KDMatt

Okay guys, quick update. I checked between the booster and master cylinder and I didn't see anything that looks like it's fallen out of place or is disconnected. Also, I removed the proportioning valve and took it apart to clean today. To my surprise it was actually reasonably clean. Here's the thing though... in continuing with my diagnostic procedure, I connected the (freshly cleaned) proportioning valve and plugged off its ends, and suddenly the squishiness in the brake pedal has returned. I've tightened the ends on it as tight as they will go (as there was initially some leaking on the top one, which has now been rectified with some snug wrenching...) Granted there might be a tiny bit of air trapped in there now that I've cracked it open and haven't really bled the system yet, but I'm wondering if the internal seals on these things can go bad enough to actually draw air into the system inadvertently? I'm sorry if I'm not making a ton of sense -- it's been a late night, but the real question here is: can the proportioning valve/assembly "go bad?" Thanks, - Matt

Thanks again for the mountain of replies you guys. Knowing that there is a mountain of knowledge here to help me is literally all that's keeping me sane with this car right now. @ Pete, noted, but I still think something is amiss. While it's true that a "healthy" pedal should have some give to it, it should feel like one hits a 'no-go' point during the pedal's travel, not a gradually increasing stiffness (i.e. sponginess), which is what I'm getting now. A few of these lines still look a tad ratty, so I'm going to pull a few more tonight and do my diagnostic procedure over again and reconnect things in a different order. I've clearly missed something. As I mentioned before, with the master totally blocked off, the pedal is tight and stiff as can be (as it should be,) and, in theory, this is how the system should feel when it's properly bled and all of that. @ carrott Don't worry, I don't plan to test it on the road just yet! Also, I've heard about this plate -- I was having symptoms before I replaced the master, is it possible that this thing can fall out without disassembly, or even break? I don't have my FSM right in front of me, but can you maybe link me to a bit more information about this part? Given that the pedal feels great when the master is blocked off, I'm inclined to think this isn't my issue, but at this point I will investigate anything somebody suggests to me. @ Travel'n Man Thanks! That's the order I came up with as well, and that's what I'll do for sure when the girlfriend is back at the house this weekend. @ John Coffey Okay, thanks for clearing that up. I'll pay more attention to how/when I crack open the screws the next round of bleeding. I can see how, after thinking about it, why that would make the most sense. Thanks again for your replies everyone. I'm frustrated to no end, but glad you guys are here for me. :x EDIT: I've also seen in other posts folks saying it's important to pull apart and clean out the proportioning valve?? Thoughts on this? Is there a procedure for that?

Okay, so I just got the rear brakes hooked back up, and bled 'em. I moved a pretty sizable bubble out of the rear circuits, and nothing is leaking as far as I can see, so now everything is bleeding cleanly. I fired up the car (wheels are still off though, so no driving), and with the assist from the booster, the pedal still feels a bit spongey. The pedal goes about half way down its travel, if not a bit more, with the booster.

Update: I had to spend a bunch of time away from the car all last week following my most recent post (the weather here simply got too frigid), but I was able to spend all day with her on Monday, and here's what's going on. I've been using my associate's suggestion of blocking off different lines and fittings at a time, trying to find the culprit to my woes. Even though I made new flared fittings to go on my master cylinder, it turns out that one of them was not up to par -- I had a pretty significant leak coming out of the rear circuit/fitting here, so I've replaced that. I moved on and reconnected the front driver's side line, letting fluid move to the caliper there. Using the "racer's" method described above, I bled the caliper, and the pedal was pretty stiff with just this one connected. I then reconnected the passenger's side front line and bled this one as well, pedal still seems nice and stiff. I've got nearly everything hooked back up again, save for the rear brake line, we'll see how this goes. Moral of the story is, I think my front lines are alright. I'll re-check the fittings for leaks before I move onto the back ones and see what I turn up. Also, how much pedal play would you folks say is normal with a well bled system? Right now I'm getting maybe an inch to an inch and a half of travel before I can't really push it down any further. It feels a bit different than I remember it feeling before all of this began... but then again, I've essentially got an entirely brand new system now, so I don't have a point of comparison anymore. Suffice to say, this is a pretty substantial improvement so far. Thanks for sticking with me everyone.

