Hello.

'85 duke auto.

Was running fine all year, two days ago it stalled when going into reverse and sputtered some but after a mile drove okay. Yesterday it had crazy high idle, accelereated on its own past 20mph with shifter in "1" position, threw code 45 (running rich). Then I noticed the vacuum hose going to the EGR was torn off at the valve. I don't know how long it was that way. So I fixed that and drove a few miles with no problems. After those few miles it started sputtering again and died. Now it will start hard (sometimes going WOT at starting will help, rich condition?), will idle high and will run okay for a few seconds when in gear. After a few seconds it will sputter more and more and it'll die. Disconnected battery to clear codes and nothing. Took the EGR off, cleaned it, it seems to work okay (when sucking on the hose the diaphragm moves, no leaks visible. EGR gasket seems ok. Disconnected tach filter. No change. I was wondering if maybe I ruptured some other vacuum hoses but all seems good. Also it smells rich but won't throw any codes anymore but that's maybe because I'm starting it only for a minute or two.

So I'm lost here. The EGR valve is new (2 years in the car). Going to block off the EGR with a plate and block the vacuum passage tomorrow but maybe someone will have some ideas until then. Thanks.

[This message has been edited by cebix (edited 07-17-2016).]

Check to make sure your MAP sensor hose is connected correctly.

Yup, looks correct all right. No idea if it's leaking though... lines look tight but with vacuum you never know. The line is plastic so it's 100% sure if it's not cracked. The fittings though... I have no idea. I tried pinching them with my fingers when the engine was running but nothing changed.

[This message has been edited by cebix (edited 07-17-2016).]

At idle is there no vacuum on the EGR vacuum line? There shouldn't be. If your EGR valve is one that you can get your fingers in and push up on the diaphragm, is the diaphragm all the way towards the engine so the EGR valve is closed during idle? The EGR valve should be closed at idle.

You can try this but not sure if the engine will continue to run - if you pull the vacuum line off of the MAP sensor while running, you should have full vacuum at the line and when you pull the vacuum line off the engine should start running quite rich.

Any chance the injector is leaking?

[This message has been edited by phonedawgz (edited 07-17-2016).]

No leaking fuel anywhere. Spray pattern looks okay, injector is new (2 years), the whole TBI was rebuilt then also.

Yeah, I can move the EGR diaphragm with my fingers. The EGR diaphragm is "down" when there is no vacuum. When I suck on the hose it goes "up" opening the valve. I'm confused a little with the first sentence - should there be full vacuum at idle or should there be no vacuum at all? I guess at idle there should be full vacuum so the valve would be fully opened?

So while working on it today it threw a code 15 on me. Gonna replace the coolant sensor as it reads low. Hope this is it.

If your EGR valve leaks at the pintle (not diaphram), it will allow exhaust gases into the intake and it will make the engine idle quite rough or it might even die. The EGR system is designed to turn off at idle. To do this the EGR system on a Duke is designed that it uses "ported" vacuum which shuts off when the throttle is closed. If the wrong vacuum line however is connected to the EGR diaphragm, that could have it held fully open causing this problem.

Btw, when you floor it the EGR system is designed to have the EGR valve closed, so at full throttle, and at idle it doesn't affect operation.

The introduction of exhaust gasses on an engine running down the highway reduces the oxides of nitrogen reducing pollution. It also improves gas mileage by reducing pumping losses. Also if you were to decide to eliminate the EGR system because you don't like the idea of the exhaust entering your intake, you should also have the PROM reprogrammed to remove the extra advance the ECM has programmed into it.

Again - at idle the pintle should be fully extended thus closing the EGR passage.

Code 15 - Make sure your CTS connector is good and plugged into the CTS sensor. The CTS has a Yellow and a Black wire running to it. If you were running the engine with the CTS unplugged that could cause the code. Plug it back on, reset the codes by disconnecting the battery and see if the trouble comes back. If the connector wasn't disturbed and has been connected the whole time, then replacing the sensor might be the solution.

[This message has been edited by phonedawgz (edited 07-19-2016).]

this sounds like a distributor problem to me. When they get worn, they start having problems when they get warm. Especially when they have a load on them. Is there a lot of miles on the car? If so, this could be the issue, i would look into changing the distributor. Many years ago my dad had a similar problem and it ended up being a bad PROM. But i would lean towards the distributor assembly.

The whole distributor is new including new ICM, pickup coil, cap, rotor so I doubt it. My previous distributor that I'm pretty sure was original to the car rotted out. Tomorrow I'll have the coolant sensor and will post if it solved the problem.

Upload: seems it was it. Replaced the coolant sensor and runs great now. Shame it didn't throw that code earlier or I didn't check the resistance table just in case since it's the easiest sensor to diagnose. And the fact that it occurred EXACTLY when I found the EGR vacuum hose torn off it never occured to me that the problem could be anything else than the EGR.

[This message has been edited by cebix (edited 07-22-2016).]