Guest bastaad525 Posted August 8, 2003 Share Posted August 8, 2003 Soooo I've been having fun tooling around at 9psi today... got my valve cover vented back into the intake... found the PCV is working good, so I was happy there. But now that I'm getting into it a bit more regularly and doing it in gears other than first... I'm noticing one VERY big problem, that I'm guessing is fuel delivery, and a smaller yet annoying problem to go along with it. The engine almost refuses to pull any farther than 4500rpm. In 1st it seems to do okay, any gear after that, it's a real struggle... It pulls really quick from 3000 to 4500 and then it just gives up, like I tossed anchor off the side or something. It will continue to climb ever so slowly if I stay on it. Still no detonation so I"m not 100% it's an issue of not getting enough fuel or what. So NOW what do I need to start checking??? I had noticed this before as just a stumble, when Yo2001 informed me that all zxt's came with a rich spot programmed in at the 4500 rpm point, so I figured that was it. But now that I'm really getting on it and keeping it floored, it's much more than just a stumble... This motor just does NOT want me to have fun. Oh and if anyone is wondering, it was doing this before I raised the boost up, and raising the boost didn't seem to affect it one way or the other. Second problem is idle. Whenever I do some WOT runs, the idle sets higher than it was before. Say I'll start the car, idle will center at about 700rpm. Then I'll go zoom around a bit, then the idle will not go any lower than 900rpm. When I got to work it was at 950rpm. It's not temperature related, as when I got off work 8 hours later and started the car, the idle promptly settled at 900rpm and stayed there at every light I hit on the way home. Found the screw on the TB today, adjusted the idle back to 700rpm. Drove around today, did a few WOT runs here or there, idle set back at 950-1000. Get outta work and start it up and it's back at like 900. It just keeps adjusting itself back up, what gives??? Quote Link to comment Share on other sites More sharing options...
fl327 Posted August 8, 2003 Share Posted August 8, 2003 Where does the guy with the installer live? I would park in front of that guys house everyday until he finds the time to work on my car. He should have never let that car out without it running better than you describe, seeing that he seemingly has engineered this motor swap before. This is the biggest reason I do all the work on my own, I cannot afford a shops rate that will offer me a warranty. For the work that I cannot perform I take work only to ASE certified technicians, or a place like such that will gurantee the work. Does it feel like you are running into a brick wall over 4500? I just fixed this issue with my car, I had to splice in a new plug for my ecu, the middle one was loose. Fuel filter I do doubt this to be an issue as well, the one time my fuel filter really clogged on me it would only idle at 1500rpm and almost stall everywhere, it didnt hit the rev limiter, since it would not rev. Does it jerk around on acceleration up to 4500, or clean up to 4500? If it jerks, sounds like tps issue. There is a scientiic method involving a voltage meter and such, but I have personally found in my experience with zxt efi that if you unplug the TPS, and problem doesnt go away (clean the TPS and connector first), I will adjust it either way right after, if that doesnt work, I use one of my small army of TPS on it. 300zx, some stanza, some early maxima with vg engines, 200sx, and a few other tps's work fine on a zxt, which makes them easier to come by in Junkyards. Fuel Pump voltage I believe this to be very unlikely as the cause You said you checked timing so its probably fine. Could be plug to AFM, ECU, TPS, Knock sensor could be going dingy, pull it off and see if it still shoots you an early rev limiter Im thinking when you get the brick wall at 4500 sorted out, it will help with the idle being slightly unstable, and would address the early limiter first and foremost. I think it is still partially the guy that did your swaps fault, but at the same time, He did get the car to start and drive, Efi glitches with these cars are not uncommon. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted August 8, 2003 Share Posted August 8, 2003 make sure you don't have to much timing, 20 is good. Clean the connections at the ecu with brake clean, I cannot stress how important that is. Then report back. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 8, 2003 Share Posted August 8, 2003 Fuel filter occured to me too, gonna go get a replacement right now. Yes it feels very much like hitting a brick wall ay 4500. Acceleration up to that point feels very smooth. The first ECU that the guy installed had loose fitting plugs, I had him replace it, the new one holds the plugs tight, and the go in with a nice 'snap'. I'll buy some brake cleaner today and clean the connections too. I'll clean the AFM and TPS plugs too. About unplugging the TPS... heheh that's funny that's usually one of the first things I do to diagnose EFI problems on these cars!! Now that you mention it I haven't tried this one yet! I'll give this a try too... I do know that the TPS is properly adjusted though, I took it to the one reputable Z shop local to here, I asked the guy to adjust it he has this kewl little device especially for that, just lights up when it's on or off, and he did it for free. He said it was way off before the adjustment. The timing is at 16* BTDC at idle, which is still a little retarded, but for some odd reason I couldn't adjust the CAS any more than this. The weird thing is, I DO think this may have had something to do with it, because I swear the car wouldn't do it this badly if at all, before I adjusted that, and I haven't really adjusted anything else on the car as of yet. I thought about the knock sensor, as I've heard this can cause the kind of problems I"m having. Question is, where IS the knock sensor on this motor? I think I know which one it is, a small black round canister looking thing, close to where the oil pressure sensor is screwed in, on the block. It has two prongs coming off of it. If that's it, it's not connected to begin with I'll take a look in the haynes manual. Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted August 8, 2003 Share Posted August 8, 2003 that is the knock sensor, to the left of the oil filter location, with the 2 connections on it. Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted August 8, 2003 Share Posted August 8, 2003 This is the same proplem I'm having but my brick wall starts in 3rd gear at about 4800rpm. Acceleration is smooth up to that point. Haven't had time to check things out yet. I'm gonna check everything mentioned previously. I'll let you know if I find everything. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 8, 2003 Share Posted August 8, 2003 UPDATE!!! Okay, went down to the car, first thing I did was play around with the CAS some more. Now when I first checked the timing, it was at 10*. I tightened the adjusting bolt on the CAS, and that advanced the timing (moved the CAS up). I tightened it as far as it would go, and rechecked, and then it was at 16*. I tried to tighten it more, but when I did and started the car to check the timing, I could hear a metallic rapping sound, I assume it was the three elevated gear teeth striking a now misaligned CAS, so I backed it off a bit. Last time I checked it yesterday it was still at 16*. Today I decided to try to back it off some more, basically to undo what I did yesterday, and see if somehow that was the cause of the 4500 rpm problem. I backed it off a couple of turns, started the car and checked the timing.... now it's at 20* BTDC, right where its supposed to be!! Strange... so of course I just left it there... I'm confused now but at least it's where it's supposed to be. Drove down to the auto parts store and picked up a new fuel filter, some STP brake parts cleaner, and some b12 chemtool to dump in the fuel tank. Changed the filter. Disconnected and sprayed all the wires and connections on the ECU, TPS, and AFM. Left the auto parts store and headed to the gas station to fuel up, got on it a little and it definately seems to have improved. It will still stumble at 4500, but now it will stumble and then resume pulling. I dont know if it was the CAS, clogged filter, or dirty connections. By the way, can someone ellaborate a bit more for me about this rich spot that yo2001 was telling me about, that all ECU's are programmed to hit a rich spot at 4500 rpm? Anyways... after I left the gas station things got VERY weird and scary. I turned onto a side street so I could really do a good test to see if the 4500rpm 'wall' had been taking care, got on it, and as soon as boost hit 6psi, the car popped LOUD, I think from the exhaust but I'm not sure, and the car jerked so badly I almost hit my head on the steering wheel.... WTF??? So I turned around, and granny-drove it back onto the other street... everything seems fine... do a part throttle pull up to 4500rpm, no boost, everything seems fine. Get on it, hit boost, BOOM it feels like my car is chained to a tree and I just took up all the slack, no pop this time. I get to a light, light turns green and I attempt to go, the car jerks back and forth a few times and dies.... AGHHHHHHH. I try to start it back up and it sounds like the starter doesn't want to turn the motor. Turn the key completely off... 10 people behidn me honking... bastards.... say a prayer and turn the key back over, car starts right up. Car feels okay again... I ease it into boost, this time, it hits it without a problem. ?????? Whaaaaaaaaat the hell was that all about???? When I got home I disconnected everything and cleaned it with the brake cleaner again... dont know why but I figured just to be sure. Now, I think I know why this weird thing may have happened, and it was probably my fault. I had assumed that brake cleaner fluid was not conductive, so I didn't wait for it to fully dry before hooking everything back up. Please tell me this could have been the problem? This time after I sprayed everythign I just left it disconnected and came upstairs. Oh and lastly, I did verify what the knock sensor is, and yes it is disconnected. Not only did the mechanic not bother even hooking it up, I dont think he even left the connections for me to do so. I see no spare unconnected wires that could connect to it. Should I worry or is this okay? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 8, 2003 Share Posted August 8, 2003 Oh I forgot to try driving it with the TPS disconnected.. probably go do that right now I gotta get some eats anyways. Hopefully she starts back up.... Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 8, 2003 Share Posted August 8, 2003 And by the way thanks for the tips thus far guys... she's definately getting there, inch by inch... I'd be so screwed w/o you guys right now Quote Link to comment Share on other sites More sharing options...
