1994 300zx na starting issues

[mistawright]

I purchased a 1994 300zx na 2+0 about a month ago. I performed the 120k timing service job, deleted the water lines under the plenum, and did a egr delete. Before doing all this the car was having an issue running with the maf connected. After doing the service this is still the case. I can get the car to run and idle, I have adjusted the tps to the best of my ability right now so the car idles around 1k rpm, without the maf connected. Once the maf is connected it dies. I should have a consult cable here by the 21st and hopefully a replacement throttle position sensor around that time as well.

https://www.youtube.com/watch?v=Qu5BgmXrzSQ

https://www.youtube.com/watch?v=bhBpuwSb_7g

any help is appreciated

[DCaff300ZX]

Welcome!
Too bad you did some deletes and mods before solving your problem, this doesn't help at this point as you may have to go over your work as it may or may not be involved in your problem and certainly will factor into testing.
This stated problem is very odd, as the engine should not run if the MAF isn't functional or is disconnected. I assume the ECU/engine can use the "limp mode" should there be an issue during operation, but to my knowledge the MAF isn't included here since it basically is responsible for the air metering and the one time I ran my engine without MAF (turbo testing) it BARELY ran, and certainly could not be brought to idle at all as you state your car will without the MAF connected.
Therefore I'd suspect that the MAF may be OK but the connection or harness may have corrosion issues or is faulty or causing a short when connected. After a careful inspection of the harness especially where is passes through the front brace, I'd clean the MAF also to ensure it should work while also checking it works, and clean the connector looking for green crud. There are many other areas where the corrosion can happen (bad Nissan connectors) so a sweep and clean of the IACV, CTS, PTU, and CAS harnesses/connectors is highly recommended.
Should all of this fail to solve the issue, then you need to do some testing. Too much info to pass along here, the "Everything you need to know...Z32" sticky has an online service manual with those tests and diagnosis to download, your best friend. Be thorough and you will find and solve your problem.
Any further questions that come up from this testing be sure to post them up, and Good Luck!

[itsa300zx]

I purchased a 1994 300zx na 2+0 about a month ago. I performed the 120k timing service job, deleted the water lines under the plenum, and did a egr delete. Before doing all this the car was having an issue running with the maf connected. After doing the service this is still the case. I can get the car to run and idle, I have adjusted the tps to the best of my ability right now so the car idles around 1k rpm, without the maf connected. Once the maf is connected it dies. I should have a consult cable here by the 21st and hopefully a replacement throttle position sensor around that time as well.

https://www.youtube.com/watch?v=Qu5BgmXrzSQ

https://www.youtube.com/watch?v=bhBpuwSb_7g

any help is appreciated

You need to connect the intake pipes to the throttle bodies (the rubber accordion ones), so the ecu knows how much air is entering the engine via MAF.

[mistawright]

The car with an aftermarket intake. similiar to this guy https://www.amazon.com/Racing-Intake-Fi ... z32+intake. Its hard to get it to line up properly at all to the point i haven't gotten it back on. I believe I need new silicone couplers for the areas it needs to bend around. will see about the silicone coupler and getting it back together and will attempt to start again. May have to wait till the weekend. waiting to hear from someone that im getting a replacement condensor from and timing belt covers and the fan below the nose panel.

[DCaff300ZX]

Those types of "intakes" (actually just different hard pipes, and poorly made usually causing the fitment issues you describe) are notorious for bad fits, and definitely need couplers to attached everything, maybe even elbows.
All needs to be hooked up air tight for the engine to run.

[NolimitZ32]

My suggestion is that you scour ebay for a set of factory accordion pipes and throw the hard pipes you have in the trash.

[itsa300zx]

My suggestion is that you scour ebay for a set of factory accordion pipes and throw the hard pipes you have in the trash.

Sound advice^^^

I have a set collecting dust here. Where you located? Shipping plus $5 bucks.

