L28ET swap 240z runs rough won't take throttle

[motomanmike]

Yeah I think i need to replace alot of the factory stuff and it will probably work out. I'm going to buy a new TPS, replace all the connectors I can source. Get the factory portion of the fuel pump relay of my stock harness working with the stock relay installed. Get a really good base of stock parts, probably put a new stock fuel regulator on replace the spark plugs again and see what happens. I can solder very well i've fixed alot of wiring and gauge pods at work over the years I work at a alternator starter shop, I can make anything crank over or charge a battery but this mess is driving me crazy LOL.

[NewZed]

Is it running rich again or is it a new problem? "crap" covers a lot of ground. It's usually best to check your circuits at the ECU connector, then you'll know that the connections, the component, and the wiring is all good, from and to the ECU.

[motomanmike]

I'm going to do some more continuity testing and report back. I know "crap" doesn't tell anyone anything and apologize, i think that post was more venting than anything. I pulled the plugs, they are not soaked anymore but are pretty dirty. Running rich still so i'll replace them or clean them really well. I've got good fire. Its all in the fuel delivery and i'm wondering whether I have a good supply or not. My gauge will shoot up, needle will sit flat at 38, then slowly slowly it will dip low down in the 25 range for fuel pressure. Walbro pump, not sure if its bad or what. Its a 7amp draw on the battery and voltage drops fairly quickly but not down into the 12.2 range or anything they just seem really finicky to charge voltage and where the car won't run on its own its really hard to set this fuel pressure I guess because the voltage isn't consistant enough it seems. I checked every vacuum line and they are all hooked up. I need to double check whether or not the vacuum solenoid vacuum lines are in the right configuration but i'm not really sure that will matter too much as my problem is more crippling than I think that would be. Car struggles to start now, when it does it putters a few times and dies. Sometimes it tries to diesel a little. While it ran pretty good the first heat cycle I had checked my timing and it was at 20 on the lower mark which from what i've read is acceptable for the turbo. I never adjusted any timing and never toyed with it since the car did run ok, I idled it over to the school across my street to try to test the day it started and ran ok but it never was driveable at all so I went to try and fix that and this is where i've ended up.The ECU pins look very very clean with a magnifying glass, and the actual ECU pins "male" are shiny no corrosion. Could this ECU be bad? Are they something that usually just works or doesn't or do portions of its functinality go bad?

[S30Mark]

I'm going to do some more continuity testing and report back. I know "crap" doesn't tell anyone anything and apologize, i think that post was more venting than anything. I pulled the plugs, they are not soaked anymore but are pretty dirty. Running rich still so i'll replace them or clean them really well. I've got good fire. Its all in the fuel delivery and i'm wondering whether I have a good supply or not. My gauge will shoot up, needle will sit flat at 38, then slowly slowly it will dip low down in the 25 range for fuel pressure. Walbro pump, not sure if its bad or what. Its a 7amp draw on the battery and voltage drops fairly quickly but not down into the 12.2 range or anything they just seem really finicky to charge voltage and where the car won't run on its own its really hard to set this fuel pressure I guess because the voltage isn't consistant enough it seems. I checked every vacuum line and they are all hooked up. I need to double check whether or not the vacuum solenoid vacuum lines are in the right configuration but i'm not really sure that will matter too much as my problem is more crippling than I think that would be. Car struggles to start now, when it does it putters a few times and dies. Sometimes it tries to diesel a little. While it ran pretty good the first heat cycle I had checked my timing and it was at 20 on the lower mark which from what i've read is acceptable for the turbo. I never adjusted any timing and never toyed with it since the car did run ok, I idled it over to the school across my street to try to test the day it started and ran ok but it never was driveable at all so I went to try and fix that and this is where i've ended up.The ECU pins look very very clean with a magnifying glass, and the actual ECU pins "male" are shiny no corrosion. Could this ECU be bad? Are they something that usually just works or doesn't or do portions of its functinality go bad?

 

I hope this helps at least a little bit. When I bought my 83 ZXT it would turn over and fire up and run for maaaaybe ten seconds. After that it wouldn't restart. I found that the ECU wasn't providing ground for the injectors. I went straight for the Z31 ECU/MAF swap as originally planned.

