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unplug cts?


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29 replies to this topic

#1 brokebill

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Posted 07 June 2008 - 10:02 AM

86 GL wagon1.8carb.,2 wd

i have some hard hot starting issues that sounds cts related.

is simply unplugging the cts an option?

thanks, Bill

#2 grossgary

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Posted 07 June 2008 - 10:14 AM

there's one way to find out, you could try it and attempt to start it. it won't hurt it to try. now as far as driving i have no idea.

#3 zukiru

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Posted 07 June 2008 - 10:19 AM

there's a resistor you can put in it's place. do a search for the rating of the resistor.

#4 brokebill

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Posted 10 June 2008 - 06:01 PM

ok, is the cts on my car located in the radiator? (just to be sure i'm fooling with the right part)

went to unplug it and the wire broke at the end of the connector.

with the one wire off and the other still connected, the electric cooling fan wouldn't kick on when the temperature got to where it should have.

cleaned the green gunk out of the connector and reattached the wire. the electric fan started working on cue again, but hard hot starting issues persist.

if this is the cts i'm messing with could it be corroded on the side in the liquid, causing my hard hot start issues as most threads i've read on the subject are cured by cleaning the contacts and wires?
also is this part an oem neccessity or will aftermarket be fine?

thanks, Bill

#5 zukiru

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Posted 10 June 2008 - 11:01 PM

the CTS that generally has the issues is threaded into the manifold.

more details on the car?

is it carburated, SPFI?

what you have there is a thermosensor for the fan.

#6 GeneralDisorder

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Posted 10 June 2008 - 11:17 PM

Fan thermoswitch (what you messed with) has nothing at all to do with the thermosensor for the ECU. Thermosensor is in the manifold - thermoswitch is in the radiator.

GD

#7 brokebill

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Posted 10 June 2008 - 11:22 PM

its carbed (hitachi)(feedback).
i swear with all the sensors and relays etc. i am starting to seriously think about a weber. wouldnt that eliminate most of this crap?

i'll check for the cts tomorrow and clean up the connections on it and see how it does.
i wondered why the posts i read on the subject kept referring to the manifold. figured it was just a difference in models.

thanks for pointing the right direction zukiru, Bill

#8 GeneralDisorder

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Posted 10 June 2008 - 11:34 PM

its carbed (hitachi)(feedback).
i swear with all the sensors and relays etc. i am starting to seriously think about a weber. wouldnt that eliminate most of this crap?


Yep - all of it actually. There aren't really all that many sensor inputs to the ECU - 8 or 9 I think. Most are not actually "sensors" in the sense you mean. Ground, RPM (tach signal), and speed sensor are inputs, but aren't really sensors in the sense you are refering to. I don't beleive there are any ECU related relays other than for the fuel pump power. Just two duty solenoids, a couple sensors, some wireing, and the entire production volume of vacuum line for the country of Japan..... plus assorted T's, nipples, vacuum valves, thermo-vacuum valves and so forth.

i'll check for the cts tomorrow and clean up the connections on it and see how it does.


It will be a brass looking 17mm (maybe 19mm) thing on the back of the passeger side of the manifold. It's got two male blade connectors on it and should have an associated T style 2 prong female blade connector attached to it. It is actually two sensors in one unit - one sensor is for the ECU, the other is for your dash gauge. They read differently on the ohmeter, and if you replace it you MUST have the two blade variety or the ECU output will not be present.

GD

#9 Andy FitzGibbon

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Posted 11 June 2008 - 08:29 AM

its carbed (hitachi)(feedback).
i swear with all the sensors and relays etc. i am starting to seriously think about a weber. wouldnt that eliminate most of this crap?


Yes. My '85 4WD wagon has a Weber, and none of the crap left except for the PCV system. I consistently get 27-29 MPG.
Andy

#10 brokebill

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Posted 11 June 2008 - 10:25 PM

It will be a brass looking 17mm (maybe 19mm) thing on the back of the passeger side of the manifold. It's got two male blade connectors on it and should have an associated T style 2 prong female blade connector attached to it. It is actually two sensors in one unit - one sensor is for the ECU, the other is for your dash gauge. They read differently on the ohmeter, and if you replace it you MUST have the two blade variety or the ECU output will not be present. GD



think i found it. pas. side manifold with 2 wires (yellow and yellow/green i think) to late to fool with tonight but at least i found it.

thanks, Bill

#11 brokebill

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Posted 12 June 2008 - 12:46 PM

when hunting this part will it be called a cts, a thermosensor or what?
the ones i keep pulling up are either 1 prong or the 2 prongs are parrallel instead of a t shape.

part # anybody?

thanks, Bill

#12 GeneralDisorder

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Posted 12 June 2008 - 07:00 PM

Rockauto should list them. They are listed many different ways so you'll have to dig - and make sure there's a picture listed.

Why do you think it's bad? The ECU will throw a code for an out of range CTS.

