Loooking for fuel injection opinion

[sheetsofsound]

I'm far from sure I'm looking in the right place - haha. Your tribulations sound more frustrating than mine. I had wondered about whether the modern electrics could fail, so your experience shows its possible. It will be an avenue to investigate further should things stop improving. At least with this forum, people have been helpful and pretty much kept me moving forward in spite of my bouts of ineptitude.

I found instructions for how to set up the optical pick up on the Chicagoland MG site. Once I moved the pick-up - a matter of a millimeter or two - the random quitting, lack of power under load, and backfiring stopped happening. The continued occasional miss as evidenced by periodic engine rocking and the uneven exhaust pulse seems less severe as well. I'll put it on my friend's exhaust sniffer next week and see if the readings are improved enough to get it on the road. After that, then the fun will really begin.

[Workshop Help]

Thank you! That's very good.

As our friend Hasbeen says, a new Pertronix Ignitor unit will cure many ills.

About the requested photos, using the article for checking your mixture found in our new Workshop Manual area, remove the bolt plugs for #1 & #4 cylinder. Start the engine and observe the exhaust color with the aid of a mirror in the plug holes. Adjust the mixture to achieve a bunsen blue color. Reinstall the bolt plugs.

Moving on to other items, I see your vent hose from the valve cover to the two carburetor hoses is missing. This is important as the oily engine vapors are not being drawn into the engine. This also is not promoting an efficient crankcase ventilation. Please fix this today.

I am glad to see you have manual chokes on your Z-S carburetors.

The EGR is also non-operational with it's vacuum hose disconnected. For emissions testing, a functioning EGR valve is necessary to cool down combustion chamber temperatures to minimize production of nitrous oxides.


Mildred Hargis

[sheetsofsound]

I have used your article before to tune my other car, which worked really well - thank you. I will do that once I return home next week, along with the crankcase breather.

I have managed to get my hands on a charcoal canister and most of the bits to hook it up. I'm missing a metal tube and mounting brackets, nothing that can't be improvised. I plan to do that next week as well.

I'm not sure the EGR valve is functional, and it is different than the one on my other car.

[sheetsofsound]

Alright. Got back at it tonight. Pulled the bolts to check the colour of the flame. I couldn't see a flame. Turned off the lights in the garage, still no spark visible. Same problem on cylinders 1 and 4; no visible spark. I have performed this operation successfully on my other car, so I don't think its something stupid that I'm doing, although bitter experience has taught me to never rule that out completely.

I noticed when I pulled the bolt on cylinder 1 that it didn't sound like it was firing evenly, so I think that is where my misfire is happening. Cylinder 4 purrs along nicely.

Pulled the spark plugs. Pictures are below. From the threads, it looks like the heat range is correct. Plug 4 shows a line on the ground strap close to the threads, which I think means too close to 0 degrees TDC? I'm not sure why the porcelain is coloured unevenly with no consistent line, but could this also be an indicator of too much timing? What is the powdery coating on the ground strap? Is this normal, or does it indicate fuel deposits?

[Workshop Help]

The spark plugs appear to be relatively new, but are misfiring due to an over rich condition. What kind and how old or dirty is your air filter?

Also, is one or more of your spark plug cables malfunctioning? Using your ohm meter, check each cable for the desired more or less 5000 ohm reading. If a cable shows a '1' on the digital ohm meter, it is bad.

Here in the machine shed, we use real wire spark plug cables that pass 100% of the electrical juice to the spark plug to prevent misfires. I have an article here in the forums on creating a set of these cables.

If you are using the stock(ish) air filter, it more resembles cardboard than filtering paper and is quite restrictive as to air flow. We use a K&N filter as it passes far more air, is cleanable, and looks to last forever.

Mildred Hargis

[FI Spyder]

Your plugs should look like this. These were recently pulled from my TR7 after 16,000 miles on an engine with over 102,000 ,miles on it, much of it loafing a around at 2,000 rpm on rural backroads. There should be a powdering of light tan on electrodes and insulator. The inside of your exhaust pipe should look the same. Mind you this is from an FI car that gives the optimum air fuel mixture but this is what you aim for.





- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[Workshop Help]

Here we go again! FI Spyder, your top spark plug indicates a weak ignition cable from the presence of those deposits.

If it's the last thing I do in this life, I'm going to have to go around to each and every one of you Goomers and install a set of real wire ignition cables on your engines! And when I get there, you'd better have a nice lunch on the table for us.

Mildred Hargis

[FI Spyder]

It looks worse than it is. My digital camera does that. Visually (in real life) they all look the same. The (no doubt cheap) wires are 8 years old now. Am going to replace them with Magnacor eventually. I had wire wires and resistors on my Javelin but will get the best of both worlds (low resistance of wire and no RF interference) of the Magnacors.

