Anonymous

Loooking for fuel injection opinion

Here’s where to discuss anything specific about your standard(ish) car or something that applies to the model in general.
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Postby Workshop Help » 10 Apr 2014 20:34

Here is a bit more diatribe as to the issue of emissions equipment, circa 1970's.

Our TR7 engines were chosen by the BL boys as it was the only new design able to meet the coming U.S. E.P.A. emissions standards. The engine was detuned to use the low compression pistons with an EGR valve, an air pump to inject air into the exhaust tract, and the use of the more refined Z-S carburetors instead of the more crudely built S-U's. Additional items included a charcoal canister to filter float bowl vapors, a closed tract fuel system, a warmed air intake system, electronic ignitions, and, in California, a single carburetor and catalytic convertor. Mind you, this was just to launch the model range in 1975. This was typical for all U.S. market cars that year along with the introduction of no lead gasoline.

Naturally, every hot rodder took one look at these newly strangled engines and recoiled in horror.

The whole problem was cleaning up the tail pipe exhaust. The solution was keeping the engines operating as efficiently after 50,000 miles as they did new off the showroom floor. The key word here is, 'efficiency'. Electronic ignitions went a long way towards this goal as the spark delivery did not deteriorate like the points/condensor system did. The Z-S carburetors, once set up correctly, held their adjustment and tolerances very well. These are the two biggest items in maintaining a TR7 engines operating efficiency. The rest of the equipment is aimed at getting the tailpipe to smell like roses and lilac water. The thing is, with the engine producing a bunsen blue flame like the flame on your gas stove, it meets the pollution standards pretty much right there.

The remaining objectionable vapors from the float bowls and gas tank are attended to by equipment having no bearing on actual engine performance. The charcoal canister and sealed fuel system are actually beneficial to the car as the vapors are returned to the intake tract to be burned in the combustion cycle. Likewise the crankcase ventilation system that creates an internal vacuum condition to lessen oil leakage. This is good stuff and should always be kept in good condition by replacing deteriorated hoses.

So, since most emissions inspectors focus on the obvious, the lack of large items like warm air hoses, missing charcoal canisters, or air pump belts, or catalytic convertor, or various unconnected hoses are easy finds to be noted to fail a car along with an out kilter tail pipe reading on the exhaust gas analyzer.

Can you provide the specifics of why the car won't pass inspection?

Mildred Hargis

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Postby sheetsofsound » 10 Apr 2014 20:52

I have tried turning up the idle. It actually passes the driving test (a few minutes running at over 2500 rpm) no problem, but the idle test fails on hydrocarbons with the idle set at @1200 rpm.

The testing folks don't care about the air pump or the other missing stuff; they only check for the catalytic converter. (As an aside, the tester missed it when he looked under the car. I had to show him where it was. He even went to get his supervisor. Not sure how locating it was so tricky.) The only objection they had to the car was the high HC levels.

Mildred, the background info was very interesting; thank you. I have had no luck at junkyards, but I think I can lay may hands on most of the stuff through a friend. This will take some time. In the meantime, I thought I would keep fiddling.

When I got the car, the connections on the carb that connect to the canister were open. When I reinstalled the carbs after cleaning them up, I left them that way: open. The car ran lean, no matter what. When I plugged the holes, I was able to use the mixture tool to adjust things until the mixture seemed right. (This according to what I have read in numerous places about lifting the air valve to adjust the mixture.) It was then that I ran through the testing station and got the high HC reading at idle.

If the lack of breathing equipment has no effect on the tailpipe emissions, then my next thought was perhaps I'm failing because the car is missing very occasionally at idle. Based on the exhaust pulse at the pipe, and the occasional rocking of the engine, it seems like this might be the case. Pulling the leads to figure out which cylinder makes it miss so obviously that its hard to tell which cylinder it might be. Driving, the car starts from the line after a bit of stutter but drives smooth once underway. Beginning acceleration is not smooth. I am going to try different plugs and leads tonight to see if that has an effect. It has an aftermarket Allison coil.

The car is a 1980 DHC. I have tried to fill in the blanks as best I can; I've only had the car a few weeks. I will include some pics when I get the car back from the mechanic friend on mine who has the sniffer equipment.

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Postby HDRider » 10 Apr 2014 21:49

If the CO emissions are high then you are too rich at idle. High NOX indicates a lean condition.

