raredesign

I have a 2007 Mustang GT with JLT CAI, 62mm TB, and BAMA tune. Other stuff too, but not relevant to the engine.

The idle is rough and even one time surged like it was stuck and I had to shut it off. Thankfully I was in neutral. When I restarted it, it just bounced like normal.
This problem was rather gradual, noticing the dip and bounce when the condenser kicked on, so I thought I had an alternator problem, but voltage looked stable.
It progressively got worse so I cleaned the MAF and TB with their proper cleaners, and then did a reset "pulled battery" and let it re-calibrate and then drove it around, but still no resolve. It was actually even after the reset that when I turned it on it surged. For the reset, I have tried both steady and easy driving, and then driving like a wild man. Neither had an affect on the idle.

This was all last fall, so I put it away for the winter, so now it is time to start thinking again.

Thanks all.

Nuke

I'd re-clean the TB and also double check the MAF electrical connections. Have you tried another tune? When was the last time you replaced the fuel filter and ran a tank or 2 of fuel system cleaner? Are all of the intake joints/connections tight (no air in-leakage)?

raredesign

Thanks for the reply.

I had cleaned the Throttle Body twice, and MAF 4 or 5 times. The tune from BAMA has worked fine in it for 3 years prior. There are no leaks (tested with ether spray), and tightened again just to be safe.
I have not however, replaced the fuel filter. I have 42k miles, so that is a good idea. It runs fine when I get on it though, and seems like the idle circuit (sorry for carb speak).

Any other thoughts? Known issues?

Simon1

You can try trouble shooting things. I recall having some issues with WOT air/fuel. Tuner had me start the car without the MAF plugged in. The car should still run at idle if the tune is correct. Sometimes people clean MAFs and put them in backwards. It would help to rule out if the MAF is faulty. But honestly, the MAFs either just comepletly stops working or works fine so it's probably not your MAF since it works at WOT.

I have also seen people forget to hook up vacuum lines or have a vacuum leak.

Have you tried taking off the BBK throttle body? They are generally worth more weight in scrap metal than putting them on your car. I have seen a lot of them cause drivability issues.

raredesign

Actually, you bring up a good point about the TB. I remember putting that thing on was a pain! I had forgotten to take the voltage reading before removing the outside screws, as I didn't realize the screws changed the voltage! Odd, right? So when I installed it, I had to put on the TB, start the car, measure the voltage (rinse and repeat) until I got it within spec. Obviously, the car had a very messed up idle until I got it in spec. Maybe something has changed slightly and I should check the voltage when I pull it out this spring. I will test again for vacuum leaks again to. Is there a better way than spraying ether around? That is how I used to test carbs. Wow, sorry to sound ignorant, but I didn't even realize I could start it safely without he MAF in. I guess it makes sense at idle.

Simon1

Seriously, without hurting your ego, the thing is a gigantic piece of trash. You shoud take it off of the car and throw it in the garbage or use in your shop to hold something down. They are notorious for causing drivability issues and offer little to no gains. It takes a very large throttle body to make a difference and you need to ad FI to it to make it worth it.

I guess the info I have is second hand. But I have seen so many guys put that thing on their cars and then have it run like crap. Just try it. See if anything changes. Put the old one back on.

raredesign

Thank you for the reply. No ego to worry about. I am just hesitant only because of the reviews I have seen from others and the "apparent" dyno "claims". I don't want to make a mistake by scrapping it, but I do think it could very well be the culprit. How would I get back to the stock TPS voltage reading? I don't have anything to go by. It was terrible enough trying to put it on, since the directions didn't make any mention of taking a voltage reading until the very end in the troubleshooting section, but then it was too late. I only got it to work by trial and error. Perhaps it was just enough toward the edge of the threshold that "whatever" subtle change recently happened, may have thrown it off. How do I adjust it correctly without a voltage reference? I sent BBK an email last night, so hopefully they have info too.

I wish it was as easy as taking it to a Ford service center, but we all know how that goes.

raredesign

I see a lot of people have a problem with the OEM TPS failing and causing the same symptoms I am experiencing. I think I will replace it with the Motorcraft part. http://www.summitracing.com/parts/mof-dy1116

Unfortunately I will not be able to post an update on this until spring.

Simon1

I wouldn't just go replacing stuff. Do one thing at a time.

I'm sure there is a way to calibrate it.

808muscle

What did you clean the maf with? Brake clean is a big no no. I know you said the proper cleaners but just checking. Aftermarket TBs are notoriously iffy.