[Ace2cool]

It's shutting off when the MAF is connected because the MAF is reading zero airflow. With the MAF disconnected, it defaults to a base map based off the TPS and the O2 sensors. Terrible for it to run your engine this way.

Get the pipes hooked up, then the MAF, and it should run correctly.

[mistawright]

My suggestion is that you scour ebay for a set of factory accordion pipes and throw the hard pipes you have in the trash.

Sound advice^^^

I have a set collecting dust here. Where you located? Shipping plus $5 bucks.

I live in tampa and could definitely do the 5 plus shipping. I'm pretty sure usps has a cheap priority mail option.

[mistawright]

https://www.youtube.com/watch?v=hL6N4DdJEIA

so I think it still needs to be timed now. I can't get nissan datascan to work as it shutsdown my laptop when connecting through windows 10. ecutalk works however. I need to get a better timing light or a recommended spark plug extension that would allow me to read the spark as the craftsman timing light would only pickup on the ptu loop. I am assuming the reading from the ptu loop is not correct from what I have read.

The idle also seems slightly choppy but i'm guessing that would be better once its timed and I make sure the tps is set properly. Any recommendations please let me know.

[itsa300zx]

Looking good so far, one step ahead. Vacuum leaks can cause an odd idle too. Has your tps been adjusted yet?

Also, I'm in Canada, I'll see what I can do for shipping rates. I'll send you a pm once I get a quote.

[centralcoaster33]

Second the vacuum leaks. You can't properly set timing and idle with those because both will bounce around irregularly.

[mistawright]

So where would you suggest I check for leaks at? I will probably print my vacuum diagrams so I have something to reference later on.

[DCaff300ZX]

OP. the OSM is your friend here- download it from the "everything you need to know...Z32" thread for lots of vacuum help. As mentioned having ALL vac and connection and electrical issues solved is paramount to even attempting to fine tune the VG30DE, so a smart move is to use the OSM flow charts and such to get a real idea of your necessary work and not be scattered in your approach. You did say you had vac diagrams which is good, but more is better and there are a lot of related concerns I can't go into yet with each of the below items.
Vacuum leaks present commonly at:
-Intake hard pipe connections (clamps, cracked/worn)
-Vac/PCV/other hose connections (hose or nipple breakage)
-IACV and balance tube (larger hose breakage, bad/stuck fast idle valve, bad IACV, bad balance tube o-rings)
-EGR in some cases (intake seal)
-intake piping connection after the MAF if stock airbox (PITA to get box/intake tube aligned correctly as I remember, been a LONG time since I saw one of those- point is, air in after the MAF is a vacuum leak)
While checking these items you will have to disconnect connectors, and which should be inspected for durability (broken/heat warped) and connectivity (corrosion), and need replacing (VERY common) especially with the IACV and CTS, PTU, and PCV. PCV replacement while doing everything is a great idea, and a possible solution as the hose there is hard to see and can easily crack as any other will from heat and oil.
Hope this helps!

[mistawright]

[youtube]https://youtu.be/qAsiVQYU03M[/youtube]

Getting annoyed with ecutalk. Do I need to set the timing through the ecu as well as with a timing light? If so how can this be done with ecutalk? I can't get nissan datascan to work on windows 10 without it shutting my laptop off. I may have figured out the driver issue in linux using a virtual machine. If it does work hopefully I can get it going there.

[itsa300zx]

Mechanical timing must me set first at 15 deg. BTDC using a timing light. If you are having trouble getting a good signal with the PTU loop then try this:

pull the wrap/sleeves covering the 3 wire on coil pack 1 connector. expose the 3 wires and use the heaviest gauge wire of the three for the signal to your timing light. loosen the 3 screws to the CAS and carfully rotate to adjust timing.