Sure thing. I've bled the system three different ways. The first way, was the modern, "poor man's" solo method -- using a mityvac to suck fluid through until there was no air coming out of the bleed screws. I started with the rear passenger side, and worked my way around, ending with the front driver side. (As an aside, next time I will probably start with the rear driver's side wheel, as the FSM makes it look like there's more brakeline between the master and that wheel.) The second way was the old-fashioned way -- Girlfriend got in the car, I'd open up the bleed screw a bit, have her push the pedal down, and when it was all the way to the floor, tighten up the screw again, tell her to let the pedal back up, and repeat the process a few times. I was getting clean bleeds using both methods (albeit the second method was a bit faster...) When neither of these bleeds (after multiple attempts) yielded any good results, I finally took the car to the shop and had them bleed it. They used both a pressurized (top down) power bleeder, AND gave it an 'old fashioned' bleed themselves, and still couldn't do much for me. I guess I'm inclined to believe that at, this point, I've got the "proper bleeding" thing just about covered. However, I've been known to be wrong before.

Hi folks, thank you for the mountain of replies and support. The calipers are mounted correctly, and shoes are adjusted as described in a previous post (as in, just barely dragging on the drums.) In response to another question, this whole debacle began after one of the seals on a brake cylinder in the back went out (as in, burst completely,) prompting me to simply replace both rear brake cylinder units. I've recently been in touch with one of my fellow Z-owners up here in Minnesota, and he's advised me to systematically go through my brake components to try and narrow down the source of the problem. Today I plugged the outlets on my master cylinder and gave the pedal a bit of a squeeze -- tight as can be! At least now I know my master cylinder is A-okay. I guess I'm just going to keep moving down the line with my plug-bolts, and hopefully narrow lines and components down until I've found my culprit. I guess it beats blindly replacing components, even if they are all dirt cheap. Any further thoughts?

This was my instinct as well, so I replaced the master cylinder. The symptoms did not change.

I've had a leaky brake booster/master vac before and it displayed the opposite symptoms I'm encountering, it was also coupled with a nasty "hissing" noise (the sound of escaping vacuum) every time I applied the brakes. Plus, when I had a leaky brake booster, the pedal was incredibly stiff, and this is not the case right now. The pedal sinks to the floor regardless of the engine running or not running... it just happens to sink a little faster when the engine is running...

Alright guys, I know it's been a while since I've posted on here -- I usually just cruise the 'search' function for useful info , but I'm really scratching my head at my car right now. I have absolutely no braking power in the thing, and I've replaced every part I can think of. It's a completely stock setup, now with brand new: wheel cylinders at the back (w/ new shoes) master cylinder brake calipers (with new pads) I replaced all the rubber brake hoses a few years ago, and I put a new power brake booster on a number of years ago as well. There are no visible leaks anywhere in the system, and it bleeds cleanly... what am I missing??? ... and the whole thing is acting like there's no pressure whatsoever! The pedal sinks to the floor every time! All I hear is a faint groaning noise... I even took it to the shop to have them bleed it (after doing it countless times myself), only to have the head mechanic shrug his shoulders and say "well, these old cars aren't meant to stop on a dime ya know" ... (to which I silently said "bull****.") I'm going to go through the FSM again, but I haven't got a single clue what else could cause this behavior. You guys on these forums have rarely failed me in my nearly 8 years of ownership. Please help.

Hey, Fastwoman. I pulled each injector clip off, one by one, and noticed a drop in RPM each time I did it. Sounds like each cylinder is 'pulling its weight' as you say. Interestingly enough, I did your yogurt cup test and did notice I had a bit of a leak near my cold start injector. Looks like I'd managed to forget a screw (:stupid:), and the gasket, as a result, over time didn't seal properly. Not sure how much air was actually getting in (my vacuum reading hasn't changed after fixing it), but I've sealed up the leak, and the idle does seem to have stabilized a little bit. I'm not sure if this has completely fixed my issue, but the car might at least be somewhat driveable now. I took it for a brisk spin last night for about 15 minutes and it didn't seem to cough quite as much at low revs. I'm out of town for a couple of days (won't be taking the Z with me, obviously), but I'll probably do some more cruising around next week to see what's what. Thanks for all the help so far!

