Minor running issues and spark plug condition

[rjkoop]

For my '81 FI, starts great, runs well but have some trouble restarting when at operating temperature. Wanted to check I'm not running too rich or lean. I've driven it only about 300 miles but thought checking the spark plugs might tell me something. How do these look? (I only pulled 3 because the 4th - closest to the cabin - is a bit of a pain to get out).





Judging by pictures online I think they are ok (greyish/white deposits).

[bradartigue]

I can't see your pictures. Good burning is brownish-white...which you may see as grayish. If things seem to run correctly otherwise then check two things: the coolant temperature sender and the idle jet o-ring. If the coolant temp sensor tests bad then replace it, then check the o-ring if the car still runs poorly

[rjkoop]

Checked the coolant sensor at the T and I got
- cold (65 degrees) - 1,630 ohms
- normal operating temp (190 degrees) - 250 ohms

And when I unplug it the engine dies right away. So the connection is good.

So I've removed the idle screw and I see the o-ring deep down. What's the best way to remove? I don't want to score the hole with anything.

[bradartigue]

A toothpick or plastic tweezers usually work. I'd go ahead and replace it - you have the thing out already and have to re-adjust since its out. It is a common enough problem to merit replacing every couple of years (especially with fuels today). You can usually find a fuel resistant one at ACE hardware.

[rjkoop]

I tried taking it out but I think it has disintegrated. I wasn't able to grab ahold of anything. Here's a few pics for confirmation.

The idle screw (can I assume the rubber at the top is normal?)...


The opening...



It's kind of hard to see but I only saw black crud around the outside. Guess I'll clean with carb cleaner, try to get the crud out and replace. Hopefully this will fix my rough idle and bad warm starts!

[So Cal Mark]

you're not posting pics correctly

[courtenay]

you're not posting pics correctly

Thank goodness Pete is back - where are you, we need a picture tutorial here!

[rjkoop]

you're not posting pics correctly

Argh! Something changed on google photos. I can't right click on the photo and Copy the image URL. I think it looked ok to me because I was logged into Google.

I did it another way and it should work.

[rjkoop]

Here's a few more closer pics. The 1st pictures look very white. When I inspect them closely they seem more brown with very little deposits. Hard to get good close pictures though...

[KevAndAndi]

To clean out the orifice, I used a cotton swab, the kind that comes with a swab on one end of a long wooden stick (just make sure it doesn't break!). These are available at the pharmacy. I saturated the swab with FI cleaner and worked from the deepest part up to the shallowest, going around and around with the threads.

What you thought was an o-ring in the orifice was probably just crud. The o-ring is that rubber thing on your screw, and it looks pretty squashed and worn-out. You should be able to find the right size at a hardware store. To repeat something I wrote in another thread:

"Virtually all common plumbing o-rings that you find in the hardware store are made of nitrile, or Buna-N, a copolymer of acrylonitrile and butadiene that resists water, oil, fuel, grease, ethylene glycol, and many other fluids (but is NOT resistant to some other fluids, the most important of which, for our purposes, is brake fluid)."

Your coolant temperature sensor resistance at 65 deg. seems to be out of spec. The ohms should be around 2100 to 3200 at that temperature.

Our car starts right up when cold without touching the accelerator, but when it's warm, I sometimes have to depress it to get the car to start.

While you're cleaning crud, if you haven't done this already, I would recommend popping off the throttle body heater cover and cleaning out whatever you find inside there. In my case, it was nasty: a combination of "rust paste" and hardened deposits that had to be chiseled out. Also, get a new cork gasket from one of our vendors. You'll only need to drain a little coolant to avoid making a mess when you open the TBH.

[rjkoop]

To clean out the orifice, I used a cotton swab, the kind that comes with a swab on one end of a long wooden stick (just make sure it doesn't break!). These are available at the pharmacy. I saturated the swab with FI cleaner and worked from the deepest part up to the shallowest, going around and around with the threads.

What you thought was an o-ring in the orifice was probably just crud. The o-ring is that rubber thing on your screw, and it looks pretty squashed and worn-out. You should be able to find the right size at a hardware store. To repeat something I wrote in another thread:

"Virtually all common plumbing o-rings that you find in the hardware store are made of nitrile, or Buna-N, a copolymer of acrylonitrile and butadiene that resists water, oil, fuel, grease, ethylene glycol, and many other fluids (but is NOT resistant to some other fluids, the most important of which, for our purposes, is brake fluid)."