[mistawright]

I actually took my craftsman timing light back that cost 70 bucks bought an innova 3351 i believe off amazon and that picks up the 1st cylinder while the craftsman only picked up the ptu. I have read that the ptu loop is no the best source to use. What about the high idle? I have the voltage set around .5 and my car is now idling at 2000 or so rpms. This is also a new tps sensor. Do I need to set the timing on the ecu and if so how do i go about doing this with ecutalk or another software other than nissan datascan? I can connect to the ecu using ecutalk but windows 10 will not allow me to use nissan datascan 1.6

[DCaff300ZX]

I've never heard of setting timing at the ECU as it has a base setting it uses only when/if the IACV is disconnected, the IACV being where the base idle screw is located and adjusted from. The ECU may change that setting for AC and other idle needs (via the fast idle solenoid attached to the IACV) but to my knowledge without a programmable ECU (custom), you will not be adjusting ECU idle settings.
I can't say often enough that using the OSM for this job is the best route, what you are doing is going about this the hard way and one we may/may not be able to comment on for that reason...

[mistawright]

ok. so I let the carm warm up friday and set the timing to 15 degrees and it looks good. I then begin to adjust the tps sensor and make sure its sitting at .5v. From there the car is running fine for a bit albeit a little high in the rpm range around 1100 rpms or so. It runs like that for fifteen minutes and then the rpms skyrocket to 2k. I disconnet the iacv and rpms drop, I adjusted things to about 650. it dips to 650 and goes up to 750 or so. I used a consult cable with conzult to read the ecu. Once it is set correctly idle adjustment screw I connected the iacv and it was fine for a bit then back up to 2k. Do I have a bad iacv? I also need to replace my coolant temp sensor as I cleaned the connectors and didn't seem to make much of a difference. I did get a fault code for that for the first time ever.

[DCaff300ZX]

ok. so I let the car warm up friday and set the timing to 15 degrees and it looks good. I then begin to adjust the tps sensor and make sure its sitting at .5v. From there the car is running fine for a bit albeit a little high in the rpm range around 1100 rpms or so. It runs like that for fifteen minutes and then the rpms skyrocket to 2k. I disconnect the iacv and rpms drop, I adjusted things to about 650. it dips to 650 and goes up to 750 or so. I used a consult cable with conzult to read the ecu. Once it is set correctly idle adjustment screw I connected the iacv and it was fine for a bit then back up to 2k. Do I have a bad iacv? I also need to replace my coolant temp sensor as I cleaned the connectors and didn't seem to make much of a difference. I did get a fault code for that for the first time ever.

The IACV is notorious for failure in a couple of ways, and generally should a shot of WD-40 into the interior of the IACV through one of the hose openings not loosen things up inside, replacement is the best route. I and others have tried the "good/used" replacement option and that doesn't usually work either. The problem is the gunk and stuff that accumulates and gets cooked solid, and inhibits operation. Another issue can be the corroded connectors, so one method of repair can be replacing them and see if that helps although that and the cleaning only work on occasions.
The OSM also has a lot of IACV tests you can use to determine if the IACV is working or not. CTS is a cheap part and always a good idea to replace if it hasn't been replaced previously, as well as the harness/connector. Check you PTU harness and CAS as well for corrosion, clean/replace if necessary.

[mistawright]

I snagged a ptu from a j30 so I have more than one. my cas seems to be working well. I had cleaned all those guys up initially thinking it was part of my starting issues. So not too sure about the connections there. Will replace the coolant temp sensor as well. I saw the thread on cleaning the iacv or spraying it with wd-40 may try that to see if it clears the idle up. The coolant temp sensor was a new code and may have to do with the loose connector as the metal clip isnt on the connector. Hopefully will know something soon. it does seem as though I am getting close and I do need to change the oil on it soon as well. Will hopefully get myself a jack and jack-stands for christmas.

[Destrto]

I know you're currently looking in a different direction, but have you capped those unused connections on your intake tubes? Those could cause issues with idle being off, as they would be causing a vacuum leak.

Another thing, if your idle drops when disconnecting the IACV connector, and then rises when you reconnect it, the IACV seems to be working. You can check to see if it is actuating by hooking it up to direct 12V and listen for a click noise.