 

After the Z31 ECU/MAF swap I had a lot of trouble getting the thing to run. I'd say study all your wiring diagrams and DOUBLE CHECK to make sure everything is getting the proper power and/or ground signal. My problem was that since my ZX is just a donor, I rushed through everything just to see if it would run and make sure my L28 was good internally. The reason I'm posting here is because I feel like I was in your shoes. I was at wits end, and I wanted to say eff it and get MS. I gave it one last thorough lookover. I cleaned spark plugs, charged the battery, double checked all my wiring, made sure I had fresh gas in it, checked/cleaned/die-electric greased all my important connections and it fired right up.

 

I feel like these cars are more sensitive to voltage drops than a sensor that may be reading slightly out of spec. I also feel like the connectors suck, so make sure they're all good and maybe even give them a wiggle.

 

Last but not least, have you pulled the rail out with the injectors still attached to see if they're spraying ok and make sure they aren't leaking? One or more could just be massively leaking into the cylinders at all times causing a rich condition, eventually fouling the plugs. Pull the rail, Key on engine off will put pressure to the injectors for you to check for leaks.

[motomanmike]

I'm spending the day checking, I went out there this morning and got the car to start and it will idle, although it idles rough it will idle. Pluggin in the CHTS mades it load up and die, unplugging it at the moment is the only way the car will run. I finally found the right batteries for my multi meter so i'm going to check all the pins for the injectors, i've got about 10 pages of the FSM of stuff I need to check, there are a bunch of pins on the ECU plug it says to check for grounds on and I am suspicious of those, does the ECU where it mounts need to be solid to the body so the case of the ecu is grounded? I've ordered a kit off ebay with all the injector plugs and the plug for the AFM, air regulator, throttle position senstor etc with the pigtails, like $70 but probalby worth it this harness is 20 years old. I am going to replace them all because many of mine are very brittle, they connect ok and the clips go on them but they just are shady to me especially with the problem i'm having. I'm wondering though, I dont have a relay for the fuel pump in my harness. I have the plug for the relay, which i've fabbed up some jumper wires in with spade connectors, I had to do this to get the injectors to fire and while the car is running if I put my scope on each injector I hear the distinct click click click so i'm pretty certain they are firing, i'd almost rather take a punch to the face than pull that rail again. I replaced all the injectors before starting the car and wiring it up with new ones, they are brown plugs, appear to be the right injectors. FJ23 I think was the PN I bought. Its frustrating, i've got 2 240z's and thought man I want a turbo Z, now i'm looking at that carbed L28 sitting in my shop floor saying man, why in the hell did I pull that thing out it ran great!! At least my other L24 powered Z fires right up and runs strong or i'd be going into withdrawl. I appreciate the pep talk, I need it. I'll keep plugging away. Fuel pressure is ok, I verified this morning it wasn't fluctuating, maybe a little too much liquid intake last night in the shop Thanks for the pep talk, I needed to hear that it will probalby work out and i'm not the only one who's almost thrown in the towel.

Edited September 2, 2012 by motomanmike

[NewZed]

I finally found the right batteries for my multi meter

 

i've got about 10 pages of the FSM of stuff I need to check,

 

So all of your other "checking" was just of the eyeball variety? It almost always comes around to breaking out the meter and the FSM and taking some measurements.

 

When I said check at the connector to the ECU, I meant take measurements at the connector, with your meter. You can check resistance on your CHTS, the injectors, the TPS, etc. at the ECU to see what the ECU sees, which is what matters. It's actually easier than trying to disconnect each component and check individually.

 

Your new fuel pressure gauge will give you a good idea of if your injectors are not leaking. How long does the rail hold pressure? If it holds overnight, they're probably not leaking. If pressure doesn't hold though, it could be your new FPR or the pump. It will only tell you that you don't have a leak, not where a leak is.

 

Good luck.

