[mangogirl205]

Okay,well I have posted on here before about my car sputtering and doing this weird bucking thing and a higher then usual Idle(not to bad) once it warms it runs better. It sputters when I accelerate and bucks when I come to a slow stop.AFTER I installed a 65mm BBK TB and spacer (plz don''t say anything rude that I haven't heard already)

Thought it was a vacuum leak..but no. So someone told me to check the TPS.
Okay I did and the volts read 1.33...I was like whoa! I know it's suppose to be .98 or .99. So I was able to tone it down to 1.17 but I wasen't satisfied with that.

I just bought a new TPS and at best read 1.12 to 1.15. Sooo..I figured that is still high let me file down my stock TPS to see where I can get it at. I was able to get it at 1.10 to 1.11 volts. And that is filed down pretty good..If I do anymore the plastic will crack.

So what else can I try?
And what is the worst that can happen with a reading of 1.10-1.11volts?
Or do I just leave it alone?

Because it is driving me NUTS I do not know what else to do.Or am I just driving myself crazy for no reason?

BTW, I installed the new tps today and then installed the modified stock one today aswell. I did NOT drive the car yet. I am assuming my TPS is working If I am able to adjust it.

Thank you for any info or thoughts,
Christina

[stal94gt]

Move your stop screw for your tb in

[mangogirl205]

Originally Posted by stal94gt Move your stop screw for your tb in

Okay,let me go do that now ...I will let you know how it goes. Thank you.

[mangogirl205]

Okay..well before I did the TB screw I just went ahead and installed the new TPS.The volts on it are reading 1.09. Which is alot better then before.

The old TPS,when I tapped on it the volts bounced around(why I replaced it)
***I checked the stock TPS before I installed the new one.It read 1.76!! But earlier it read 1.10-1.11...I have a feeling that TPS was going bad.Good thing I didn't test drive my car then.***

Okay then I adjusted the TB screw and the idle went down to 540/550 vs. it was idling 10 minutes ago at 750-850 RPM. So that is a plus too.

Volts are better, Idle is WAY better and car is running smooth.I have yet to drive it though.But I have a feeling it will run better now.

So would you say..just leave the volts alone on the TPS? Because that was the best I could get it and it's new.And I am SO happy the RPM's went down.I think that worried me the most.

I'll let you all know how my drive goes.

[mangogirl205]

Well..took the car for a ride last night. The car felt like it was going to stall! It freaked me out but I had to pick my cousin up from work.

I got out and checked the TPS volts and they read 1.47.

So this morning I went ahead and did a BISS (Basic Idle Set Screw).Basically reset everything.
1.Start car and let it warm
2.Disconnect IAC
3.Adjust TB screw to get 850-900 RPMS
4.Connect IAC
5.Turn car Off and disconnect battery for 15 mins.

I started the car and it idled fine,at 850 then it dropped a little around 800.But in gear at a stop light it idles at 900RPM.

I checked the volts on TPS and it read 1.27.

I'm just having a hard time adjusting them and trying to get them to match right...RPM and TPS volts.

I did notice when I put my car in park the RPM jumps to 1200 RPMS and I rev it twice and it then goes back down to normal.The butterfly isn't stuck shut and the TB is new and clean.

So anything else I can try? I'm suppose to take my car WED to a mechanic but I don't see what he is going to do that I didn't already. :-(

Anyone know what I can do?

[Jetflo]

Originally Posted by mangogirl205 Well..took the car for a ride last night. The car felt like it was going to stall! It freaked me out but I had to pick my cousin up from work. I got out and checked the TPS volts and they read 1.47. So this morning I went ahead and did a BISS (Basic Idle Set Screw).Basically reset everything. 1.Start car and let it warm 2.Disconnect IAC 3.Adjust TB screw to get 850-900 RPMS 4.Connect IAC 5.Turn car Off and disconnect battery for 15 mins. I started the car and it idled fine,at 850 then it dropped a little around 800.But in gear at a stop light it idles at 900RPM. I checked the volts on TPS and it read 1.27. I'm just having a hard time adjusting them and trying to get them to match right...RPM and TPS volts. I did notice when I put my car in park the RPM jumps to 1200 RPMS and I rev it twice and it then goes back down to normal.The butterfly isn't stuck shut and the TB is new and clean. So anything else I can try? I'm suppose to take my car WED to a mechanic but I don't see what he is going to do that I didn't already. :-( Anyone know what I can do?

I did not have any better experience with larger TBs on the 3.8L Mustang. They gave a bit more peak power at the expense of torque most everywhere else. This is a nice way to say the car ran like crap with a larger TB.