The mixture adjustment on the carbs is fairly sensitive. I usually adjust no more than 1/4 turn at a time. Clockwise is richer by the way. I doubt that you can truely accurately adjust them without a gas analyzer, or at least some readings to see where you are. By ear you should be able to get the carbs balanced as far as airflow and mixture.

Usually they feel lean when they are in a setting that will pass SMOG. Unless everything is perfect on the motor you will most likely need to richen them up after you pass.

If you have ruptured diaphrams or other mismatched/broken/worn parts on the carbs you probably won't get a steady enough reading to pass.

Edward Hamer
Petaluma CA

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Postby jeffremj » 10 Apr 2014 21:51

I think the main problem is either a missing air pump or the catalytic converter has failed. I was surprised you had a cat, but as you have one, it must be a 2-way and Wikipedia says:

A two-way (or "oxidation") catalytic converter has two simultaneous tasks:
1.Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 Â￾¨ 2CO2
2.Oxidation of hydrocarbons (un-burnt and partially burnt fuel) to carbon dioxide and water: CxH2x+2 + [(3x+1)/2] O2 Â￾¨ xCO2 + (x+1) H2O (a combustion reaction)

Note the need for oxygen in the exhaust so that un-burnt HC is reduced and I guess the missing (?) pump means your HC is high. Then again, what are your pass figures for un-burnt HC? In the UK an old TR7 can pass an MOT with 1200 ppm at 1200rpm - my V8 passed with a throat coating 800ppm at 800 rpm - my MOT tester certainly knows I have visited!

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Postby HDRider » 10 Apr 2014 22:50

When set up correctly a carbed TR7 will still pass SMOG without a cat. The cat is really there to adjust for out adjucstment systems. I got the wifes car to pass for years with an empty Cat.

The air pump adds oxygen to the exhaust on overrun so it has little effect on the test as it is taken under power.

Edward Hamer
Petaluma Ca

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Postby Hasbeen » 10 Apr 2014 23:11

Being rather cynical, I have always believed that the air pump was a con job. Rather than actually do anything about the emissions, by adding air, & increasing the total volume exiting the tailpipe, they reduce the percentage of nasties, without actually changing their volume. Voila, the thing passes the test, without any real change to anything.

Of course there is some chance the things actually do some good for the atmosphere, but I reckon it is a pretty slight chance.

However, regardless of any actual environmental good an air pump might do, it might do the most important thing, & GET YOUR CAR ROAD LEGAL. So find a pump, fit it, & if necessary, fit a bigger pulley, so it pumps more air for any given engine revs. They would not exist if Triumph had not needed them to pass that test. If fitting one back on there gets your car on the road, they will have served their purpose.

Hasbeen

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Postby Workshop Help » 11 Apr 2014 00:21

You just used the magic word! Misfire! I have an article on replacing the standard modern carbon filament ignition cables with the old fashioned real wire ignition cables. The article also addresses how to test your cables for the desired resistance level. I suggest you make up and install a set of REAL WIRE cables to eliminate any chance of misfire.

After that, rebalance the air flow and synchronization of the carburetors and lean out the mixture a bit. Your idle should be at 800 RPM. Please be aware your ignition timing should be at 2 degrees After Top Dead Center with all the hoses connected. The engine vacuum should be reading about 19 to 20 inches on the vacuum gauge with the engine at full operating temperature.

About those disconnected hoses to the charcoal filter and the anti dieseling valve right next to it, they should be hooked up or a lean condition and higher idle will result.

As to parts, if you can find something similar and compatible, get it and install it. Around here, we ain't fussy about originality. It's a sure bet, the Laguna Seca Concours won't be sending out any invitations to the likes of us anytime soon.

Why do I have the nagging feeling all you boys need to come on down to the machine shed so we can get this fixed once and for all?

Mildred Hargis

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Postby sheetsofsound » 11 Apr 2014 01:53

If my car would run, a trip to your machine shed sounds just the ticket. Unfortunately, I am sitting behind the wheel of a running but unroadworthy (according to local gov't officials) Triumph.

The wires I was not able to replace today, but new plugs are in. The charcoal canister and other bits I can't get 'til next week but, once I get my hands on the stuff, I think I will have all I need to hook up things pretty much to stock - Laguna Seca be damned. New wires (as per Mildred's article) should be constructed and in sometime this weekend. Testing stations this weekend will probably be closed by the time I get things ready, but hopefully Monday will see me ready to have another go.