FastWoman, I forgot to mention I did use heatshrink actually. They came with the kit that the guy on ebay sells. No worries there. Also, I've performed the electrical tests outlined in the FSM and EFI bible, and everything has come back fine. I also forgot to mention that, last night, when I cranked up the car, I did the screwdriver-to-ear-to-injector thing (where I put the screwdriver on the injector, and put my ear to the butt of the screwdriver), and listened for the injector sound. All of them sound like they're pulsing correctly and consistently.

Done and done. I replaced the brake booster a couple of years ago, when it was leaking it was pretty obvious (I just never bothered to paint the new one, d'oh!) Does that help? @ Fastwoman: Sorry, haven't had a chance to do the yogurt cup test yet (need to track down a place that'll sell me Yotastic, anything else I can use if I can't get any luck?) I also haven't peeled apart the harness just yet (it's been raining a ton, so I didn't get any time on the car until last night). I did some more circuit testing and cleaned up some more connections. Everything still seems A-OK, sans how it's actually running. In terms of the new connectors, I did the coolant temp sensor, and the six injectors. I skipped the thermotime switch and cold start because, like you said, they don't do much when running. I usually have my cold start disconnected anyway because it leaks! I only have it connected now as a last-ditch effort, hoping it'll richen up my mixture a bit as a result. My new connections were made by soldering the copper wire together (after a twist), then wrapping with electrical tape. I'll check out the dropping resistors, but I've physically cleaned their grounds, and also tested them according to the FSM, and, if memory serves, they came back fine. I had a leak once at my custom intake near the throttle, but this was pretty obvious when it happened as I could both hear and feel the air leaking through. Then, when I'd wrap my hand around the intake, my covering the leak would cause the engine to run a bit better. However, I'll check it out again. Like I said, at this point I'm willing to explore any avenue of possibility, as my brain alone has not yielded much success. Interesting factoid about vacuum. I'll give the engine a bit of spray tonight and see what happens (oh, and I'll see if I can grab some pics of my ignition components before I do, just for you.) Anything else I'm forgetting or I can do for anyone? :/

Hey guys, thanks for the quick responses. @FastWoman: Indeed, I'd be atonished now too if it weren't electrical ... this just means I seemingly have miles and miles of wiring to climb through now, which has me less than enthused. I'll take some pics of the ignition components, just for arguments' sake, but I truly believe they're a-ok. I pulled apart the ECU, there were a few dirty looking solder joints, and I resoldered them. Other than that there was no obvious evidence of moisture in there. The terminals on the coil have all been cleaned (the coil itself, in fact, has just over 20,000 miles on it) -- it's one of those Accel Super Stock coils. We tried swapping a stock coil back in, and it actually made it run noticeably worse. The connections on the TPS, AFM, and CTS all seem to be fine (i.e. they look metallic and not green/corroded). I actually bought a bunch of connectors from that "forrest" guy on ebay, and replaced the Bosch connectors on all six injectors, plus the CTS, so those all ought to be nominal. I'll pull them and look again though if you think that's a good idea. I also had all of my injectors sonic cleaned and refurbished at about the same time. Also, yeah ... the vacuum isn't ideal. My only point was that I don't believe the low vacuum to be the direct cause of my current problem (again, I'm open to being wrong about this) -- I was only pointing out that the car was running pretty well before (running rich, in fact), with the vacuum about where it is now. @ZedHead: Yeah, I remember at one point when this first started setting on, I could pull the injector clip off of #4 or #5 pretty interchangeably and not see much of a difference in the running condition of the engine. Are you talking about those tiny christmas tree lights? I have lots of those. I'll check out the PCV hose as well. Anything else I missed? Oh, and here's an idea I had. To make this is easy as possible for you helpful folks, I'm going to try and take pics of everything.... granted I'll be using my phone, so the pics may not be brilliant, but they'll be something nonetheless. Here's an overhead pic of my engine, and I'll go investigate anything anybody thinks looks a bit suspicious, and then take pics of that. Thanks again for all the help so far.

Zed, at this point I'm willing to try just about anything. I've got an extra injector two lying around somewhere, I could break/tear off the bosch connection and wire it up to a bulb or something to see if it's pulsing right. Also, the area by the ECU looked pretty dry. I could see a bit of moisture creeping along the door sills, but it wasn't in contact with the ECU itself.

