duowing

Alright hopefully you guys can help me out with this. I switched my CHTS. Well my car started up, and ran down the street with no problems right from the start! So it looks like I may have finally solved that problem, although there's at least one more run due to kinda make sure.

Ok so I have a few new issues. Well after this my car seems to run the same pretty much cold and warm. It runs pretty much decent when I'm not getting hard on it. It seems that it's not until harder throttle that I begin to get popping or hesitation. Alot of times it doesn't pop or anything, it just feels like the power isn't there. Although I well get a bit of hesitation or missing, but like I said it seems to be when I'm at WOT trying to go all out. My other issue is my boost gauge, even if the pedal is at the floor the boost gauge is barely reading into boost. Also, I don't know how much the O2 sensor can affect things, but I checked my O2 sensor, because it seemed like it got banged up some when I pulled the manifolds/downpipe. Anyway on the bottom of the ECU there's that LCD that's supposed to flash. It flashed back before I pulled the manifolds, now it just stays green. So I'm wondering if it's possible that the O2 is sending an incorrect signal? I'm gonna go buy a new one.

These are about my only issues. Hopefully you guys can give me a heads up, but if the car is good at all temps that'll be quite helpful and make it that much more useable as a daily driver.

thxone

13/16th inch O2 sensor socket that's 13/16"
The O2 sensor is the number one cause of poor fuel economy and can cause hesitation and poor idle. Replace it period every 30,000 miles. If your boost is barely reading boost you could have a small leak on the pressure side of things. I would uncover the ecu, pull the three connections then plug them back in...take it for a drive...if it seems better then the wires at those plugs are suspect...just like mine Also, if you want your turbo to run really fast then buy a 1997 Twin Turbo 911....problem solved

duowing

Yeah, I'm thinking since the light on the ECU doesn't seem to be flashing per-spec and like it used to. Plus I was always suspecting, especially since the connector part on it got bent up and banged around if it was working right. So since the light isn't flashing, I'm wondering if it's almost like the car is receiving a signal, but rather than a changing signal, if it's more or less receiving just a straight constant signal that's causing issues. It's reminds me of when I first changed the O2 sensor, but in reverse. It seemed like I barely had low end power, but everything else was normal. Now it's like my low end is pretty good, but my high end is where it fizzles out.

Also, I've had this car for a little over a year now, I finally get it running pretty good, and almost get hit twice. Both at red lights. A big ol' SUV almost took off my front driver's side fender when he decided to cut his left turn a bit too sharp, and then getting off the freeway, I look in my rear view mirror and see a honda civic flying up behind me ridiculously fast. I kinda tightened up as you hear the brakes squeal and see the whole front of that honda dive as it came to a screeching stop, and I could see the girl sitting in the passenger seat covering her mouth with her hands. You could tell she was pretty freaked out at how they almost slammed into me.

duowing

The 3 pieces of vacuum hose that are on the turbo/exhaust manifold, can you use regular vacuum lines, or do they need to be high pressure, because I used a regular line. Also where does the boost gauge connect at? I'm not sure if it's the gauge or if there's a leak.

thxone

The vacuum lines...I would use thick lines...something sort of stiff and a bit heat resistant in that area. I would think for the gauge you could tap into with a T one of the hoses coming off the pressure side of the turbo...I haven't hooked one up before but it would most certainly read boost there. I don't know how the stock gauge works...it's electric I think.

snwbrderphat540

i think he is talking about where the stock boost sensor is, its electronic, as for adding a boost guage it comes with everything neccessary when you buy it and place the T in the FPR vacumme line. you dont neccessarily need thick lines you might just need to clamp some lines, like my brake booster line will blow off if used enough in boost, and im using silicone lines pretty flexible

jfairladyz

The ECU doesnt use the O2 sensor at WOT. ECU goes into open loop at WOT.

duowing

Hmm, well the O2 sensor does need to be replaced, but my main thing is my boost gauge doesn't seem to be reading correct at all. I think my boost still seems to work fine, just the gauge isn't reading right, but I'm not sure. So that's why I was wondering where it connects to so I can at least check it. I'm not sure what I might have done when I pulled the manifolds that would cause the issues at Full throttle or high rpm because before I pulled the manifolds at least when the car was warm it ran like a raped ape. I know the CHTS is not the issue seeing as it ran the same now as it did after I finished the manifolds, but hadn't changed the CHTS. I did plug off the EGR tube, but I know that would cause a problem at WOT.

