RX7Club.com - Mazda RX7 Forum

RX7Club.com - Mazda RX7 Forum (https://www.rx7club.com/)
-   1st Generation Specific (1979-1985) (https://www.rx7club.com/1st-generation-specific-1979-1985-18/)
-   -   What's this vac line go to? (https://www.rx7club.com/1st-generation-specific-1979-1985-18/whats-vac-line-go-1131795/)

Saminya 11-24-18 05:41 PM

What's this vac line go to?
 
Recently picked up an '83 Limited Edition, and I managed to get it running. But it only stays running if I hold the gas pedal down a bit, and dies if it goes below 1k-1.5k RPM. Was asking around, and it seems like this line is supposed to go to something, but i can't get a solid answer on what. Currently it just seems like there's an oily rag like material stuck in it. Any help would be appreciated.
https://cimg3.ibsrv.net/gimg/www.rx7...afd0ea54c3.jpg

j_tso 11-24-18 06:53 PM

See attached page, is the tube it's supposed to attach to present?
You can download factory service manuals at foxed.ca

https://cimg5.ibsrv.net/gimg/www.rx7...e1411992c3.png

j9fd3s 11-24-18 07:02 PM

basically if you follow the pipe from the air cleaner down, it should go pretty much to the vacuum rack, there is one nipple on that side and its kind of pointing right at the air cleaner.

you sure its an 83? its got the 84+ windshield washer setup, and power steering

Saminya 11-24-18 08:06 PM

Essentially trying to solve this issue. Car hasn't ran in 2 years, I just bought it, and was able to get it to start after new plugs/plug wires, oil/filter, fuel filter, new gas w/ premix, and a new battery. It started and stayed running so long as I held the gas to keep the idle above 1k-1.5k RPM. Once i let off the pedal, it would die instantly.
Vid of it starting and running. Seems choppy idle only because I was tapping the gas rather than holding it.


Originally Posted by j_tso (Post 12315515)
See attached page, is the tube it's supposed to attach to present?
You can download factory service manuals at foxed.ca

As far as I was able to tell, no. There was no missing vac lines that I was able to see.


Originally Posted by j9fd3s (Post 12315517)
basically if you follow the pipe from the air cleaner down, it should go pretty much to the vacuum rack, there is one nipple on that side and its kind of pointing right at the air cleaner.

you sure its an 83? its got the 84+ windshield washer setup, and power steering

I didn't see any missing lines coming off the vac rack, but i'll give it another go when I'm next over at it.

Yep, it's an '83 LE. Here's some more pics of it. Just has some upgraded goodies from one of the previous owners.
https://imgur.com/a/xsFUrb6

mazdaverx713b 11-25-18 08:06 AM

The port that it connects to on the rack is larger than a standard vacuum line port if that helps. If the car has been sitting, there is a good chance that it needs a carb rebuild, plugs, wires, cap rotor, belts, air and fuel filters, oil and coolant change etc. Make sure the base systems are good before you dig into other things. A vacuum leak can cause the engine to stall at idle. Address those right away.

KansasCityREPU 11-25-18 10:02 AM

The spider/rats nest side where that line goes is causing a big vacuum leak. I had the exact same issue. My solution was to but a cap on the spider side.

https://cimg3.ibsrv.net/gimg/www.rx7...d81c77d397.jpg

Saminya 11-25-18 02:10 PM


Originally Posted by mazdaverx713b (Post 12315586)
The port that it connects to on the rack is larger than a standard vacuum line port if that helps. If the car has been sitting, there is a good chance that it needs a carb rebuild, plugs, wires, cap rotor, belts, air and fuel filters, oil and coolant change etc. Make sure the base systems are good before you dig into other things. A vacuum leak can cause the engine to stall at idle. Address those right away.

Only things on that list that haven't been done so far is the carb rebuild (was hoping I would get lucky and not need one, but I did order a kit just in case already), the belts, and the cap/rotor. But everything else has been done. I will look for that port then, as it SEEMED like everything was connected, but I guess I missed something.


Originally Posted by KansasCityREPU (Post 12315614)
The spider/rats nest side where that line goes is causing a big vacuum leak. I had the exact same issue. My solution was to but a cap on the spider side.