It was not fun to drive no matter what I tried and immediately improved when I went back to the stock TB I half shafted and ported. Since then I've tried a stock TB "modded in 5 minutes" with the screws ground flush and throttle stop ground down to open just shy of 90 degrees with similar results.

I've seen from data logging that the 5-minute mod stock TB hits the same MAF peak air flow rates as a larger TB on stock and Windstar intakes. The throttle body is not the restriction in the system. Hence, a larger TB won't help at all while it will create substantial drive-ability problems.

Could you put the stock TB back on the car? I'd bet it goes back to running properly.

If you need to keep the big throttle body, then please set the idle point lower. You might try something like 700 rpm. If you set the mechanical stop for the idle at or above the target idle speed, then you leave no room for the IAC to function. Put another way, the IAC needs to be partially open at steady idle.

Why doesn't the big TB work right?
Your car needs to be tuned for a larger throttle body. The stock fuel table will not provide rich enough mixtures at partial throttle positions. That means your car runs lean and feels anemic or perhaps even like it is bucking or shaking under acceleration. At steady speed it will run fairly well because throttle position isn't as important as mass air flow (MAF) to the car's computer under steady state.

It follows that if you want your car to accelerate better the stock TB will do the trick. Port it if you want to get a bit more top end power. On the street, there isn't much reason for a larger throttle body.

Thanks!

[mangogirl205]

Originally Posted by Jetflo I did not have any better experience with larger TBs on the 3.8L Mustang. They gave a bit more peak power at the expense of torque most everywhere else. This is a nice way to say the car ran like crap with a larger TB. It was not fun to drive no matter what I tried and immediately improved when I went back to the stock TB I half shafted and ported. Since then I've tried a stock TB "modded in 5 minutes" with the screws ground flush and throttle stop ground down to open just shy of 90 degrees with similar results. I've seen from data logging that the 5-minute mod stock TB hits the same MAF peak air flow rates as a larger TB on stock and Windstar intakes. The throttle body is not the restriction in the system. Hence, a larger TB won't help at all while it will create substantial drive-ability problems. Could you put the stock TB back on the car? I'd bet it goes back to running properly. If you need to keep the big throttle body, then please set the idle point lower. You might try something like 700 rpm. If you set the mechanical stop for the idle at or above the target idle speed, then you leave no room for the IAC to function. Put another way, the IAC needs to be partially open at steady idle. Why doesn't the big TB work right? Your car needs to be tuned for a larger throttle body. The stock fuel table will not provide rich enough mixtures at partial throttle positions. That means your car runs lean and feels anemic or perhaps even like it is bucking or shaking under acceleration. At steady speed it will run fairly well because throttle position isn't as important as mass air flow (MAF) to the car's computer under steady state. It follows that if you want your car to accelerate better the stock TB will do the trick. Port it if you want to get a bit more top end power. On the street, there isn't much reason for a larger throttle body. Thanks!

Wow, thank you for the information. I guess I should just put my stock tb back on. I am just hoping that when I do the TPS sensor will read right and I wont have to adjust anything.It will be like it never happend.

I think this is best at the moment.Because this mod is causing more problems. I mean If there is no HP gain it's pretty much useless..right?

Thanks alot for such a great write up and for being understanding and explaining everything.
-Christina

[SNmustang95]

unplug your MAF and take it for a quick drive then tell me how it goes. i had the same problem in my gt till i did this.

[polemonkey]

would a bad TPS make it idle around 2 grand with the clutch pushed inafter coming out of a gear and coasting to a stop?

[mustangmike!]

welcome to late model BULL SHIT ...

[Green_6er]

Originally Posted by polemonkey would a bad TPS make it idle around 2 grand with the clutch pushed inafter coming out of a gear and coasting to a stop?

it sounds like your TB is getting stuck open maybe. but could be the TPS.

[mangogirl205]

Okay everyone..thanks for all your help. But I have to say that I removed the 65mm TB and put my stock one back on today.And let me tell you...it's like night and day.

No more sputtering,bucking,bad volts or inaccurate revs and high idles.And I forgot how much better it runs...with the stock TB.

It feels SO much better. I mean maybe our 3.8 isn't capable of adjusting right to the BBK TB. I believe you have to have a turbo or forced induction that way you can take advantage of the 65mm upgrade. OR it's just my car.

Good luck to anyone who does install one of these upgrades..it just wasen't right for me. And tooo many problems..lol.

I guess I will sell it so If anyone wants it let me know.I'll post it in the "For Sale" forum.


Thanks alot again,
Christina