[Casper]

Here's my situation:

Swapped in a ported early 2000 manifold and the FC 65mm TB. Love the throttle reponse, and the mid-range punch. Everything works like a hot damn, except for a SLIGHT hanging rev (somewhat normal from what I hear) and a HORRIBLE idle.

It sounds like its about to stall, and the RPM bounce around 600-800 constandly. At idle, its sounds like crap. I've got a CEL to boot. So far i've tried:

- Unplugging various sensors to see if any of them are the culprit. MAF, IAC, TPS. The only one that made a difference was the IAC, which I replaced with a spare I had. Minor improvement, same problem.

- Went over and sealed any vacuum leaks. Copious amounts of gasket maker later, the hanging revs are mostly gone, idle remains.

- Its not the idle adjustment on the TB, and the TPS IS in the correct position.

- Checked the gascap, re-set the computer. At this point I suspect a TPS, but aside from the idle, I have NO problems with the way it runs.

So, before I start throwing money at a new TPS, any suggestions?

I'm working on getting my hands on a code reader to pull the DTC to make sure that its really the problem.

[OAC_Sparky]

If your TPS was fine before the install, what makes you think it's bad now? That's backyard mechanic thinkin'.

First, pull the code. Sounds to me like a vacuum leak. Did you plug the IAC back in? Or get gasketmaker in an IAC passage?

[Casper]

I typically share the same sentiment, but i've heard MANY stories of the TPS being rather fragile, and easily breaking with a simple swap to the new TB.

[OAC_Sparky]

Sorry, I was editing as you were posting. Did you plug the IAC back in? Or get gasketmaker in an IAC passage?

[Casper]

IAC is plugged in. Only used a TINY bit of the gasketmaker over the OEM rubber seal, nowhere enough to cause a problem. Only did this to the 2nd IAC that I put in, and the problem existed with both units. At this point, i've more or less ruled out the IAC.

[mo_focus]

Casper,Jun 1 2006, 10:32 PM Wrote:I typically share the same sentiment, but i've heard MANY stories of the TPS being rather fragile, and easily breaking with a simple swap to the new TB.
[right][snapback]190934[/snapback][/right]

I went for a tire change and my CEL came on. so it was the TSP. it could be just bad timing and it could be your TSP. anyways start from the cheapest part and start replacing :D

[OAC_Sparky]

I would still pull the code first before replacing anything.

I haven't worked on too many Zetecs, so I'm not positive on the porting of the IAC passages, but do they go through the manifold or the throttle body? The reason I'm asking is that it's possible that the passage may be blocked internally in the TB or intake, either by gunk, gasketmaker or gasket. Just a possibility.

It brings to mind a problem a friend had, back when I used to build up V8s in my youth; a friend had replaced the intake on his 302 with an Edlebrock, couldn't figure out why he was running so hot. He replaced the thermostat, rad, belts, still no go.

I asked him why he went about throwing parts at it; all things being equal, rule out what YOU did first.

It turned out that the manifold gaskets he got from Crappy Tire were defective -- they forgot to punch out a water jacket hole, the water pumped into the head and couldn't exit into the manifold fast enough.

Another mistake I see a lot of people make is gooping the bejesus out of anything and everything with gasketmaker. Unless it specifically calls for it, it's not needed so much. Sometimes it actually makes it worse. Just some free advice, no offence.

Can you try putting the old TB back on?

[Casper]

That's on the schedule too... gonna pull the TB and double check the gasket. Might need to do some trimming around the IAC passages to be safe.

Just picked up a cheap code reader on eBay. $50 shipped isn't so bad. Far cry from the $250 that Canadian Tire wants. Pretty basic... just reads the codes and clears them. All I need.

[dBlast]

Sounds like either a vacuum leak or blockage in the side passages for idle air to pass through when the main butterfly valve is closed on the TB. On the FC TB there are 3 little holes on the side for idle air. Make sure these aren't blocked by the gasket or whatever goop you use to seal it.

[02ztsian]

Casper,Jun 1 2006, 04:32 PM Wrote:I typically share the same sentiment, but i've heard MANY stories of the TPS being rather fragile, and easily breaking with a simple swap to the new TB.
[right][snapback]190934[/snapback][/right]

They are fragile-I broke one just putting it in place, not even tightening it down.

I have a similar problem, the erratic idle and slight hanging revs. I also have a ported 2K intake and FC T/B with a brand new TPS. Sometimes it will actually stall at a light. I have just been blipping the throttle at lights to keep the revs up. The revs slowly drop and fluctuate and I can only point to the TB as I have the exact same problem with the TB on a stock 02 intake. I also used Hylomar gasket dressing for the TB base, very sparingly. I feel there is a leak between the three
side passages and the main throat as the gasket is very thin here. I think I am going to try a slightly thicker gasket material and hand-cut it. Something to provide a better seal between the two openings.

[OAC_Sparky]

Any resolution to this issue?

[Casper]

Yup!

Picked up a cheap OBD reader for $50 shipped on eBay. Delivered to my door in 2 business days!

One DTC, 2 pending. All TPS. Got one on order from the local Ford dealer... only ones available are in the east... should be here any day.

[OAC_Sparky]

Casper,Jun 9 2006, 04:09 PM Wrote:Yup!

Picked up a cheap OBD reader for $50 shipped on eBay. Delivered to my door in 2 business days!

One DTC, 2 pending. All TPS. Got one on order from the local Ford dealer... only ones available are in the east... should be here any day.
[right][snapback]192146[/snapback][/right]

Well that's good, even though I was off on the IAC, I'm glad you pulled the code. Your code reader will pay for itself.

Did I mention how much I hate it when people throw parts at cars before pulling the codes?

:lol: