87 Z runs then dies... :(

[kasilvia]

Okay, so heres the situation:87 Non Turbo Z, car will start and run for approximately 15-30 seconds. If you dont press the gas, it will slowly wind down and sputter out. If you try to feather the gas it, it will attempt to rev up, but then it sounds like it loses fuel and dies while making alot of not good sounds (popping through the intake piping, and generally sounding like the filter housing is off). I have replaced the distributor because it fixed a similar problem in the past, where it could be held to the floor and it would pop and backfire and never made it past 2200rpm all while sounding like the timing was retarded to 0 degrees BTDC like the two step on my KA-T. this did nothing but lighten my wallet. I replaced the fuel filter, and the car seems to have decent fuel pressure. I havent put a gauge on it yet, but as soon as I dig up my inline pressue gauge, its going on it. I checked to make sure the EGR valve wasnt sticking, or stuck open, no problems there. I havent found any vacuum leaks, but I really dont know this car as well as my 240's (sx's not z's).I searched high and low but nobody ever seems to follow up on their threads to help keep up a good source of information, but I fully plan on returning to update what fixes this problem. I am a technician by trade, and Im not scared of technical lingo and usually love a good challenge, but I am trying to sell this car quickly to recoupe from buying my house last month and really need it running. Anybody had this problem before? Thanks in advance to anyone who chimes in here.

[evildky]

tps, mas, fuel pump, definitely check the fuel pressure, the tps you cna check with a multimeter, and mas is a bit more difficult, and have you checked the ecu for codes?

[Perrenial Badass]

Well, the first part sounds like the CHTS might be bad. I had some serious idle issues on my 87, figured it was the CHTS. So I replaced that but... it still didn't seem right. So I randomly replace my air regulator with a spare and that ended up being part of the problem.

Sure that the dist. is set right? My friend put his distributor one tooth off, and combined with a dying battery his car refused to run right. Reset that, threw in the battery from my 87, and it runs fine now.

Damnit, I just remembered that f***er still has my battery!

[kasilvia]

I know it builds pressure, and lots of it upon turning the key on. I dont know how much, but it will shoot fuel over 20 foot out the hose when the hose comes off. (accidentally left hose loose) I need to run the fuel pressure numbers for sure, but still cant find my fuel pressure gauge... I think someone borrowed it without the intent of returning. It smells like pure gasoline out the tailpipe when I get it to stay running, but it wont do anything more than idle. What kind of ohms reading should I expect from the TPS at close and WOT? Is there a method to test the MAS? I know on my Z32 MAF its just a matter of factoring in the ambient temp into the resistance across the hot wire to determine problems there. I havent checked the ECU for codes as I am still not 100% sure about the turn the selector method. I was taught the OBDI and OBDII stuff, but not much about the early ECCS systems. I suppose I should stop being a puss about it and learn the troubleshoot mode on this computer. How do I check the Cylider Head Temp Sensor? I am going to assume its at the other end of the wire that travels down through the timing cover and disappears, correct? As far as installing the dizzy properly, I am positive I got that part right. It ran the same before and after the install, and not trying to be over confident, but having owned small block ford engines in the past, I got pretty good at pulling and installing the distributors that arent on a keyed one way only.Im gonna check back and let you guys know what I find. Any resistance values or reference voltages I should check that you guys know the values for would be much appreciated. Thanks guys, I was hoping for an easy/cheap fix, but sounds like this may get pricey!
Modified by kasilvia at 6:39 AM 8/17/2009

[evildky]

just because the fuel pump comes on and builds initial pressure doesn't mean it's good, somethins they fail under load, at idle vacume allows the pressure to star low (38 psi iirc) and when you accelerate the vac drops off raising the fuel rpessure

the tps is a potentiometer, you want to look for a sweeping impeadance

and checkgn codes on an ODB 0 ecu is simple, just a matter of rotating the dial one way and back or some such, been a while since i've done it myself

[kasilvia]

Yeah, Ive been reading up on it. It doesnt seem like its too complicated, just a matter of getting to it. I will let you know what I find. I assume the tps should sweep from 1.x to a maximum of 5 volts. Typical tps voltages? I think I could splice the signal wire on the ecu from the MAS to see what the signal wire voltages are. It could give me an idea what its seeing coming in. Thanks evil, I will let you know what I find probably in a couple days.

[kasilvia]

Okay, so I dug up my fuel pressure tester this morning. Actually, sadly enough I had to borrow it from a co-worker since mine took the furniture, the dog, and all the food from the fridge and left my tool box in the middle of the night... Gonna run some tests either on lunch break today, or tonite, or maybe later this week. Ill be back to update what I find. I will check sensor voltages and readings as well at that time. Gotta dig the computer out from its mounting bracket and then I can put it in diag mode. Thanks for the help in pointing me in a general direction, but hopefully the info I gather will help some other Z owners out should they have similar problems.

[kasilvia]

So a little weekend update. Had great fuel pressure numbers before and after the car dies, kinda think the fuel pump is ruled out now. 45psi key on, idle (for about 6 seconds) 32-35psi. I checked the TPS and it had a good sweep from closed to WOT, no jumping of any measurable sort. Checked the voltage from reference and it swept voltage as it should, increasing voltage from close to WOT. Gonna check the MAS somehow and read the code/s from the ecu. Hopefully will get a chance to work on it again in a couple days. I will get back with results. Any suggestions on other items to check?

[evildky]

when the car dies, will it restart immediately? if not that can make trouble shooting a lot easier

[kasilvia]

It will start right back up. Every time. But then falls flat on its face again. Sometimes it will idle for longer than 5-7 seconds and actually last for almost 20 seconds, but its not smooth.