EDIT: You know I was thinking. Would it make a difference at WOT since the Turbo doesn't detect when the car goes into WOT? If I recall doesn't the TPS on the Turbo only determine Idle and off-idle?

jfairladyz

^ You know something, I didnt even stop to think about the fact that the turbo doesnt have the WOT switch like the NA's do. So yeah, that could be a possibility. When I mentioned the ECU not using the O2 at WOT, I was refering to the non-turbo EFI.

duowing

As far as my boost gauge goes, I don't know if I have a pressure leak or not. Because when I got the car running the boost gauge was working fine, then I swapped the CHTS and the boost gauge was working fine. I get back home, check the timing and everything, try setting the timing with the TPS unplugged to see if that works. Now the boost gauge isn't working right, but the car seemed to be running the same. Switched the timing back and the boost gauge is reading the same. Next day now even with my foot practically to the floor the boost gauge is barely reading into boost, but when I don't even have my foot on the pedal, it's reading barely under boost, so I don't know if my gauge is at fault or not, or I have a leak on the pressure side? The only thing I messed with was replacing those vacuum lines on the Turbo/Wastegate while the manifold was out of the car. The only nuts I removed where the nuts attaching the downpipe to the turbo.

duowing

Ok. So I changed out my O2 sensor, that LED on the ECU does flash again which means it's working correctly now. Anyway I went for a drive, still have the same problem.

When in Park or Neutral my idle seems to be way too high, around 1300-1400RPM, I'm thinking there's gotta be a leak somewhere. I'm hoping it's not my intake manifold gasket, but if I do the oil filler cap test the car sputters like crazy, and goes back to normal. So it seems like I don't have vacuum leaks.

My boost gauge barely registers. I can barely get it to move off the middle part and the boost sometimes seems to go, but not as good as it did before I did my intake/exhaust manifold gasket. So I'm thinking I must have a leak or something. I don't think I messed anything up, but I'm wondering if I could have messed up the pop off valve when I was messing around with my wire wheel and it's causing a pressure leak?

I have two vacuum lines that come from my AFM that I've plugged off. I know one of them went to the line for the EGR, although I'm not sure which, and the other I have no idea where it goes. I don't know if that's enough to cause an issue. The little thing in green that I outlined is what I think supplied vacuum to the EGR valve? Is that right? I have that plugged off.


My other small issue is it seems like I can smell something burning sometimes, I don't know what, I'm wondering if there's a line to close to a pulley, or something too close to the exhaust manifold, or it has to do with the fact that I pulled the little heatshield off that was originally on the exhaust manifold. It seems like there's more heat coming out of my engine bay than I remember, I don't know if plugging off the EGR would cause this? My temp gauge reads at halfway though, and I haven't noticed any issues that would be caused by overheating, so I think I'm ok in that respect.

Any ideas where to start? I really want to get this thing running perfect. It's just problem after problem with this car. I fix one thing to have another issue show up.

jfairladyz

if your boost gauge is having a hard time giving a reading AND you've got a high idle, then I'd definitely consider the idea of a vacuum leak somewhere between the boost sensor (possibly the boost sensor itself) and its vacuum source. The factory boost gauges were inaccurate, but not unreliable.

As far as the extra heat under the hood, could just be from removing that heat shield.

duowing

Tomorrow I'm thinking I'm going to pull off the j-pipe, and the tube that goes from the AFM to the turbo and inspect those for leaks. Also like I said, I replaced the hoses on the turbo that go to the wastegate, etc. I used regular vacuum line, would that matter or would it need to be high pressure line? I think I'll have to try and replace that vacuum line between the boost sensor and the intake manifold. Could a boost sensor that's going bad cause the car to run improperly? Also would a leak cause the boost gauge to read differently when out of boost? I swear I thought my gauge when I wasn't in boost used to read about halfway between -7 and 0, and now if I'm not even pressing the accelerator it reads just before the 0 mark on the gauge, and even at pedal to the floor it just barely will read past the 0. Also how does that work or what exactly is the point of having the gauge read -7 to 0?

