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Old 02-27-2017, 03:09 PM
adamdrives adamdrives is offline
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Question Rough idle/smoke @ cold start

Hey guys, I'm having an issue at cold start where the car takes a few minutes to achieve smooth idle and produces lots of blue/gray smoke. When the car starts, the idle is violently rough for the first second or two (almost dying), but after a few seconds becomes more stable and RPMs increase. A few moments later it is relatively smooth and up to cold start RPM (around 1300) but I can hear one cylinder missing. This clears up after a few more seconds and then I have no more issues with misfiring/performance.

Potential issues:

-If I don't cycle the GPs a few times, the car takes excessive cranks to start
-I've adjusted the pump to limit dark smoke under acceleration, but am getting a grey haze (I'm colorblind but it isn't black, white or blue)
-Since flushing the coolant system I've had to add a few gulps of coolant to get the res back from min to max. This seems within spec to me after draining/refilling coolant but would be indicative of a problem obviously if it continues.
-IP has a small leak at cold start lever arm. It will make a few drips, usually when the car is first started.
-I haven't been able to checked compression yet (need to make an adapter) but engine runs strong other than starting issue.
-Coolant exp tank does have a lot of pressure in it, even hours after driving

What work I've done

-Adjusted valves, all within .02mm
-Set IP timing to .90mm
-Set cam timing
-New GPs
-New wiring harness
-New fuel filter
-Good battery (idk what group size but its large, 1000 amp)
-WP, Timing + IP belt replaced, tensioned to spec
-Later model GP relay
-All fuel return (braided, oem) lines new
-New eBay turbo, bigger compressor, stock turbine housing @18psi
-I am monitoring EGTs

Am I pissing in the wind until I rule out the leaky IP? As far as I can tell it is leaking only from cold start lever area. HG/compression are concerns, but too soon to be sure, and car runs strong once up to speed. Greenbook says to test pump for leaks rig up a fuel source above pump and start, but this seems to be more related to diagnosing rough idle when running than a fuel/air leak when starting cold. Would it be worthwhile to do this test even though the car only runs rough the first few seconds? Obviously this is a 30 year old car and there could be a multitude of issues, but I'd like to confirm it is the pump causing the hard start before I spend bucks on rebuilding it. Apologies if there is a lot of unnecessary info here, wanted to be thorough with everything I've noticed. Thanks!
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Old 03-02-2017, 11:58 AM
v8volvo v8volvo is offline
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Doesn't sound like a fuel system issue. This reads like a text book case of some dead GPs. Even if you replaced them, a sticking relay or other issues could have given a short life, their recent replacement doesn't rule them out, particularly considering the way these symptoms sound.

I would start by testing continuity of the plugs in the engine now. You can do a partial test in a couple of minutes, testing the rear two takes much longer, but by removing the bus from the front four, you can check each of them individually. Then, check the resistance of the terminal leading to the part of the rear bus that is still connected to the #5 and #6 plugs. This will only give you real information if you find an open circuit there, indicating two dead plugs -- if you find continuity then you have at least one live plug or maybe two. Regardless, testing this way, you'll at least know conclusively about the front four and might know about the rear two also.

In theory, if there is continuity on the rear two, you could make an educated guess on whether you have two live plugs on the circuit or only one based on the resistance you find, but that requires accurate measurement equipment that most inexpensive handheld DVOMs can't achieve. If you have an excellent meter, though, and can use it well, you have the potential for making some more conclusions.

If you find dead plugs, you have your issue. If you find 6 live plugs, then it will be less clear, still could be a glow issue (voltage drop or bad off-brand plugs), or could be something else affecting cold combustion (some severely worn or damaged injectors, or compression). However, your description more or less rules out loss of fuel prime as a cause. If cycling the plugs multiple times changes it, and if the systems are relatively consistent, then it's not a fuel supply issue. Air leaks tend to be less consistent in behavior (often affected by parking angle and other factors). Leaks at the advance arm shaft typically don't cause starting problems either.

FWIW, you can replace the two O-rings for that arm quite easily without removing the IP or getting it rebuilt, takes some care but not difficult at all. But I wouldn't suspect it as a cause for your concerns.
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Last edited by v8volvo; 03-02-2017 at 12:02 PM.
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Old 03-02-2017, 08:19 PM
adamdrives adamdrives is offline
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Thanks for the reply. Just to clarify, cycling the GPs doesn't affect the hard starting issue, it will just start with fewer cranks (but still idle rough once it starts). Anyway, testing 1-4 is easy enough so I'll start with that. I got a good deal on some Bosch plugs so if they are bad I will have replacements. The ones I got were listed as "champion replacement" on rockauto for a great price, but they aren't any brand I can pronounce, looks like cyrillic characters on the box, lol

GP relay is revised design as a member here recommended, the GPs haven't stuck on (at least indicator light hasn't stayed on) since I've had the car. I'll check for a voltage drop, but all the wiring is new and there isn't much to it. Will check it though.

Good to know about o-rings on advance arm. I may send you a message about that. Parking on an incline doesn't seem to affect starting, although I will try with rear lower, not sure I've parked it that way.
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Old 03-03-2017, 10:01 AM
ngoma ngoma is offline
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Quote:
Originally Posted by adamdrives View Post
The ones I got were listed as "champion replacement" on rockauto for a great price, but they aren't any brand I can pronounce, looks like cyrillic characters on the box, lol.
Champion GPs known to mushroom or break off in the combustion chamber, get those out of there! If the broken bits find their way into the cylinder you got bigger problems.

Another way of testing the GPs in situ: Energize them a few times on a cold engine, then feel them (and around them) to see if they are warm. Use a non-contact thermometer for more precision.

