1980 2.3Turbo Overboost

[rat-racing]

I have been in the process of trying to get all the vacuum lines back in their original/stock locations. The car is running better, However, I am now getting the Engine Warning Light accompanied by the "Overboost" warning buzzer under heavy acceleration. The green "Turbo" light comes on and I can hear and feel the boost then if I continue acceleration the buzzer and warning light happens Any idea what vacuum hoses ultimately control the wastegate actuation to dump off boost? I see 2 lines originating below and slightly forward of the turbo. The smaller of the 2 and forward-most is connected to the main metal vacuum line coming from the rear of the engine. The larger of the 2 lines and rear-most is not connected to anything. I was informed by another FEF member that the larger line was supposed to connect to a fitting on the base of the aircleaner in the rear. The manual I have does not show the routing of either of these lines but describes the larger line as the "rear wastegate actuator vacuum line"

Anyone have any ideas what my problem is? It apperas that the wategate is not functioning and allowing the excess boost to dump off. I am not familiar with how this works but I suspect it has something to do with these 2 vacuum lines and how they ar connected.

Thanks,
Mark

[79turbocobra]

my 79 turbo does the same thing. it just might be normal. hope someone on here can share their input cause i would like to know also.

[gr79]

At least the warning lights are working.

Is there a c-clip on the wastgate arm end at the wastgate 'lever'?
Is that little check valve on the little hose facing the right way?
Any deviations like no check valve, too long of hose may cause the over boost.
I found that out experimenting with that little hose. Was trying to find out how to increase the boost a little. It was sensitive to the above hose mods. It can hit 10-12 psi.

A boost gauge would tell how many psi you have.

I dunno, mine works fine the way its connected.
Car is an 10/78 build. Maybe Ford changed something on later builds?

The Ford shop manual schematic, of the 79 turbo engine vacuum routing, does show the big hose connected to the manifold tee, located below the front of the carb. When i switched the hose connection there nothing worked right. Maybe yours will.
They made that big hose a certain diameter, shape, and length so it can only reach so far.

The little one works fine connected to where they say to (#4 runner).

[79turbocobra]

i just read a post by gr79 helped me out big time!!! now i know what that extra hole in the back of the air cleaner is for

[79turbocobra]

took the old cobra out this morning NOW THAT I HAVE THE HOSES IN THE RIGHT PLACES ON THE WATSE GATE!! car ran great now no over boost light or buzzer ran it up to 6k more responsive with no pinging. went from 4th to 3rd floored it could here the watse gate dump the boost SOUNDS SWEET!!! but now cant keep the car from stalling when comming to a red light!!@@!@ back to more adjustments on the timming i am guessing now that it runs better?? unless somebody has a better thought???

[gr79]

took the old cobra out this morning NOW THAT I HAVE THE HOSES IN THE RIGHT PLACES ON THE WATSE GATE!! car ran great now no over boost light or buzzer ran it up to 6k more responsive with no pinging. went from 4th to 3rd floored it could here the watse gate dump the boost SOUNDS SWEET!!! but now cant keep the car from stalling when comming to a red light!!@@!@ back to more adjustments on the timming i am guessing now that it runs better?? unless somebody has a better thought???

Great.. glad to help..was beginning to wonder if mine was somehow different. Just curious.. Where was the big hose on yours?
Every engine is different as far as tuning goes.
Yah play around with dialing it in. Idle screw, timing, idle speed. If you have a vacuum gauge, it should pull a steady 18-20" at idle, engine warmed up.
Tach will stay put, like exactly 1000 rpm or whatever. The vac hoses to the carb affect the idle/stall thing. Pull a little vac hose off the intake manifold to see if the idle picks up or smooths out.

With a little tinkering i have cured a similar stall. It used to stall the first 2 stops when cold, then was ok once engine warmed up. Did that ever since new. Engine always liked a little higher idle speed too. It was a vac hose connection-did not mess with timing which is set as far up as it can go without knock. Never ran good with the choke. Choke is always wide open now, even in the winter up here.