Guest szlash280z Posted August 8, 2003 Share Posted August 8, 2003 that sounds similar to the "engine washed" TPS syndrome that is so popular among the N/A crowds. get some contact cleaner and spray some in there after you do the brake cleaner thing, it should help to dry it out much faster. on my N/A whenever I would wash the engine, the TPS gets wet and the contacts short together, when you hit 3000RPM, all fuel is cut out, feels like your car is connected to a tree, when you drop back under 2500 or so RPM, the car gets fuel again until you hit 3000 and it repeats until the water is dried up. it jerks and bangs the whole time. I don't know if turbo cars do this or not. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 8, 2003 Share Posted August 8, 2003 Yeah I had had that happen on my old N/A ZX before, after cleaning the engine. This was similiar, however, it didn't correspond to the RPM of the engine, rather, it would happen whenever the boost came on. After leaving the gas station I did a part throttle acceleration and it pulled all the way to 4500rpm no problem, but of course there was no boost. When I got on it WOT and it hit boost, then it would cut out. Anyways I am now 99% sure it had nothing to do with the brake cleaner fluid. As I said, when I got home I cleaned everythign off again, and this time just left everything disconnected, and came upstairs for about 30 mins. I went back down to the car to go get some eats, and double checked all the connections before hooking everything back up, everythign was completely dry. Drove to the food place, doing as many short WOT/full boost bursts as I could, and I got it to cut out one more time, in the same manner, as soon as boost hit the car just jerked, and definately a pop out of the exhaust (wasnt' sure if it was exhaust or intake last time). I went around the block a few times before returning home, and was not able to get it to happen again. *shrug* I dont know what to make of it. When I got out of the car this time, I disconnected the TPS... kept forgetting to try it that way. I'll drive it around like that for a day and see if it does it anymore. By the way, I will say the car feels even better now, especially off boost, now that the timing is at 20* like it was supposed to be. I"m also 99% convinced that I had overtightened the CAS the first time, and that this somehow was causing the 'wall' at 4500rpm. As I said, it will still stumble for a second at this rpm, but then it will continue to pull happily whereas before it would not. The idle is still doing it's own thing, though this time I think it may have went back up due to the increase in advance timing, so I once again dropped it back down, and will see what happens. Backfiring thru the exhaust means it's running rich right? I keep thinking, it feels like it's cutting fuel, but if exhaust backfire means rich, this doesn't make sense. But for it to dump so much extra fuel in when the boost comes on, as to cause the car to stumble really hard and pop... doesn't make sense either!! Quote Link to comment Share on other sites More sharing options...
