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A simple but probably stupid question: is it possible to test whether an injector is working properly (LH 2.4) by pulling the injector from the manifold and observing the spray whilst cranking the engine? Disconnecting the coil of course to prevent any sparks.
Ian F
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Before you get all excited about wanting to pull injectors and checking spray patterns, there's a simple test you can perform at the Diagnostic Link Connector to verify all the injector solenoids are at least trying to operate normally. See the 700/900 FAQ here under Engine: OBD Diagnostic Codes. Diagnostic Test Mode 3 (on port 2) is used to get the ECU to exercise some of the system components in a continuous cycle, among them the IAC valve (goes tick-tock), the electric fan (low then high) and pulsing the injectors (tick-tick-tick). You can put your hand on each injector in turn to sense if it's operating and at a similar intensity to the others. If you still suspect an injector problem then refer to the Fuel Injector topic in the FAQ in the Engine: Fuel Injection section. Pulling and testing an injector to casually check spray pattern and volume used to be a whole lot easier in the old CIS systems. Fortunately the newer pulsed injector systems have very few injector problems and such testing is rarely needed.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Thanks Dave. I have read the FAQ section on injectors, but it doesn't mention looking at the spray pattern, hence my question. It would seem to be a very simple thing to do - the injectors look as if they would come out easily?
I'm thinking about this because at my last test (here in Scotland) the emissions were high in HC. The 940 is running fine, plugs look perfect, new lambda sonde, new cat etc. It's a 1991 so has a cat, but doesn't need to meet cat emission standards, so a bit of a puzzle🤔
Ian F
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Many thanks Art. I think I am prepared now, appreciated!
Ian F
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High HC means incomplete combustion. Given that you've replaced the O2 sensor (Lambda Sond) so the ECU knows how it's doing, consider inefficient combustion on the ignition side from things beyond the control of the ECU. Timing is not adjustable on these engines, so generally nothing to worry about there. Think more along the lines of plugs, cap/rotor, wires, even a weak coil. Apart from the coil, these are routine replacement items and you don't need to test them to prove they're a problem, better to replace them on a timely basis before they become an issue
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Thanks Dave. Time for a confession: the coil, distributor and plug leads are original (1991 vintage). I do change plugs/oil/oil filter etc.etc on an annual basis of course. I think I may have cleaned the inside of the distributor once, but I can't recall when🤔.
I will give these items some attention.......
Ian F
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Incredible! Never heard of leads/wires lasting that long. What’s your secret? The Scottish climate? :)
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Will I buy another Volvo??? We'll see....
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Well I guess I may just have been fortunate? I am used to looking after old British cars with points in the distributor, and since the 940 doesn't have anything similar, I have just treated it as a non-service item. (If it ain't broke don't fix it🤔). The 940 has always been incredibly reliable except for two failures of the "radio suppression relay" - always carry a spare one, and an early failure of the crank position sensor.
Needless to say I will probably order some new ignition components this weekend, but I will certainly be hanging on to those original parts.
Ian F
P.s Dave - you are clearly much better acquainted with the Scottish legal system than I am 😇😇
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Replaced the distributor cap, rotor and cables yesterday, and also fitted a couple of new seals after cleaning the distributor itself. All OEM from Skandix in Germany.
The original rotor arm was rather black and pitted on the tip of the arm, so definitely replacement was overdue!
The result? The 945 now idles smoothly and generally feels better. Just hope it will help with the HC emissions.
Thanks for the advice!
Ian F
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On the right track, methinks. I'm not sure of your local pricing, but I’m guessing you're ahead of the game on cap/rotor and wire pricing compared to a couple more bottles of single malt in order to pass emissions :) :) Doing the distributor seals is a bonus. In case you didn’t do it, make a mental note so next time you’re in there 30 years from now, also to replace the distributor shaft bushing. It’s not a Volvo part, but is included in a number of aftermarket kits.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Changing the distributor cap, rotor arm and ignition leads on my 945 has fixed the high HC problem, passed the emissions test here in the UK last week. A simple enough fix, so thanks for all the advice! Just pleased it wasn't the injectors or something else more complicated.
Ian F
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Makes me wonder how you've been able to pass emissions testing all these years without changing at the very least the cap/rotor. My engines would be stumbling and stalling by now. Just how many miles on your engine or how much single malt have you needed to bribe the inspectors all these years in order to pass?
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Think I'll have to take the fifth amendment on that one Dave!!
Ian F
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Take the fifth or take a fifth (of whiskey)? I see your right to silence is actually Section 34 of the Criminal Justice (Scotland) Act 2016, but that would just confuse people.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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