Could you give me a close up, or a more general area of it? Not able to access the car till a little later in the week, but wanna know what specifically I should be looking at.

KansasCityREPU 11-25-18 04:26 PM

https://cimg6.ibsrv.net/gimg/www.rx7...8f4c352495.jpg

ray green 11-25-18 05:40 PM

2 Attachment(s)
Looks like you've got an 84/85 air cleaner, not the 83 cleaner that came in the LE.

That nipple on the air cleaner you're asking about isn't present on the 83 LE models (I checked, I have an LE).

So you need to know if you have an 83 LE rat's nest or an 84/85 rat's nest (they are different).

Could be a complete engine swap to the 84/85 12A and emissions, which would make j tso's diagram for the 84/85 nest accurate.

In any case you may want to figure out what you've got before depending on the FSM diagrams, they are different for 83 and 84/85 with respect to emissions.

In any case your symptoms are consistent with a serious vacuum leak (or maybe several vacuum leaks).

For a start try spraying all the vacuum connections with starter fluid, if you notice changes in rpm you've localized your leak.

Doesn't sound like much fun but when you find the leak, fix it and the 12A idles like a kitten it's all worth it.

I just happen to have my Nikki out at the moment, so I was able to get a couple good shots of what the 1983 LE emissions should look like:

Attachment 748681

Attachment 748682



.

Saminya 11-26-18 09:44 PM


Originally Posted by ray green (Post 12315706)
Looks like you've got an 84/85 air cleaner, not the 83 cleaner that came in the LE.

That nipple on the air cleaner you're asking about isn't present on the 83 LE models (I checked, I have an LE).

So you need to know if you have an 83 LE rat's nest or an 84/85 rat's nest (they are different).

Could be a complete engine swap to the 84/85 12A and emissions, which would make j tso's diagram for the 84/85 nest accurate.

In any case you may want to figure out what you've got before depending on the FSM diagrams, they are different for 83 and 84/85 with respect to emissions.

In any case your symptoms are consistent with a serious vacuum leak (or maybe several vacuum leaks).

For a start try spraying all the vacuum connections with starter fluid, if you notice changes in rpm you've localized your leak.

Doesn't sound like much fun but when you find the leak, fix it and the 12A idles like a kitten it's all worth it.

I just happen to have my Nikki out at the moment, so I was able to get a couple good shots of what the 1983 LE emissions should look like:.

So I was able to stop by and see the car for a few minutes today, and I got a few pictures of the rats nest. I assume it is in fact from an '83, since i don't see any larger vac line that would go to that.
https://cimg5.ibsrv.net/gimg/www.rx7...b3093c0617.jpg
https://cimg6.ibsrv.net/gimg/www.rx7...6b55f057e3.jpg
https://cimg8.ibsrv.net/gimg/www.rx7...0b2d231482.jpg
https://cimg7.ibsrv.net/gimg/www.rx7...f79f4980f4.jpg
https://cimg4.ibsrv.net/gimg/www.rx7...bb4e87860c.jpg

ray green 11-27-18 03:12 AM

Yep, that looks the same as on my 83 LE.

So it must be that you have an 84/85 air cleaner swapped in there.

Which means that port does nothing but let a little air from the engine bay into the air cleaner.

Since you've got the cold air intake installed you might want to plug that port to force only cold air into the carb.

LongDuck 11-27-18 08:19 AM

Something to add is that your video shows a cold start without use of the choke. There will be a choke pull inside the car that blocks several intake paths until it's electrically released, which helps the car to run properly when cold. Unsure where you're located, but this could be necessary with very cold intake air temps.

As the other guys mentioned, you can cap that blue metal tube to prevent the intake from accessing unfiltered air. Apart from that everything else looks good, and the video seems to show a large vacuum leak somewhere (else).

Saminya 11-27-18 08:35 PM


Originally Posted by LongDuck (Post 12316010)
Something to add is that your video shows a cold start without use of the choke. There will be a choke pull inside the car that blocks several intake paths until it's electrically released, which helps the car to run properly when cold. Unsure where you're located, but this could be necessary with very cold intake air temps.

