XJ6 & XJ12 Series I, II & III 1968-1992

Hard start, low rough idle, stalling

 
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Old 03-16-2019, 02:35 PM
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Default Hard start, low rough idle, stalling

Good afternoon.
I am having issues with my 83 xj6 series 3
after finally having some decent weather and some time, I finally changed my fuel tank changeover solenoids. One of them was bad and only had use of the right side tank, left side tank was dumping into the right side.
anyway, car has sat for a couple of weeks and the battery died ( I believe I have a draw) so I jumped started it and ran the car but after a few minutes the car developed a very low (400-500rpm) rough idle
I cannot increase it because it will get worse and stall. When it does stall, with enough cranking I can get it to start and hold my foot on the has pedal to make it to up to 3k rpm but eventually it forces itself back down to that low idle and any attempt to raise it results in a stall, with lots of popping
Could this have something to do with those solenoids? I made sure the correct one is in each place. And made sure the wires were correct when connecting.
I have tried putting the paper clip on the coolant temp sensor, as well as the thermotime which had no change. Disconnecting the coolant sensor, as well as the AFM will each make it stall
disconnected the cold start injector with no difference.
I don't have access to a noid light, however I can physically feel each injector clicking.
When physically moving the AFM flap the fuel pump relay clicks.
the fuel pump works and can manually power it with the power probe
I'm not sure where to go with this. This car is so temperamental.
while it's idling badly, i get a strong smell of fuel so I checked the pressure regulator, there was what I would describe as dampness maybe slightly wet at best so yeah maybe that's going bad but enough to make it run that bad?

any help would be greatly appreciated
 
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Old 03-17-2019, 05:16 AM
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Old 03-17-2019, 09:55 AM
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I've read through this 3 times this morning. Maybe I'm just missing something or I'm not getting it.
just makes absolutely no sense to me. If I can get it to start it'll run at like 3k but slowly drop off to not allowing above a 500rpm bad idle.

perhaps i need to find a place that specializes in these cars because I'm growing pretty fed up with its constant issues and it's causing me to overlook something .
Unfortunately the only ones I can find would come with a horrendous towing bill due to distance.
 
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Old 03-17-2019, 10:18 AM
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what year is the car? not the Registration / Model Year, but the BUILD year. It will be on the Driver's door sticker
 
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Old 03-17-2019, 10:24 AM
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never mind, it is probably a 1982 BUILD.

Does it have an Oxygen Sensor at the exhaust manifold "Y" ? Does it have 1 wire only?

if yes, get a thick copper wire and wrap it tight around the metal base of the O2 sensor, (with engine cold), then loosen a bolt nearby and wrap the other end of the wire around the bolt and tighten it. See if it makes any difference. (I doubt it but try it).
 
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Old 03-17-2019, 10:27 AM
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you might have a sticking Auxiliary Air Valve, maybe Doug will show up and explain it.
 
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Old 03-17-2019, 10:40 AM
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February of 1983
it does have the 1 wire O2 sensor. I am aware of adding the ground to it, And I have been meaning to do that modification for a while now but with the winter and all...havent had much snow but where I am has had weeks of serious cold.

I can just run a wire long enough to the grounds on the back of the water rail correct? Last year I was having issues, or thought I was, with the ignition amplifier and thought it needed a better ground. So I tried adding one off the body which I seemed to have a hard time finding. Maybe due to the fact everything is painted in there.
I will have to stop at my storage unit tomorrow after work and dig out my old spare harnesses from when I worked for Chevy and pick some wires off it
 
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Old 03-17-2019, 10:46 AM
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Originally Posted by Jose View Post
you might have a sticking Auxiliary Air Valve, maybe Doug will show up and explain it.
the car always did have a high idle in park/nuetral but fine in drive. Which I read could cause that. I put it on the list of things to do after its other random running issues were sorted out....i wonder if that's contributing to my constant on and off issues
 
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Old 03-17-2019, 10:52 AM
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This is generic information only. My experience with the DOHC ended rather quickly after I got the car!!

