Rookie here with Vacuum issues possibly more.

[trailerparkzero]

Sho'nuff I had the dizzy in wrong. I had to set it slightly before 10:30 so it would end up at 10:30 after it was engaged. Started right up after I did that. Thanks for all the help.

Too bad the vac leak under the carb didn't solve my idle high when hot problem tho. I'm pretty sure there is no more leaks, im really thinking I should just rebuild a carb i picked up from petros for spare parts and toss it on and see. The car runs fine for about 15 min then the revs start creepin up as it gets warmer, when you hit the throttle it is slow to return. everything seems fine the trottle is in the right position when you crank it by hand you can see the TP working like it does before this happens. The fuel is slightly higher when this is happening, when its working normally the level is neer the middle of the window and when its idling high its at the upper pinch of the window.


Can anybody recommend a good carb repair kit or will an autozone or rockauto be fine? I already have a cheapo from autozone that i used to replace the gaskets between the carb and spacer.

Looks like I'm going to have to put some more miles on the bicycle! Baja is calling us tho so i cant wait too long.

[dlb]

good stuff on getting the dizzy sorted out. on to the next! or back to the first, i guess.

the fact that it idles high only when warm still suggests a vacuum issue to me, either a vac leak or something is incorrectly routed. i think this because the TVSV directs vacuum to different devices depending on engine temp—as the engine warms up and the TVSV starts directing vacuum to the 'hot' running stuff, any 'hot' running issues will become apparent. keep looking. check all diaphragms (choke breaker, choke opener, throttle position, vacuum advance, AAP, etc). just put a hose on each one and suck, then plug the end of the hose with your tongue. each diaphragm should hold vacuum until you take your tongue out of the hose. if you can suck air through, the diaphragm is broken. disconnect and plug lines going to broken ones until you can replace them.

[Petros]

the engine idle increasing from cold is normal for a carburaterd engine. As it warms there is a kick down cam that drops the idle speed, but you have to blip the throttle to get it to drop down. once it is is fully warm the fast idle cam should be fully disengaged and it down on the main idle stop. If it is not than you need to check your throttle cable tension, it may not allow it back all the way down to the idle stop. Also, on the other side of the carb from the throttle cable bell crank there is throttle stop that is vac operated to keep the throttle plate from slamming shut (when functioning properly it holds the throttle open a few sections and allows it close slowly), it may be out of adjustment (just back the screw off a bit and see if the idle slows down).

lube up the linkage just to make sure it is not sticking or hanging up to prevent normal idle speed.

If there are no vac leaks and everything is adjusted properly and it still will not idle down that it is possible the throttle shaft is worn and allows air to leak past the throttle shaft. I can not reliably get might to idle below about 850 rpm, but I leave it around 1000 rpm so it will not stall on me (my engine has a a lot of modifications, and a 300k miles on the carb). So do not expect to get a reliable low speed idle. If you can get the idle down below about 1200 you usually can live with it, and it will not affect economy much.

[trailerparkzero]

Well I found the my HIC valve is bad. Its has a pinholes worth of air flow no matter what temperature it is. I though this was good becuse I checked it when it was hot and the flap was down but I checked it again and the flap was up. A vacuum gauge helped me find this. the vac pulls about 21" when cold then falls to about 16" and flickering when hot. I plugged off the HIC and the leak was reduced but not eliminated, it now pulls about varies at 18" with slight flicker. Plugging the HIC didn't fix the issue but it made it a lot better. it still will idle high sometimes but not as bad. its weird it will be fine for awhile then it will wont. I know its running rich because I can smell it and its hard to start when warm and smokes a little when it does. I plan to keep chasing it down but wanted to give an update on my status. I replaced the AAP diaphragm awhile back so I dont think thats the issue but maybe something that controls the vac to it? I have a new TVSV in there but like a bonehead I didn't test it before installing it I need to pull it and test it to be sure thats not my issue.
Anybody have luck with junk yard HICs? I tried to look on the internet but have come up with nothing.

after i find a good replacement I plan to check the EGR modulator, various vac switches, TVSV, AAP function. If I dont pin it down after that.. well you here from me.

