rshockey78

I have a 2005 GT, manual. It semms to boggle back and forth in lower gears 1st, 2nd and 3rd really bad between 15 and 35 mph, like its milkshaking, and jerking back in forth. As I slow and smoothly step on the gas, the car jerks back and forth, the harder I accelerate the more smooth it is. I made some bolt on mods. It has the 62 MM BBK throttle body, cold air intake, BBK pulleys, BBK long tube headers into a BBK catted X-pipe into a cat back magna flow exhaust, and I also replaced the coils with MSD masterblasters, and changed the plugs at the same time, and I have a Diablo predator tuner for it, and the jerking has steadily gotten worse over the past few months. When I got the exhaust put on, it did not come with rear 02 extenders, so I drove around for a bit like that with my engine light on, and figured this may be a problem so I finally put the extenders on it, and I reset the computer back to the stock program, and then back to the 93 performance program. I talked to a buddy after it still kept on doing it, and he recommended I change out the throttle response sensor, so I did, and it got a little bit smoother, but 2 days later it was back to doing the same thing. Someone else recommended the fuel filter, or the timing is off on it. I know I can modify the timing on the Diablo programmer, but don't know exactly how to do it, or set it. If anyone has any ideas and can help make it run smooth again, I would appreciate it. You can email me directly at rshockey78@yahoo.com

dysan

There's a bunch of things that can cause those issues considering what you've done. The first thing I'd do it put your stock throttle body back on. There have been a ton of issues with aftermarket throttle bodies. Secondly is your long tubes, you have to get a custom tune with long tubes and from what I'm reading you just have the stock tunes from the predator that you're using. 3rd thing to try is put your stock coils back on...they are another thing that many people have had issues with aftermarket ones as well. There's plenty of people with the stock coils well over 700rwhp.

Sorry to be the bearer of bad news but that's alot of wasted money there. I'd first put your stock throttle body back on and then order a tune from a reputable tuner based on the mods you have. Considering you have a predator I think your best bet would be Bama Chips since they do Diablosport Predator tunes.

Nuke

+1 on going back to the stock TB. Aftermarket TB's won't provide any gain unless you're FI and are known headaches. I'd also get a better tune if you have the Diablo tune. And be sure you're not lugging the engine when you notice these issues. Too low an RPM in any gear and the car will jerk and buck a bit.

rshockey78

Thanx guys.
I got in the car this morning and engine light was on. Checked the codes and got P0430- Catalyst Sensor Efficiency Below Threshold ( Bank 2) and P2197- O2 sensorsignal stuck Lean-Bank 2, sensor 1. So I called American Muscle to talk to a tech since thats where I ordered all this from, and explained what's going on since putting the parts on, he told me that the car needs to be tuned, and to call Diablo and talk to them. So I called Diablo and talk to a tech, and I told him the trouble codes, and he said it doesn't need a tune, he said whoever put in the headers probably installed them with the sensors connected and therefore basically one of them is not working on the passengers side, so he said to look at the sensors and harnesses and find out which one is bad. So I put it on a lift today, and could not find anything noticeably wrong with any of the sensors or harnesses. The only odd thing I noticed is, 3 of the sensors are the stock ford one's, and 1 of the sensors looks like an aftermarket Bosch sensor, but that one is on the front drivers side. The tech believes replacing the bad sensor should fix the problem, so I'm trying to decide on replacing the 2 passenger side sensors, or just replacing all 4?