Your coolant temperature sensor resistance at 65 deg. seems to be out of spec. The ohms should be around 2100 to 3200 at that temperature.

Our car starts right up when cold without touching the accelerator, but when it's warm, I sometimes have to depress it to get the car to start.

While you're cleaning crud, if you haven't done this already, I would recommend popping off the throttle body heater cover and cleaning out whatever you find inside there. In my case, it was nasty: a combination of "rust paste" and hardened deposits that had to be chiseled out. Also, get a new cork gasket from one of our vendors. You'll only need to drain a little coolant to avoid making a mess when you open the TBH.

Kevin,
Thanks for the info. So the o-ring seals the top of the screw and the bottom is just tapered into the metal seat? I guess that makes more sense. I'll look for a new o-ring. From your info I should be able to use a nitrile o-ring because it resists fuel, right?

I had the entire head off and already cleaned the throttle body heater cover as well. Mine wasn't too bad.

I'll do another reading on the temperature sensor. I'm getting closer to the end of season so I'll probably replace in another month or so if the reading is still out of whack.

I'm going to do the propane test and check for vacuum leaks. From what everyone says vacuum leaks cause a multitude of issues so you have to make sure things are air tight. I probably have a vacuum leak at the idle screw o-ring area for sure.

Richard

[rjkoop]

No vacuum leaks with propane test (even at the idle speed screw). Couldn't find a replacement o-ring yet but the old seems good enough for now. I'll still get one when I can find it. Double checked timing and it's at 10 BTDC no problem. Also checked that all 4 spark plug wires are getting spark by attaching the timing light clip onto each spark plug wire.

Exhaust is kind of smelly (not fuel smell, not coolant, just regular exhaust... whatever that is!). It runs good at 900 rpm but then every 2 -> 6 seconds or so RPM changes a bit (usually down I think) and then I can hear what sounds like a muffled miss/stumble/backfire. Not a backfire I don't think because it's not really noisy. Just a minor miss and a muffled sound out of the exhaust. And then it's fine again.

Any ideas? I cleaned the AFM last year and ensured a clean track on the dial. Or maybe this is all because of that silly o-ring on the idle screw?!

[bradartigue]

Get a new o-ring, get the idle back to spec, then check/adjust the ignition timing. Your pics are posting now - it may be a tad lean but you are burning evenly. The o-ring replacement may fix that.

Absolutely replace that o-ring on the speed screw, that thing looks hard, flat, and original. If it is letting in a little air it can make you run a little lean.

According to my L-jetronic guide you are in spec for the coolant sensor.

[rjkoop]

Get a new o-ring, get the idle back to spec, then check/adjust the ignition timing. Your pics are posting now - it may be a tad lean but you are burning evenly. The o-ring replacement may fix that.

Absolutely replace that o-ring on the speed screw, that thing looks hard, flat, and original. If it is letting in a little air it can make you run a little lean.

According to my L-jetronic guide you are in spec for the coolant sensor.

Brad,
Thanks for the info and spending the time to help out. I'll look around for the that o-ring size again. Went to Lowes and Cdn Tire and they didn't have the size. From what I've read I need 10mm (3/8") outside, 6.5mm (1/4") inside and thickness of 3.2mm (1/8").

Wife is gone for 2 weeks so I have as much time as I want to work on this.

Richard

[bradartigue]

Get a new o-ring, get the idle back to spec, then check/adjust the ignition timing. Your pics are posting now - it may be a tad lean but you are burning evenly. The o-ring replacement may fix that.

Absolutely replace that o-ring on the speed screw, that thing looks hard, flat, and original. If it is letting in a little air it can make you run a little lean.

According to my L-jetronic guide you are in spec for the coolant sensor.

Brad,
Thanks for the info and spending the time to help out. I'll look around for the that o-ring size again. Went to Lowes and Cdn Tire and they didn't have the size. From what I've read I need 10mm (3/8") outside, 6.5mm (1/4") inside and thickness of 3.2mm (1/8").

Wife is gone for 2 weeks so I have as much time as I want to work on this.

Richard

I've bought them off of the Vitron o-ring rack at Ace Hardware!