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Discussion Starter #1
Hey Guys,

This is definitely a safari specific question as I have a LWB 1994 TD42T Turbo Diesel Safari. The issue that I have is the diesel injection. I got the truck with only 67,000 km (Verified by the maintenance logs that came with the truck and the overall condition of the truck) and ever since I picked it up at the docs in Vancouver there has been a slight miss (or misfire) from a slow standing start; much like the miss you get when you try driving, or throttling up on a cold morning before the engine is warm (It does that too). It also has this miss after applying a slight throttle after coasting down a long hill. It also does this miss when you have been traveling at 120 Km/hr for about 2hrs and then slow down to about 80Km/hr and try just touching the throttle to maintain 80Km/hr (Sometime mor than others). Once you hit about half throttle the problem completely goes away with no smoke whatsoever. Even at full throttle there is no smoke, which makes me think the injectors are still in good condition. The power is excellent and the engine naturally burns no oil even while running 5W-40??? This truck will spank my old SWB SD42 Non Turbo any day of the week and will hold 110Km-120Km up any hill through B.C. (Roger’s pass)… The thermostat is also working as it should, so this is not an engine temp thing. I had that with my SWB and this is not the same thing and it did it in the 33C summer days on 8hr trips.

Theory: I notice that it has recently been having trouble starting at colder temps, but a check of the glow plug system has revealed that everything is in check. I did notice that the turbo diesel 4.2 has a “boost diaphragm” on the top of the VE pump with an adjusting set screw and lock nut. A vacuum size line runs from the engine intake line, to the “Boost Diaphragm” (You TD42T people will know what I am talking about). I assume that as the turbo boost pressure increases, this line sends boost pressure to the “Boost Diaphragm” to all more fuel to be injected into the system. My theory is that this “Boost Diaphragm” is not returning back to its closed position and allowing an overly rich mixture during idle and low RPM; hence the starting issues and incomplete combustion issues.

Has anyone else had this problem with their TD4.2T? I would like to know before I start to adjust the factory setting on the “Boost Diaphragm” set screw. Is there a return spring in this diaphragm that can weaken or break?

Any help, thoughts or ideas are appreciated.

Thanks,

Zach
 

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Discussion Starter #2
I forgot to mention that I have also changed ALL of the filters; even the little in-line screen(They were clean anyway) and tried every diesel fuel condition under the sun (Howes, Forte, Standadyne, etc, etc, etc) with no real quantifiable results.
 

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I highly doubt it is the boost compensator, more fuel at idle setting would mean high idle.

aldrichuykho, air is a good theory but if air, wouldn't this show up at high power as well?

I wonder if the EGR system is giving you trouble? You can temporarily disable it by blocking the vacuum line to the exhaust EGR valve behind the intake manifold and doing the same to the butterfly valve actuator on the intake. Before you do this confirm the butterfly is operating correctly. After engine has warmed up the butterfly should be closed at idle, open a bit off idle and open all the way once any real power is demanded.

You might consider 2 stroke oil as an additive for the IP.

I don't remember if you have the normal fuel filter head or the one with 2 extra hoses?
 

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Discussion Starter #5
I have the filter head with the extra two hoses!

Wouldn't it run richer with extra fuel but the same amount of air, or does the butterfly valve automatically open up if more fuel is leaking in? Isn't the butterfly valve on the air intake controlled by a vacuum line from the pump to the intake? All seems to be working fine.

I don’t think there is an air leak as the misfire is followed by a puff of unburned diesel smoke. I assumed over fueling, or incomplete combustion? If air was the problem, wouldn’t I get no smoke (or very little) after the miss?

I don’t know…. I think I will remove the boost compensator vacuum line and suck back some air to see if this does anything before I start it next time (It’s cold in Calgary now). If it fires with no missing, we may have found the culprit and if not, I guess I am back to the drawing board.
 

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Ok, first stop thinking of metering or controlling the air like a petrol engine. In our TD series only the fuel is metered. Your old SWB did not have EGR and thus did not have a butterfly valve. Your old SWB had a straight through intake with nothing in the way, more fuel more power simple as that. More revolutions more air. Your `94 turbo has an EGR system that is absolutely useless. There is very little vacuum produced without a butterfly valve (thus the vacuum pump on the back side of the alternator). Because of the low vacuum the exhaust gases do not flow into the intake very well. With the butterfly valve sufficient vacuum is made to help the flow of exhaust gases into the intake manifold. This is the only function of the butterfly valve on the TD42 and TD42T.

"I don’t think there is an air leak as the misfire is followed by a puff of unburned diesel smoke. I assumed over fueling, or incomplete combustion? If air was the problem, wouldn’t I get no smoke (or very little) after the miss?"

More info. From what I have read an air leak into the injection system can cause white smoke from unburnt diesel. A few weeks ago when I overhauled my injectors I did get a few puffs of white smoke after startup. I then ran to the back to smell it and sure enough it was pure diesel.