rshockey78

I had a noticeable difference in power and performance with the mods I made. Originally the car was running like a well oiled machine, I was stationed at Fort Benning and we only had an 1/8 mile track nearby, but the first thing I did was put on the throttle body and CAI with the Predator CAI tune, and there was a big difference at the track and just driving it around. I wish I had a dyno nearby so I could have tracked the improvements. But on street tires no slicks, I was running 7.9's to 8.1's in the 1/8 after those mods, I was originally running 8.3's to 8.5's. My buddy had a stage 4 turbo neon I was beating and going back and forth with, and he knew it wasn't a stock mustang, I told him the mods on it, and he didn't even believe the throttle body and CAI + tune would do that much, because he had raced stock GT's before, and blew them away, it convinced him to put slicks on the neon and I couldn't come close. So then I ordered the LT's, X-pipe, exhaust, Pulley's and coils, and took it to the track immediately, without getting it dyno'd and tuned, there was a lot more power, before with just the throttle body CAI + tune I would burn a little in first, and a little squeek in second, after the new mods, I had no traction in first, and I would continue to burn in second, I had no grip unless I let off. So yes I need the slicks, and I know there was definate power increase from the mods I did. All the mods I did had good reviews and good documented power gains, but your not the first one that has told me I wasted some money. The car ran really good after the 1st upgrades, then after the 2nd upgrades, thats when the problems started. The exhaust shop that did the install, said the kit didn't come with any O2 extenders, so my rear 2 were not connected for a few weeks until I could get those, I would have some throttle response problems when I got low on fuel, and my engine light was on, until I put the extenders on, but originally the car wasn't jerking like it is now, so I'm wondering if it can be as simple as replacing the O2 sensors, or I'm hoping so. If that doesn't work, I'll try putting the stock coils back in, but I don't think it's the throttle body, the BBK throttle body was good for me, and I never had a problem until I did the exhaust and coils. But I will definately get in contact with Bama Chips and see what they can do, thanks for the help. I would like to find a dyno in the Nashville area since I am at Fort Campbell now and get it tuned that way, but I'll call Bama and see what they can offer. I need to get it back to running smooth again before I deploy to Afghanistan, so my wife doesn't have any problems or get worried driving it around while I'm gone, we plan on going down to one car while I'm deployed to save money, but I know she won't like the jerking action.

Sorry to be the bearer of bad news but that's alot of wasted money there. I'd first put your stock throttle body back on and then order a tune from a reputable tuner based on the mods you have. Considering you have a predator I think your best bet would be Bama Chips since they do Diablosport Predator tunes.[/QUOTE]

dysan

If you want to be able to pass emissions, which I suspect you want to since you got a catted mid-pipe, you'll need a custom tune to account for the pre and post o2 sensor's new locations being further away from the engine. That may take care of the problems you're having. The issue is that the computer tries to control the air/fuel based off the lean/rich reads the narrowband o2 sensors provide but since their distance has changed, the computer can't compensate on it's own. It's probably been trying to re-learn as you've been driving it and it's having more issues the longer it's driven.

I suggest just calling Doug @ Bama Chips and talk to him about it and he'll let you know the specifics.

rshockey78

dyson,
OK thanks, I had a hell of a day at work today, from 600 am till about 20 minutes ago, and gotta be in at 530 tomorrow, so as soon as I get a chance I'll give Doug a call at Bama Chips, are they open on saturdays, because thats the way it's looking that I will get a chance this week.

dysan

I don't know if they are open on Saturday or not. I also couldn't find their phone number on their site but I looked it up on bbb.org and I came up with (205) 302-0231.

rshockey78

OK, I got the O2 sensors today, gonna put those on tomorrow when I get a chance. Also ordered the 93 performance tune online for $50 from bamachips.com, and had to order the interface kit from diablo sport, so we'll see what the new O2 sensors do, while I wait for my tune to be emailed to me. Thanx. I may go back on there and order the 91 performance tune as well.

rshockey78

OK, well I replaced all 4 O2 sensors, originally I just replaced the 2 passenger side and it ran smoother, but still had hickups in second gear, but noticeably smoother all around. So I decided to replace the other two and see if that fixes the problem as a whole and gets it running like old. Well once again it is a little bit smoother after running it for awhile, but when cold its still very jumpy just like before. I'm wondering if the computer is just learning and needs time to adjust to iron out the problem. It's smoother but not perfect, so I'm a little dissapointed. I'll have to try and disconnect the battery and see if that does anything. I have the PC interface on the way, and the custom tune from Bamachips, can't wait to get that and put it in there and see if that helps. Hopefully it does, otherwise I don't know what to do except put the stock throttle body back on to see if thats the problem.