At least now I have something to try. Thanks to all for the opinions and info. The collective knowledge residing in this community is priceless.

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Postby sydney.wedgehead » 11 Apr 2014 03:22

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by sheetsofsound</i>

I have a car with fuel injection that doesn't run. (Previous owner said it overheated and seized.) I have a second car with Z-S carburetors that runs, although I am in a constant battle with the emissions testing station here to get it roadworthy.

I read Roger Williams singing the praises of FI over carburetors in "How to Restore...". Most other stuff I have read says you get better performance from carbs.

Until I read the Roger Williams piece, I hadn't considered moving the FI system to my running car. Is this a good idea from a performance perspective? Would it make any difference to my emissions testing woes? Any opinions would be welcome.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Replacing the running carb system with the non-running fuel injection seems an expensive, non-productive retrograde step.

If I was undertaking this I'd want to use a more modern engine management system that would support (at least) wasted-spark ignition and potential to upgrade to sequential injection (requires Cam & Crank sensor).



Owen, aka:
- Marsu (570 posts, last dated 28 Nov 2011)
- omichaelshar (557 posts, last dated 17 Mar 2009)

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Postby Workshop Help » 11 Apr 2014 12:17

It was a restless sleep last night. My brain wouldn't turn off as it was focused on your rich condition at idle.

Do you have an ohm meter? If so, confirm all the wires have the same resistance, which should be in the 5000 ohm area, more or less. Next, pull the float bowls and reset the float levels to 11/16". Then, replace the float inlet needle valves. If you can get the 'Gross Jets' as shown in the VB catalog, they will work, too. Dropping each float bowl is a twenty minute exercise and is done with the unit remaining on the car.

It is worth knowing as time goes by, the friction twixt the metering needle and the jet hole in the carburetors does wear the hole larger. Not very much, yet still enough to alter the mixture being drawn into the engine. At the same time, the throttle shafts are wearing their bushings allowing extra air into the intake tract to give a lean condition. The miracle remedy is the mixture adjusting screw can be altered to compensate for these changes.

My carburetors are 37 years old with 166,500 miles on them and have NEVER been off the car. The idle speed when hot is about 800 RPM. There is no valid excuse for anyone with a pair of Z-S carburetors to have an over speed idle. It can be fixed, and usually at no or very minimal cost.

Mildred Hargis

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Postby sheetsofsound » 11 Apr 2014 22:35

Alright - thanks to all; I still have much to learn and I thank everyone for their patience, although Mildred, it pains me that you lost sleep over this.

I have actually checked the float levels two different times over the past couple of weeks, although I did find it easier to remove the carbs from the car and measure them that way. The throttle spindle seals I have replaced, though not the brass bushings. Seeking leaks by spraying with WD40 has not revealed any.

I also rebuilt the bypass valves and I have a question about them. Using the Buckeye Triumph guide, it said to disconnect the vacuum before adjusting the bypass valve. According to the article, when the vacuum is disconnected, the idle should rise. This did not happen. Remember, the PO disconnected all the engine breathing stuff, including the EGR valve. The vacuum line now runs straight from the distributor to the carb closest the firewall. I'm not sure what effect, if any, this will have on the carbs in general, or the bypass valve settings in particular. Should my idle be rising when the vacuum is disconnected?

When I lift the air valves, it behaves as if lean; it almost stalls with the merest hint of upward motion on either carb. The only reason the idle was at @1150 to 1200 rpm was to help with the HC reading for the emissions test. I can get it to idle at @850, but it does seem to be missing occasionally and it is more obvious at the lower idle speed. The air valve test says lean, but the tailpipe reading shows high HC. I am now assuming that is because of the misfires. Am I wrong about this?

My mechanic was going to put in new plugs and wires today, although I haven't heard if that solved the misfires. When I get the car today I will check the resistance.

I have had to work late the past 2 nights and have not been able to pick up the car. That will happen tonight when I'm done work. If the wires and plugs haven't been attended to yet, I will do that tomorrow - a day off! Maybe that will stop the misfires. (The new plugs and wires, I mean.) I will take some photos of the engine bay and post.

