max_wagon_bk

so i've been very frustrated with my 87 maxima wagon recently. i'll start by saying i'm not the most knowledgable guy when it comes to cars, but I like to try and fix things myself before seeing a mechanic (I know, dangerous attitude)

its been running real rough and misfiring for the past week or so. only in drive when sitting still at a light. first thought was to change the spark plugs. did everything right according to the manual, yet it didn't improve my situation at all. then changed the fuel filter, still no better or worse.

those were the two things i considered easy enough for me to try and fix myself. now I notice a clicking sound coming from this thing -

it sounds like electricity leaping or something. like when you start a gas stove. every time the click happens, it drops the idle low for a second then picks back up. my friend disagrees that its electrical and says its a vacuum leak. i dont think i threw the timing off, as it would be misfiring in park and neutral as well then right? any ideas?

lowpost99

I have a very similar issue as well. Doesn't do it 100% of the time, but I can't find a pattern. I think I notice it more when the engine temp reaches warm from cold starts, vs not so much when its already been driven and is semi-warm to hot say after a 20 min stop. Only happens in drive, only noticeable at stops and during pulling off from stops. It's not noticable after about 10mph.

The acceleration curve or lack of any exist until I hit about 45mph, and then is suddenly ok. Like at the drive through wash when that thing at the beginning grabs and begins to pull your car through the wash "sudden power" from the throttle.

I cleaned the MAF, checked my vacuum lines(only 70% certain about these) I don't have a diagram. Doesn't feel like a misfire, not continuous, someone told me that vacuum lines may open or close due to stress at different speeds or vs. sitting at idle. Basically the hole or cracked line may only lose air until it gets to a higher speed or the opposite when it sits still.

max_wagon_bk

ah yeah, i forgot to mention the issue doesnt start until the car warms up for a while. which i hear is indicative of vacuum issues?

vernk

I would replace all vacum lines, easy to do, just take your time and do on at a time, be sure all plug wires are down all the way (posible cause of spark noise) and make sure your idle is set right, be sure all grounds are good and all plugs are clean and pluged in....

vernk

Max just looked at the pix, yea you have a crack in vacuum line on your FPR, the plug your pointing at doesn't do anything but does look like the boot on the plug wire is sitting up a bit....

max_wagon_bk

you can see the crack in the pic? i followed all the lines out of the FPR and dont see anything.... I also dont have the best eyes.

the plug boot was stuck on really badly when i first changed the plugs so the rubber kinda just slid up higher from all the tugging. my first assumption was that i messed up the wiring for that plug but if the problem only happens in drive and after the engine warms up, it must be a vacuum thing right?

vernk

yea it's cracked where it pushes on right on the end and looks like it should be push on more, but it's best just to change all of them on engines of these ages, it's cheep easy to do and saves a lot of time trying to run down issues. You want to make sure the spark plug wire boot is slid all the way down since it's not that far of a jump from the plug to the head. A couple things happen when shes all warmed up 1. rpm drops, with that the voltage drops, keep a close eye on your voltage gauge sometime which will cause a weaker spark and eletricity takes the path of least resistance so if the air fuel mix is harder for the spark to jump on the plug it will jump to the head, one way to check that is look at it at night if you haven't push the boot down yet....... 2. the ECU goes to open loop in which it takes feed back from the O2 sensor and other sensors instead of just running the preset injection pulse, which is also tied in with fuel pressure so if your FPR isn't getting the vacuum that the ECU thinks it is then it will mess with A/F in which case it will know though the O2 sensor and try to fix it.....

but yea I would say your first step is pick up a bunch of vacuum line and replace all of them (don't remember how much it takes but somewhere close to like 10 feet), make sure all plug wires are on all the way, and the boot is where it should be, if the wire has slid up or down a little eletrical grease with help the wire slid though the boot and onto the plug, what I do is push the wire so the end is just inside the boot, push onto spark plug and make sure you hear/feel it click on, then slide boot down. If you beat on the wires to get them off and haven't replaced them in a bit might not be a bad idea to get new ones. other then that make sure your idle is set right, if it is set to low it will run rough..... another random thing to check is make sure your valve cover screws are tight since it could suck air if they are not sealed well....

