Connor280ZX

With boost, pressure should increase. Go beyond "or something". It's very important. Though unfortunately it doesn't at all. I can't get it past 39-40 under any circumstances. I'm gonna try pinching off the return line.

Stupid_fast, you think it's an electrical issue? I've gone through the FSM procedures last week, reseated the ECU connections, checked all of the sensors, compression check etc. Even with such low fuel pressure, you think it's EMS related? I'm getting 39-40 psi MAX even with the regulator unplugged. FSM calls for 44PSI or something at WOT. With the regulator in I'm getting 32 MAX. Fuel filter and hoses are brand new. It pops and chugs throughout the rev and the throttle range, not nearly as much without the regulator. I'm in El Granada btw.

Alright, so i finally found a pressure gauge that works with this car and here are my results: Idle: 29-30 PSI with FPR plugged in, 40 PSI with FPR unplugged. WOT: 32-33 PST with FPR plugged in, 40 PSI with FPR unplugged. So I'm pretty sure that at this point its the fuel pump unless you think otherwise.

Well that sounds much more suitable. Is there a specific potentiometer I should be looking for? Since i don't need to cut anything, I'd like to try this out.

Ok, I understand that, but what i'm trying to do here is find out exactly what my issue is here. It may be old tired electronics such as the AFM like you said, or maybe it's the fuel pump. I'd rather not hack up my wiring harness until I know for sure what the issue is, but if it comes down to it, i might have to do that. I bought a fuel pressure tester today, only come to find that our rails do not have test fittings. The shop doesnt sell "T"s to put in the fuel hose either... So I guess i have to make some sort of hack job tester with a gauge, hose, and barbs or something.

Yeah, haha might have to come to that. However today i swapped the good CHTS from my good ZX into the ZXT and no change, so at least i've ruled that out.

First off, its a bone stock L28ET paired to a T5. I got this car as is because it's going to donate its engine to my N/A ZX. But, before I do the swap I obviously need to make sure the engine is running in top shape... which it isn't. When i first got it (9 days ago), the engine idled fine, this the exception of it randomly dropping a cylinder if iIlet it idle for a long time, and it sounded like fuel starvation. Taking it on the road, with more than 15-20% throttle applied it would stumble, sneeze, and front fire very harshly. If i was able to get it into boost, it would smooth out and pull better. Same thing when i'd try to free rev it, Popping and stumbling and the engine would rev up very slowly. It would sometimes start right up, and other times would need to crank for an extra 2-3 seconds before it stumbled up to idle when cold. Warm starts are better. First thing I checked was the ignition system. Cap and rotor are new, as well as plugs and wires. Plugs looked clean. Then I started testing sensors. (6 days ago) First being the CHTS. I could unplug it and the car would run better, but brutally rich (Black smoke, even at idle). It would rev up decently (Still a bit of a stumble) and pull a bit harder, then the engine would fall on its face at 4500 RPM, no backfiring, just wouldn't accelerate further, so I plugged it back in and it went running the same way it intially was of course. So at this point I was thinking a fuel issue and started testing other components. Fuel pump seems to be quieter than my N/A's, but seems to work fine. I tried replacing the fuel filter, and no change. (3 days ago)Then, i unplugged the vac line to the FPR and the car seemed to run way smoother. When cold, the car fires up right away. Under throttle, acceleration is smooth, but the turbo lags, and it just seems to be really low on power. Doesn't backfire, or stumble, but still hesitates and revs up rather slowly in neutral. I know some of the veterans on here will probably slam me for not performing resistance and fuel pressure tests (YET) but It's a holiday weekend and my local auto parts store has been closed, therefore i haven't been able to purchase any testing equipment for the electronics or fuel system. So i'd like to gather some ideas here in the meantime since I can't do anything about the car but gather information. Google hasn't done me much justice so far...

At the time I had about a quarter of a tank. There was a very noticeable cloud of black smoke in my rear view mirror when I revved it.

Yeah, i've acctually swapped back to stock a few days ago just in fear that the way it was tuned and the unknown factor of the functionality of the vacuum systems would be harming my engine, it did ping a bit after all. When i looked at the stock TB's butterfly, there were three ports positioned slightly apart, and closer/further to the rotating shaft of the butterfly, so I'd say you're right about each valve getting certain vacuum at different throttle. The black smoke was maybe caused by the timing being so retarded (To compensate for no EGR), though it did look like gas dripping from the purge line when I took it off, now that i think about it more, i'm not 100% sure it was gas, maybe just a bunch of condensation. I had the TVV bypassed, and was running everything off of one splitter, instead of 3-4 splitters if I used the TVV.

Yes, canister purge line is what I meant, my bad. This section in the FSM is mainly what I've been going off of.

Bump

Yes, I have the strong need to do 120+ regularly BUT good news, took it to yet a different shop a few days ago, and they claimed my front left was "missing a weight" they re balanced all the wheels, and now it rides smooth as glass... Amazing. Definately not taking my car back to the other places if they couldn't spot a missing weight.