[mistawright]

I believe the iacv is working, or operating but is it working properly? I havent had a chance to take the plenum off and ohm test the components and probably won't have time till like monday unfortunately. What i noticed initially was that the car was idling fine once i had adjusted things. 15 minutes after running around 1k it jumps up to 2k and hasn't been back down since. If i disconnect the iacv it sits where the base idle screw is set. I would think this would be an indicator of things wrong with the iacv.

[Destrto]

I believe the iacv is working, or operating but is it working properly? I havent had a chance to take the plenum off and ohm test the components and probably won't have time till like monday unfortunately. What i noticed initially was that the car was idling fine once i had adjusted things. 15 minutes after running around 1k it jumps up to 2k and hasn't been back down since. If i disconnect the iacv it sits where the base idle screw is set. I would think this would be an indicator of things wrong with the iacv.

If it adjusts itself after plugging the IACV back in, then it is working. It's one of those parts that either works or doesnt. I just recently did a bunch of research into the IACV, because I thought mine went bad. Turns out, my troubles were being caused by an exhaust leak.

If the car drops in idle when you unplug the IACV, and jumps up initially after plugging it back in, then the IACV is funtioning as intended. If the idle is ramping up a short while after that, then something else is causing that. There were quite a few other posts on here about similar idling issues, most of them ended up being vacuum leaks, exhaust leaks, or faulty TPS units.

You can check to make sure your O2 sensors are working by following the steps at the bottom of this link, Put the car into Mode 2 by shorting the far right bottom 2 pins on your OBD1 connector under the dash. Then following the steps for testing the O2 sensor. https://z32.wikispaces.com/ECU+Diagnostics. That is an easy way to tell if they are functioning properly.

[Ace2cool]

If you've still got those pipes held on with electrical tape, then I'm going to guarantee there's a vacuum leak there. Get the things installed properly first, then troubleshoot. This is a finicky car. Not like an old cavalier where you can literally duct tape everything together. Everything on this car has to be in proper working order, otherwise you're gonna be chasing ghosts the entire time. Use the correct parts.

[mistawright]

ok guys, update time. I pulled the plenum and ohm tested the iacv and inspected the air regulator. I cleaned the iacv using some carb and throttle body cleaner I had after that i made sure to spray some wd-40 in it and allow it to drain. Having put things back together the car is no longer sitting at 2000 rpm but around 1100 and jumps to almost 1500. I disconnected the iacv assuming that I needed to set the base idle. Doing so and moving the base idle screw has no effect as it did before I took it apart. Did I break it?

[Destrto]

ok guys, update time. I pulled the plenum and ohm tested the iacv and inspected the air regulator. I cleaned the iacv using some carb and throttle body cleaner I had after that i made sure to spray some wd-40 in it and allow it to drain. Having put things back together the car is no longer sitting at 2000 rpm but around 1100 and jumps to almost 1500. I disconnected the iacv assuming that I needed to set the base idle. Doing so and moving the base idle screw has no effect as it did before I took it apart. Did I break it?

If you give power to the IACV pins, do you hear a click? Indicating that it is working?

[mistawright]

damn it, might have to take the damn plenum off to check that. might be able to run a wire from the battery to check that way. Is it a possibility of the spring losing tension?

[Destrto]

damn it, might have to take the damn plenum off to check that. might be able to run a wire from the battery to check that way. Is it a possibility of the spring losing tension?

Granted it's a bit cramped, You shouldn't have to pull the plenum to access the IACV. But hearing it click will tell you if that unit is receiving power. It's one of those pieces that either works or doesn't, no in between.

I used some old wire with alligator clips on both ends and tested it that way. I had to tap it a couple of times to start hearing the clicking noise. Possibility that it is stuck and needs coercing.

[mistawright]

car is running better replaced my leaking hoses. Woke up on the 1st to a voicemail from the landlord of the apartment that i need to move my car. moving it to my moms house. I'm looking to replace my front bumper and hopefully get it registered in the next 30 days and on the road. I want it looked over by premier z in clearwater even if its just a glance.