I picked up a 74mm throttle body today at a local junkyard (came off a E55 AMG ), gently cleaned the throttle plate with some isopropyl alcohol, and got it swapped out. I followed the PDF guide by Rekcah. I performed the throttle reset and started it up.

It started by idling a little high (~1000 rpm). After a few seconds it shot up to 2k and started "surging" between 1.5k and 2k.
I checked every connection and hose in the immediate area and can't find anything loose.

I tried to drive it down the driveway but, it was completely undrivable with the revs bouncing all over the place.
It threw a CEL after a while and gave me a code P0100: MAF or VAF Circuit Malfunction.

The guys at Advance Auto Parts recommended I test that MAF sensor by disconnecting it, then starting the car to see if it runs any different. I did that, and it just stalled out immediately after starting. Should I assume that the MAF is good?

My other mods are TVT intake, magnaflow exhaust, and a Eurocharged tune if that helps.

Any suggestions?

 

I got some MAF cleaner at the parts store tonight and sprayed down the MAF sensor.
Put everything back together and tried again. The car ran idled like normal, but once I tried to accelerate it went back to the bouncing revs again.

I ordered a new MAF sensor that should be in tomorrow, so I'll find out for sure then if that's the problem.

 

Hii, did you put the 68mm MAF sensor back in the 74mm housing?

 

1. did you do a throttle pedal reset ?
2. are you absolutely certain you have no vacuum leak ? ( maybe the new O ring slipped during install, or you overlooked connecting a hose ? )

 

Yep, this sound verrrrrrry familiar!

 

And then, you could do like Max did : take it to a dealer twice, get no results, then wait a day and the condition will go away. ( I think his roadster cured itself out of fear of another dealer trip )

Anytime mine has an issue, I just head towards the dealer and 9 times out of 10 it will cure itself.
Crossies have a real aversion to Chrysler dealers, sort of like the red headed step child being forced to go home.

 

I'm actually running the original 68mm MAF AND housing for now. I have to find the bigger housing somewhere.
I've taken the TB off and on several times now and checked the o-ring each time, so I know it's in that groove.
I actually went back to the original 68mm Throttlebody and it did the same thing, but was bouncing between lower RPMs, maybe around 1200 - 1500.

When I press the gas, the RPMs shoot way up to like 4000 and hold there until I shut off the car.

As far as hoses go:
- Y-hose with the 2 connectors on top of the TB
- Hose connected to driver's side of the elbow

That's all of them, right?

 

yes, that's all the vacuum hoses that might be an issue with this.
so, the throttle reset didn't help ?

you might try disconnecting the negative battery lead for 10 minutes for a complete computer reset .

 

I've done multiple throttle resets. I tried disconnecting the negative terminal for a good 15-20 minutes.
It's seemed to idle better after that, but as soon as I *tap* the gas, the rpms jump to around 4000 and hold.

Thanks everyone for all the suggestions.

 

[QUOTE=alaxfire;692834then wait a day and the condition will go away.[/QUOTE]

Mine took more than a day, but this is starting to be more common, I am exchanging PMs with someone who is having the same issue but with installing his intake.

In my case, Max's case, and several others, it worked itself out, but I was still able to drive mine, as it is a manual...

 

I think I might be going insane...

I stopped at home during my lunch break and started up the car (out of despiration), and it ran fine. I drove it around the block and had no problems at all. I noticed the throttle was a bit more responsive, which is nice.
I drove it back to work (only about a 5 minute drive) and as I pulled into the parking lot, I noticed it idling a little high. I was still able to drive through the parking lot just fine but the RPMs were bouncing around 1000-1200.

I did a throttle reset before I got out, so I'll see what happens when I try to drive home tonight

 

The problem came back when I tried to drive home tonight. I picked up the replacement MAF sensor that I ordered. I left the battery disconnected while I swapped it out to reset the computer.

No difference with the new MAF sensor.

After narrowing everything down, I'm thinking it almost has to be a vacuum leak, but I don't have any good way to test it. Any suggestions?

 

So, I got some starter fluid and started spraying the area around the MAF, throttle body, and intake while it was running and got absolutely nothing. I also checked around those valve-cover type thingies on either side.

I'm grasping at straws here...
Would my tune have anything to do with it? Has anyone else had a tune done BEFORE installing the 74mm throttle body?

 

I had to let mine SIT for a week and it magically went away.

 

I had to drive the ever living **** out of mine on the Dragon, and the problem went away LOL

 

I got so frustrated at it that I dropped it off at the local import shop to have them look it over. If they can't find anything, I guess I'll just park it for a few more days and let it brew.

 

I had to take the screens out of the MAF, baffles out of the elbow and change the spark plugs to fix mine. I would also have eurocharged do a retune. It seemed to help mine as well.

 

I'll check with Eurocharged once I get the car back. The shop ordered a new OEM MAF sensor. They said that if it doesn't work, they won't charge me for it. I already removed the screens and put in some NGK Iridium plugs a few months ago, but the baffles are still there.

Unfortunately, I have to leave town tomorrow and won't be back until Wednesday. Maybe when I get back, it'll magically have fixed itself like Max's.

 

I got the car back from the shop. They noticed it running considerably better after they installed the new MAF sensor and did a full reset (touch both battery terminals together for 10 minutes).
When I picked it up, it was still idling around 1000 and didn't drop revs as fast, but it's not spiking 4000 rpm at random anymore. I did a throttle reset and took out to some side roads and beat on it a bit. It still had all the power and seemed to run smoother.

I'm going to have Eurocharged retune it for me and hopefully that will balance everything out.

 

It was not the battery terminals you touched together or you would want a new battery and maybe hospital treatment, it was the battery cables ends that attach to the battery.
We would not want someone to try that.

When I did my old car I had no trouble, you could have a duff TB connector, bent pin or something.