Your symptom description reads exactly like bad GP(s). Depending on the weather and general engine condition, even one bad GP can make these cars difficult or impossible to start.
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Old 03-03-2017, 03:50 PM
adamdrives adamdrives is offline
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Well, all GPs test good. Used multimeter and did diode test on each. Took one out and compared resistance to new, very close. I did find that the 8mm nuts holding the bus bar to #5 and 6 were loose. Not too bad to get to these with an offset long handled wrench. Anyway, got that all tightened up, I'll see how it starts tomorrow am. If the problem persists I guess I'll swap them out for Boschs. #6 was just such a pain last time around...

Forgot to add I tested voltage at the power to GPs. I'm getting around 11.2 volts. Too low? I rigged up a wire straight from th battery and it read 11.7 volts. Battery voltage was around 12.7
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Last edited by adamdrives; 03-03-2017 at 04:05 PM.
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Old 03-04-2017, 05:54 PM
adamdrives adamdrives is offline
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The car had the same hard starting issue this morning, so I went ahead and put the Bosch plugs in. The whole process only took about two hours, I could have cut that down by half an hour atleast if I would have put the 8mm nut on the 6th plug before installing it into the head. Wasted a bunch of time trying to get the little bastard on before I realized the only reasonable way to do it is before installation. Having the right length 12mm wrench makes all the difference, actually screwing the plug in only really takes a few minutes once you have the right position. Tightening the 8mm nut with the plug installed is of course fiddly as well, but not too bad with a long handled open wrench. The most time consuming part is probably getting the plug into position in the head, using a combination of a magnet tool to get it in position from behind the pump bracket, leveraging it forward with a long handled screwdriver, and then rotating it a few times with a magnet took some patience. In any event, they all went in without issue, and the car started right up. Leaving it overnight will be the real test. In temperatures around freezing, is it typical to have to cycle the plug multiple times to get a quick start? I've seen some videos of d24ts being started after months of sitting and starting up quickly, but it's not clear how long the plugs are energized. I don't think I've had a quick, trouble free cold start in any condition just letting the plugs energize once.

I'm still curious about if my voltage drop was acceptable, but thinking about it I believe that a voltage drop of about a volt could make sense considering the plugs are drawing nearly 80 amps. I took a DC theory class in college a few years ago but can't remember the equation to calculate what the "ideal" drop should be or if it would be the same from a power source like a battery.

I also picked up some clear fuel line to install between the injectors and pump to see if I have any air bubbles if the starting problem persists.
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Last edited by adamdrives; 03-04-2017 at 05:57 PM.
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Old 03-05-2017, 07:11 AM
adamdrives adamdrives is offline
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Went for a drive this morning in ~25 F weather and she started right up on the second cycle. Very cool. Issue now is that my GP relay is sticking, indicator light wouldn't shut off. Had to unplug it. My old relay would stick occasionally but would click off if I gave it a tap, no dice. Not sure why that could be or if I messed something up while testing the system. Either way, it was definitely the plugs that were the issue. Pretty crappy that brand new plugs were no good.
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Old 03-05-2017, 11:18 AM
v8volvo v8volvo is offline
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Good news. Yeah, should start immediately on the first glow cycle, even at very cold temps and even if the engine is pretty tired. Should never take multiple glow cycles and generally you don't even need to wait out the light for the first cycle.

Sounds like you have a wiring issue causing the sticking glow relay. Two wires could cause this, in the 4-wire plug on the bottom of the relay - there's a brown wire that comes from the GP temp sensor and controls glow duration, if it has a bad connection it could cause extended glow time. There's also a starter wire, green I think, that tells the relay when the starter is running and shuts off the plugs a few seconds later. If this wire has a bad connection the relay won't get the signal to cut off. Wire harness problems on this era are common so you might want to inspect the wires, connections, check resistance, etc.
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Old 03-05-2017, 11:43 AM
ngoma ngoma is offline
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Quote:
Originally Posted by adamdrives View Post
I also picked up some clear fuel line to install between the injectors and pump to see if I have any air bubbles if the starting problem persists.
For the injector spill lines? You may see captive persistent air bubbles at the top of the spill line arcs. They do not necessarily indicate a problem with air intrusion.

Quote:
Originally Posted by adamdrives View Post
Pretty crappy that brand new plugs were no good.
Champion GPs are problematical, so are Autolite.
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Old 03-05-2017, 03:53 PM
RedArrow RedArrow is offline
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Your original write-up about the no-start/hard-start problem describes *exactly what was happening with mine a few years ago, when 3 of 6 glowplugs suddenly went bad. They were the good Bosch units but probably got tired, idk. If it happens again in the future, I will only use the Bosch Duratherm again.


Getting that clear fuel line replaced is always a good idea. I have been hating to see the old, discolored (fully dark brown) hose between the filter and the IP, so I fixed it today.
Thanks for the `quick project` idea... although I will have to redo it asap because I used vinyl clear tubing, that, I`m sure, is not tolerating diesel for too long.

BTW, where to get the proper, CLEAR, diesel rated hose from?
I see tons of similar items all over the web, but no sellers mention diesel fuel.

It took some time to do this fix, bc the old fuel line lost all of its flexibility, completely hardened, became brittle so it did not give up easily.
I decided to not risk disturbing the pump AND hurting, scratching, denting the banjo nipples by using tools; so I removed both fittings with the hose. After that, I simply torched the old hose endings a lot until I could pull them right off.

It`s nice to see green diesel (without bubbles) in the clear hose! Those banjos need a good cleaning too, I`ll do it next time, when I replace a section of rubber fuel hose junction under the car.
I just want to get diesel rated tubing now... any idea?
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File Type: jpg ip fuel hose.jpg (15.0 KB, 12 views)

Last edited by RedArrow; 03-05-2017 at 05:10 PM.
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