Edited September 2, 2012 by NewZed

[motomanmike]

None of my checking has been of the eyeball variety there is no way it would have gotten this far i wouldn't think unless you've done about 5 swaps or so. I have two meters and one I like a little better its alot more sensitive. I probed all the stuff I could on the ECU pins before it started lightning thunderstorm really bad and I came inside. Heres what I got. Control unit circuits, 28-36 107 108 109 112 113 all have ground. On the air regulator circuit, Pin 108 has between 34 and 37 ohms resistance. Seems to check out. TPS at the ECU does not check out. At the tps itself it does. On the power circuit pin 108 is supposed to have 12v when cranking and it does. IT says in the FSM to make sure you listen for an operating fuel pump well I'm not using the stock relay so i don't know what that tells me my fuel pump runs when I turn the key to acc since I have it on a separate relay. The relay they say to check continuity on certain pins, well the plug for the relay mine would have only has 4 wires and the fsm relay has 5 pins, so something doesn't jive there and could be part of my problem with my ecu sending the right signals. Maybe wrong fsm not sure but everything else I check with this FSM has worked so far. On the EFI plug, pins 101-106 all have 12v with key on. There are two portions of my stock harness that are probably causing my issue and I need some info on them. The one is for the fuel pump relay, I have jumpers in it so the injectors would fire. wires coming in are black/white, black/white, solid black, and brown. I have the black/white two wires jumped together, I had a pig tail before with 3 of them connected, the two black/white, and brown, with a ground jumper to a body ground, no change in the way it responds. Curious what this might tell someone, I've still got to test the tps circuit resistance and the afm. Most all i checked at the pins at the ecu seems ok, but still a few things to sort out that relay worries me not being in there. There is a plug near the fi relay with all pins but one in it, pretty sure its 10 pins, is this the portion of the harness that would control your fuel pump if you had that wired in? I'd like to get everything to the portion where I could feed my pump with the 5 second prime and then on when running. I'm not sure whether the way I have it wired up is affecting how the ecu is responding to fuel its just a thought of mine. The "EFI relay" test, it says to test pin 35 for battery voltage and it has 12.6v. start signal tests ist says to check pin 9 on the 20 pin connector and it has 12.6v. Why in the fsm does it tell you to test specific injector cylinder numbers if they are batch fire? My guess it to isolate a single cylinder misfire issue? The car will start and run. I drove it back over to the school with my allen wrench playing with the fuel pressure and it had no affect on how it ran. It is still loading up. As soon as I try to mash throttle it loads up and I have to back off, if I give it gradually it will rev slowly sputtering most the time followed by a big back fire and then it will rev more and spool up some but no where near to the level of responsiveness it should and then sputters because its had enough, under load it loads up and wants to choke out. Its all in this fuel delivery. I wanted to check so I did remove the rail, and all the injectors, none are leaking fuel with the pump on and will spit fuel when you crank it kinda crazy i've never done that before. At least everything was new so it came off fairly simple. The new FPR will leak down its china junk i'm sure. While the pump is on it stays steady but you can hear it hissing and the needle will slowly creep down after you turn the pump off. Now i smell like gas and i'm done for the day. Im going to wait until these connectors get here. I noticed eventhough I cleaned the pins on the TPS sensor, looking at the bottom of the plug where the pins slide into the molded plastic they are green, so i know the inside of the wire is green and can't be contacting very well eventhough the pins are shiny. With the car idleing unplugging the TPS plug it slowly loads up and dies, but that doesn't mean its working right when it is plugged in either. On the bright side, I did get to drive it, not very fast I didn't get out of first gear but it steers a whole world better than it did before I swapped my suspension. No matter how well it idles, if I plug my CHTS sensor in it loads up and dies. I couldn't find the portion in my fsm to test i have to make sure i printed that page. With it out the car will start and idle, hard to start, not a very steady idle, but pluggin that sensor in it will load up and shut off, and will not restart with it plugged in. Until I get fuel solid, I can't really do a whole lot, I will replace these connectors when they get here and go from there.