[Petros]

the HIC is very reliable, so junk yards are a good bet. You can buy pass it and just cap off the vac lines for driving. I disabled mine so it stay open drawing cold air all the time, cold air gives you slightly better fuel economy. Also you can do the same with the AAP, cap it off. And you can also cap off the EGR and run without it, having the EGR disconnected will also improve your fuel economy some. These are also simple tests, temp disconnect the device/vac lines and see how it drives. Only do one system at a time however, you want to make sure what you are testing and you do not want to try too many things at the same time.

If you are sure it is running rich and it is not the AAP, the only other thing I know that will make it too rich is a float level too high (inspect the sight window on the carb), or some crud in the carb holding open the meter valves. Either way you have to take the top of the carb off to clean it out.

[dlb]

regarding disabling the EGR, the only way to completely bypass it is to remove it from the intake manifold. if the pintle shaft is not sealing, exhaust fumes can leak in all the time whether vacuum is applied to pintle shaft via the diaphragm or not. so disconnecting and plugging the vac lines going to it will not stop an exhaust vac leak there. to remove it, you must undo the large nuts on either end of the metal tube that goes from the exhaust manifold to the EGR—be careful not to strip them. they're on there tight, what with all the corrosion. you will then need a large bolt to plug the exhaust manifold because the bolt that is currently in there is a banjo-fitting style and won't seal. take the old bolt to a hardware store and get a short normal bolt with the same width and thread size. to remove the EGR itself, disconnect and plug the vac lines going to it and then undo the two nuts holding it to the manifold. cut a piece of steel to roughly the same size as the base of the EGR, drill holes in it for the mounting studs, cut a gasket for it out of a cereal box (or go buy one if you want), and mount it in place of the EGR to block off the intake manifold. sounds like a big job but it's not actually.

[ARCHINSTL]

As dlb mentions, an uncapped/unplugged steel EGR tube will lead to an obvious exhaust manifold leak; this is easy to remedy.
Just get a bolt sized 20x1.50mm - and also use some shallow washers when installing in the manifold threaded hole.
This is an ordinary bolt - nothing special. This also provides a tad more room.
Tom M.

[Petros]

capping off the vacuum line to the EGR will tell you if the moduator is a vacuum leak. But DLB is correct about exhaust leaking into the intake manifold, which will effect power out put and economy greatly.

I have found a metric after market replacement oil drain plug (from any auto parts store) usually fits and plugs the manifold outlet for the EGR perfectly.

[Mark]

I had a vacuum leak in my EGR modulator so I removed it and plugged/capped the hoses. A few days later when I was driving up a steep highway (DLB's Malahat), there was a strange, strong smell from the exhaust and the engine died. This kept happening when the engine was at high rpms and under heavy load. I found another vacuum modulator at a scrapyard and put it in and the stall problems went away. Without the egr, combustion temperature is much higher from what I understand. This might have led to pre-ignition and buggered timing? -Anyways, after that, I'm not a fan of disabling the egr.

[dlb]

As dlb mentions, an uncapped/unplugged steel EGR tube will lead to an obvious exhaust manifold leak; this is easy to remedy.
Just get a bolt sized 20x1.50mm - and also use some shallow washers when installing in the manifold threaded hole.
This is an ordinary bolt - nothing special. This also provides a tad more room.
Tom M.

thanks tom, i was hoping you'd see the post and chime in! i couldn't remember the size and couldn't find the thread.

I had a vacuum leak in my EGR modulator so I removed it and plugged/capped the hoses. A few days later when I was driving up a steep highway (DLB's Malahat), there was a strange, strong smell from the exhaust and the engine died. This kept happening when the engine was at high rpms and under heavy load. I found another vacuum modulator at a scrapyard and put it in and the stall problems went away. Without the egr, combustion temperature is much higher from what I understand. This might have led to pre-ignition and buggered timing? -Anyways, after that, I'm not a fan of disabling the egr.

yes, a properly functioning EGR does reduce combustion temps a bit, in addition to reducing emissions. that's odd that your terc would stall out without it. i wonder if there wasn't some other vacuum line you missed plugging, which allowed a huge vac leak under those conditions. lots of guys on here have partially disabled or completely removed their EGR's (myself included at one time) and no one has reported a similar problem so i'm curious. i don't even think anyone here has mentioned having predetonation issues just from disabling an EGR. even if you got some pinging though, that wouldn't change the timing.