As the other guys mentioned, you can cap that blue metal tube to prevent the intake from accessing unfiltered air. Apart from that everything else looks good, and the video seems to show a large vacuum leak somewhere (else).

So I was able to get it to idle by itself once it was warmed up, while holding the choke out. Held idle at about 1k for a good 10 seconds. But it eventually did die again, and when I tried it again, it held for 5, then I let go of the choke and it died. So I assume the carb needs to be tuned, along with a vac leak SOMEWHERE in that mess. But it also seemed like even when holding idle at 1k-1.5k it ran a little rough. I assume this might be fixed by solving the vac leak and tuning as well?

And here's a vid of it when warmed up, and giving it a bit of a rev.

KansasCityREPU 11-27-18 09:25 PM

If you're having to hold the choke out while first starting, then the choke itself isn't working. When cold, the choke should stay out by itself when cranking. Ensure the temp sensor on the back of the water pump housing is hooked up.

Are you sure the engine has good compression? Have you done a compression check yet. If you don't know how to do it, the first gen section is loaded with threads on how to do it.

ray green 11-28-18 03:52 AM

Could be lots of things but you should start with finding the vacuum leak(s), they are easy to find and easy to fix.

Just get a can of starting fluid (other volatiles will also work, brake cleaner, etc) and survey all the vacuum lines one area at a time by having someone maintain a constant idle while you spray the starting fluid in that area.

A change in engine speed indicates a vacuum leak in that area. Fix the vacuum leaks first, if that doesn't do it move on to other things.

KansasCityREPU 11-28-18 09:34 AM

From your pics I can see that the choke water temp sensor is plugged in. The wires break really easy though.

It does not like the altitude sensor is not plugged in though (I could be wrong but that's what it looks like in the pic).

Saminya 11-28-18 01:33 PM


Originally Posted by KansasCityREPU (Post 12316135)
If you're having to hold the choke out while first starting, then the choke itself isn't working. When cold, the choke should stay out by itself when cranking. Ensure the temp sensor on the back of the water pump housing is hooked up.

Are you sure the engine has good compression? Have you done a compression check yet. If you don't know how to do it, the first gen section is loaded with threads on how to do it.

No, I have not checked the compression quite yet. I have only had a few hours to be under the hood, and most of that was replacing old fluids and filters and the like. It's on my to check list however.

​​​​​​​

Originally Posted by ray green (Post 12316164)
Could be lots of things but you should start with finding the vacuum leak(s), they are easy to find and easy to fix.

Just get a can of starting fluid (other volatiles will also work, brake cleaner, etc) and survey all the vacuum lines one area at a time by having someone maintain a constant idle while you spray the starting fluid in that area.

A change in engine speed indicates a vacuum leak in that area. Fix the vacuum leaks first, if that doesn't do it move on to other things.

Im honestly toying with the idea of just outright replacing all the vac lines just to be safe. But I will give this a shot before then to be sure. Although out of wonderment, what sizes of vac lines would I be looking at to replace every single one?

​​​​​​​

Originally Posted by KansasCityREPU (Post 12316196)
From your pics I can see that the choke water temp sensor is plugged in. The wires break really easy though.

It does not like the altitude sensor is not plugged in though (I could be wrong but that's what it looks like in the pic).

I know the coolant level sensor is broken and I have a replacement, I just gotta get around to wiring it. Which other wires should I be looking at?

KansasCityREPU 11-28-18 03:19 PM

This connector right in the center of the pic.
https://cimg0.ibsrv.net/gimg/www.rx7...ecc284e328.jpg

ray green 11-28-18 03:27 PM

You can replace the vacuum lines but that would be a lot of work and the fitment wouldn't be as good as the original pieces, which are fitted specifically for each application, some with different size openings on each side.

Chances are if you have any leaks at all in the rats nest tubing it's only one or two tubes and the problem is that the tube is disconnected or missing, not defective.

If you're missing a tube you can either fabricate that one or let me know, I have lots of extras.

The rats nest rubber tubing connections themselves have remarkably long lives and yours look to be in good shape, so if it ain't broke I'd suggest don't fix it.

