Nick86

iTrader: (1)

I'm pulling my hair out here.

For a while now my car ('86 GXL) has been running ultra rich and not driving very smoothly. Gas milage was way down and it just wasn't right. I decided it was time for a good solid tune up. First thing I did was check the timing. To my surprise, when I flashed the light onto the main pulley there was no mark to be seen. I figured that this was the cause of my problem, and would be an easy fix.

I put the car at TDC, pulled the CAS alligned the marks then reinstalled it. The car started right up, and once warm, the red mark on the pulley lined up perfectly with the light on L1. Put the light on T1 and the yellow mark is right on. Success right? Nope. Under load the car stumbles and backfires between shifts, and feels sluggish compared to 10 minutes earlier!

Put the timing light on the pulley and everything still lines up perfectly. I also made sure to put the timing clip on the plug lead away from other wires in case of pickup.

So, my innitial reaction is that TDC on the pulley is somehow not right. I do a bunch of searching and come up with this great article:

http://www.teamfc3s.org/info/articles/demystifying.html

Following these directions I locate a new TDC and mark it.

1. Remove both rear rotor spark plugs.
2. Rotate the crank until you can see an apex seal (tip of the rotor) in the trailing spark hole. The trailing plug hole is restricted, making the seal somewhat difficult to see. Use a flexible light and a mirror. When the seal is seen, mark the crank.
3. Rotate the crank until you see the same apex seal in the leading spark plug hole. This plug hole is not restricted, which makes it easy to see the seal. Mark the crank.
4. Halfway between your two marks is TDC for the front rotor (#1) rotor.

Again I pull the CAS and line it up with the new TDC. Car starts right up abut is even WORSE now! It bogs, pops and bangs under any load! WTF!?

I'm pulling my hair out over this.
-The CAS and Ignitors are in spec as per the Haynes.
-Injectors were recently cleaned.
-New Spark Plugs.

What is going on? Before the car wasn't perfect, but now it is completely undrivable. What is going on? Any hints or tips?

Thanks for the help!

Nick86

iTrader: (1)

Any theories?

Is there anything that would (could) change my timing like this?

classicauto

iTrader: (3)

Well, first thing I'd do is ditch the TDC method.

The marks on the pulleys (although they did have paint on them) were actually scribed or punched into the pulley's rear edge. I've even luckily been able to find them on horribly rusted pulleys by sanding them and watching for the "nicks" where the two marks are.

Then align your dots on the CAS' bottom gear, insert and try.

I know alot of people have had success using a "manual" TDC method, but in a case like this I'd say you're best to go back and try a full on FSM installation.

And Nick, if you can't find the marks on the pulley, I may have a set here I can send you.

Edit: Oh, on the note of what might slowly change the timing. I haven't the foggiest Maybe mileage is going down because of something entirely un-related? How much emissions equipment is still on the car? (I recall a thread where you passed? So maybe lots is left?...in which case the 02 sensor comes to mind...)

FCKing1995

iTrader: (3)

Well he said he saw both the red and yellow marks, so Im guessing thats ok.

Im having similar problems as you, so were in the same boat. I replaced all external seals recently, which involved me pulling the engine. When I put it back in and set the timing back, it was much harder to start (my marks were hard to see cause I painted over them like an idiot). It also runs a bit worse. It now lags for nearly a second when I get on the throttle hard. It gets much worse fuel milage and just overall runs like crap. It also is a bit jerky when taking off and it likes to buck a little. Maybe someone knows what our problem is.

classicauto

iTrader: (3)

lol, just re-read that. Oops

I'd still try re-stabbing the CAS using the marks on the pulley as opposed to the TDC method and see what you get.

As far as something that would alter the timing progressively.........I have no idea in the stock system. I mean, short of a coil burning out or a sensor telling the ECU the wrong thing....even then, what sensor would have an effect on the stock timing curve?

FCKing1995

iTrader: (3)

Thats what has me stumped. Ive re adjusted and checked the CAS and timing several times. My timing might be off a few degrees but not nearly enough to make the car run so poorly. Everything else is hooked up correctly as far as I can tell. All that I changed when I took the engine out was to remove all emissions. So whatever is wrong I havent the first clue of how to fix it.

On second thought, how much would the coolant temp sensor throw the timing off? Doesnt it have some role in timing? Im pretty sure mine isnt working now that Ive thought about it. I just had forgotten about it.

classicauto

iTrader: (3)

Thats why you always check the timing (in a stock ECU car) when the engine is warm ie. full running temp.

FCKing1995

iTrader: (3)

Even still, wouldnt that only alter it by maybe no more than 5 degrees? Thats not exactly enough to make the car run as terrible as it does. And yes I ussualy do check the timing with a warm engine.

antnicuk

i'm following this with great interest as i need to set the timing on my new engine and need to get it spot on.

So in theory, When i put the timing light on the leading front plug wire the strobe should pick up the yellow mark and the red mark when on the trailing fron lead?

