Adjusting rev down/idle issues

[StealthyWeasel]

My car has a bunch of issues.

1) It lopes in idle- done it ever since I got it tuned last year. Sounds like it's cammed.
2) Revs hang sometimes and sometimes they drop REAL fast. Sometimes they'll hang at 1200 until I come to a complete stop, and THEN they go down. A complete stop always brings them down to a normal idle. This has happened ever since I installed a new 65mm TB (done correctly). The only difference is it has no hole in the throttle plate and has a bleeder control on the side of it.
3) Afterfires as loud as a gunshot if I accelerate hard (to around 5600rpm) and press in the clutch or shift. Doesn't do it every time, but frequently does.
4) Throws a P1131 rich code sometimes. The check engine light comes on, goes off, comes on, repeat.

Maybe I need to adjust mixture, and maybe I need to change the "transition from closed to open loop" from 2 seconds to <1 second. I saw BlackCoog mentioning that, seems like it could be relevant. Would the DPFE have anything to do with it? I have no idea what it does.

[StealthyWeasel]

I get about 240 miles a tank driving sanely, that sucks too. Makes me wonder about where all the gas is going..

[wadespencer99]

I just replaced the EGR Vacuum Canister on the back of the UIM and it seems to have fixed my race car idle. Try that.

[StealthyWeasel]

EDIT: "The vacuum canister sits on the UIM just above the DPFE sensor" (I didn't know what/where it was :rofl:)

Thanks FastCougar, search button FTW.

That i'm going to try.

[SingleShot]

1,2, and 4 sounds like my car. except I got bank 1 and 2 Lean on the DTC. Any suggestions? I recently did the "Throttle Hang" how to fix where you get the copper cap and drill it. Worked wonders. But I still have a cammed sound (which I like Lol) and some slight throttle hang at 1200.

Wonder if changing the vacuum canister would do anything. Maybe worth a shot.

[SingleShot]

1,2, and 4 sounds like my car. except I got bank 1 and 2 Lean on the DTC. Any suggestions? I recently did the "Throttle Hang" how to fix where you get the copper cap and drill it. Worked wonders. But I still have a cammed sound (which I like Lol) and some slight throttle hang at 1200.

Wonder if changing the vacuum canister would do anything. Maybe worth a shot.

[mond12345]

I really think #1 is in the tune some how Josh. Mine car started doing that right after my tune also and we went to the same place....

[fordrule]

how much was the canister and DPFE. i think i have the same problems with mine. but then again i haven't driven mine in almost 2.5 yrs

try a datalog with ur wideband hooked up and see what it looks like....

[wadespencer99]

Nevermind...canister didn't help at all.

[ironworker]

If You Have One Of Those Mity-vac Vacuum Pumps Take The Vacuum Line Off Your Egr Valve While The Car Is Idleing And Hook Up The Pump, And Pump It A Couple Times, If The Idle Doesnt Change The Egr Valve Is Stuck Open And You Need A New One...

[Gorman]

i have one of those 65mm TB's on my 2.5L and it does that 1200rpm hang stuff too. Is it possible that the amount of air this TB passes at closed position (meant for 4.6L) is too much air for the 3.0L and 2.5L idle, so it over revs until the idle air/ecu adjusts?...G.

[ironworker]

Are These Optimized Tb's ?

[Gorman]

mine was ported polished the whole shooting match...it's fxxxxin' great. As long as you don't go WOT...it's much better than an SVT...G.

[ironworker]

Its Possible It Can Be Over Optimized...if You Can See Any Gap Around The Throttle Plate That Will Cause A High Idle...

[Gorman]

true..a poor fitting butterfly will let air through. I'm not too worried about the revs thing..i've just learnt how to get the best out of this TB. Part throttle lets more air in and maintains velocity. Go WOT and the velocity seems to be lost. Might be different when my cams go in...Also i was reading on CEG about an over rich setting the ECU has for WOT...if it's wrong for stock...that setting is gonna be useless for modded...G.

[wadespencer99]

Chipping in my two cents here, mine is a bone stock SVT TB..never modified.

Oddly, it sounds like some similar problems we are having. Mine is a stock tune on a 2.5 with bolt on mods.

[Gorman]

well high idle usually means a vacuum leak...if not, it must be something you've changed..that's where i am...G.

[wadespencer99]

*sigh*

nevermind.

[AndrewM6097]

I'm having the same "race car" idle problem. I've got a tuned 3L also Stealthy..... My guess is a vacuum leak so i will be resealing my Bugzuki plates and replacing all the vaccum lines that come off the tree. I'll post up my results.

