Plenum pull oops!!! Now another oops!!!

[schwar74]

My brother and I succeeded in a fairly smooth first time plenum pull to get new injectors installed. Up until the last step that is. In pulling it out, I failed to see a zip tie holding an electrical connector to the plenum and the wire broke somewhere down in the nether regions in the back of the motor. I'm looking for help in identification. It was a 2 pin plug with a yellow and a black wire coming into it. The other end just had the yellow wire coming out. The black wire ended in a mesh surrounding the yellow wire. Any ideas? Hopefully I didn't sink the ship with this f-up.

Thanks for your help.

Scott

[t.mcginley.jr]

A picture would be great

It's probably one of the IACV connectors though

[Ace2cool]

Yep, you killed it. Just sell the car and buy a new one.

J/k. Post a pic so we can see what you're looking at.

[schwar74]

I'll have to get them tomorrow. The cars at my brother's place.

A little better description:

The plug looks like the ones that connect to the coil packs, gray with the tab connector. The IACV plugs both had the wire retainers if I'm correct. There are 2 - 3 pin plugs that are immediately adjacent to by the rear driver's side of the plenum.

Pics will be coming.

Thanks.

Scott

[schwar74]

This is where it connected to the EFI harness.

(I'm not sure how to make my images clickable/enlargable)

The only other 2 prong connector in the area is the VTC(?) connection (this goes to the solenoid on the back of the head, right?) that's surrounded with a white woven shroud.

I'm fairly sure now that its the detonation sensor wire. After I figured out where the sensor was, I realized that that's where the wire came up from (just under the EGR). And looking at the wire, it could just be a discolored white wire, not a yellow wire. In looking at the wiring harness diagram, it shows a white wire with a dotted line around it going to the knock sensor. Is this the way of denoting a wire surrounded by a mesh of other wire? I couldn't get my fingers down where the sensor is to feel if the wires are missing. I guess I just need to get a new one and attach it under a plenum bolt. Unless you guys think its ok to run an NA with just the resistor band-aid technique.

Thanks again!!

Scott

[ThisIsSparTTa]

I doubt it was the knock sensor unless you had a relocated one that you forgot to move...but if it was relocated, it should have been pretty obvious that it needed to be disconnected. Then again, the only other 2 prongs in the area are the VTCs, I think. I guess its always possible you just caught a wire that wasn't actually attached to the plenum as well. The O2 sensors should be 3 prong as well as coil packs, etc.

[schwar74]

It was just attached to the plenum by a zip tie, it wasn't actually plugged into it. I had already disconnected the plug from the main wiring harness. The free end of the wire (after it broke) came from somewhere below the EGR, which should be where the knock sensor is. Like I said, there's not really any way to see or feel where it was or to look for a broken wire down there.

Scott

[t.mcginley.jr]

Its still hard to tell what exactly it is from the small pics, but based on the connector its either the knock sensor subharness or an O2 sensor. Like you said, the vtc wire has the white sheath so you know it isn't that. The only other 2 pin gray connectors like that back there are knock sensor and O2 sensors.

Btw, uploading pictures to photobucket.com and then linking to them (with the [ img] tabs) will give you big expandable pictures

[schwar74]

I'll look to see if the O2 sensor wires are intact as they're visible on the exhaust manifold, correct?

Any thoughts on just using a resistor to "replace" the knock sensor in an NA? Anyone done it?

Scott

T.Mc. - I used photobucket for the upload and put the url between the [img]/[img]. Was it an option I missed on photobucket to have them be expandable?

Thanks again guys!!

[ThisIsSparTTa]

You won't find a lot of support for cheap fixes around here, even if you are on a NA. Some people claim the cheaper aftermarket Knock Sensors work fine. I'd go with that and a relocation if you're going on the cheap.

[schwar74]

Well, it started right up!! It ran a little rough initially, and steamed a little from where the water had spilled out of the TB coolant lines, but then smoothed out.

It has symptoms of a knock sensor failure (sluggish low end acceleration and fast idle), but a new one is on the way. I'm kind of wondering, as easily as the wire broke, if it had already failed.

I also didn't have replacement vacuum line to get from the balance tube to the carbon canister, so thats just capped at the balance tube.

