you are doing the plugs make sure you clean the rubber COP boots and then spray them down with silicone spray to protect and lubricate them. Also clean out the plug wells to the best of your ability before you pull the plugs to prevent debris from getting in the combustion chamber. Use a dab of silicone dielectric grease on the COP spring end where it connects to the spark plug.

As for the FRPS that is a common Cobra issue but GTs are not known to have it. Its so bad a lot of Cobra guys actually carry a spare FRPS in the car

98GreenGT · Mar 27, 2007

My car has the same exact problem, I still have not figured it out. It will fall on its face when im racing, which really sucks. It dies for a second then goes. It doesn't do it everytime. Im running out of idea's only thing i can thing of is maybe fuel pump or regulator, two things i have not tried yet. But since you have a 01 your fuel system is very dif. then mine (no fuelrail mounted regulator, dif. fuel pump). But if you try a fuel pump and it works let me know . If i don't get a chance to try it first. Good Luck..

Shiroelex · Mar 27, 2007

Kilgore Trout said:
I think it is either fuel or spark related. Change your plugs make sure you gap the new ones perfect. For your car I would suggest somewhere between .050 and .054 for the gap. I would suggest Motorcraft AGSF-32C plugs. Also change your fuel filter. Plus might as well change the oil and SeaFoam all three ways. After doing all that reset the PCM and let the car relearn the idle properly according to your owner's manual.

It should run a lot better after all that

If it still does not run better after all that it could be the fuel pump or bad coils.

Also, when you are doing the plugs make sure you clean the rubber COP boots and then spray them down with silicone spray to protect and lubricate them. Also clean out the plug wells to the best of your ability before you pull the plugs to prevent debris from getting in the combustion chamber. Use a dab of silicone dielectric grease on the COP spring end where it connects to the spark plug.

As for the FRPS that is a common Cobra issue but GTs are not known to have it. Its so bad a lot of Cobra guys actually carry a spare FRPS in the car

I've done all of that already I redid all of my coils when I just put in new Motorcraft plugs @ .54, and the gas is a fresh tank of 89. I just added some Lucas fuel treatment, and nothing noticeable happened. Fuel filter is brand new. This next weekend, I will do the oil and I am going to try some Royal Purple. The ECM probably got reset when my battery died over winter, but I will reset it just to be sure. I have a big can of dielectric grease that I plan on shooting into each cop boot as well. Any other ideas?

Mike97gt · Mar 28, 2007

Shiroelex said:
I've done all of that already I redid all of my coils when I just put in new Motorcraft plugs @ .54, and the gas is a fresh tank of 89. I just added some Lucas fuel treatment, and nothing noticeable happened. Fuel filter is brand new. This next weekend, I will do the oil and I am going to try some Royal Purple. The ECM probably got reset when my battery died over winter, but I will reset it just to be sure. I have a big can of dielectric grease that I plan on shooting into each cop boot as well. Any other ideas?

you need to get a fuel pressure gauge on it and read the fuel pressure when this happens..

most of the time when a fuel pump goes bad you will loose power at high load across the board not just after a hard up shift, but it won't hurt to check the fuel pressure.

also check to see if any water or other fluid somehow got into the plug wells, this is a common cause of problems like this and misfires.

Shiroelex · Mar 28, 2007

Will a gauge that works off of the Schrader valve be ok, or do I need something obd-related?

Shiroelex · Mar 28, 2007

Alright. I figured out my problem. It's really embarrassing. My stupid IAC mod (the one that goes in the hose) had turned sideways. I removed it altogether, and she roasts 2nd now. I redid all of my cops with silicone spray, and swapped out my Champions with the plugs Kilgore suggested as well, so that may have helped a bit, but I'm sure the IAC thing was the biggest problem.

40th GT · Mar 28, 2007

Glad ya got it fixed.

Bogging on hard shift

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