GD

#13 brokebill

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Posted 12 June 2008 - 07:13 PM

just troubleshooting a hard hot starting problem that started a couple months ago and from looking up old threads that seems to be a common cause of it.

it would be nice to have it in laymens terms how this part contributes to hard hot starting problems.

thanks, Bill

#14 GeneralDisorder

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Posted 12 June 2008 - 07:54 PM

it would be nice to have it in laymens terms how this part contributes to hard hot starting problems.


If the CTS signals to the ECU that the engine is cold, then the ECU supplies too much fuel. The mixture is too rich, and the engine is hard to start.

Now - that's an extreemely generic statement. It applies to a lesser or greater degree depending on how bad the sensor is, and how much control over the fuel system the ECU in question has. In the case of the SPFI for example, it would probably start and run very poorly if the CTS reported a cold engine when it was hot due to the position of the idle air control valve, the cold enrichment being applied, etc. But the ECU would likely figue out what was going on pretty quickly, ignore the CTS sensor input, illuminate the check engine lamp, and go on it's merry way using a suitable replacement sensor input - it pretty much knows the engine is warm once the O2 begins reporting so it can safely enter closed loop operation. Cold starting is more likely to be a problem as most times the CTS's fail to higher resistance rather than lower (indicateing the engine is hot when it is cold).

In the case of the feedback carb the ECU doesn't have enough control over the idle circuit, and has no control at all over the choke, so it can't really cause difficulty in hot starting that I can see.... and if it's not throwing a CTS code then I can't see any reason to mess with it.

The EA82 feedback is a mess of a system. You may have a thermo-vacuum-valve that is opening a vacuum leak when hot and closing it when cold.

What symptoms do you have when it's difficult to start? Is it flooding or starving for fuel? Does it run rough? Are you pumping the pedal? Etc?

GD

#15 brokebill

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Posted 12 June 2008 - 10:38 PM

never had cold start issues, choke and fast idle seem to work great.

when warm or hot it used to always catch the second you bumped the key.

couple months ago it started turning over 3-7 sconds before it would catch when warm or hot.
i've tried pumping the gas , holding it to the floor, holding it barely down, not touching it at all (the way it used to work just fine) and every combination.

if i cut it off for less than 5 minutes, it fires right up without touching the gas just like it always used to, but when it sits for 10 min to a couple hours it gives me trouble.

its never not started but my starter dont need the abuse.
runs out wonderful, just suddenly got harder to start when hot.

at times when hard starting it does seem like its flooded(gas smell)
but i cant say its everytime.

thanks for the good job explaining the cts . it always helps to have an understanding of things as opposed to just blindly changing or even fixing things without ever knowing what you actually did.

thanks, Bill

#16 GeneralDisorder

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Posted 12 June 2008 - 11:16 PM

This is going to be very difficult to diagnose. You only get one shot to reproduce the symptoms every 10 minutes - that's a bummer.

Well - I am of the opinion that you should try disconnecting the duty solenoids and seeing if anything changes. With them disconnected the ECU has NO control over the carb whatsoever. You're mileage will go in the toilet for as long as you have them disconnected, but this is just a test to see if for some reason the duty solenoids are being opened too much durring hot starts.

If that changes nothing with respect to your hot start issue then you can safely assume that the feedback system has nothing to do with the problem directly (indirectly it does - It's existance in the first place changes the vacuum system in fundamental ways that are probably driving this issue) - in other words none of the "electronics" or "sensors" would be at fault. It could be a thermo-valve or thermo-vacuum valve that isn't controlled directly by the ECU.

By FAR the best solution to all your problems (high idle, hot starting, acne, sinusitus, mother-in-law, etc) is to install a Weber. The price you will pay if you look for a deal is nothing compared to the satisfaction the little guy will give you, the performance increase, and the simplicity. I gaurantee you will spend less on a Weber and installing it than you are spending now wasting your time with an antique electronic carburetor. Your time is more valuable than a couple hundred bucks on something that actually works - and look at it this way - you don't HAVE to sell the carb when you sell the car. Keep the old system completely intact - buy a used manifold and pull the whole thing off in one swoop. That way you can put the Hitachi feedback back on it when you sell the car and either recoupe your money by selling the Weber to another member here or on eBay, or just put in on the next car you buy. :)

GD

#17 brokebill

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Posted 13 June 2008 - 02:10 PM

cleaned and wd40 the cts connections, no change on hard hot start.

without touching the gas pedal, let it turn over till it started (after warm) ( cold start and choke still working fine) and seems to be flooded .

took bout 7 seconds to fire and smell of gas was strong.
ran fine after starting.

havent tried hot cranking with duty solenoids unplugged yet.

thanks, Bill

#18 brokebill

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Posted 13 June 2008 - 03:26 PM

ok, i disconnected the duty solenoids and not sure if it helped hot start, but

it idles smoother,
it has more power,
it runs cooler,
and it actually runs quieter(not just under the hood but what comes out the exhaust)

what is the downside of running with them disconnected?
will i have to manually give it a little gas at warm/hot start up since the duty solenoids are disabled?

thanks, Bill

#19 Gloyale

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Posted 13 June 2008 - 03:34 PM

You know, it sounds like a plain old misadjusted or failing float/needle valve to me.