Tim240z Posted August 8, 2003 Share Posted August 8, 2003 Have you tried disconnecting the BOV? Tim Quote Link to comment Share on other sites More sharing options...
mobythevan Posted August 8, 2003 Share Posted August 8, 2003 In the several times I have driven my turbo car I haven't noticed anything at 4500rpm. It hits boost near 3K and pulls all the way to 6k before I shift. I had my share of other problems that caused it to hit a wall at boost(faulty fuel pressure ragulator), I also had coroded tps connector that caused other things. But now it seems to run good all the way through, I'm curious to see if you continue to have the "rich" issue at 4500 as you keep fixing things. Tim brings up a good point as I am not running a BOV yet. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 8, 2003 Share Posted August 8, 2003 Hahah Tim I was just wondering on my other thread when you'd pop up with a suggestion for me No I haven't messed with the BOV any further. You mean just disconnect the vacuum line that controls it? Or take it completely out of the loop? This problem is very sporadic I think, for it to be the BOV... wouldn't it happen more constantly if it were something mechanical like that? It was also showing some of these symptoms well before I even installed the BOV. And it's had the BOV on there for almost a week now, whereas this problem just showed up today. I'll cap it off completely and see what happens. A faulty fuel pressure regulator does make sense. As boost comes on and pushes it open maybe it's opening too much letting too much fuel get by, hence the huge stumble an backfiring. Wish I had a way to test this right now. I may go get another one today... theyr'e about $40... but I'd really rather wait on that one, I'm already saving for an adjustable unit, but it's gonna be a week or two before I can get it... would be a waste of the $40. Again it would surprise me if it was the FPR though only because if it were, shouldn't it be happening every time? As for the TPS... like I said I'll leave it disconnected for a bit and see what happens, or doesn't happen I think the unit itself is fine (I assume if it weren't the guy who adjusted it with is computer thing would have been able to tell?), but the connector is most likely screwed. I noticed that if I just wiggle the connector while the car is idling, sometimes the idle will bounce around, but sometimes it wont. Maybe when the boost comes on and the car suddenly accelerates, this is in effect wiggling that connector, doing something funky and causing the stumble and backfire? Heheh you guys are doing a good job of narrowing this down for me... at least I have some likely culprits now. I might just go buy an FPR, test to see how it does, and if it doesn't fix the problem, or even if it does, I can just return it... at least that would help me narrow it down some more. Keep the suggestions coming guys. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 8, 2003 Share Posted August 8, 2003 PROBLEM SOLVED! Or, I'm almost sure it is Went out for another spin in the car, this time I left the TPS disconnected. Wouldn't you know it, I couldn't get it to cough or bog for the life of me, and believe me I tried!! I did a lot of slamming the throttle wide open at very low revs, which would almost always get it to sputter before, but not this time. Also did a lot of WOT runs on full boost, not one hesitation there. The idle is now pegged at 750.. well okay it fluctuates a little one way or the other, but always settles back at around 750, so unplugging the TPS seems to have solved that issue also. The vacuum is now pegged at 20-22hg's at idle, that's really good right? So anyways, I'll be getting another TPS on there. Thing is, I'm still relatively sure it's not the unit, rather it's the connector, after I remembered how the idle would change from just wiggling the wires. So when I put a new one on there I'll probably cut the wires and redo the connector just to be sure. I will say that the engine seems to pull just the slightest bit less strong now that I have it disconnected, maybe just my imagination. So just so I know, what are the disadvantages of running around with my TPS disconnected? It will probably be until Sunday before I get another on there, or maybe I"ll just leave it this way if it's not gonna kill anything this is so funny of a coincidence though... I've always said that odd problems will follow me from one car to another, different cars, same problems. My N/A ZX ran super rich and bogged badly when I first got it, disconnected the TPS on that one, and it ran perfectly after that, even putting 160hp to the ground on a very mildly build up motor with just the typical bolt ons. I'd only ever reconnect it when I had to go get smogged. Tim, I did cap off the BOV and disconnect the vacuum line from it, but I didn't notice any difference from this. So now I guess that's about it... timing is where it's supposed to be, engine pulls hard up to 6k (still that little pause at 4.5k, but barely noticeable unless your'e watchign the tach), idle staying where I put it, the only other problem I know about is the #6 cylinder is still running super rich. This should only be caused by either the injector not working right, or by out of adjustment valve lash, right? I got ahold of my mechanic finally... he's out having a blast in vegas, but