So I recently installed an MSA TB. I'm having some issues with the EGR and possibly the vapor valve working. As far as i know the vac advance is working Main reason is probably being that the stock TB has three ports, for the Vac advance, EGR, and vapor valve, and the MSA one has only one. So what i did to try and conteract this issue was to bypass the TVV, and run most of the lines off of a splitter. I had made one soft mount port in the aftermarket boot that i used with the MSA tb like the stock boot. I ran the Vapor line there first. However, i noticed that if i gave the engine any more than 10% throttle, i would get FULL EGR causing the engine to run like crap unless i stepped on it. I knew this because i felt the valve retract completely into the housing. It wouldn't release immediatley when i let my foot off either, causing a near-stall. I switched the EGR with the Vapor line, and now i get what appears to be no EGR, becuase i guess there wasnt enough vacuum from the boot. And i need EGR because i'm running a cat (Cali laws), and it will ping unless i have the timing at 5BTDC or lower, which rapes my top end power. I think now that the vapor line is hooked up to the splitter from the TB, it's getting too much vacuum and sucking in fuel, causing black smoke (Line was also dripping when i removed it). So, what can/should I do about this?

Alright guys, so I've done some further testing, and found some additional things to mention. So, Once I start accelerating past 80MPH, the wheel wobble fades, but simultaneously, the car starts to develop a shake/vibration that gets worse until about 120MPH, then starts to fade away and becomes smooth again. I feel it mostly in the footwell. This can be mainly felt up slopes, not as much going downward... Now that i think of it, it occasionally did this with my old set of wheels/tires too. So at this point i think we've ruled out tire/wheel balance...

Interesting. All four are set to 32 psi cold. They are 215/55/r16

Oh yeah, thanks for bringing that up. Once I burned my rears off a bit, I swapped them with the front and the only difference was it stopped pulling to the right. Same steering wheel wobble at the same speeds.

Yes, 3 rotations and alignments done in the past 18,000 miles, and all of the front end bushings have been replaced.

All wheel bearings have been checked, all of the drivetrain mounts have been replaced and tightened. The hubs, I haven't checked that's a new idea, not sure how to check them however.

Oh right, yeah I've had 3 alignments done in the past 18,000 Miles. Most recent one being about 6-7K ago. Never wrecked.

Nearly two years later, new ball joints, rack bushings, sway bar bushings, tension rod bushings (rubber, not poly), new springs/struts, a new set of tires and wheels and i'm still getting the same wobble in the steering. Starts around 50-55 MPH, starts to fade away around 70-75MPH, and is not felt during cornering at these speeds. Jacked car up, checked wheels for play/possible bearing failure. All solid. I'm pretty confused, and it seems like the only things left to replace are the brake rotor and tie rods. Is there anything i'm missing?

Ok, so I opened up the dizzy, and figured out how to manipulate the advance with a screwdriver, and the green wire to the ICM was moving very slightly. I re crimped it, plugged the advance back in, and now the car runs fine again, no more weird lurching/cutting or tach jumping. I still don't know what the max advance is (Before it was 56* total), because I don't have a digital timing light like my mechanic does.

Hmmm, that's interesting. Another thing to mention was during testing the car was getting 56* total advance... It's supposed to be 40* IIRC. The car is in the shop getting rust repaired until thursday, so i'm trying to gather as much info as a can to be ready to work on this when i pick the car up.

It all started when i was getting random ignition cuts while driving. Not something you'd normally expect out of a "cut". For a split second, it would appear as though my ignition system lost power or something, but then continue running. Sometimes at low speeds the car would lurch HARD when this would happen. The tac needle would also flicker/drop when this occurred. I could make this occur purposely by slowly pumping the throttle while driving the car. Dizzy is a rebuilt unit from A1Cardone which i installed 13,500 miles ago or so. The expiriments began. Drove the car with no TPS; Besides the lack of power, car acted the same, so i plugged it back in. Then, I unplugged the vacuum advance and what do ya know... The car started running perfectly. No more cutting, and the tach doesn't flicker/drop, though i am getting worse MPG now. (Been driving the car like this for 500 miles or so). I'm not to sound oblivious, but does this mean my vac advance is bad? I talked to my mechanic after i did this and said that it could be the advance weights, or pickup coil. but i'm not sure.

On this KA TB, however, that idle air bypass hose that connects under the stock TB is no more, so i will be controlling my idle the old school way by using the butterfly adjustment screw. The BCDD will also be deleted (Tested mine, not working). Will talk to a machine shop about making a spacer that utilizes the fitting off of the old TB to the air regulator. Will also need to make a custom TB to AFM boot (developing blueprints with mechanic). I will make a full writeup on this for the purist, or CA owner who still needs to utilize most of the stock hoses and units. Your advice is appreciated, feel free to give me any further feedback. P.S: Contacted the owner of graytech, he is no longer in buisiness.

Seems like a resonable idea, how ever with this upgrade i am still trying to make the engine look as stock as possible for inspection reasons (Though it wont be at all). Main reason why I want a ported spacer, to enable me to use the stock EMS systems such as the air regulator, which is factory. Also going to be making a custom throttle to AFM boot hat utilizes the airy bypass, vac advance, and PCV line, so it looks stock.