I need to get a camera and grab a picture of the two vacuum lines that I have plugged off. That picture above with the little thing highlighted on the left of the pic, was that the line that went to the EGR? Even if that is, I still have another line plugged off that I don't know where it went to. Like I said, I don't know what I might have messed up when I did this whole gasket. The only thing I really changed were the vacuum lines on the turbo/wastegate and plugged off the EGR. I'm just hoping I didn't mess up and cause myself an intake leak where the manifold meets the head, but spraying brake parts cleaner/carb cleaner all around where the manifold meets the head I didn't find a leak, and I'd think a leak there would be alot more apparent.

jfairladyz

the gauge will read below zero when its seeing vacuum. The fact that it hovers around zero (atmospheric pressure) is what leads to believe that the line to the boost sensor could be leaking. If there's a leak in that line then whatever vacuum and/or boost that the sensor should be reading is bleeding off. The sensor itself could be bad as well as I'm sure it relies on a diaphram of some sort to work. If that diaphram is ruptured or the sensor is worn internally then it could cause the same symptoms as a leaking vacuum line. This is all based on the assumption that then turbo is infact producing positive boost. I dont see a vacuum leak thats small enough to allow the engine to still run causing you to actually lose all boost pressure.

Also, the line u circled has a check valve in it. If Im not mistaken the EGR system doesnt have a check valve, but the vacuum advance does.

duowing

So I wonder if maybe I do have a leak around where the manifold meets the head, but I don't know how to tell for sure. I've been every so often spraying brake parts cleaner and such around the engine bay and not noticing a raise in idle.

Update: Anyway I went out there and started looking around, well I finally found out why I had two vacuum lines plugged off. One is obviously for the EGR, and I have that split into two seperate plugged parts, but I guess even though it was right in front of me, I didn't have one of the vacuum lines connected, I had the one side plugged off, but the other side I didn't. Anyway I plugged that back on, my idle speed dropped from around 1400-1500 to right around 1000, my boost sensor started registering without any throttle real low on the boost gauge, and then it goes into boost with just a little bit of throttle and I can get it to go pretty far into boost again. The car seems to be boosting better now, but my problem seems to lay around the 3250 mark. If I give alot of throttle it seems like my tach races to 3000 then kind of hangs and seems to lack power a bit above the 3250, that's when I get popping, if I give it less throttle it seems to get past there, but I'm not really sure. Generally by the time I hit 3250 I'm either going too fast, or have a car right in front of me, so I can't tell.

As for that check valve, I was wondering, would that check valve restrict vaccum at certain RPM? Because I thought the EGR had a valve that would block the vacuum at idle, and would also block the vacuum at higher throttle, or is it just that the Vacuum is not great enough to open the EGR?

For now I figure I'm gonna at least run seafoam through the car to see if I have any exhaust leaks, and mess around looking for vacuum leaks and stuff. The car is going better today, but I wonder if I have at least a small leak at the intake manifold or not. I was spraying brake cleaner, above, below, against the head, around the manifold and no difference, I even pulled off a vacuum line and sprayed brake cleaner just to see if I could notice a difference and I did. So maybe there's some little thing I'm missing. Like switched vacuum lines, or a vacuum line that's leaking just a little?

UPDATE 2: Ok, so I seafoam'd the car to see if I have any exhaust leaks, looks like I still have some exhaust leaks to take care of, but the manifold seems to be sealed up good. Anyway I switched those two vacuum lines, I plugged off the line with the check valve, and switched it for the straight line. Well anyway I had got a lot of seafoam in the car and took it down the street, it was popping and bogging down a bit there, once the seafoam had made it's way through the car came round. Anyway I get on the freeway for another test. Set it to 1, foot down, the tach jumps, boost straight past 3500 and up, I get it to 2nd get it boosting to 6k, then put in Drive. The thing did it with no popping or hesitation, although I remember it used to feel just a bit quicker I thought, probably because I did have the timing advanced a couple degrees before, but a couple full throttle tests on the freeway seemed to all get the same result, good throttle response with no popping, sputtering, or just feeling like the power dropped off. So I'm gonna let the car cool down, take it for another drive later, and hope I've finally fixed it.

thxone

I would double check your timing again anyway...unless you re-timed it AFTER you found your vacuum line/leak problem....better to do it now and get it right then not do it at all, I wont think anything bad about you if you double check your work...it's just good housekeeping.

duowing

Haven't checked my timing yet, just went and dropped the car off at an exhaust place to get a muffler so the thing won't be so loud. Anyway I got some good driving time in the car, WOT the car goes pretty decent, although like I said it feels just a bit slower than I remember so I don't know if it's possible I still have a leak or it's just because my timing is retarded some. Anyway in regular traffic, also I know an auto tranny doesn't help, but the car does feel a bit slow on initial throttle and it feels kinda sluggish when cold.