he said bring it down on sunday and he'll swap out the 6th injector. The valves dont sound like they're tapping too bad so I'm thinking they're fine. The one thing I worry about... and I know this is maybe grasping straws... but I'm worried that since that #6 running rich will give an overall richer signal to the O2 sensor, it may end up leaning out all 6 injectors to compensate... could this happen? I've been boosting 9-9.5 psi and havent heard or felt one sign of ping. I know I've said this like 100 times already, but thank you everyone for all the tips and for the emotional support this car is now officially *BITCHIN* and has become so much fun I get sad every time I park it... "awwwww just one more time around the block" man are my gas costs gonna skyrocket... switchign from an SU'd engine to an EFI engine... I promised my g/f that it would give me so much better gas mileage... LOL ummmmm sorry... boost eats gas like it's going outta style "sorry hon I didn't know that was gonna happen" Think I'm gonna go for another drive! Z ya! Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 9, 2003 Share Posted August 9, 2003 #@$*!!!!! Okay now the car is just f'ing with me... damn idle again. This car has now thwarted like 20 attempts to get it to idle in the 700-800 range. Every time I adjust it, it will stay where I put it for as long as I drive it, but then when I park it, go start it up again some time later, the idle always finds it's way back up. Now, as far as I can tell all the parts on the intake manifold that are supposed to control idle have been disconnected (dont look at me I didn't do it!). So I dunno how it's doing it, but it keeps getting back up to 850-950. I'm just gonna leave it alone this time, if it wants to idle at 850, whatever, but I'm worried that it will keep rising on it's own. I would think it's just the adjustment screw on the TB moving around, except, you adjust it from the bottom, and screw it in/up to raise the idle, I would think it would shake itself loose/down if anything and keep lowering the idle. I'm thinking of putting a locknut on there but it would be very hard to get to, adjust, and lock. What else should I look for now? Also... and this doesn't worry me too much because I know it will be cheap/easy to replace, but now my fuel pump has just started making this weird ticking noise at idle, about one click every 1/2 second or so. Doesn't do it every time, just sometimes. You guys think it's going bad? If so, I'll see if I can get the mechanic to swap that out on sunday too. Quote Link to comment Share on other sites More sharing options...
Guest GreenZ Posted August 9, 2003 Share Posted August 9, 2003 Just some info for you here: 1 The TPS has three prongs on it, but only two are used, you should have continuity at idle only. 2 I would replace that crank angle sensor with a 82 or 83 distributor. Hookup is identical. The sight on the CAS gets dirty and causes problems. Try cleaning it in the meantime. 3 Get a fuel pressure guage connected to the system, it sounds like fuel starvation to me. 4 The idle is controlled by the computer, without the tps connected the computer does not know to send signals the the solenoid that controls the AAC. With all this working properly the car should idle fine, unless you have an intake leak. I had a bad solenoid, replaced it and the car idles perfectly. Check the system for proper operation. good luck, keep us posted on what you find out. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 9, 2003 Share Posted August 9, 2003 The idle would change even with the TPS connected. Eventually I'll get to reconnecting all this idle and vacuum control stuff. I think I've eliminated all my vacuum leaks. Still is kinda odd to me that the idle would change every tiem I start the car though, even with this stuff disconnected, that should mean the computer is no longer controlling the idle, but there is an idle adjusting screw on the TB, so if I set that to a certain RPM, how does it keep changing? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted August 9, 2003 Share Posted August 9, 2003 well it wasn't the TPS. Last night me and my g/f went to dinner, still driving with the TPS disconnected, and it stumbled really bad twice, with backfires. Once right after I got on the gas after a shift, and once just putting around in a parking lot. Now I just really really hope that this problem is being caused by the #6 cylinder running so rich. I mean it is really really badly rich... Guess I'll find out tommorow. Quote Link to comment Share on other sites More sharing options...
Idnevno Posted August 9, 2003 Share Posted August 9, 2003 check all your connections at your injectors make sure that they are all clean and tight as well. i keep running into the same problem in my 77 280. you can drive it great slowly but when you squah it hard it seems as though the car turns off and on again repeatedly. on mine i found a loose connection at the computer if i wiggled the harness i could get the car to die and run. when mine would hit that wall so to speak i was getting spark but no injector pulse. also check your AFM and pop the cover off and make sure it is clean inside as well as the connector pins are clean and tight. D Quote Link to comment Share on other sites More sharing options...
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