I have a 2005 NA Limited Roadster, put the MagnaFlow cat-back exhaust on about a month ago. Got my 74mm MB TB and Needs Wings single CAI installed this past Friday, and threw the updated EuroCharged tune into the computer. Car runs great, sounds great, and performs great... most of the time.

Every once in a while, I'll find it idles high, like 1500rpm compared to the normal 750-800. Some times it does this right off start up, some times it does it while driving / in between shifts (if I hold it in neutral for a while), or at stop lights. Some times it goes away on its own, some times I can load up the engine some and force it down and it stays, and some times I have to cycle the car off / on and it goes back to normal.

As I changed 3 things at once (TB, CAI, EC Tune), I can't say for sure what the actual issue is. I doubt the CAI did it, unless I screwed something up with the MAF and it's causing an issue.

Any thoughts?
-Kevin

 

For some odd reason no one has resolved.. it happens. Also seems like the car eventually works past or greatly reduces this event.

 

Seems that way, Mrmiata - some get it, some don't, seems to go away in time. I figured that, being a little later to the game of upgrading my XF, someone may have cracked the nut by now. Oh well... Fingers crossed! Thanks.

 

sounds like a vacuum leak where the tb is mounted to the intake manifold

 

I'll spray some starter fluid around to see if I get any rev changes, but it has been happening less (if at all, hard to tell at times) since doing a throttle reset yesterday.
-Kevin

 

No change with the starter fluid test, but the issue had started increasing in frequency, and I noticed the rear-wing started deploying when I first started the car. Time to replace the battery (best I can tell, Origianl battery from 2005). Car idles like a champ now, so I'm guessing it was some interior mechanism forcing a high-idle to keep the voltage / amperage up where it should be, or just a weird electrical gremlin side-effect of the dying battery.

 

Kevin,
I just installed the 74mm parts (tb, elbow, maf, original maf sensor,o-ring) yesterday, same symptoms as you have. I performed two throttle resets at different times, this changed things a bit, along with 20 miles of driving. I'm thinking like mrmiata, it will 'sort itself out' with time.

I'm now wanting the EuroCharged tune. I'm beginning to see this upgrade desire may become a serious disease.
John

 

John,
The battery swap did most of it for me, and what little fluctuation was left cleared up on its own. Don't bother doing any more throttle resets, just let it figure itself out.

The EC tune is going to make a big difference I imagine. I kind of wish I had gone back to stock for a few days before having them change the tune from the pre-mod upgrade to the post-mod upgrade. Either way, they do some good stuff.

Unfortunately for your disease, unless you have an SRT, there isn't much else we can do to the crossfires. Bolt in exhaust and CAI... There's a project in the works for the Ground Control suspension setup... and I hear in 2 weeks there will be a prototype turbocharger out on the streets...

 

Did my TB, MAF swap last week. Had the "usual" symptoms of rough running and rev extremes ...too slow - too fast, also the BAS/ESP light came on. When I shut the car off and then restart it the light went off. However here's what it's doing now; start it up...erratic idle, give it the gas and it smooths out. Take it out on the road, give it the gas and wow...she really moves, let off the gas, the BAS/ESP light comes on and I get no throttle response, stop the car turn off the engine, restart and take off, runs great until I let off the gas, then the light comes on again and again no throttle response. Did a couple of throttle resets as well as disconnect the battery with no change. I'm thinking perhaps air leak somewhere or ECU learning process. Anybody care to hypothesize on this?
These are the codes from my Torque Pro.

 

Quite possible you got a bummer used 74mm TB.
You might try removing the plastic cover and using some electrical contact cleaner on the little fingers and the circuit board.

 

^^^ I'm with him on this one.

 

Not to sure they are 'normal symptoms' as I did that mod and the car never even coughed.

As others have said you may have a bum throttle body. Especially with those codes.

Did you reinstall the old MAF sensor?
Did you use a new O-ring and make sure there are no air leaks into the system?
Is your battery a good one and not ten years old?
The answer to all these questions should be yes.

 

As others have said you may have a bum throttle body. Especially with those codes.

[SIZE=2]Did you reinstall the old MAF sensor?
Did you use a new O-ring and make sure there are no air leaks into the system?
Is your battery a good one and not ten years old?
The answer to all these questions should be yes.

Yes to all of the above, (will double check for leaks) I'm going to try cleaning the TB mechanism and see if that fixes it.One more question; will the mechanism of my original TB work in the 74mm TB?

 

If I recall correctly the mechanism is hard to remove and one person said it was not worth trying to take apart as it breaks easily, you would end up with two bum parts. Maybe it will not fit and maybe it will not work, who knows.
The Service Manual probably tells you how to test the TB.

 

Well the TB issue is now on hold. When inserting the bolts into the manifold I managed to strip the threads on two of the openings in the manifold...

Am now searching posts to fix this.

 

Time to get a helicoil or similar thread-repair product. Bummer man. To your original issue, I'm guessing something wrong with the TB, too. Mine had some 'learning curve' issues, but never like you're describing.

 

Bob_Ham.... "Time to get a helicoil or similar thread-repair product. Bummer man. To your original issue, I'm guessing something wrong with the TB, too. Mine had some 'learning curve' issues, but never like you're describing."


I searched the forum for "stripped", "stripped out"...didn't find anything to help me. Since I have no professional training in mechanical repairs, I solicited advice from two of my brothers, one a technician for refrigeration systems for an ice cream plant, the other an electrical technician. Heli coil seems to be the way to go.


I still haven't answered the question; air leak or bad TB...

 

Just my .02 but if you are planning on using a helicoil look into time-sert thread repair. They are a more stout and in my opinion a better product and cost difference is negligible. good luck with the repair, it's all part of the auto mechanic game.
Tim

 

Just my .02 but if you are planning on using a helicoil look into time-sert thread repair. They are a more stout and in my opinion a better product and cost difference is negligible. good luck with the repair,
Tim


Thanks Tim, I'll check it out.

it's all part of the auto mechanic game.


Yup, sure beats going brain dead watching TV...lol

 

Obviously whatever insert you use it will be best to get one that will let you use the existing metric bolt.
Just keep all chips out of the engine, keep the insert going in square and do it right the first time.