Sometimes we forget about the simple, mechanical aspects of repair, just because glitches in electronics are so often the cause. Sometimes it's just plain old mechanics.

#20 brokebill

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Posted 13 June 2008 - 08:05 PM

did not help hot starting.

it does act like its flooding.
pulled the top of the air cleaner off as soon as i cut off the motor and after about 5 minutes of sitting there, the choke started closing.
after about 15 minutes it had closed at least half way.

had the wife turn it over while i held the choke open and it fired right up.

where to go from here?

thanks, Bill

#21 GeneralDisorder

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Posted 13 June 2008 - 09:15 PM

did not help hot starting.

it does act like its flooding.
pulled the top of the air cleaner off as soon as i cut off the motor and after about 5 minutes of sitting there, the choke started closing.
after about 15 minutes it had closed at least half way.

had the wife turn it over while i held the choke open and it fired right up.

where to go from here?

thanks, Bill


Excellent - so we have narrowed the problem to a non-feedback issue (for the most part), and there's good evidence that the choke is at fault.

Taking your whole situation into account, I think that possibly you have a bad choke bi-metal spring. Now the downside is that these are difficult to find in junk yards because they are nearly always broken, and they are ridiculously expensive from the dealer (somewhere north of $100). Pull it off and take a look. I think you'll find either that the spring is broken near the tip where it's supposed to form a hook, or you will find that it looks burnt, etc.

I would pick up an $8 manual choke conversion kit from you local auto parts store and convert it to an old-school pull style choke on the dash. I did it with the Hitachi on my Hatch and it works just fine.

As for disconnecting the duty solenoids.... your mileage will go in the toilet. It ran cooler because it went rich when you disconnected them. The added fuel cools the combustion - this same technique is used in turbocharged applications and is the reason turbo cars use more fuel when common sense says they should use less. To some extent the added fuel gave you more power (at a huge cost in fuel consumption I assure you), and running cooler allows the timing to advance without any ping. So your symtoms are right in line with a very rich mixture. To overcome that you would have to rejet the carb to non-feedback specs. Basically you would need a donor Hitachi that came from a non-feedback (non-california 4WD model) to pull the jets and air bleeds from - but you could just swap the whole carb a lot easier.

GD

#22 brokebill

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Posted 17 June 2008 - 12:03 PM

when i connect the slow duty solenoid the car immediately idles very rough. disconnect it and it smooths back out.

when i connect or disconnect the main duty solenoid i really cant tell any difference other than *maybe* it is a little smoother throughout driving range when connected.

hard hot starting still exists regardless.

why the extra rough idle with slow duty solenoid connected?

what cleaning up, cleaning out procedures can be done to the duty solenoids?

i know the thread is turning into another troubleshooting a hitachi feedback carb thread but ......

thanks, Bill

#23 GeneralDisorder

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Posted 17 June 2008 - 09:40 PM

why the extra rough idle with slow duty solenoid connected?


I couldn't tell you for sure. It's related to the mixture being leaned out too far most likely. Weather that is because the duty solenoid isn't opening and closing the way it should, because of a vacuum leak, or because the ECU is telling it to be open/closed too much based on poor sensor inputs.... I do not know nor is there a way for me to tell. If you want to troubleshoot the feedback system there is no other way but for you to get a factory service manual (I don't have one covering the EA82 feedback) and go through all the testing and troubleshooting procedures.

what cleaning up, cleaning out procedures can be done to the duty solenoids?


None as far as I know. They are sealed units that open/close at a high cycle-per-second rate. I wouldn't dissasemble one and expect it to work afterward anyway. They are only exposed to clean filtered air so there shouldn't be any contaminates in them.

GD

#24 brokebill

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Posted 17 June 2008 - 09:57 PM

They are only exposed to clean filtered air so there shouldn't be any contaminates in them.GD



little plastic black filter cannister has a "patched" crack in the nipple, so could have possibly gotten contaminated.


maybe a little deep creep seafoam down the in and out hoses and hope for the best.

otherwise, probably just keep running with it unhooked and the main duty solenoid hooked and keep an eye on the plugs to see how it burns.

i really do need a good book for the car, not just the Haynes one i have.

thanks, Bill

#25 GeneralDisorder

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Posted 18 June 2008 - 06:31 PM

otherwise, probably just keep running with it unhooked and the main duty solenoid hooked and keep an eye on the plugs to see how it burns.


That will most likely be a bad combination. The ECU will know the slow solenoid is disconnected and may go into limp mode as soon as it sees it's gone.

GD




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