[SingleShot]

I ran a fog machine through my intakes and found no leak. Fog just started pumping out of my SRI after a few minutes. I'm just guessing that its one of the IACV, DPFE, or EGR has gone bad. I'm gonna replace them one at a time lol. Or start by cleaning each one up.


Found this.

Idling- Rough Idle/Moosing Sound - If your engine is idling differently that it normally does, It might be your IACV (Idle Air Control Valve). It's located behind your Upper Intake Manifold. Be sure to get it diagnosed to pinpoint the problem. Also if you experience a "Moosing" sound the IACV is also the culprit.

Full thread:

http://www.newcougar.org/forums/problems/6051-faq-cel-codes-now-cel-codes-problems.html


This how to also helps with ALOT of throttle hang and is very simple.

http://www.cougardb.com/howtoshow.php?howtoid=21

[Gorman]

i just tried something to fix the hanging rev's. I put plumbers tape around the vacuum lines in the UIM. Only at the top by the elbow...i didn't want those barbs to slice up the tape and allow it to be sucked in the manifold. That's the brake booster and the accessory lines. It seems to have almost eliminated the hang. I'm still getting several cycles on the ECU after disconnecting..but it seems to have reduced the hang almost completely ..try it LMK...G.

[StealthyWeasel]

The throttle body has a hex bolt that adjusts the bleeder, since I did the TB, i'm certain the process has no "leaks."

The IACV, DPFE, nor EGR is the problem. My EGR is off, the IACV has been replaced, and the DPFE I changed.

Joe, I agree it seems to be a tuning issue but now my car does that same crap on the stock tune, implying a mechanical issue..

[StealthyWeasel]

i just tried something to fix the hanging rev's. I put plumbers tape around the vacuum lines in the UIM. Only at the top by the elbow...i didn't want those barbs to slice up the tape and allow it to be sucked in the manifold. That's the brake booster and the accessory lines. It seems to have almost eliminated the hang. I'm still getting several cycles on the ECU after disconnecting..but it seems to have reduced the hang almost completely ..try it LMK...G.

I'll have to do that.

[Gorman]

Lol; no seriously man...i must have had an air leak. When i coasted in neutral at say 40mph the revs refused to settle to 8oo rpm until i was stationary. Now i can free wheel and the revs fall back straight away and stay there....just thought others may have poorly sealing vac' lines as well...come on, anyone else tried this ?...G.

[mond12345]

So Josh, are you un-tuned right now?

[StealthyWeasel]

Hi Joe.

No, i'm running the dyno tune right now. Does your car have that lope very badly? Maybe something that Ray did causes it, im not sure. I think my only option is to buy PRP and try to fix it. Who knows.

[mond12345]

Its really weird with the idle. Sometimes it idle great, very smooth and calm. Other times the idle will move around so bad. I have changed everything in that engine bay almost and nothing has changed. I cant see it being a vacuum leak since it doesn't do it all the time, maybe it is in the tune somewhere. I really don't know the tuning program since i never had a chance to look through any of it or have access to it...

I'm sorry your having issues, its annoying, i know.

[StealthyWeasel]

Yup, were having the exact same problem.

[Gorman]

thinking back..i remember a conversation with the guy i bought my TB from about the voltage that the TPS was set to being different from stock. Do you guys remember what the stock idle TPS voltage was and is it the same as your TB TPS is set to now ?....G.

[StealthyWeasel]

I used an SVT TPS

[Gorman]

i bought mine with the same TPS. I believe the guy was saying that the idle voltage was slightly higher to compensate for the higher initial airflow when the butterfly opens, to stop the engine stumbling. I'm not sure about this 'cos i never checked it...i was glad to get the TB plug and play. I also remember discussing this with cpapashley. I'm just trying to be helpful and i'm sure the guys with xcal's should have a much better handle on this aspect of setup...hope some of that leads to something useful....G....EDIT..just been reading over on CEG..seems the pcm zeros the TPS value when it powers up...damn...G.

[fordrule]

i wonder if you use the 65mm tb over the svt tb u will have the same issues. i have a prp and when i get home i intend on tackling this issues also.....

i have been following this thread and it has my curiosity

[Chromed CoUgaR]

I have this same similar issue with the revs hanging at around 1200 until I come to a complete stop.. I just did the SVT lite, headers and CAI mod and now I have this issue.. I thought it might be the DPFE, but now I am not so sure. When I plug a Scan Tool in it said that the car hasnt completed the EVAP test yet, so that is where I am looking right now. Problem is I dont know much about the EVAP system and where to look for a problem... maybe there is a leak somewhere in mine which is causing symptons similar to a vacuum leak?