Basic factoid. IC engines need air, fuel, spark and compression. Each at the right time and the correct amount.

Clearly, your car is a short on one or more.

1. Make sure the battery is up to 100 % charge or close to it.

2. Old and/or contaminated gas can cause odd running.
3. Run a compression test. One or two dead holes can do this...
4. Fuel pressure guage. Regulated to about 35 PSI ?
5. Spark at the plugs. Crackling blue. Wimpy yellow not enough.

Carl
 
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Old 03-17-2019, 11:12 AM
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I've felt the frustration you expressed above. Hang in there, it is probably something simple but overlooked and once you find that issue it will purr like a kitten. I had an old American car that had continuing problems. I checked everything a dozen times and everything looked perfect, still no love. Finally replaced the distributor and it purred. This issue was over a year but .... Finally got it. Of course I wasn't depending on that car to get me to work on time. Give our Forum experts a chance to help you resolve it.
 
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Old 03-17-2019, 11:18 AM
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the factory ground strap is at the front passenger side, between the rear of the engine block and the front of the transmission bellhousing, and then it is bolted to the body laterally accross. Remove it and clean all the contact points shiny with a wire brush.

also clean the two power posts sticking out of the firewall, and the wiring ring terminals, those are hot always so disconnect the battery first before messing with those posts and wires.

grounding the O2 sensor: no you don't need to go to the opposite side of the engine, just run a wire from the sensor to one of the cruise control bracket bolts, that's all. For my 1984 I did a O2 sensor strap with ring terminals, you can see it in my website below. It did improve my idling, My engine idles very stable.

I still suspect a clogged / sticking Auxiliary Air Valve.
 

Last edited by Jose; 03-17-2019 at 11:22 AM.
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Old 03-17-2019, 11:39 AM
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Originally Posted by Yellow series3 View Post
I've felt the frustration you expressed above. Hang in there, it is probably something simple but overlooked and once you find that issue it will purr like a kitten. I had an old American car that had continuing problems. I checked everything a dozen times and everything looked perfect, still no love. Finally replaced the distributor and it purred. This issue was over a year but .... Finally got it. Of course I wasn't depending on that car to get me to work on time. Give our Forum experts a chance to help you resolve it.
Working on my old American car (Camaro) and sometimes my newer ones, are a dream compared to my jaguar lol, but I suppose it keeps me busy and they all keep me from being cooped up in the house.

Originally Posted by Jose View Post
the factory ground strap is at the front passenger side, between the rear of the engine block and the front of the transmission bellhousing, and then it is bolted to the body laterally accross. Remove it and clean all the contact points shiny with a wire brush.

also clean the two power posts sticking out of the firewall, and the wiring ring terminals, those are hot always so disconnect the battery first before messing with those posts and wires.

grounding the O2 sensor: no you don't need to go to the opposite side of the engine, just run a wire from the sensor to one of the cruise control bracket bolts, that's all. For my 1984 I did a O2 sensor strap with ring terminals, you can see it in my website below. It did improve my idling, My engine idles very stable.

I still suspect a clogged / sticking Auxiliary Air Valve.
I visited your website and saw the part you sell, which I will of course be more than happy to purchase from you. I looked into making my own but no one seems to have a ring terminal that large in stock. Not even Lowe's
I was just wondering about the ground usage in general, if it would have been easier to use an existing one. Surely I'll find something much closer.
as for the air valve...does that sort of work with the cooling system? Like, as the engine gets hotter it opens or closes? I suppose if it's stuck closed and it's not allowing enough air and starts to choke the engine down....maybe that's why when I first get it running and I can wind it up to 3k but slowly lose the engine speed? And if it is stuck closed and wouldn't allow the engine to even start as its doing now, along with possibly being flooded, as I am able to get a mild odor of fuel.