[79turbocobra]

****!!! found the issue the screw came out of the carb on the 2nd barrel of the carb. would have been super easy to fix IF i would have seen it first!! damb it!! now i have to readjust the timming and idle scews fuel screws SINCE I STARTED MEESING WITH THOSE FIRST SOOOOOO PISSED SINCE IT TOOK ME HOURS TO GET THE CAR TO IDLE AND RUN PERFECT! back to square one AGAIN!!!!

[gr79]

Great follow-up, nice pick off. Gotta love the obvious ones...
Its all be worth it in the end. No breakdown miles from home base.
Detailed inspections are forever a part of maintenance and troubleshooting.

[79turbocobra]

YUP!! LOL! well looks like its very close to normal lol well where it was tuned before. next is going to install a 3 row aluminum rad to keep her running cooler.

[rat-racing]

79turbocobra, Did connecting the large hose to the air cleaner take care of the overboost problem?? Mine right now is laying against the fender well connected to nothing. I have an open hole in the rear of the air cleaner base but there is nothing to connect to. Can you send me a photos of what this looks like. I also checked my timing because even under normal acceleration it was "Rattling" the valves. I found it was advanced as far as the vacuum advance canister would go (counter-clockwise) before it hit the engine block (approx 40 degrees advanced) I backed the timing way down to around what the specs call for (6 degrees BTC) It now idles a lot smother but I also now have the same issue with it dying when I push the clutch in to stop. It is only now that I dropped the timing that I am getting the overboost!! When the timing was way advanced I was not getting the overboost but it was probably because I never wound it up because of the detonation!!! When I first start it cold the idles goes up to around 3000 RPM. My choke stays completely closed even when it is warmed up and when it is warm it idles so low I can't keep it running!!! Any suggestions

[rat-racing]

79turbocobra, I also forgot to ask you what screw were you referring to that you found had come out?? Just trying to not overlook something obvious, either!! Thanks

[kckeener]

all the screws and all the mounting screws come loose VERY frequently. I put split lockwashers on them all

[79turbocobra]

79turbocobra, I also forgot to ask you what screw were you referring to that you found had come out?? Just trying to not overlook something obvious, either!! Thanks

the screw on the pass side of the carb that lets fuel into the 2nd barrel of the carb put some loc tite on it its not comming out again lol.

[gr79]

"Previous owner had this line going through some type of adjustable valve???"

Now gotta figure out rat-racing's delima.
Previous owner messed with things. Who knows what.
Need to check everything. Its not the big hose.
Dist. may be in wrong having to move it that far.
Choke always closed, idle 3g, overboost= lots of things to sort thru.
Cam timing, correct 3 connector Duraspark box, etc.

[rat-racing]

You are correct gr79 about a previous owner having modified the routing of the large hose through an adjustable valve. My guess was this was some sort of way to "trick" the wastegate into thinking the boost was not as high and therefore allowing the turbo to put out more boost before the wategate opened?? Curious how you knew that?? Do you know the prior owner? Is he a FEF member? I bought the car from FEF member pharrison who bought it from (I believe) the original owner in Wisconsin. It was like that when he purchased it as far as I know because he had posted a thread back in Dec 2008 requesting help with this same issue with the carb and running rough

I took the car out for about a 70 mile cruise today and on the open road it performs perfect, except for the overboost on wide open throttle. The other issue is that when it is warm and the choke is wide open (as it should be on a warm engine) it will not idle. If you hold the choke almost closed with you hand it will bring the idle up. Just the opposite of what you would expect with a warm engine????? I am beginning to think there is either a "big" vacuum leak somewhere I can not find or there is a problem with the idle circuit with this carb. I still have no clue about the overboost issue??

[ashley roachclip]

Don't those carburators have screws that hold the base plate to the carb body ?
If so I would check to make sure they were all in and tight , use split washers as others have stated.
YOu are right , if you have to close the chike on a warm engine , you have a vacume leak , or idle circut blockage

[gr79]

"Previous owner had this line going through some type of adjustable valve???"
was quoted from other post about waste gate. No connections here, r-r.

Engine off check:
When that little hose on the waste gate actuator is slowly pressurized, say with a mity vac pump to like 6 psi., wast gate arm should move toward firewall.
The wast gate has to open to dump the extra boost and keep the over boost light off.