[evildky]

will the engine continue to run if you continue to rev it?

[kasilvia]

Nope. It will try to rev, then fall flat on its face. Seems like its either not metering the air coming in, or its getting unmetered air in. Alot of signs point to the MAS, but how to test it without getting a replacement? I also have some sort of air injection pump that drops in right before the MAS. One of the hoses goes nowhere, never had anything connected to it since Ive owned the car (going on 7 years now). This car has been relatively problem free since Ive owned it, then this slowly progressed from being a rough idle that could be solved with a few quick revs, to falling flat on its face after running a few seconds.

[evildky]

it counds like a fuelo isue, if revingthe engien or workign the tb helped it run longer that would poitn to an air issue

the hose taht goes nowhere? there should be no outside air getting intot he itake anywhere bewteent he mas and the engine, if you have an open hose anywhere, it's a problem! it should be routed somewhere to something

[kasilvia]

It goes in before the MAS, so whatever passes through it, then a valve, then another hose, travels to the inlet before the MAS. I have had it blocked for some time now. I know that it has sufficient fuel pressure, so where should I look to? Injectors? Perhaps the MAF could still be suspect if its not sending any info to the computer, right?

[evildky]

have you checke d the ecu for codes?

[kasilvia]

I work/live 30 miles from where the vehicle sits. I only get the opportunity to work on it on the weekends. The future in-laws were in town last weekend, so I only had about a 2 hour window to drive out and check what I could. I will be into the ecu this weekend, will update with results.

[kelloggman]

take lots of pics definitely helps out

[evildky]

the mas should throw a code, also you said ti only runs for a few seconds, is it possible it's as simple as a blown fuse? remember these cars need voltage when cranking as well as when running, couod also be an ignition swithc for that matter

[kasilvia]

I hadnt thought to check the fuses. Would feel like an idiot if that were the problem! But the fact that it hprogressed instead of just quit makes me feel that it has to do with a sensor or moving part of some sort. Im gonna check for codes this weekend, hopefully that gives me some answers.

[evildky]

the car only needs 3 things to run, fuel, air and spark, we just gotta determine whihc you are nto getting, whihc is difficult considdering it works then doesn't and repeats, if it woould stay nto working it's a lot easier to track

[kasilvia]

Yeah, it sounds simple! Too bad there's a computer in there that determines the fuel and the spark! I know that it will show itself soon enough. I am gonna do some work on her this weekend and see if she will give up any secrets! I'll keep this thread updated, and perhaps even throw up some pics of what I find/do.

[evildky]

yes but if we can determine what it's nto getting it at least lets us know what path to follow to find the source of the problem

[kasilvia]

Well, pulled codes and it looks like the timing covers are coming off! Code 13, CHTS circuit malfunction... Also has a 41 code too. Fuel Temp Sensor malfunction... If that is the sensor in the regulator, then that code was set because I disconnected it while I was trying to determine what that sensor does. At least Im headed in the right direction. Any hints for a smooth replacement on the CHTS?

[evildky]

the chts is located inside the distributor, that means you need to replace the distributor, or you have a bad timine belt or missing teethe, which could mean bent valves

and yes the fuel temp sensor is the one in the fpr

[kasilvia]

So I need another dizzy? This is a replacement unit. How does it read cylinder head temps from there? New timing belt less than 10k miles ago. What is the sensor that runs down behind the timing cover on the left head?

[kasilvia]

Alldata says this is on the left cylinder head. Also says the job pays 7.9 hours, so I am gonna have a few hours on the job replacing it. Looks straightforward, and hopefully with the aid of some liquid motivation, I can get it done saturday morning. Will update with the result. Might get some pics this time.

[evildky]

Alldata says this is on the left cylinder head. Also says the job pays 7.9 hours, so I am gonna have a few hours on the job replacing it. Looks straightforward, and hopefully with the aid of some liquid motivation, I can get it done saturday morning. Will update with the result. Might get some pics this time.

the distributor is on the drivers side head, it's driven by the drivers side cam, it's a 10 minute job, uless aldata assumes you are gonna dismantle the distributor and replace the innards whihc as far as I know are not available seperately, I guess it's one of those overcharged jobs to make up for the undercharged jobs that the tech will add charge to if neeed, but won't cut you a break on the severe overcharge on a simple job like this

[kasilvia]

But the cylinder head temperature sensor is available from the Dealership. Wholesale to me is only 25 bucks on the part. They told me it was located on the left bank (drivers side head) behind the timing belt. Ive replaced the timing belt twice on this car. The distributor houses the photo-eye crank sensor and cam position sensor. The CHTS is also refered to as the "engine temp sensor". It takes a reading directly from the head, you follow the wires that travel behind the timing covers and down the left side of the head. I did my homework on this one! Now that I think about it, I should check to make sure the wires havent been damaged while the covers were off! Not trying to be pompus, just hoping the info Ive read and the techs at Nissan are giving me good info!BTW, I am a technician by trade. I specialize in front end service, alignments, wiring, diagnostics (OBD1 and 2), and major mechanical repair. I will never take my cars somewhere to have them serviced because I know what I charge people to work on their cars! The reason I asked for help with this one is to help narrow down my search criteria to possible known problems. I didnt have alot of resources for this car, and was happy to have such good response and help from everyone here. I just wanna make sure everyone knows how much I appreciate the help everyone has given me thus far. Ive owned this car for nearly 7 years now, and all Ive ever had to do is routine maintenance. I never took the time to learn my Z as I was always busy with my 240. Now I truely can say that I know alot about my Z31 now, and its not as difficult to work with as I thought it would be. Kudos to Nissan for building cars I like to work on!
Modified by kasilvia at 5:51 AM 9/1/2009