CMax03

iTrader: (3)

Check your EGR valve for leaks as well!

max_wagon_bk

you guys are genius. thank you. after further inspecting the spark plug wires i notice one looked a little funky. It was almost definitely the issue because i patched it up with some electrical tape and the engine misfires about 10% as often. new wires are in the mail. if it weren't for you guys advice i would have spent forever searching through vacuum lines and sensors and whatnot

CMax03

iTrader: (3)

Should've wet your hands, closed your eyes and felt around you would've found that one rather quickly! LOL....Glad you know what it is....

lowpost99

Hadn't seen this before...Also having trouble getting the correct size vacuum tubing anybody know?

maximase86

iTrader: (24)

FPR = fuel pressure regulator. It's the device the return line is hooked too on the fuel rail.

vernk

5/16 OD vacuum line most parts stores should have it.

lowpost99

Hey Vernk, I replaced all the vacuum lines I could find using about 13.5 feet of 5/32 tubing. At the carbon canister, I even replaced the larger line with 7/32 tubing. I didn't replace the 4 inch line at the canister that appears to go right back into it. That "first stage" got really better and the second stage after warm up wasn't' so bad either. Still got some significant rumble, so I want to follow the remaining checks but need some help.

Will check the valve covers ASAP!

How do you check the FPR for proper operation?


I could use some help I think with re-checking the EGR as well. I've tried the diaphragm check before, think it was good, but no expert here. (The thing is 26 years old) and if not so very expensive I'd would have just replaced it already. I couldn't quite understand how to check it electrically with my multi meter. I don't know where to touch the +/- probes for continuity.

Also read in another thread that I should check the entire intake for debris or other clogs. I've never taken this apart on a car, but I believe I just need to start unbolting the airbox, and then work my way back towards the throttle body right?

vernk

FPR will take a guage and hooking it into fuel line...... for your egr if the diaphragm is working the only thing other then that is it getting plugged up in which case you will have to take it off and clean the tubes out, if your going to do that, be sure when you put it back together to start all the threading on all parts before tighting them down or you will end up fighting with it forever.....

best is to check the ECU for codes, then go from there

for the intake yea, start by pulling the air filter check the screen that is right under the air filter, you should be able to pull the rubber piping off with out unbolting the parts that are mounted. be sure to check the rubber piping for cracks.....

have you cleaned or replaced the cap and rotor? other then that make sure spark plugs are good. Be careful dealing with spark plugs be sure to make sure there isn't dirt or other debris that will fall into engine when you pull the plug out.

one other thing that could be a issue is the headtemp sensor, it's the two wire plug that comes off the head right under the distribitor, when you check for codes on the ecu it will say if that is a issue, I can tell you how to change that with out having to take the timing belt covers off, it's a pain. It might be one of those things you could just replace if you are going to be digging deep enough to replace the cam seals.....

have you replaced the fuel filter lately?

CMax03

iTrader: (3)

What's your drive idle rpm when standing on the brake as well as your park idle rpm?

lowpost99

At normal op temp, the needle is at 1000 rim in P, and 500-750 in D, with foot on brake. Gonna try to remove and clean the EGG today. I'll start the threads by hand when putting it back on... I read about the checking spark plugs wires and will check out the far as well. If I wanna replace The FPR is there part brand you recommend or is local part auto brand ok?

vernk

have you checked the ECU for codes yet?

lowpost99

Ok I've got the 5 mode ECU. And some direction that is leaves a bit to be desired:

Here's what I get in each mode with the key in the ON POSITION:
MODE 1) Exhaust Gas Monitor Result R+G SOLID
MODE 2) Mixture Ratio Feedback Monitor Result G SOLID
MODE 3) Self-Diag Result 55
MODE 4) Switch Check Result Red came one and went out when I cranked the car. Green did not come on
MODE 5) Test Mode Nothing came on in this mode in either the on or run position. What am I doing wrong in mode 5?

Is Mode 1 a problem? My explanations only indicate open and closed loop as no green or a blinking green. It says RED+CHECK ENGINE LIGHT is a MALFUNCTION, but I don't have a check engine light on the dash...that I know of...

I cleaned the ERG Valve out, also pulled a 5-6 in. ported metal piping out of the manifold that also had a metal gasket seal built onto it. It did not appear to have gasket seal on it before, so I did not put any on here during the re-install. The ported side was re-inserted facing away from the motor and facing the throttle body. Was this position upside down? My first drive following the clean and replace was kinda of rotten eggy smelling... and then went away after about 15 min or so.