Edited September 2, 2012 by motomanmike

[motomanmike]

 

Here is a link of what the car consists of. My temporary wiring for my fuel pump is a nice piece of new dual strand silverized trailer wiring. I will have it plumbed through the cabin once i get everything sorted out but i have it hooked direct to battery when this video was taken. The car runs pretty good at idle although it runs high but this really shows me many things. The timing is close, i checked it with the light after i took this video. The firing order is correct. The thing will run ok if I get the fuel sorted out, no ticks no real odd noises so i know my block pistons, head etc are all ok. The big filter you see is temporary, I want to mount it lower, its off a pathfinder or something, same 5/16 size as the rail. I ordered the EV1 connectors, AFM etc etc the kits the guy on here was selling and is now selling them assembled on ebay. I've got a new stock regulator on the way and a new adjustable one that cost me over $130. I'll try the stock one with a gauge inline and if the pressure isn't steady i'll put on this aeromotive one thats coming. I hope that clears up most of my issues because I havn't skimped anywhere else on the fuel system. Walbro pump, new lines, all new AN fittings. Nice russel -8AN filter in the back before the pump and filter before the injectors. We shall see. I'm getting suspect of the old Jpipe fitting near the manifold but I would think you would hear it and if I spray ether near the seal there is no change in idle so i think its sealing pretty well. I have jb welded any of the fittings you see sticking off teh manifold as they were huge vacuum leaks at first. The one T seen is running to the fpr. i think the others were for the AC and who knows but this is where i'm at right now, runs like this, throttle it and it blaaahhhh it dies or sputters really really bad.

Edited September 3, 2012 by motomanmike

[NewZed]

if I plug my CHTS sensor in it loads up and dies.

 

With the CHTS unplugged, infinite resistance on the circuit, the ECU calculates the lowest possible temperature and adds fuel. Super-rich. Plugging it in should make the mixture lean. So it's probably not "loading up" with extra fuel, it's probably leaning out. You might have a giant vacuum leak somewhere. Don't forget that the PCV system is connected to the intake manifold so any PCV system leaks are also intake vacuum leaks.

[motomanmike]

I have another manifold and gaskets. Its the non egr type and very clean. Is it beneficial to do away with all the air regulator and egr equipment or should I get a good base first with what I have? I will change the pcv valve and make sure the hose is decent for good measure they are cheap enough. It looked ok when the engine was on the cradle but looks aren't everything. I appreciate you guys taking a look I really want to get this thing driving it sounds so cool!! That whistle is intoxicating!!

Edited September 3, 2012 by motomanmike

[motomanmike]

NewZed, I thought alot about your post and it makes alot of sense. The way this thing is acting is very similar to my other Z when the fuel tank had rusted up and was starving. Would idle great but as soon as a load was applied it died. My fuel tank in this car is very clean and i'm getting a good supply, it just doesn't seem to be feeding it the supply it should. I won't have any news until next week but again thanks for looking I appreciate your time. I've read alot of posts you've offered suggestions and helped people out, I really appreciate the thoughts.

[JSM]

Something is not right with your CHTS if once warmed up it doesn't tell the computer to quit running rich. It has its own connection to the harness from the sensor to the main harness maybe a foot long. My connectors were corroded and solved the problem.

 

You said your base pressure is 38 lbs? That seems high to me at idle. What is it at 3K?

 

For simpilicty, take a stock Zx fuel pump and hook it directly to a fuel injection line with the source being a gas can. Run the return to the same gas can. This way you can see if your having any tank / fuel line issues and also easily check the function of the FPR.

Edited September 6, 2012 by JSM

[HowlerMonkey]

Maybe he has fuel pooled in the intake manifold.

 

I've seen a L28 run for 5 minutes with the fuel pump electrical connector unplugged at the dealership.

[motomanmike]

Megasquirt it is folks. I'm done messing, I edited the long post and accidentally deleted everything so my luck is just going that way i guess.

Edited September 8, 2012 by motomanmike

[NewZed]

Megasquirt might be better, but I'm not sure it's easier. Seems like you might be overlooking something important that seems insignificant. You're not really reporting details, just general descriptions of what's going on, plus even your detailed stuff isn't quite right. Like fuel pressure - it's very easy to find out from the FSM or hundreds of posts on the forums, that fuel pressure should be 36.3 psi. But you have set yours to 31 psi for some reason. You said that all of your measurements are "in range" but don't tell what they are. And "runs terrible" means different things to different people. Watch what is happening while it runs then dies, does the fuel pressure drop? With fuel injection, it's all about the numbers.

 

Even with Megasquirt you'll have to be methodical,take good measurements and take notes. If you can't get the stock ECU to work, Megasquirt's probably not a solution.

