Help! New Exhaust, Engine Bogging Down!

Blinkstang · Jul 16, 2005

I have been having a problem the last few days with my car. This has never happened before, my car has run perfect before my exhaust was installed.

I just got MAC LT Headers, MAC O/R Prochamber, and Magnapacks put in. The motor is stock. Its a 5-speed, 2002 GT.

The other day i was going to work in the morning and started up my car, all good. But as soon as I started driving down my alley, it felt like it wanted to die. I pulled in my driveway, let it sit for five minutes and revved the engine a few times, then drove and it was fine.

The again yesterday morning, went to drive my car for the first time that day and it was doing it again. It idles fine, but when I put it in first gear the car feels like it has no gas and is about to die. It just sputters and bogs way down, kind of like when your in too high of a gear then you should be, like as if I was in 4th but should be in 2nd, the car has no power and feels just like i ran out of gas, it bucks like it wants to die. But if I pop it in neutral, it idles fine and feels normal. So I pulled into the gas station on my corner, let it sit for 5 minutes and revved the engine a few times again and then it was perfect!

So i dont get why it does this when cranking for the first time, or when it sits for awhile. That same day I went to a carshow. Parked the car at 3:00pm. It sat till 9:30pm. Then we were all cruising to another spot and my car was doing it when I put it in first, so I just mashed the gas with the clutch partially engaged, I kept the RPM,s high and kept revving it and got it to drive normal after about a minute of slowly doing this down the street while following the pack, since I couldnt pull over to let it sit.

So what should I do? What could be causing this? I have gas in my car, half tank, so its not that. Its never done this. Would appreciate your help before it gets worse!

Thanks

40th GT · Jul 16, 2005

With all those exhaust mods, it's more than likely that your car is running too rich. Did you reset your computer after exhaust?

KronicRacer · Jul 16, 2005

^^i agree you need to pull the plug on the battery (negative terminal) for an hour or so and then start fresh, the comp needs to relearn.

MyEarsHurt · Jul 16, 2005

Are you throwing any codes? If so, do you have MIL's yet? If you dont have MILS the a/f could be messed up from the retarded electronics.

Blinkstang · Jul 16, 2005

MyEarsHurt said:
Are you throwing any codes? If so, do you have MIL's yet? If you dont have MILS the a/f could be messed up from the retarded electronics.

Hey, yeah actually I have MIL's and the extensions hooked up, cuz of the LT's, and I’m still throwing a code. My Service Engine light is on. I have disconnected my battery, and the light goes away. But after I start driving for like 45 minutes it will come back on and stay on. I have disconnected it like 3 different times and each time the light turns off, but re appears after driving for a bit. Each time I only disconnected for about 5-7 minutes. Should I disconnect it longer?? Would that make a difference, as one of you said i should wait an hour.

And how do I stop it from running too rich?

Thanks for the help guys!

KronicRacer · Jul 16, 2005

it has to be more than just a few mins

leave it disconnected over night, or an hour.

if your still throwing an engine light after this get to autozone to pull the codes. you need to find out if you've got a bad set of mils or if something else happened.

then look into getting a high flow air filter kit. or the basic air silencer removal with k&n air filter. the way im looking at it is the you have got plenty of exhaust flow coming out now with the exhaust set up you have. now you have very little air coming in. you need some sort of intake upgrades to help the intake airflow.

the last resort item would be getting a hand held programmer and throwing that tune on. also turning off the mil sensors on the computer itsself through the programmer.

and another thing im wondering who installed the lt's and how did they do it? was the engine lifted out? maybe something is loose in there somewhere that causing the cel to be tripped. the easiest way to tell is if you get the codes pulled first hopefully its just as simple as pulling the battery plug and air filter upgrade .

then how many miles are on the car?........ theres one more thing and it seems to be over looked with most of the people in this forum. the fuel filter(mostly over looked) if you havent changed it run fuel injector cleaner throught the fuel system and change the fuel filter out now esp if youve been running 87 octane . also spark plugs and pcv valve (blow by does happen on the gt also). this stuff needs to be addressed now at the 3 year mark.
i would also reccommend an oil separator to catch the excess blow by oil that flies through the pcv valve into the plenum.

KronicRacer · Jul 16, 2005

(this is without the benefit of being present to see what the car is doing)

if it were bogged down you would have a surge right afterward and it would be followed by black smoke out of the pipes. then you can say its pig rich. im thinking whats happening is that not enough fuel is getting delivered to the cylinders. usually due to the lt's since they tend to make engines run just a tad richer. check the pcv and the fuel filter.

MyEarsHurt · Jul 16, 2005

It needs at least 30 minutes to reset itself with the battery off. As for the mils, you shouldnt be getting a code if you have mils. What brand mils did you buy? I have heard of a lot of brands that just plain out dont work. Mine are steeda's and they have worked perfect for over a year now.

67efivert · Jul 16, 2005

when we put long tubes om by buddys 96 his af meter went stupid and after a little researce the 2 black wires were crossed in both of the o2 extensions
his had other non realated problems so i dont know if that could cause ur problem but with bad readings could very well be

Disturbed One · Jul 16, 2005

I know this is my 1st post, I have a 97 mustang gt 5 speed. I remember reading in a mustang magazine that when installing LT headers you need to get a tune cause the o2 sensors are moved farther back in the exhaust and they only gained 9hp.... but then with a hand held tuner, I think Diablo, they were able to get it set properly and gained more out of it. Anyone know if this is true with the 4.6? I think it was on a 5.0 in the magazine.

I've been reading the forums before replying and trying to ask questions that have been mentioned before.

Blinkstang · Jul 16, 2005

To answer some of the questions, the car has 28k on the clock. And I too have the Steeda MIL's. The guy that did the install said the tabs on the MIL's had to be clipped because they didnt fit. I have also read about other people having to do this.

And, I too was thinking that maybe I need a tune. Because after driving the car for about 5 days now, I do not really feel any difference. I thought for sure the car would pull harder with the full exhaust setup, especially with the long tubes.

Im on my way to Autozone now to have them pull the code, to get a better idea of what is going on. And Im going to leave the battery unplugged tonight and hook it back up in the morning. Since the most I have left the neg. cable off for is less than ten minutes.

As for the tune. I have never gotten one. Would I have to buy a programmer, like an SCT2, and go to a dyno tuner and have them set it up?? Or how does it work and how much would it run.

And also, someone said that maybe my airflow is restricted. Right now I just have a stock air filter and the air silencer removed. I was going to order a JLT RAI soon, as I have heard good things and it is plastic tubing. Do you really think I would benefit from this with the exhaust mods?

Like I said, I thought my car would be pulling a lot harder than it is, it feels just the same as before the setup, like a turd.

Thanks for the help, keep it coming!

Help! New Exhaust, Engine Bogging Down!

Blinkstang

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40th GT

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KronicRacer

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MyEarsHurt

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Blinkstang

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