RPMs are now right around 1100 in P, and standing on the brakes, I'm still between 750-500 rpms, but less frequent bouncing between the two. Now sitting at about 750RPM for about 45 seconds and then at 500 for quite some more time like 90 seconds and then I lope suddenly once about every minute or so.

vernk

the tube in the intake is to get the gasses to the middle of the intake from the EGR, it should be facing the back of the intake, that way incoming air doesn't try and go into the exhust while the EGR is open. I think there should be a gasket on both sides of the flange of the tube, one sealing it to the intake one sealing it to the EGR.
The rotten egg smell is a sign of a bad cat.

do you have a FSM or what did you go by to run the self diag?

lowpost99

No FSM, only Haynes. I tried to use http://www.troublecodes.net/Nissan/pre88nssn/ when working on the ecu. So those holes in the tube need to face to the right and not the left? I installed left. Damn. Ok new game plan. Rough day atwork and I came home and took it out on the car.... So this time, I removed airfilterbox, MAF, AIV, related vacumn hoses, unclipped electrical connectors, and now I can see the bottom bolt on the EGR flow tube. I'm gonna hit it hit with liquid wrench, each hour tonite, and try to remove for 100% cleaning of the egr and down tube, flip my intake insert tube back over. Let me know if you think trying to remove it is risky? I honestly am gonna wait to hear from you guys first...

lowpost99

Ok I've re-installed the EGR port tube insert with the "portholes" facing away from the intake towards the right side of the car. I'm re-installing everything after I deal with the EGR down pipe. The nut began to round with the adjustable wrench, so I think I am going to give one more shot with a pipe wrench. If still no go then I'll leave it and re-install the air-box and piping, I have found and 89' ECU for my 88' max and want to give it a try, but I need a 300zx MAF from between 85-89 right? I know the ECU was specific to engine type, what about the MAF? Does it also have to be same year, trans and emission std in order to not throw bogus errors?

vernk

if your talking about where the egr pipe goes on to the exhust you might want to heat that to get it off.... yea the holes in the tube should be facing the right side of the car (right side while sitting in drivers seat) I wouldn't take it out unless you are getting rid of egr, or the odd bank (cylinders 1,3,5 the ones by the fire wall) will get all the gasses from the exhust the tube puts the gasses in middle of the intake.

I will get you pixs of the FSM for running self diag....

as far as going to a 3rd gen ECU you would have to switch the whole intake and wiring since 2nd gens use vacuum to control things and 3rd gen is electrial, but would give you 10 hp gain with the varible intake, so if you have the time and can get all the parts.....

lowpost99

Vernk, wanted to clear that up. It's the same ECU for 88-89. I picked the ecu according tohttp://jimwolftechnology.com/wolfpdf/ecu-id.pdf
Was told here or read same engine Z31VG30E, trans type A, non turbo, and fed emissions. Would you check with me? I have ECU A01 A18 M85. It says its for 88 an 89 Z s with non turbo, auto, fed and Z31Vg30E. I'm gonna try with my existing MAF and see if it throws any codes or runs poorly. Any luck with confirming my codes or how to use mode 5?

lowpost99

I can only guess that 27 years on the same cat one could be an issue.. Since that smell only came after I cleaned the EGR, and put the port tube backwards, and it went away, is the CAT still suspected? I do have sluggish acceleration all the way up to 55-60mph.

lowpost99

I've tried liquid wrench, and heat and no joy getting that bolt on the EGR down pipe to the exhaust to turn left to loosen, so I think I'm gonna give. Is it advised to shoot any carb cleaner down this pipe to clear or breakup carbon deposits? Will the solvent just burn away without causing other issues?

vernk

don't think it should be a issue, if it gets plugged it will choke the engine (plugged exhaust)

which end are you having a issue with? I wouldn't shoot anything down it you could run the chance of plugging cat.

a couple old school things you could try (do at your own risk) fill up with high oct. take car out and do spirited driving for a bit, get her good and warm, get on her a bit (be sure fluid levels are all good and tranny is in good shape) don't need to horse beat her but a hard drive, or as grandpa said "it's good to blow the carbon out once in a while". the next thing I might get flamed for a bit but I will tell you anyway..... open the air filter box take filter out (be sure it's not a dusty day and there is nothing that can get sucked in, use a spray bottle filled with water, with the engine running slowly spray water into the intake, rev engine a bit while you are spraying so you don't stall. if you are not on a level area put car so the back is down hill, are a bit of that you will notice black water coming out of the tail pipe.......

