Idle high after injector/tb swap

[tablesaw]

I put in the 19lb (yellow) injectors and a 4.0 TB on Thurs. and since doing it the idle shoots to 2000 rpms at start up for about 20-30 secs. I thought the computer just needed to adjust itself but it's not getting better. I did change out the 2 sensors and triple checked all nearby vacuum hoses. Is this normal, does it go away, and if so after how long? Thanks, greatful for any opinions or ideas.

[Jester32]

Sounds like its trying to compensate for the extra fuel. It can take up to 15 starts to even out if it can't I would see if you can watch the fuel trim on a scanner. If its always negative I would be looking at a cause. I run the 5.0l injectors and mine did that for about a week.

[tablesaw]

Thanks, it's only been 3 days. It seems like I read another on another forum somewhere that it took a couple of weeks.

[Vlad]

Did you move the TPS, MAP, and IAC from your throttle body to the 4.0 one?

[tablesaw]

Did you move the TPS, MAP, and IAC from your throttle body to the 4.0 one?

Yeah swapped those too, no map on mine. Saw a suggestio to swap iac housing also, going to give that a try next. It's just the first 20-30 secs of each stert up, everything else is fine.

[tablesaw]

Found it ! The plungers on the iacs are different. 2.5 is tapered and 4.0 is flat. Changed the iac housing on the side of the iac and solved the problem. Would have been much easier to do BEFORE tb was on the motor.

[luis]

How do you like the tb and injector swap? Im planning on doing this mod on my 2.5 aswell

[tablesaw]

It made a big difference. I swapped the tb at the same time, so I don't know how good it is by itself. I bought the injectors used off of e-bay for $50 and the tb for $30. Popping out the reducer in the front of the airbox made the single biggest differnce so far.

[luis]

It made a big difference. I swapped the tb at the same time, so I don't know how good it is by itself. I bought the injectors used off of e-bay for $50 and the tb for $30. Popping out the reducer in the front of the airbox made the single biggest differnce so far.

Did u do anything to the electronics for the injector or did you just install them? Did you change the gap of the plugs and increase fuel pressure? I want to do the tb swap but never thought of the injectors

[tablesaw]

No electronics changes. It's really a simple swap if you know the pitfalls to look out for. The injectors are 19lb (yellow) ford 4.6l. They just plug in. The main benefit is they have 4 holes in the end where the stock ones only have one hole. You get a much better atomization of the fuel mix. The hard part is getting the suckers to go into the fuel rail, I swapped the o-rings with the originals, someone on jeepforum said he put motor on them to help them slide in. Just make sure they're seat all the way. The throttle body is what had me pulling my hair out. Everyone says you have to reuse your oringinal sensors ( tps and iac) and you do. WHAT they don't tell you is you have to swap out the iac HOUSING on the tb. There is a gasket, be careful not to mess it up, I don't think you can buy just the housing gasket. Don't forget to buy the tb gasket though. Other than that, it's super simple. I also put on an Accel performance coil (easy, 2 bolts, 2 wires) If I haven't mentioned it before, remove the reducer in the front of the airbox. This is imeadiate free power upgrade Good luck, if you have any questions just ask. There is also a reducer in the lid of the airbox. They both pop out with a screwdriver.

[luis]

No electronics changes. It's really a simple swap if you know the pitfalls to look out for. The injectors are 19lb (yellow) ford 4.6l. They just plug in. The main benefit is they have 4 holes in the end where the stock ones only have one hole. You get a much better atomization of the fuel mix. The hard part is getting the suckers to go into the fuel rail, I swapped the o-rings with the originals, someone on jeepforum said he put motor on them to help them slide in. Just make sure they're seat all the way. The throttle body is what had me pulling my hair out. Everyone says you have to reuse your oringinal sensors ( tps and iac) and you do. WHAT they don't tell you is you have to swap out the iac HOUSING on the tb. There is a gasket, be careful not to mess it up, I don't think you can buy just the housing gasket. Don't forget to buy the tb gasket though. Other than that, it's super simple. I also put on an Accel performance coil (easy, 2 bolts, 2 wires) If I haven't mentioned it before, remove the reducer in the front of the airbox. This is imeadiate free power upgrade Good luck, if you have any questions just ask.

Awesome I'm going to be doing the tb swap. My ill upgrade the injectors aswell. I dont think I have the air box restriction since I have a tj and I think that's only I yj thing. But I can be wrong