another 3500 throttle body option

[asylummotorsports]

Here is what I have learned from my TB experience with my 3500.

The IAC motor needs to be compliant with the ECU and the engine that came in the car.

I had TONS of idle and surging issues until Rodney made me buy a brand new 3.1 MPFI IAC for my car. Put it on the TCE 65 mm and it idles like a it was new!

WHAT A DIFFERENCE!!

[americasfuture2k]

do you think the IAC that is on my '98 4.3 70mm TB would cause an issue with my 7730? all seems very well right now. when the fuel wasnt running too rich, it held idle fine.

[asylummotorsports]

I am in no way going to know or claim to know too much about this, however I can tell you the IAC does have a big affect on idle quality and drivability.

The guy who tunes my OBD-1 (3400beretta) insisted I buy the correct one for the car, NOT THE MOTOR, and it's just fine now.



At WOT it really doesn't matter I suppose, but that is just my experience.

[americasfuture2k]

well i guess i will see how things work out when i get that tune for a decent starting point from superdave

[asylummotorsports]

Well Dave certainly knows what he is doing.

Good luck with it!

[ForcedFirebird]

I am in no way going to know or claim to know too much about this, however I can tell you the IAC does have a big affect on idle quality and drivability.

The guy who tunes my OBD-1 (3400beretta) insisted I buy the correct one for the car, NOT THE MOTOR, and it's just fine now.



At WOT it really doesn't matter I suppose, but that is just my experience.

Odd. It's just a stepper motor being controlled by the ECM 0-5v. As long as the seal wasn't broken. Isn't it the ECM that actually moves it? Wonder if they have different tips on them. I have a ton of IAC's, probably should check them out.

[SappySE107]

Every IAC I have here is the same.

[asylummotorsports]

Well that is interesting.

Perhaps the air passage is more efficient on the TCE TB, and I just needed a new IAC anyway.

It did make a significant difference.

[IsaacHayes]

Old IAC's can stick, and maybe when it was put into the CNC TB it was bumped and a bit of carbon was disturbed and made it stick. I'm using the DOHC 3.5L Intriuge TB IAC and TPS just fine. Actually had to change the TPS on it, as it was bad, and an off brand. Swapped it from a spare 3100 52mm TB and all was good again.

[3400beretta]

IAC's between a quad and v6 are not the same, they have different tips on them. Look closely, the angle is different, and they will not seat properly. Also the plug is at a different angle. The issue with using a different throttle body is the passageways are no longer the same size, and the computer tells the IAC to open "X" amount and expects a certain amount of airflow as a result. This no longer happens when the passages are smaller as in Eric's case with the quad throttlebody, as it is meant for an obviously smaller engine. Yes you could spend time to correct everything in the tune, but in Eric's case he was also having issues with the transmission not shifting correctly, which I was sure was due to the improper linkage of the quad 4 throttle body. So I didn't want waste time pissing around the iac crap when he was probably going to end up swapping throttlebodies anyways.

[IsaacHayes]

I see your point. The LX5 TB must be the same or close enough as my idle does not give me any problems, no stalling, surging, or hesitation, etc. IAC counts are just the same as the 3100 TB. I've never messed with a 4 banger TB though. If anything the idle is better than the 3100 TB's IAC as it would sometimes bounce the idle when slowing down or want to stall out if I just tapped the starter instead of giving it a good crank (old style starter) but eventually it would fire after it the motor went silent for a second (funny). Maybe I've always had a bad/sticky IAC though.. but I've had 4 different ones on between 3100/3400 TBs... The motor fires up really quick now it seems after the 2.5" exhaust too which is cool.

There is an update for my ECM that fixes cold weather drive-ability issues, so they may have tweaked the code to fix that, but mine always did it in hot weather not cold.

Next time I have the LX5 TB off (going to paint the TB adapter black when I do a CAI) I will compare IACs. I'm thinking where they seat are about the same as 3x00 ones.

[robertisaar]

There is an update for my ECM that fixes cold weather drive-ability issues, so they may have tweaked the code to fix that, but mine always did it in hot weather not cold.

i think thats the change they did for the W's as well, and i ended up with BLZX, which as far as i know, is the latest 95 3100 W tune.

[3400beretta]

Next time I have the LX5 TB off (going to paint the TB adapter black when I do a CAI) I will compare IACs. I'm thinking where they seat are about the same as 3x00 ones.

More than likely the lx5 shares an identical iac and close enough passages that it would not cause a problem.

[IsaacHayes]

The IAC is actually a different part # than the 3100/3400 IIRC. But yeah it's close enough. I didn't think of a 4 banger TB being different.