I would be very surprised if your boost compensator idea did anything. I would wager in air or the EGR system. Disconnect and block the hoses as I suggested. Try to find an air leak. Does you hand pump on the filter head go hard when you pump it? One of my rigs has the same filter head as you and it self bleeds if you just pump it.

You might try pressurizing you fuel system to look for leaks.
 

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Fuel system leaks do occur and produce issues at start or during driving depending on the fuel demand. I have known people to spend months and $$$ chasing a strange miss or hesitation only to eventually find a small crack in a line, hose or housing. As Twinotter recommends, try pressurizing the fuel system (no more than 9 psi) to find fine cracks which could be sucking in air. You could also add a pusher pump close to the tank. That will do a few things. It will make the life easier for your lift pump on your IP. It will reduce the likelihood that a small crack will be able to suck air. And, it will help you identify any small cracks by pushing fuel through them. It is unlikely you will see fuel streaming out; you'll just see a damp looking spot. The other plus is an electric pusher pump makes bleeding to the IP a breeze.
 

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Please let me know, because I just recently had the same issue not arise. Exact same symptoms.
I have a '91 SWB non turbo wagon so I am 100% confident it is in the fuel system, not anything to do with a turbo.
Murray.
 

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much like the miss you get when you try driving, or throttling up on a cold morning before the engine is warm (It does that too).
Zach, Murray

None of my rigs do/did this. I could start at -30 with only the glow plugs and drive away no problem.

My '94 turbo I thought had a/some bad/dirty injector(s) but now I think it is the glow plug(s). At about -10 it misses at raised idle for a few seconds.

Zach has reported white smoke when he is getting his hesitation, Murray are you getting white smoke as well?
 

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naturally asthmatic
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I do drive away with a cold start too. The best way to warm up is a to drive it keeping the revs below 2200 rpm until you are up to operating temp. As my wife is on the freeway in 5 minutes, I do a bit of an idle warm-up int the morning.

Back to the subject, after doing the thermostat, the bit of smoke my wife's truck had is gone and it runs much smoother and with more power. But Zach said the thermostat has been done and is working properly as is the glow system.:confused: It is kind of confusing as those are the two things which would be suspect if it is only a cold weather issue. Zach, did you check the EGR as Paul suggested? That is the only other thing that is temperature dependent.
 

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Zach, Murray

None of my rigs do/did this. I could start at -30 with only the glow plugs and drive away no problem.

My '94 turbo I thought had a/some bad/dirty injector(s) but now I think it is the glow plug(s). At about -10 it misses at raised idle for a few seconds.

Zach has reported white smoke when he is getting his hesitation, Murray are you getting white smoke as well?
Exact same symptoms. White smoke and all. I do not suspect the glow plugs as this problem continues when you slow down from high speeds and give it a bit of gas.

I as well could start up at -30, but for sure with alot of miss-fires and smoke. I am not to concerned about it because the warmer the engine is, the less it misses, meaning its just the engine warming up.

Zach and I could be having a problem with thinner air (being up in Calgary) but if he as a turbo he shouldn’t really have any air issues. And you would figure that Canuck would have similar issues being out in BC.

That's why it has lead me to believe that it has to be in the fuel system (Injectors, Injector pump, fuel lines. etc.). My truck is due for new injectors (120,000km's) And I was hoping that that would fix the issue. Although with Christmas spending, I don't know how soon that will be :confused:.

All suggestions are welcome.

Murray.
 

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Oh and I have run some lucas oil through, to no avial.
And I suppose it could be to do with engine thermo., but I have full heat and nothing seems to be out of order.

Happy Holidays.
 

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murrdawg02, does your thermostat function properly? I know we have conversed a fair bit but I don't remember if we discussed the gauze filter under the banjo bolt. Another Canadian Safari owner spent a fair amount of money trying to find his issue just to find out the gauze filter was plugged.

If all is good, even cold starts will result in a smooth idle once you bring up the revs to normal.

Canuck is at sea level in warmer air but he does travel the interior a lot.

You might try to duplicate your issue with the diesel filler cap off. Dry conditions only.

Did you try with your EGR system disabled?

As you accelerate does the power drop off sharply above 2200 rpm?
 

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I do know about the banjo filter, I figured I would check for it when I do the injectors.
I have tried it without the filler cap and there is no real diffence.
Havent touched anything with the EGR system, but that will be the next step.
And the power does drop as soon as it misses (some times is does, others not). If it doesnt miss it has pleanty of power no doubt.
 

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I was asking if the power drops suddenly above 2200 ish with no miss but your saying the power drops as this problem occurs which means fuel....or air there in....

On a side note, if your injectors are squirting rather than spaying it will make for rough starts.
 

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Forgot, if the butterfly is staying closed too long then it's starving for air on acceleration.
 
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