I've replaced these Autolites with NGK G Power plugs and could notice a difference of going over the Malahat in overdrive with more power.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[sheetsofsound]

Once again, work has interfered with what's really important and I am currently out of town. However,I was reading some articles and came across something of interest. Someone using the same Crane/Allison ignition system had a misfire problem due to the tachometer. I am wondering if that could be part of the misfire problem. The test is to disconnect the tach from the coil and see if the misfire disappears. Something to try when I get home.

Also, as Mildred has pointed out, the plugs look as if the beast is running rich, yet the raise-the-air-valve test at idle seems to indicate that it is running lean. I'm not sure how to interpret that, except that perhaps to clean the plugs and run the engine for awhile and see if they look the same. I didn't clean up the plugs after my initial attempts to start the engine, so perhaps my earlier runs at leaning out a rich mixture are still evident on the plugs?

[Workshop Help]

Please, refresh our memories.

Did you replace the float inlet valves? Did you thoroughly clean the accumulated scale off the floats? Did you set the float level at 11/16"?

Given the previous owners less than stellar efforts, returning the engine to a stock-ish condition will establish a plausible base line and enable you to pass the emissions test.

Mildred Hargis

[Hasbeen]

The trouble with buying a second hand car is you have no idea of what little things may have been done to it by a previous owner. One may have fitted richer needles.

Someone may have sanded down your carb needles, or set the thing up so the needles rubbed on the jet, wearing both not enough to see, but enough to change the mixture.

My current 7 had this problem. The jets were worn oval. The thing ran so rich at higher revs, blipping the throttle would blow enough soot out the exhaust to be seen on the grass behind it. I could still get it to idle quite nicely. Tracking down some of these little modifications can be quite difficult. Do your carbs have the correct needles in them?

In your case, perhaps fitting the next stage leaner needles, or removing the air filter, to allow easier airflow, may get you through that test.

Hasbeen

[sheetsofsound]

Inlet valves were changed and the floats were cleaned and set to the specified height.

Taking your point about modifications, I have another pair of carbs on a running (but rusty) vehicle that I am trying to sell. As I have had no luck unloading it, I could try swapping the carbs. Those carbs I rebuilt a year ago and I got that vehicle through the emissions test with very little effort.

I think that if the misfire can be solved, the car will pass. Right now the car passes the NO, CO, and HC during the driving test, and only flunks the HC test at idle when the misfire is most apparent.

The question seems to be whether the misfire is caused by an electrical fault, a carburetor fault, or a combination of both possibilities. Am I right in thinking the state of the plugs suggests the carbs? Certainly the haphazard installation of the aftermarket ignition suggests electrical. (Most of the electrical connections were made by tying bare wires together using some sort of knot and covering it with electrical tape. I have undone, soldered and covered most of the connections with heat shrink, but I haven't investigated the connection to the tach.)

As I have not been able to see the car for the past few days, this has been a thought experiment of sorts and I have not been able to test my theories. I should be home tomorrow to investigate further.

[Workshop Help]

Thanks for the memory refresher. Please go ahead and install a Pertronix Ignitor. Confirm each of the spark plug cables is more or less 5000 ohms of resistance. The custom set of real wire cables can wait. Clean the spark plugs by sanding the contacts on the spark plugs with emery paper to get shiny metal.

This should eliminate the ignition misfire.

Mildred Hargis

[sheetsofsound]

Alright. So frustrated.

New wires, all at similar 5000 ohm readings. Cleaned and re-gapped the plugs. Car would barely start; had to retard the timing to get it going and then reset the timing to 8 degrees BTDC once warm. Had to turn the idle screws all the way and still could barely get the idle to 1000 rpm. Weirdly, the misfire seems better, based on the exhaust pulse, although the engine shakes like an alcoholic with the DT's. This is wildly different from before I removed the spark plug wires and pulled the plugs. I'm starting to feel like a right idiot.

Tested my theory about the tach interrupting the ignition. Yeah, its never something that simple.

I am back to thinking its carburetors and that I've just set them up improperly. Or perhaps, as suggested, the needles are worn. The air valve test indicates that its running lean. I didn't get to checking that carbs were still synchronized, but the idle was moving up and down slowly by 100-150 rpm or so every minute or two. This would indicate that the carbs are not synced?

It just got too late and I ran out of time for more tests. If I had the moral courage I could maybe give up sleeping altogether, but not today.

I haven't hooked up the engine breathing stuff - charcoal canister, metal tubes, etc. Perhaps I should try to get as close to stock before I rent a metal crusher for the weekend.