But be sure to pay attention to a larger ~3/4" hose that runs from the lower right (passenger) side of the carb down to the intake manifold along the firewall.

This one is a notorious vacuum leak. It connects to the intake manifold down near the exhaust header, lots of heat wrecks the rubber tubing wear it connects to the intake manifold.

It's also a good idea to spray all around the intake manifold and carb while you're at it.

Saminya 11-30-18 09:57 PM


Originally Posted by ray green (Post 12316263)
You can replace the vacuum lines but that would be a lot of work and the fitment wouldn't be as good as the original pieces, which are fitted specifically for each application, some with different size openings on each side.

Chances are if you have any leaks at all in the rats nest tubing it's only one or two tubes and the problem is that the tube is disconnected or missing, not defective.

If you're missing a tube you can either fabricate that one or let me know, I have lots of extras.

The rats nest rubber tubing connections themselves have remarkably long lives and yours look to be in good shape, so if it ain't broke I'd suggest don't fix it.

But be sure to pay attention to a larger ~3/4" hose that runs from the lower right (passenger) side of the carb down to the intake manifold along the firewall.

This one is a notorious vacuum leak. It connects to the intake manifold down near the exhaust header, lots of heat wrecks the rubber tubing wear it connects to the intake manifold.

It's also a good idea to spray all around the intake manifold and carb while you're at it.

Well buddy, you are amazing. I checked that hose and it had a thumb sized crack on the inner corner, could only see it when the line was pressed down on. Me and my friend taped it up to test it, and the car is now able to hold an idle, albeit a bit rough. So a tune is in order. But now I can start focusing on other problems like the missing drivers side window, and busted speedo.

ray green 12-01-18 11:51 AM

Nice work!

I have a driver's side window you can have for the price of shipping if you can't find one locally.

That 12A sounds really good, almost no smoke, pretty amazing for a 12A that's been sitting a lot.

Looks like you got a good one!

Saminya 12-01-18 01:25 PM


Originally Posted by ray green (Post 12316792)
Nice work!

I have a driver's side window you can have for the price of shipping if you can't find one locally.

That 12A sounds really good, almost no smoke, pretty amazing for a 12A that's been sitting a lot.

Looks like you got a good one!

It had quite a lot of smoke before we got it to idle, but it seems once we took it for the drive and revved it out a little, it stopped smoking.

And that would be a huge help. Some people drove by and smashed the window one night apparently, for no real reason.

ray green 12-01-18 03:03 PM

The OMP might have been overworking compared to the poor combustion you were getting due to all the air the vacuum leak was letting in so you may have been burning excess OMP oil.

You might want to check your spark plugs, chances are good they're gummed up with black oil residue that will shorten their life if you don't remove it,

They clean up pretty well on a wire wheel or brush or you can replace with new ones but the NGKs and Densos are getting pretty expensive these days at about $5.00 a plug. I would not recommend the autolites, you get exactly what you pay for.

https://www.rockauto.com/en/catalog/...park+plug,7212

On the tune up, a word of caution. Do not be tempted to adjust the air/fuel mixture screw until you have everything else squared away, no vacuum leaks, good plugs, ignition wires, dizzy cap and rotor, etc. If you try to adjust the mixture screw with any of these things out of whack you'll just mask the problem and lose your mixture setting, which should be pretty good already as long as no one has messed with it.

If you have a bus station near you Grayhound shipping would be most cost effective for the window. It's over sized for USPS or FedEx shipping so their rates are going to be pretty high. It will be shipping from 30549 if you want to poke around to find out about shipping options.

If you want to replace that manifold to afterburn hose with a good one I think I have a spare in good shape I could toss in for $15. New ones go for $40 plus shipping from Mazdatrix:

Cart Price Check Part:13-7560-N201

http://www.mazdatrix.com/Pictures/c-...iAfterburn.jpg

Also check for anything else you might need, I have lots of spare used parts and we can save the shipping costs by sending everything together.


All times are GMT -5. The time now is 12:05 AM.


© 2024 MH Sub I, LLC dba Internet Brands