[Petros]

if you had enough pre-ignision to stall the engine you should have heard a lot of crackling noises (ping). sounds like you had a vac leak or something.

[Mark]

I didn't hear any pinging/knocking and it idled fine. It only lost power and died under unusually heavy load (going up a steep hill at highway speeds with the gas pedal floored). With an automatic, this gives very high rpms. It's probably rare for most drivers to subject their engines to this condition. When I re-installed the egr system, this stopped. It might have been something to do with the vacuum line to the distributor which ties into the EGR modulator. Maybe I wasn't getting the right vacuum to the distributor for timing advance.

[Petros]

actually it is normal "subject their engines to this condition" with a 62 hp Tercel. It should not have done that, this engine will reliably put power out and rev to well past 6,000 rpms. this same short block was used on much more powerful engines such as the 4age used in the MR2, so you will not damage it running it at full throttle. timing could be an issue, you should check it out. Set it at 10 deg BTDC (rather than the stock 5 deg) and verify that the mechanical advance is working. if the spark does not advance it could act just like this, loose power at high rpm.

You can also check the vac advance too, but it will run fine without it working. It helps part load economy. If the vac advance is failed however it can act like a vaccum leak, if it does not work it should be capped off.

[Mark]

My engine runs fine at high loads when the egr is connected. Looking at the vacuum diagram, when I capped off the EGR vacuum line, the distributor was still getting vacuum, but since this vacuum wasn't being adjusted in the egr modulator, maybe the distributor advance wasn't actually correct for the air-fuel mix. When exhaust is directed into the engine I assume the mix is lean and the timing is advanced. Maybe the timing was advanced, but the mix was richer than normal (without the egr).
Anyways, I'm rambling. You guys have much more experience than me on these vehicles so I should take your word for it that disabling the egr is a good thing, but I'm stubborn dammit. You'd think we're race car engineers or something, talking about timing advance, fuel-air mix and combustion temperatures in a 62hp car.
-One thing for you guys that have disabled egr: Have you had problems with burnt exhaust valves from the higher temps? -Or is the temperature rise not that significant?

[Petros]

It does not appear you understand the function of the the EGR. It is supposed to bleed exhaust gas into the intake at part throttle conditions, the exhaust is assumed to be inert without any oxygen nor unburnt fuel, it will dilute the incoming fuel-mixture and reduce the peak temperatures and pressure, and thereby reducing the NOx emission. If functioning properly it should not be operating at idle or at full throttle, but only in part throttle mode (where the combustion pressures and temps are not as high anyway). It will have the effect if reducing efficiency and reducing power output. the spark timing needs to be advanced when the EGR is egaged because combustion is slower, if it does not advance it will cause burnt exhaust valves.

I have a hard time believing there is an overall net reduction in emissions, but it does reduce parts per million NOx. If you need to burn 15 percent more fuel to travel the same distance, than overall fuel consumption and overall emissions per mile is higher, but their PPM of NOx is lower. this seems like a bad trade off. Many cars did not have EGR up through the 90's even, and none had it before about 1980. No race car ever uses it where max power output is prime consideration.

You exhaust valves get hottest at full throttle so it does not seem that it would help much cooling the exhaust valves at full throttle since it should not be engaged than. It should lower the exhaust temps at part throttle positions, but that is not where the exhaust is hottest. The thing that most affect exhaust temp is the amount of still burning fuel air mixture in exhaust stream (making it hotter). so proper spark timing, and properly working advances will reduce exhaust temps. That is why we recommend using 10 deg BTC advance rather than the factory (emissions friendly) 5 deg. I owned a number of older classic cars (before smog) that had no vacuum advance and the static timing was set at 16 to 22 at idle. More of the fuel is burnt before the exhaust valve opens, and the exhaust gas temps will be lower with more advance.

In fact, for max efficiency and power output, you always want the most spark advance you can get WITHOUT getting pre-ignition or ping.

So if everything is working properly it can reduce exhaust temps, but if anything is not working it could result in higher exhaust temps too. the best most efficient way to reduce exhaust temps is to have as much of the fuel air mixture burn in the combustion chamber before the exhaust valve opens with more advanced spark timing. disabling the EGR should not result in lost power, and should not result in a higher risk of burnt exhaust valves.