Blocking air (choke closed) causes carb to supply a too rich fuel mix to a warm engine.
Engine is somehow getting extra air, leaning that mix up enough to run ok.
Running ok warm, with choke closed, indicates a overall too lean fuel condition.
In this case, running bad with choke wide open means the overall fuel mix is too lean.
Too much air to fuel is a indication of a possible vac leak, a source of extra air from
a loose intake, carb, vac hoses, cracked parts, gaskets, charcoal canister, etc.
The air/fuel ratio may be ok for regular driving but goes too lean for boost (spark knock).

Get the engine to run smooth, then spray some carb cleaner or the like around vac sources, carb base, manifold. If there is a leak, engine will suck in the spray and run shaky.

A big vac leak could be multiple little ones or mis-routed/missing vac hoses.
Engine should respond to adjustments of idle mixture screw and curb idle adj. screw.

Its a puzzle for sure finding any hidden mods, parts out of spec, recalib of engine.
Threw in some thoughts and book hints i have went thru to fix a similar problem.

[rat-racing]

gr79, Thanks so much for the info. I will definately go "on the hunt" for a possible vacuum leak. I really think that is my problem.

Your explanation of the function of the small hose and it pressurizing the wategate actuator and ultimately opening the wastegate to dump boost all makes perfect sense. Is there a way to manually check if the wastegate arm is functioning properly?? Also what is the function of the large hose coming off the wastegate actuator and where is it supposed to be connected???

Thanks again!!

[gr79]

It was time to dig out the factory shop manual vac schematic for the 79 2.3 turbo, 49 state.
Schematic shows the big hose connected to the vac tree where the power brake booster taps into, under and in front of carb.

What is the big hose's real function? I wonder too. Assume a dual port actuator (2 hose).
Typed in a search. Read this, especially the part about Control, pneumatic.
http://en.wikipedia.org/wiki/Wastegate

Seems to be saying the big hose function is to slow down the opening of the wastegate.
Interestingly, the article states "the second port is not necessary.."

Again, to see the wastegate arm/actuator function: Engine off, slowly pressurize the actuator small hose port to 6 psi.
Connected directly and correctly, a Mityvac pump is the perfect tool for doing this.
The actuator rod should push the gate arm from about 6 o'clock (zero psi, closed) to 4 o'clock (5-6 psi, wide open) as psi increases.
Release pressure, and the rod pulls the gate arm back to the 6 o'clock position (waste gate closed).
This is a manual check to verify the wastegate control assy. is functioning independently.
If nothing is connected to gate valve, no boost will build. Exhaust will simply blow the flapper open.

[Sellis1012]

RR, I pmd you. Sorry for the delay. I answered your questions and it looks like we're all on the right track.

You are correct gr79 about a previous owner having modified the routing of the large hose through an adjustable valve. My guess was this was some sort of way to "trick" the wastegate into thinking the boost was not as high and therefore allowing the turbo to put out more boost before the wategate opened?? Curious how you knew that?? Do you know the prior owner? Is he a FEF member? I bought the car from FEF member pharrison who bought it from (I believe) the original owner in Wisconsin. It was like that when he purchased it as far as I know because he had posted a thread back in Dec 2008 requesting help with this same issue with the carb and running rough

I took the car out for about a 70 mile cruise today and on the open road it performs perfect, except for the overboost on wide open throttle. The other issue is that when it is warm and the choke is wide open (as it should be on a warm engine) it will not idle. If you hold the choke almost closed with you hand it will bring the idle up. Just the opposite of what you would expect with a warm engine????? I am beginning to think there is either a "big" vacuum leak somewhere I can not find or there is a problem with the idle circuit with this carb. I still have no clue about the overboost issue??

[Sellis1012]

This should help you guys.

[Sellis1012]

[79turbocobra]

was going to post those pics but looks like sellis beat me too it lol

[79turbocobra]

too bad us guys that own these turbo cobras don't live closer too each other so we can compair vacuum line routing LOL!!! since every turbo car i have seen is a little different in where the vacuum lines go.

[gr79]

I noticed colored plastic vac lines vs rubber hoses.
1980 cars look to have some different parts and routing than 79.
Real treat to see that clean one. Its been too long.
I agree about meeting and comparing notes, especially 'transporting' to fla.
Winter/cold weather up north here put a halt to most outdoor work and play.