 

Here's a thought - is the gas in the tank new or old? I've spent a lot of time on various engines of different machines (lawnmowers, chippers...) only to find that the gas was over a year old and no good anymore. Changed gas, everything back to normal.

 

Hate to see a give-up. At least get that thing to idle right.

[motomanmike]

I'll get it sometime, you don't know me too well Thanks for the input again Newzed, You've been plugging away trying to help me.

Edited September 8, 2012 by motomanmike

[motomanmike]

Ok, Got spark back, car will start and idle, same running issue. Tested a whole lot, bought another tester from the snap on today when I went out jees they are really proud of it too, new batteries for the tester, like this one alot. Air temp sensor test in FSM= 1.99 ohms at 76 degress outside, same at unit, same at ecu plug. Lower than spec but really close. Insulation resistance OK at AFM too. Air flow meter test. pin 33 and 36. has .202k ohm? Measuring pins 33 and 26 at the AFM 2.02ohm ? pretty sure thats not a good thing. Test 2 on AFM, partially open, .255k ohm at about half open. AT pins 33 and 31 at the ecu plug I get 145.00 ohm. If this is the actual AFM pin configuration - - - - On the left, to the second from left I get .257, third from left to far left I get .257, far right and far left I get 2.02 ohms. Its probably a dud. Throttle valve switch IS A OK on all tests I won't elaborate it matches the FSM to a T continuty when closed, no continuity when pedal is depressed, beeps when you let off the pedal.

 

CHTS sensor tests. Ohm meter to pin 23 on ecu plug and body ground my meter reads 0 and blinks. If I put my meter on the pins of the CHTS sensor at the motor, negative of my tester on right, pos on left, I get 1.434 k ohms. Heat it up with a heat gun I get 1.109 k ohms. The motor was warmer than the outside air temp because it did run earlier but was not hot to the touch, just warm, could hold your hand on it all over. This all baffles me, the pin configuration in the FSM shows only one wire missing on the 16 pin connector and mine is missing 2. All the wire pin numbers it says to test in the FSM exist however so i'm not sure if that is relavant. I havn't probed enough to see if I can get a reading oh the CHTS that matches what it does when I touch the 2 pins of the CHTS and i'm not sure if you do? Strange to me it runs different when it is plugged in so it is doing something and has to be signaling to the ECU somehow but I can't get any readings on that pin when I test. So I've got real problems that are evident in my mind, I've either got a wiring issue which is I take the plug of the CHTS, run a stripped jumper wire into it, and the other end to ground, then probe the pins 24 and 23 on the ecu plug with one ond of the meter and the other to ground i've got continuity beep just fine so i'm fairly certain the harness is good and allow flow of current throughout. Odd, I will buy a new one and retest after installed.

 

Tested resistance on the pins of the injectors just to make sure they were right and they are 2.8 ohms at the injector pins itself.

 

Between making an aluminum bracket, wiring the HEI and testing I've messed with it enough today and some thinking to do.

 

Let me hear it guys :/

[NewZed]

The CHTS thing might just be distracting you from and AFM or AFM harness problems. 33-26 and 33-31 are the two sides of the potentiometer that tell the ECU how much air is entering the injection so that it can adjust fuel. Your one measured number is way off. 33-26 should be 280-400 ohms, 33-31 should be anything but zero or infinite. According to the FSM.

 

You got 33-26 = 2.06, should be 280-400.

33-36 - typo? that's not an AFM measurement.

 

Does it pop and backfire through the intake with the CHTS connected if you try to rev it or drive it? That would be lean, and a common sign of a bad AFM.

[motomanmike]

Those are the exact numbers no typos. So the AFM probably is bad and I measured everything exact 2-3 times each before making notes.

 

It does pop and backfire slightly. I am in the process of posting a vid to youtube i'll post the link up in a bit. I run the motor awhile with all sensors connected and then unplug the CHTS and it runs a little better. Probably is the AFM.

Edited September 8, 2012 by motomanmike

[NewZed]

If you were measuring at the ECU connector, then the next step is to measure directly at the AFM. The pin numbers are probably molded right in to the plastic at the connection point onthe AFM, unless they changed things from the 70s Z cars. Take the AFM out and measure directly.