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Postby Hasbeen » 11 Apr 2014 23:35

If your distributor diaphragm is in good order, direct connection will have no perceptible effect, as no air passes from the distributor.

If on the other hand your distributor diaphragm is split or holed, air will be entering that carb from it, making a satisfactory idle impossible to achieve.

Try sucking on the hose at the carb end. If you get a flow of air, you need to replace the diaphragm, which may be very hard to find. It was the unobtainable diaphragm module for the 4.6L V8 in the 8 that sent us down the path of computer controlled ignition s couple of years back.

Hasbeen

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Postby Workshop Help » 12 Apr 2014 02:32

Let's stay focused here on each area.

#1. A. I was hoping yours were the only Mr Goodwrench hands working on the car. This can be a huge complication as someone elses efforts can be a detriment. They ALWAYS are in my case.
B. Did you replace the float bowl inlet needle valves? These needle valves do wear out and let fuel into the bowl(s) causing them to overfill and richen the mixture.
C. What have you done to balance the air flow and synchronize the carburetors? What tools did you use?
D. Do you use a vacuum gauge?
E. Does your car have manual chokes or the FASD?
F. Are you running the stock air cleaner assembly?
G. Remove each of the carburetor air valve assemblies and measure the length of the needle. They should be the same. Clean the needles of all deposits and dirt. A filthy coated needle will produce a lean condition.
H. Confirm no silicone sealant was used to goop up the float bowl drain plug O-Ring. Gasoline over a period will cause it to loosen and be sucked up the needle to block the fuel flow, giving a severe lean condition and harsh stumbling of the engine.

#2. As for the ignition system, A. What type and what gap are the spark plugs?
B. What are the ohm readings for each of the ignition wires?
C. Have you cleaned the distributor cap contacts inside the cap?
D. Have you cleaned the contact tip of the rotor?

Yours are the only trust worthy hands to be working on your car.

Mildred Hargis

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Postby sheetsofsound » 12 Apr 2014 05:01

#1A: Yes, I have learned the hard way that I should not have entrusted things to someone else; I just got the car back tonight and it barely runs. It stumbles so badly off the line that I almost couldn't drive the 6 blocks home up the hill.
B: Yes, the needle valves are new.
C: I used a length of rubber hose to balance the carburetors.
D: I don't have a vacuum gage. [:I]
E: Manual chokes.
F: Yes - stock air cleaner assembly, although the last test was taken with the air cleaner off.
G: Measured and cleaned the needles when I cleaned up the carbs. They are the same length with no gunk.
H: No silicone sealant. One float bowl has the plug and I replaced the O ring. The other does not have a plug.

#2A: Plugs are Champion RN12YC. My mechanic friend set the gap. I will check tomorrow.
B: Ohm readings will be tomorrow; its late and I'm just too tired, but the wires are new.
C: Yes, distributor contacts were cleaned.
D: Yes, I cleaned the rotor tip. I will re-check both of these tomorrow.

Readings from the testing station:
Driving test (rpm's over 2500)
HC - 23.000 Max allowable - 249.000 - PASS
CO - 0.11 Max allowable - 1.83 - PASS
NOx - 423.000 Max allowable - 2603 - PASS

Idle test
HC - 1359 Max allowable - 413 - FAIL (rather spectacularly, if I do say so myself.)
CO - 2.48 Max allowable - 4.61 - PASS
NOx not tested at idle.

Its still missing at idle and I am wondering about valves. I think Hasbeen, or maybe someone else, mentioned about being out by a thou or two because of build up or crud on the valve seat, and that knackered his tailpipe output and prevented getting a smooth idle. According to the paperwork I can find with the car, it was last insured for a day of driving in November 2001. It sat in a field under a tarp for at least the last 3 years, and before that who knows where? Maybe the prolonged inactivity is preventing one of the valves from seating properly? What are the symptoms of a valve out of adjustment? God, I don't want to pull the head.

According to the test report, things are fine when driving. This is born out behind the wheel; once the rpm's are above 2500, the engine seems very responsive and smooth. Below 2500 rpm under load it drives like a motorized toilet, farting at the tailpipe like my crazy old uncle after chili dinner. Smells about the same, too.

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Postby Cobber » 12 Apr 2014 06:28

Vacuum test gauges are cheap, so buy one. It's false economy to buggerise about without one!



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