Alright, so I've been struggling with my car since last October (more so than ever in the last month). I've been having an ongoing 'lean' condition problem. Here are the components that were called into question and have been replaced: Fuel Pump (brand new, tested and working within spec) Fuel Tank (washed/recoated) Fuel Pressure Regulator (Tested and working within spec) Fuel Injectors (replaced approx 20,000 miles ago) Fuel Filter (less then 5000 miles ago) Water Temp Sensor (replaced approx 20,000 miles ago, with injectors) Components that were/have been called into question: Air Flow Meter (swapped with a second unit I have handy, produced the same results) Ignition Coil (tested according to FSM, along with Ballast resistor, both seem to be within spec) Ignition Module (no idea yet) Dizzy Cap/Rotor Plug Wires Throttle Position Sensor (tested according to FSM specs and seems to be working okay) ECU (checked solder joints, a few were a little dirty -- resoldered, same results) Auxiliary Air Valve (Currently have it taped off/bypassed, results are only marginally improved) Vacuum Check (low at 14.5 psi, but the car used to run just fine at this pressure) ... and that's all I can think of right about now This morning I thought I had fiddled with it enough to try and take it for a little jaunt. I put the car into the carwash and let her sit, engine off, as the power sprayer washed off months of crud (actually got a pretty heavy dousing INSIDE the car on the driver side). Anyway, about 1/4 mile after the carwash things got almost INTOLERABLE. It was coughing, sputtering, and backfiring worse than ever. I honestly thought it was going to peter out and die. I was very fortunate to have gotten it home. Anyway, since the symptoms were so pronounced I quickly ran inside and grabbed the camera and shot a couple minutes of what it's doing, so hopefully I can get some other ideas about what's going on. Something screwy is going on here. (Oh, and before I get a million people suggesting ignition, the last time I read the plugs they were all lean .. all of them. I'll double check once I've got some daylight to work with, but I'm pretty sure they'll come back lean again, even though I haven't put many miles on the engine since changing anything).

Hey Fastwoman, since my pump is no longer in question, I'm going to start a new thread. Got some new stuff to report.

Alrighty, so I followed through with the general battery of mechanical fuel tests you recommended. At idle, when I pulled the FPR's vacuum line, I got it to stay at 36.3 PSI, even while I revved it. When I blocked off the return, I got the pressure to spike at around 70 psi with the engine running. I think it's safe to say my FPR and fuel pump are both doing their jobs, eh? Regrettably, I haven't done the yogurt cup test yet, but I will get to it if you still feel it's relevant. I had a fellow Z owner over this evening to help me sort through some of this crap, and he was pretty adamant in the possibility of it being ignition related, even though I'm not so sure I'm convinced yet. (He wants to investigate the ignition module under the passenger side dash). We also measured the resistance of the water temp sensor and compared it to the resistance chart in the FSM. It looks like it might be slightly out of whack? At 122 degrees, the FSM says the resistance out to be between .74 and .94 kiloohms ... or rather 740 and 940 ohms. We measured the resistance with the temp at about 124 degrees, and my multimeter only gave me about 650 ohms. This doesn't take into account the fact that the resistance was at the thermostat, and we were measuring temperature at the radiator, which would be cooling off faster. Still ... it could be off by anywhere from 100 to 300 ohms of resistance. Is this significant enough to cause a difference? EDIT: Oh, and here's the particularly odd thing. My RPM stumbles/misses a bit in its lower range, but once I get past 3000 to 3500 RPM, it smooths out and pulls hard. :/

Thanks for the quick responses guys. @FastWoman: Now that I have the later, ZX-styled rail, removing the vacuum line will be a cinch, so I'll try that out. I'll also try plugging the return to see what's up. Also, I saw you mention your 'yogurt cup' test in another thread, and I've been trying to find your video/instructions for it, but I'm not having any luck. Can you help me out with that? Also, interesting bit about the ECU. My car used to run somewhat rich until, one day in September, it just didn't... Unusual for it to go so wonky so quickly? ... or does that seem common enough? @Zed: My first inclination was the AFM. I've got a spare in my garage that I swapped in when this first set on, and this didn't change anything. Is there a guide somewhere for checking to see if it's "within spec?" I've been combing over my FSM and haven't seen mention of this. Thanks!