I deleted the TB water lines and disconnected the EGR and capped the tubes while I was in there too. It was so much easier to get on than to take off with those things done.

A very satisfying project!!

Thanks for the tips.

Scott

[t.mcginley.jr]

Sounds like it went well. Getting rid of the TB coolant lines helps a TON with plenum install/removal, as does the EGR delete.

Most people end up relocating their knock sensor to the back of the upper plenum just for convenience in case it goes bad. It's 9999% times better to relocate it and keep the KS intact then to bypass it, more for TT but its still important for NA too. You can get a brand new OEM knock sensor for ~$35 off eBay and a new harness for it from Z1 (upgraded design) for ~$25 and then pick up a longer bolt from a hardware store for a few bucks.

And I have no idea why your pics aren't expandable lol

[schwar74]

So, I found another mistake I made . . .

Last night, like I said, she started up and ran pretty darn well. A little sluggish, but it idled smoothly. So I go to start it tonight, and no start. I got just a little hint of it firing for a split second, then nothing. Cranking but no fire Checked and had fuel flowing and no leaks, so i checked the spark and nothing!!! Looking around, I found I'd failed to connect the ground at the rear drivers side of the plenum. Reading about this, it looks like this can wreck a PTU. (btw, it's the new style). Im assuming the loose ground was laying somewhere that it was making a little contact last night, but that it moved and lost a connection. Then, it turned over, the plugs all soarked once, and this was the kiss of death

I pulled it off and couldn't get continuity anywhere from any of the pins trying every combination I could think of. The fsm writup wasn't very clear to me. I did reverse polarity for each combo. I'm assuming this means it got toasted.

I also checked to make sure the ignition relay was working. According to what I read, 12 v coming from the center slot of the coil pack clip means that this is ok. I couldn't find anything about a fuse that may have blown.

Does this all sound reasonable? Is there something else I should look at before I order another PTU?

I hate to keep sounding like a cheapskate, but I found some used PTUs on eBay for $24. Much less than the $160+ I saw for a new one. Are the new PTUs enough more reliable that I could feel comfortable with a used one? I was thinking of just buying 2 so I could have a spare. Is this smart shopping or a really bad plan.

Ps. I have a new oem knock sensor and harmess on the way.

As always, thanks a ton.

Scott

[ThisIsSparTTa]

I'm assuming you followed this: dead-cylinder-can-t-figure-out-why-read ... 64452.html

I did this 2 days ago. I was initially confused as well and not getting any results, which was weird. I was confused because one side of the PTU has numbers and the other side has letters, so I connected the numbers to each other and got NOTHING. Then I looked closer at the diagram and noticed the 1, 2, 3 they have circled. THOSE are all the connections you need to make. So for the first test of connecting 1 and 3, you will connect "3" or 'd' to pins 1, 2, 3, 4, 5, 6. Then you will reverse the polarity and make all those connections again. The same thing follows for the rest of the tests.

I just want to make sure you didn't make the stupid mistake that I did initially. If you do the math, you should be making 6*2 + 2*2 + 6*2 + 6*2 = 40 total connections. I'd recommend seeing if you can have someone give you a hand, because it was definitely laborious trying to get the probes of the DMM lined up and to stay in place on 2 sides simultaneously.

[schwar74]

I thought I'd give one final update to let any future searchers know how things turned out.

I got a different PTU and a new knock sensor. I got the PTU installed, and relocated the knock sensor under an upper plenum bolt. It fired up immediately. I pried the old PTU open, and there was a metal connector that had burned up.

This car is so much more impressive now!! I'm sure I'd been running on 4 or 5 cylinders since I bought this thing back in October. Its my first sports car, and I'd never driven a Z until I bought this one. I kept reading how NA's are not the fastest cars, and I was chalking the poor performance up to this.

Thankfully, about 3 weeks ago, I saw an ad on CL for a TT swapped 2+2 and stopped by to check it out. The guy let me drive his car, which he swapped about 6 years ago, and he drove mine. He immediately told me that it was running poorly, and showed me how the idle changed when playing with the injector clips. I'm stuck in a small town in KS. Z's are few and far between. I just got lucky to run into this guy and he could get me pointed in the right direction so I could get all this fixed.

Thanks guys for your tips and help.

Scott