My idle sits around 1000 sometimes goes up a little, and sometimes sits a little lower. Anyway I checked my ECU again and now the light isn't on at all for the O2 so I don't know if it's my wiring, my O2, or my ECU, but the sluggishness of the car reminds me of the first time when my O2 crapped out, once I fixed that the car had more go from stoplight to stoplight. Anyway I'm gonna take the O2 back and see if I can get a new one. I no longer have the O2 sensor heatshield on my downpipe, I don't know if that would ruin my O2 sensor or not. Like I said, I'm not sure if I have a bit of a intake leak or vacuum leak somewhere, or maybe I have a leak in my exhaust that's not giving me much back pressure? Anyway the car seems to be running pretty much better than it ever has and I feel like I'm finally nearing completion on fixing this engine. So any suggestions would be great from you guys.

Also, I don't know if it could cause a problem, but if there's a vacuum leak for the vent/AC system, would that be enough to cause an issue with the engine, or still count as a vacuum leak?


Thanks to all you guys here at Zdriver for all the help you've provided me with! If it weren't for you guys I would never have come this far with my Turbo Z.

jfairladyz

u can pick up a vacuum gauge at a parts store for relatively cheap. Or get a combo vacuum/boost gauge. Either way that would help you identify better if there even is a vacuum leak.

As for the climate control system possibly being the cause of a vacuum leak: remove its vacuum source at the engine and plug up the nipple. See if that changes anything. If it does then you can go on the hunt for a leak in that system.

But check your timing and go ahead and try to get that O2 sensor replaced and see if that makes any difference.

duowing

Would the fact that the little bit of heatshield the O2 sensor used to have on the donwpipe not being there, be enough to ruin the O2? I'd assume it wouldn't because the fact that Nismopick's custom downpipe didn't have a heatshield, and the MSA Pipes don't come with a heatshield for the O2.

thxone

99% of cars with O2 sensors don't have heat shields on them.....age, improper engine tune (running rich) and stuff like that will wear out an O2 sensor, especially the running rich...if you see black smoke out your tail pipe, that smoke is clogging your O2 sensor and making your car run even worse.

duowing

Hmm, I wonder if I clogged my O2 when I loaded seafoam into the car.

duowing

Well, I replaced my O2 sensor, so that's working now. Found 2 more vacuum leaks, one was coming from my intake manifold, the line was fine, but the hose was pretty much broken where it met over at the Vent/AC crap. So I replaced those lines, and some other lines that looked old and brittle. My Fast idle at cold seems to have lowered some, although my idle when warm still seems to be right around 1000 RPM, although more towards the lower end of 1000. Car from cold runs good, car runs great while warm.
It just feels to me a bit slower than I remember, maybe it's me, maybe it's the fact of my 280Z 4-speed vs the 280ZXT Auto.

Right now I figure I'm gonna grab a vacuum gauge and check my vacuum to see what that's reading at least to find out if I have a vacuum leak still that might be pushing me up to 1000 RPM at idle. I figure if need be, I could probably adjust the screw on the TB to lower the idle a bit. Does a 1000RPM idle necessarily mean a leak or mean something is wrong? Also I'll check my timing.
I also went ahead and ordered a K&N Air Filter. Seeing as I have no idea when the air filter was last replaced, and I hear a lot of good things about K&N I figured I might as well.

Overall it seems like I'm finally at the end of the road as far as fixing my L28ET goes. Now it seems like it's time to upgrade!

jfairladyz

has the idle always been high or was this something that developed? If its always been that way then theres a chance a PO raised the idle at the throttle body to compensate for something. I know when my air regulator first took a crap on my ZX I just raised the idle a bit at the throttle body to compensate on cold starts until i replaced the regulator.

duowing

I can't say for sure if the idle has always been higher or not, I don't remember if it was ever lower than 1000 RPM or not. That's why I was thinking I might as well test the vacuum to see. I'm thinking the idle may have been raised because of how much the fast idle seemed to drop after fixing the few vacuum leaks, but the idle still seems to be about the same. I don't know how correct this is, but I was just reading through the FSM and I got to the section about idle adjustment when warm. Now it says on Automatic cars the car should be set in D with the parking brake on and blocks blocking the tires so it won't move forward, etc. So if that's the case, because when I'm at a light with the car in D the idle sits more around 700-800 or so, which is about right, so maybe my idle is fine?

jfairladyz

Yeah I think you're alright then