I've recently encountered a somewhat annoying cold start issue. I'm not sure how the coolant lines are ran to the '00 TB. I'm running '00VI by the way, mated to the vq35 heads. It's either the TB or the IACV thats sticking. Once the car has been initially started it starts up fine the rest of the day.

My speculation is that during the initial start, (in the morning for e.g.) the coolant is cold, the plunger for the TB then keeps the TB open to allow air in, and once it warms up (the coolant) the IACV takes over. Again I'm not sure if I have an external or internal coolant line for the '00 TB. I really can't tell, if someone can guide me I'd appreciate it.

Lastly, I will soon be upgrading to the larger .70MM Pathfinder TB which I know has no coolant lines, so will I experience the same problem? Is there anyway we can run coolant lines to the PF TB?

 

The Pathy TB has coolant lines running through the IACV that is mounted on the bottom of the TB. The problem is you have to remove the IACV because it interferes with the egr valve underneath the TB. If you remove the egr valve, then you can keep the PF IACV with the coolant lines. I don't expect the A32 ecu will be able to control the PF IACV properly, though.

 

ive said this a million times, I have a pathy and TB coolant lines are removed. Also i have no probs with cold start at all. Iam the second person ever to install the pathy TB ive had it on over 3 years.
My climate where i live gets to -0F and it still runs just as good as stock.

 

Alright so then my question is is the IACV important to cold starts? In other words is it used during a cold start? If so then the only logical conclusion I can reach is, my IACV is sticking in the morning.

 

I'm almost 100% positive that lack of coolant in the TB would not affect cold starts. The IACV is controlled by the ECU which measures temperature through the coolant temp sensor. The IACV doesn't control itself based on the temperature of the coolant running through it. The coolant lines exist in a TB to prevent the TB/IACV from icing up in the winter and sticking.

IACV greatly affects cold starts. You might want to take out your TB/IACV and give it a good cleaning.

 

You're forgetting one thing...the fast idle cam. The coolant flowing through the TB (at least in the 4th gen) serves two purposes. One is for the fast idle cam and the other is to prevent icing. I don't know about the 5th gen IACV, but in my experience the 4G IACV only has two settings. It's not variable like the 5th gen unit might be. One setting is a/c off, the other is a/c on/power steering pressure switch based high idle. This means that the high idle at cold starts is caused by the fast idle cam plunger holding the throttle open until the coolant warms up and the TB closes completely at which point the IACV takes over exclusively. In other words, the 4G IACV doesn't exclusively control idle speed at cold startup.

You 5th gen guys don't have a fast idle cam since the IACV is what causes the high idle and lowers the idle as coolant temp rises. The only ways to get around this if you're using a PF or DE-K TB is to either hold the throttle slightly open at cold start or to adjust the throttle stop screw to get the same effect.

Cliff notes: If you're gonna use the PF or DE-K TB you will fast idle control period. Adjusting the throttle stop to hold the TB slightly open seems to be the best idea.

 

I disagree.

I have a 2000 VI with a Pathy TB with the Krismax special adaptor block. The coolant lines that ran to the EGR and TB are looped so it bypasses the TB, so no coolant goes thru the TB or EGR. The Pathfinder TB IACV stuff that was bolted to the bottom of it is removed and Chris made me a plate to cover it all up.

The adaptor block has the 4th gen IACV and AC/PS fast idle cam sensors and my car cold starts fine. It revs up to 1500 like it did with the stock manifold and ive never had an issue with it. The ECU controls the idle via IACV on cold starts and adjusts the RPMs accordingly. Its very important to properly adjust the TPS to spec and to leave the TB throttle screw alone, it's calibrated from the factory and messing with it is not good.

 

If what you're saying is true, the fast idle cam built-in to the 4th gen TB is useless.

 

Yup Ive thought about getting rid of them.

Chris doesn't even use them, they've been weight reduced.

 

This is kinda off topic, but this is a TB thread sooooooo ... I was reading the 3.5 Sticky and it says modify your TB or use Mallfinder TB. Is the Mallfinder just a slang/funny term on the ORG for Pathfinder? If I decide to do this, when should I begin to pray my CAI will still fit?

Just to throw in another question. If you want a UDP do you get the 3.0 or 3.5 UDP???

*Sniff Sniff* We need a step-by-step write-up for this so noobs like me can undertake it. It sounds easy.

 

Yes, Mallfinder = Pathfinder. Most Stupid Urban Vehicles never see a dirt road and only use is commuting, taking the kids to soccer practice, or to the mall.

The UDP for the 3.0 and 3.5 is the same except there's a timing ring that added to the 3.0.

The FSM manual shows you step by step what you need to do to remove and install an engine. All you really need to do is remove the drive axles, remove vacuum hoses, fuel hoses, electrical connecters, remove the clutch cylinder, remove the speedo from the tranny, remove the starter, disconnect the y-pipe, attach the engine to a lift, remove the crossmember, remove engine mounts. I prolly left something out, but you get the idea. The engine and tranny can be taken out together.

When I do my 3.5 swap on monday, I'll take some pics.

 

While the FSM may provide information on removing the engine, it's not the most detailed thing around. The FSM assumes you have a working knowledge of what goes where and won't spell things out for you. It tells you what to do moreso than how to do it. If you want a step-by-step guide, get a Haynes manual for sure.

 

It is useless and also i got rid of the fast idles solenoids that increase rpm slightly for ac and PS use, in the IACV and there useless also.

 

It's one person's name for the Pathfinder. It was a little funny the first time, I suppose.

 

I may not be fully understanding what your talking about when you say the fast idle cam is useless....BUT....

I just got my VI installed with 5G TB, still working some problems out...But before i did this manifold swap i actually bypassed the coolant lines on the 4G TB since i figured it would do me some good (colder air, more power...right? ). Well what i noticed, was that it was perfectly fine, but everytime it got cold and i was driving, i would come to a stop and notice that my fast idle would kick in right at 1600 RPMs even tho the car was at opperating temp, so basically the cold temp OUTside would trip the sensor in that coolant line... after i ran the line back thru, my problem completely went away.

I am concerned now with this 2kVI install, seams to be like im going to run into the same problem, however the 5G TB doesnt have that coolant line anymore...so am i in the clear?

 

My 5g TB has the coolant lines. I have bypassed them but my cold start is horrible. I have to give slight throttle at start up to keep the car running until it warms slightly. It will crank over & start but then it low idles and dies. Probably need to adjust the TB butterfly screw again but I'm kinda tired of messing with it.

 

Ok....well i dont know what your talking about, but the 5th gen Coolant lines actually run thru the IAC on the bottom of the TB, since u said you have an idle adjustment screw on your iacv, im assuming you have a 4th gen IACV, so you DONT have coolant lines anymore unless you just left the 5th gen IAC atached to the bottom of your TB, wich i think is impossible (EGR gets in the way)....

So i have NO idea what your talking about....

 

Even if you did leave it pluged in, how did you figure out your wiring harness? U got two IAC's?

 

I have the 5g TB and IACV still attached, no EGR. Sorry for not being clear, I forget how many different options there are for this swap.
The harness is connected to an extent... I just spliced the 6 wires together by color. So obliviously the IACV isn't really working properly due to the starts, so I have to adjust the idle via TB screw.