I have noticed that the VG likes to be warmed up really good once in a while, mine will start to run a bit rough (not as smooth as she can) if she hasn't been taken out lately, my drive to work is like 8 miles so after a while of just back and forth to work she starts to get a little rough, my other job is a hour drive which I only do a couple times a year, but after that drive she runs really nice and smooth for a bit....... I have seen this in a couple VGs I have owned....

lowpost99

It's the end that is not on the EGR itself, but the other end which is a bolt with exposed threads going into the exhaust. I will put it all back together later tonight, with the 88 300Z ECU. lol flamed? why? not supposed to do that with the water spray in the air intake? Will all the water get removed from the system?

vernk

yea all the water should come out if the car is ran for a while after, biggest danger is hydo lock which will bend rods (cylinder full of water with no where to go, water doesn't compress well) thats why you don't want to spray so much water that it will stall engine, reving it up a bit will suck the spray more and keep it from pooling in intake...... well it's not that your not suppose to, since water injection is used on high performance to prevent knock.... but it will also help get rid of carbon build up though out the engine, intake runners, valves, exhuast system.... mainly it's a cheep way to do a bit of cleaning with out the smoke and such of using things like seafoam.....

yea that end you will need to get the hot wrench out and get it red hot (mainly the exhuast pipe part) to brake loose plus have a good amount of room to get a wrench with a pipe on it for leverage.... then you still run the risk of twisting it of (brakage).......

lowpost99

Vernk, I put her all back together last evening before dinner, and drove it around kind of hard. I still have the drops, while standing on the brakes, so I guess its onto that FPR, timing recheck and check of the plug wires.

I use Lucas fuel system treatment about every 3rd fill up, and SeaFoam like every six months. Does the water procedure work(clean) on different area(s) of the engine that the Lucas or SeaFoam can't get to? Should I still do it?

I need to check and quite possibly adjust timing. I have read several threads on how it is to be performed and I still don't know if I got it right, and confused if there is anything that's required to make it stick. i.e. I read that the ECU got involved and there was something needed to make the ECU understand and keep the changes made. Any info appreciated and I'll report back when I get to that step.

vernk

oh man timed out and lost all I had typed.......

in short, have you checked the idle with the idle up solenoid unplugged? I looked back and I think your idle is set a bit low.....

the water will clean in a differnt way, basicly it will dissolve carbon, be turned into high temp steam and then condense in exhuast.....

if you send me a text at 763-221-6167 I'll send pix of the FSM, I will try and get them taken tonight, but don't get off till 11 pm MT time, but should be able to send them tomarrow afternoon, but I will be out of town this weekend for work so won't be on here.

lowpost99

You want me to disconnect and just read the tach right? P n D?
PM'ed and repped.

lowpost99

No rep on this board, so big props and many thanks!!!

lowpost99

Turns out I had burned spark plug wire. It burned thru the side of the boot about a 1/2 in. From the bottom. I missesd this first. My friend did recheck and did something extra. With the car on, he disconected each boot and held them against some metal on the block and sparks shot from the offending wire thru the boot. We replaced this one, and bingo, bango, and whoosh on the first drive.

I was missing all this time.. cleared up everything, and this baby runs bettter than I remember from 20 years ago. No hard shifts, quiet, no jerks, no studder in D at stops, great pickup from 0-40mph. P.S. I slipped the 300z ecu in before we found the issue, and there was a noteable kick added. Even better afer the fix.... Any brand recommendations on new set of plug wires?

First, Many thanks to MaxWagon, for allowing me to basically jack his thread. I figured there weren`t too many offended and there aren`t many of us on here. Thanks to Cmax and Vernk for staying with me on this issue.

vernk

I think you set idle in P, then the idle up takes care of the rest, but will have to double check that.....

glad to hear you got her all fixed, one of these days I will have to scan the parts of the FSM that covers such things and post it on here, but that will be sometime when I'm not working 3 of my jobs all at the same time.... but need to support my car habit...

lowpost99

That would be great! Yes if you can post or send "check/set idle" "check/set timing" "check ECU" & codes" Those are the things that I think I need most now...

vernk

I didn't forget about you, got the pixs taken just need to upload to photobucket, which sucks on my computer, nothing like a dell 1720 running on a 65w charger.......

vernk

http://s107.photobucket.com/user/vernk/library/FSM

that should be a link to my photobucket....

if I get the go ahead from I will start a thread with the pix posted but there are a bunch of them.....