Is there a problem with the method shown for finding TDC as i dont have the correct pulley for the new engine so i will have to set it up but i need to get it right.

I hope you get it sorted.

classicauto

iTrader: (3)

To be honest, I don't know what the full range of advance would be on your (s4? S5? N/A? TII?) car from cold cranking to full warm.

But if your temp sender isn't working (which one BTW theres a few) then how does the ECU know the engine is warm and make the required adjustments? If it doesn't know it can't adjust and it will always be out.

FCKing1995

iTrader: (3)

That is a good point. For some reason that didnt cross my mind. So I guess the computer treats it as completely cold is no temp sensor is located or used. My car is an S4 T2, and its the sensor on the rear of the thermostat housing/ waterpump housing. That might just be it for me. It has no way to know when its up to operating temp, so it cant correct for fuel and timing. Wouldnt it cause it to treat the engine as cold and inject alot of fuel? Which is why I get horrible gas milage and a rough running engine.

Nick86

iTrader: (1)

Thanks for the replies guys!

As for emission equipment, I have all of it... on my garage floor. The car has no air pump, no cat, and no ACV valve installed at the moment.

When I rebuilt the engine (5 years ago) I made the timing notches on the pulley more pronounced and repainted them. Getting the car timed properly as far as that is concerned - I can do. I even pulled the inspection cover off the CAS so I can hold the gear in place while inserting it into the engine - that way I know for sure it isn't getting knocked out of allignment during reinstallation.

That thermo switch is definately something I need to look into. I remember that I broke the one on the bottom of the rad - but am 99% sure I replaced it. Is that the one that sends the signal to the ECU? If not, which one does?

Thanks again guys!

classicauto

iTrader: (3)

IIRC, the large one on the back of the water pump housing (its got a green bum ) is what the ECU reads from. The oneson the bottom of the rad is for the cold start I believe and the one below the oil filter is for the stock gauge.

Its something to try anyway...hope it helps

FCKing1995

iTrader: (3)

I remember now. I broke the clip off of the plug and it now wont stay on, so Im trying to locate some wire to wrap around the wire then around the waterpump housing to hold it tightly

FCKing1995

iTrader: (3)

Ill be damned. It fixed the problem. I also was having issues with starting the car. I would have to turn it over the first time for close to 5 seconds with my pumping the gas for it to start. Once it started no matter how much I feathered the gas it would die. Second time it will start easier but will die again till about the 4th time. Then It will stay running as long as I keep it above 3,000rpm, until it warms up to operating temp. Now it starts just like it used to. Nice and quick and easy to keep running. Throttle response is back, seems like its not running as rich as it was, at least by the smell of things. I ended up having to use 2 pieces of tie wire. Both 6'', each with a loop around the plug, with the other end running around to the front of the waterpump housing. Then I twisted each end together to pull it tight. Works fine so far.

Nick86

iTrader: (1)

Glad to hear it worked! I hope it is my problem too....

Does anyone have a way to test this sensor/switch?

FCKing1995

iTrader: (3)

Remove it from the car. Put a pot of water on the stove. Check it at room temp (~70F or 20C) by dipping the sensor end into the water, keep the plug area dry. It should read 2.45ohms plus or minus 0.25ohms, then gradualy heat it to ~175F or 80C degrees, then it should read 0.32ohms plus or minus 0.032ohms. That acourding to the FSM

Luckily for me it was like night and day when I plugged it back in. Was like a whole different car.

Nick86

iTrader: (1)

Well, unfortunately (or fortunately I suppose) my sensor was plugged in and it tested perfectly on the stove top.

I'm at a loss. Any other ideas?

FCKing1995

iTrader: (3)

Sadly I dont know. I would say recheck the CAS but Im sure youve probably already, and if not I dont know if 1 tooth off would be enough to make it run that badly. Maybe a combination of things? TPS out of adjustment? Sorry to hear the coolant temp sensor wasnt the issue.

How about an intake leak? not sure how it owuld suddenly spring one if you didnt touch anything. did you accidentaly knock a connector or hose off when you pulled the CAS? If you went to the other side of the bay did you maybe knock the AFM connector off? Check all the hoses and wires you can see if you havent already. If thats not it then Im sorry I have no help for you

HAILERS

During the START cycle, the ECU uses rpm, water thermosensor and the start signal on pin 3B to determine what the amount of fuel injected will be.

If the water thermo sensor is broken, the ECU defaults to a temp of 176 F. See the attached jpg of how the amount of fuel works with different temps.

A higher temp will mean less fuel injected during a start. IF the engine is cold, it won't be enough fuel. That's why a car with a broken water thermosensor is difficult to start when cold BUT not when fully heated up.

FCKing1995

iTrader: (3)

So if the coolant temp sensor is non existant or not working, does the ecu set a default injection time? or does it still vary accourding to other inputs? though looking at that it looks like there are no other inputs... if so do you know what the operating time is