I appreciate the advice so far. It is starting to make me feel a bit better about getting this problem fixed
 

Last edited by HeavyMetal80; 03-17-2019 at 11:42 AM.
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Old 03-17-2019, 12:02 PM
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I bought those giant ring terminals from a company that only sold them in a package of 50, so I had to buy them. The strap I use is a braided copper strap,
very nice quality. Mine has been installed since the mid-1990's. It will reach from the sensor's base to the cruise control bracket bolt with plenty length to spare.
You could try adjusting (opening or closing) the hex screw at the Aux. Air Valve, but you need a bent Hex wrench with the right "curvature" to be able to access the screw. I think Doug uses a socket mounted hex tool. The size is 7/32" The one I have was given to me by a member of this forum who made a few of them.

Doug is the one who understands that aux. air valve. I have no clue, I've only adjusted it once and it was for idling.

 

Last edited by Jose; 03-17-2019 at 12:16 PM.
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Old 03-17-2019, 12:27 PM
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Wire and electric stuff source. source.

I was playing with my VIZIO smart TV. You Tube. Air shows at OSH Kosh!!!.

A vendor had a huge display of wire, connectors covers, zip ties, shrink tubing,
super looks and quality. "Wireit" on his short. I've not searched to verify...

Carl
 
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Old 03-17-2019, 12:30 PM
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Okay I think I see what you are talking about. This is on the distribution block itself, on the intake right next to the throttle body?

or the air valve itself that's attached to the water rail with the 2 wire connector
Since I'm not able to run outside at the moment I took a picture from my parts book I use someone has in their website.


I have plenty of hex keys, I'm sure one can be sacrificed for a good cause
 
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Old 03-18-2019, 04:11 PM
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Jose,
when I got home from work, I modified a hex key to fit the screw. I started moving it, crank the engine, repeat until it started and eventually ran.
before doing this I had unplugged a few things to check the connections and plugged them back in except for the air flow meter. Upon realizing I forgot to plug it back in, I did and the car died. It ran, though not very well, with it unplugged. Started the car back up and after whatever excess fuel was in there cleared out, ran just fine. Idled high which it always had, about 1200-1300 rpm in park.
after adjusting the screw it now idles normal at 800-900 rpm in park

freak thing?
Having the meter unplugged and plug back in reset it somehow?
so far multiple engine starts and no stalling or running poorly
perhaps I'll just close the hood and pretend it never happened.
 
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Old 03-18-2019, 04:25 PM
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wow, those AFM can be a total mystery!! But I am glad you got it running good. OR, maybe moving that idle air screw did something? OR maybe the AFM got an electric shock to wake it up?
 
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Old 03-18-2019, 06:34 PM
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Well I took the car for gas, started right up both here and there, and obviously made it back. Idles in park between 800-900 and in drive like 650ish. I'm not sure what happened. Maybe you're right moving that screw did something or the afm got a kick in the head.
perhaps when I jumped it Saturday using my Silverado, the voltage caused it to have a senior moment and running the car with it unplugged and plugging it back in woke it up

or perhaps I need to schedule an exorcism lol.
I did also threaten to trade it for a Peugeot.....so maybe she was like...alright you win
in any case hopefully it stays running this way and I can finally move on to other things I'd like to do to the car.

I thank you for the advice, pointing out the air valve block and adjustment helped out big time
I am also interested in purchasing that ground for the O2 how would I go about doing so?
Tim
 
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Old 03-18-2019, 06:59 PM
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Tim,
with the AFM what happened was that you cleaned the contacts at the plug by removing it and reconnecting it.

and by moving the hex screw back and forth it unstuck whatever was sticking . Can't be anything else.

for the strap, just go to my website, click on contact and send me an email.
 

Last edited by Jose; 03-18-2019 at 07:02 PM.
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Old 03-18-2019, 07:26 PM
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I am sure you are right and hopefully these issues are resolved
thank you
I will be buying that strap from you soon!
 
 
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