Zed, thanks for responding. This was her first time out of the garage since I parked in November. I was having the same running lean/bucking/backfiring issue in the fall. When I pulled her out about 4 or 5 weeks ago, I ran through gamut of tests listed in the FSM, thinking that my fuel injection electronics were at fault (It feels like the pulses are too short or something), when all of the results came back within spec, I turned my attention to the physical/mechanical aspects of the EFI, which led me to drop the tank and get it flushed, and replace the pump (and now, the rail/FPR as well). The last time I checked the vacuum, that hadn't changed (and I've faced vacuum leaks before, this isn't behaving like a car with low vacuum). I'm really just at a loss, and I would like to be able to drive the damn thing. The only other component I can maybe think of is the Auxiliary Air Valve/Air Regulator etc. I had a thought the other night that if it were to get sticky and not close all the way, this stood the chance of throwing off my fuel mixture. Otherwise... is there a testing procedure for the ECU itself?

Alright, I'm losing my mind over this now. Through the generosity of another local Z-owner, I acquired a later, ZX-styled fuel rail with FPR that were both tested and working good. I installed it on my car, and the fuel pressure was right where it ought to be. I took it out for a spin, and it's bucking/backfiring/sputtering/struggling to climb hills... This is the exact same behavior I was getting before I replaced anything! It was this very behavior that led me to believe my pump was bad, that led me to believe my tank was clogged, that led me to believe my FPR had gone kapooey. All of these components have been changed, in addition, I've done the battery of tests recommended in the FSM, and everything checks out. I'm really at a freaking loss here guys. The only thing I feel like I haven't tested or even considered is the ECU itself. What are the odds of that thing going out? I don't want to have to gut the EFI and go Megasquirt or something if I don't have to... but if there's no other alternative.

Hey, Fastwoman I checked out the fuel return today (would have done it sooner, but I had a film competition to participate in over the weekend), and it looked pretty healthy both with the engine off, and with it running. I opened the throttle a bit too, and the return flow grew stronger when I did this. What are we thinkin' ... FPR?

@darom, Thanks for the link, I'll check it out. @FastWoman, My FPR is a replacement aftermarket one, made by "Niehoff" ... from Kragen/Checker/CSK a number of years ago. If you want the long story, last fall I was getting a lean condition, and low pressure. Since I'd replaced the FPR a number of years prior, I assumed that my aging, untouched pump and tank had something to do with the problem. The tank, I knew, was full of crud, so dropped it, and figured I ought to replace the pump at the same time. That's why we are where we are now. I've tested the EFI pretty extensively, and all of the electricals check out too. The low idle pressure still remains, and this is leaving me fewer and fewer components to be suspicious of. However, I will try your test, and see what the return flow looks like with the engine running.

I'll check that out FastWoman. At this point though, I'm starting to wonder if perhaps my FPR has something to do with this. If I fiddle with the vacuum hose attached to it (i.e. clamp it) the pressure goes up. Right now, at idle, I'm sitting at about 30 PSI, but if I clamp it, I can take it up to 33/34, which is leading me to believe that the flow may not be as bad as you suspect. I've been considering getting a solid aluminum fuel rail and adjustable FPR, perhaps now is the time.

So ... an odd turn of events... the car is running now. I drained the tank and disconnected the pump... I then just hooked up a long hose to the inlet on the tank and stuck it into a container filled with gasoline, when I gave the pump some power I got a few 'spurting' and whirring sounds before it then silently took up the "slack" and my pressure gauge slowly rose to 37. I thought this was odd (and also grew concerned, worrying that my tank was, indeed, at fault) ... but I hooked my pump back up to the tank anyway. This time, when I turned the key, it started flowing like it was supposed to... and voila, the car starts! This just strikes me as odd... nothing has really changed, except maybe now the pump is primed or something? ... also darom, I'd be curious to know your setup, and where/how you had issues with your car under load. EDIT: I'm mostly curious because the E8312 is also listed as a replacement for the turbo models. That being the case, I imagined it being more than adequate for a N/A car like mine.

That's the same pump I've got Zed. Is yours pretty loud? Mine's making this horrendous racket.