I'm having some issues with my 2002 3.5. It's mostly standard - just got extractors, K&N panel filter & RPW flowed throttle body (standard size).

Since fitting the throttle body it has a problem at a neutral / trailing throttle - the revs suddenly drop for 1/2 a second or so & then it picks up again with a jerk. It's not really bad, but not great to drive - particularly now it's on a manual box.

I've set the throttle butterfly to 1 1/4 turns open as per the workshop manual & have fitted a new idle speed control motor, which helped, but did not eliminate the problem - and it seems to be getting worse again. The throttle and accelerator position sensors are probably a bit out but I'm told that this shouldn't really be a major issue.

It's booked into a dyno shop next week for them to take a look at it, but the guy there reckons that once you upset the standard air flow with a modified throttle body & extractors, there's not much you can do unless you go to a piggy-back ECU.

Is he right, or does any one have any suggestions to fix this without piggy-backing the ECU?

Take off TB. it'll do next to nothing anyway without a retune.
what you do;
Extractors.
High flow Cat conveter
Sports muffler
SKR Flash tune
Enjoy awesome fast magna for next to no money spent.

(Search for SKR tunes on here, plenty on the topic already)

Very helpful post, Tufftr. He's spent the $$ already & I assume he doesn't need anymore paperweights lol

TB & extractors aren't going to make much difference to air flow - not that it's going to be noticeable to the average driver.

Plenty of people here have done what you've done with no dramas. Have you tried putting the old TB on to see if it makes a difference, (or has that gone back to RPW on exchange)? If so, maybe see if you can pick one up from a wreckers to see if the TB is at fault.

I know you prob dont want tohear it, but take the that throttle body off and put the stock one back on as there are no gains had by changing it.

The rest of the mods wont effect the cars running at all.

The gains to be had are in the lighter throttle response. No KW gains.

This 'mod' is actually returning the TB to how it was developed for the vehicle by Mitsu originally. They then put the lip in to reduce the risk of some 'cardigan' running up someones rear end accidentally. A worthwhile mod, according to Steve Knight.

Anyhow, none of this is helping the OP with his problem. Should the TB be causing this problem?

Clearly if the issue has started since the TB was installed in there lies the issue

Is the TPS working and set correctly for starters, is the air control valve on the new TB working correctly. Both of these can cause exactly the issue yo have

Playing with the throttle set screw is a bad move, even if this so called "high flow" TB was really that, it should not need to be touched. How you get to flow more air through the same size hole gets me a bit bemused to be honest but hey, it will give you go sooner for less throttle openeing, personally I prefer just to put my foot down a little more as it is a lot cheaper

To properly test the TB, get another one or your old one and see if the issue is solved. I know in the past RPW have had big issues with teh TB's with plates not closing properly thus having to put additional springs on them etc etc

As for the claim that the only way to make a modded magna smooth is to use a piggy back, tell these dyno "experts" to get their minds out of the stone age, that fred flinstone may have had issues with his rock car but in our cars we can do a lot without touching the ECU or tune

Didn't have much choice about changing the throttle set screw - it was basically fully closed so no air flow at all with the throttle closed. Don't ask me why, but that's the way it was.

It's certainly turning into one of those things you wish you hadn't done! Still, I've decided to go with a piggy back ECU as it does allow more flexibility with the tune and I'll probably need it at some point in the future anyway. Just means spending the money earlier than I planned...