I installed my 74mm throttle body and MAF (74mm housing with my v6 sensor) yesterday, when I first started the car it idle like crap and almost stalled many times. I did the throttle reset and it seemed a little better so I drove it around the block. It seemed to run better and didn't have a problem idling anymore. I drove to work this morning, started it up, idled right at 700 or so, and ran great. Once the engine warmed up it still would run great but when I push the clutch in instead of dropping down to idle it will surge to 2000 then down to 1000 then back up, does this a few times then settles at 1000. If I shut the engine off and then start it again, it will idle at 700 until I touch the throttle, then it starts all over again. I searched and could only find people who had problems with a rough idle, which I do not have. Any ideas? I initially thought air leak but it idles much better than it did with the old throttle body, what should I check first?

 

I'm not the expert here in this area, having not done this mod, but it sure sounds like a vacuum leak of some kind.

I'm sure someone will chime in with additional insight.

If it was runnin fine before the Mod, that's most likely where to look first...

 

Mine was doing the exact same thing when I first did the TB upgrade (A while back so memory is not really clear on all I did to fix it.)

I know I retorqued the TB to 7.5 foot lbs I think it was, did another TB reset and everything was good to go from then on

I think the first time I had the torque wrench set wrong.

 

That's what I was thinking but shouldn't I have a really rough idle? It doesn't stumble, its not rough, it actually seems to be smoother than before, only problem is the surging, which is also smooth.

 

check the connectors to ensure they're fully seated

 

I would check that all the fittings are on properly, like the two hoses from the valve covers and how they are on the 'Y' fitting on top of the TB, and that the 'Y' is in the TB correctly. The O-ring between the TB and inlet should be new as the old one gets deformed and will fail to seal once it is disturbed.

Failure to seat the engine cover on the MAF housing can cause trouble if it is not on tight. Mine was loose when I got the car but caused no problem.

Also check the two electrical connections on the MAF and TB.

Lastly the new TB could be bad, so you could go back to the OEM and see if that cures the problem.

Very frustrating though.

 

Sounds like the TB acting up. Do what 180 says and revert back to 68mm TB and see what happens

 

I second that, and after you get the 74mm in your hand, If you are brave, you can remove the 4 or 5 clips that hold the plastic cover and look inside.
What you will find is a motor, 3 sets of nylon gears and a big return spring.
Push the throttle plate wide open and let it go - the spring should return it to idle position pretty fast.
If not - lube up the nylon gears with white lithium grease and try again.
If it still sticking, then deal with the source where you bought it for an exchange,
YOU DO NOT WANT TO TRY TO REMOVE THE THROTTLE PLATE AND SHAFT.
( Although the experts do when they bore one out )

 

I did that today, it did not have any sticking. I also rechecked all the vacuum connections and made sure the bolts were all tight. I am doing a throttle reset now by disconnecting the battery but I do not think it will work because last night it did not help. I may just have to go back to the 68mm throttle body and hope that one works out.

 

Ok, so quick update. I checked the 74mm throttle body thread and realized I had used the wrong gasket, I got the correct one and installed it. Checked all connections and everything seems fine. Did a throttle reset after the new install and drove to work today. It seems to be a little better but again after about 20 minutes of driving it will rev up to about 1500 when I push in the clutch. Once I come to a complete stop it will slowly go down to 700 where it will idle beautifully. Also I do not know if this is relevant or not but when the engine revs on its own my ultra gauge shows the throttle % going up. I am going to check again for leaks when I get home from work and then swap to the old tb and maf if I can't find any. Is there an easy way to check for leaks besides just looking to check that all the hoses are connected?

 

You said "old TB and MAF"
The concensus of opinion is that the 74MM should retain the 68MM MAF ...........
( that's what I did, and have NO problems )

 

Sorry I should have been more clear. I meant the 68mm tb, 68mm MAF sensor with 68mm MAF housing. Right now I have the 74mm tb, 68mm MAF sensor and 74mm MAF housing.

 

An old trick is to use a propane torch. Crack it open w/o lighting it. Any vac. leak will suck in the propane, and cause the engine to rev up

 

Neat trick - I'll remember that, thanks.

Twice I have left the hose that goes from the TB to the sensor valve on the driver side fender ( not sure what it does ) off, and I got the surging idle syndrome ( SIS )

 

Propane, huh? How about this:

http://www.youtube.com/watch?v=9CPqb...eature=related

Or I have always used Carb/MAF cleaner. Maybe I'll change my ways!

 

I love it...

It sounds a little scary...But I still love it.

I'm gonna add it to my bag of tricks.

(At least until I hear about some knucklehead blowing himself up, and his car... )...

 

How about pressurizing the manifold with smoke:

Finding Engine Vacuum Leaks With A Cigar - YouTube

I can't see myself using that method since I dont have the smoke gen. and I can't stand the smell of cigars

Note: If using the Propane method, there is no need for cutting the wand and fitting a hose. The wand on it's own will reach in most places

 

I started getting the exact same thing this morning, except mine was going nearly exactly from 1500 to 2000 RPMs, drop back to 1500 and surge to 2000, over and over this morning.

The throttle reset helped, mildly, but idle is still at least 1500 RPM.

I am going to try a few things tonight, just wanted to see if anyone else could chime in...

Thanks!

 

Interestingly enough, I get those same surging/stalling symptoms after I have had my engine cover off.
( I have to unplug the MAF sensor in order to remove my cover with the gen 1 NW CAI - and I usually forget to plug it back in )
However, I have an easy way to tell : the UltraGuage shows the IAT at -40 F - not gonna happen in Alabama.

( another symptom is that the radiator fan runs with the engine cool ..... )


BOTTOM LINE : CHECK THE MAF SENSOR, CONNECTOR, AND CABLE FOR PROBLEMS.

https://www.crossfireforum.org/galle...y.php/cat/2153

 

All connections are sound and everything tight.

All I had time to do yesterday was disconnect the MAF and the negative battery terminal (30 minutes minimum) to get the ECU to reset. I test drove twice, and other than a little higher idle, it was fine. I got in this morning to go to work and the problem came right back.

I am going to swap the MAF sensor and see if that helps. Next move is to take apart the TB or swap back to the 68mm. I will keep updating the thread for the next guy