1.9TD (D4192T) electrical(?) problems

[voivoi]

First, pardon my English.

It's a 1999 S40 with the 1,9TD with almost 350 000 km on it. I got it about a year ago with a blown head gasket. I replaced that (got the head machined too) and a bunch of related parts, water pump, belts etc. Turned out that the gasket wasn't the only problem.

It starts up nice hot or cold, but doesn't run right maybe half of the time - or more. And when it doesn't it hunts on idle and jerks a little when driving. And it seems to be totally random. Another problem I noticed in the autumn is it sometimes does't seem to be responding to accelerator pedal. So it first runs ok, but suddenly, often when changing gears, it just won't accelerate properly until the revs get up to 2200-2400 and the turbo kicks in. After next gear change same thing. Or sometimes not.

Also occasionally there comes a horrible rattling or knocking noise. I can't really describe it, but somehow I think it might be related to timing. I think it's the same sound I once created by pulling a connector (maybe green) by the feed pump while the engine was running. When driving, the sound stops when I lift my foot from the pedal. Also the triangular warning light with lambda symbol lights up quite often even when there seems not to be any problems.

I've had the codes read two times now months ago. They gave the same result and in between I changed the EGR valve (the dealership said it was faulty, I was quite certain it wasn't after cleaning and testing and blocking, but I happened to get one for a reasonable price so thought to try anyway). I also changed the solenoid valve controlling the actual EGR valve with no success. But the codes. The second time it was a Bosch reader and it gave some descriptions in Finnish, too. I don't know how accurate they or my transalations to English are, but here goes:

EFI-122 Air intake temperature sensor; Impulse too high
EFI-235 Exhaust gas recirculation adjustment; Impulse too low
EFI-732 Accelerator pedal position sensor; Impulse too low

I think that in some more detailed description it said "impulse ratio" and when driving the EGR adjustment didn't get any higher than 40%. This is also what the mechanic at the dealership said and what he thougt to be an indication of a faulty valve. Btw, he hadn't worked on this engine type ever before.

I've done my best to test the AIT and APP sensors with a multimeter but they seem fine. I've also tried to find vacuum leaks and broken wires, changed vacuum hoses, checked connectors and pretty much everything I can think of. Battery seems fine, too and on idle it measures 14,4 V on the terminals. I'll have to check the alternator brushes on the charger, though. Anyway, I think it must be something electrical but I don't really know how to find it without spending too much money. And I don't want to do that.

I found a (partial) wiring schematic for year model 2000 but I think it's a little different. And it's missing some pages. Any help on that? Do those sensors and EGR solenoid valve maybe have a common grounding point or reference voltage or something?

Any thoughts?

[Baffler]

Any other electrical niggles? Radio or dash lights flickering or going off on occasion? The wiring loom which is routed under the rad is known to corrode so can cause a world or electrical problems.

The fuel filter housing on these has a primer pump incorporated into the lid and the diaphragm can go weak over time causing starting issues. You don't appear to have this problem but the hunting on idle could be caused by fuel starvation due to air getting into the system or lack of draw up from the fuel tank. When it's hunting on idle try prime the pump on top of the fuel filter housing to see if it improves.

There is also a fuel shut off solenoid in the distributor pump but, as it's been many years since I had mine, I can remember where it's located on the pump. The solenoid may be functioning fine but the wiring to it maybe the source of your problem...hence why I mentioned the wiring loom under the rad.

The S/V40 wiring diagrams (PDF) should be here on this section of the forum...try the search option.

[voivoi]

Thanks for the input, Baffler.

Well speedometer lights go dimmer/brighter occasionally, but that's maybe something else since one section is totally dark sometimes. I should check the lamps. And quite recently I noticed that the blower motor sometimes when turned on full power speeds up little after a while.

When you say "rad" you mean radiator, right? And the corrosion of the loom happens most propably just there under the radiator? (Edit: After a little research the answer to both of these is apparently "yes".)

I'll try that fuel primer pump trick.



Does the red arrow point to the shut off solenoid? It has a rubber cap on it secured with a cable tie and if I remember correctly there was a little diesel under the cap. How is it sealed and anything special to consider, if I was to take it out?

I changed the alternator brushes. There wasn't much left and the slip rings were quite groovy, too. Didn't notice any difference on test drive, though.

[Baffler]

Originally Posted by voivoi

Does the red arrow point to the shut off solenoid? It has a rubber cap on it secured with a cable tie and if I remember correctly there was a little diesel under the cap. How is it sealed and anything special to consider, if I was to take it out?

That's the one. Remove the rubber cap and it should look something like this.

[voivoi]

Pumping the primer resulted in no noticeable effect.

Jacked the car up to take a look at the loom. It's in hard(ish) corrugated tube and looks just fine. Any closer inspection is definetely not a job to do outside, swimming backstroke under the car, in these temperatures. It's been awfully warm lately and only about -9 C today, though.

Found this under the rubber cap. injectionpumps.co.uk says it's an advance solenoid. Does it act as a stop solenoid, too?







I don't know what to call the other part in the last photo, but the o-ring under it was hardened. The other o-ring was in better condition, but they both seemed quite thin to me. Anyway, I picked two similar from a local parts store. They said, they're not really meant to be in touch with diesel, so I'll have to replace those with something decent.

Made a really quick test run and at least it's not any worse. We'll see.

Solenoid has some weird marks on it, as seen in the second photo above the o-ring. What could that be? Corrosion?

Oh, and I somehow forgot to mention, that there's been occasionally a significant amount of white/blue smoke from the exhaust. It's not burning too much oil. I guess air in the fuel system and/or something electrical could cause that?

[Baffler]

Pumping the primer resulted in no noticeable effect.

So no air getting into the system. That's good.

Jacked the car up to take a look at the loom. It's in hard(ish) corrugated tube and looks just fine. Any closer inspection is definetely not a job to do outside, swimming backstroke under the car, in these temperatures. It's been awfully warm lately and only about -9 C today, though.

That's the problem with the loom, it looks fine on first inspection, but inside that conduit the loom is wrapped in insulating tape which traps moisture close to the wiring so try to imagine what effect years of heating/cooling/freezing/heating has on it. Just be mindful of this if you start to see some strange electrical issues.

Found this under the rubber cap. injectionpumps.co.uk says it's an advance solenoid. Does it act as a stop solenoid, too?

My mistake, I'm not a trained diesel expert, I thought that was the stop solenoid. The only other electrical connection I can think of is the Throttle Position Sensor on top of the pump so if you follow the harness it should take you to the stop solenoid.

You may have stumbled onto something...have you tried to actuate that advance solenoid when you had it out on the bench?

I don't know what to call the other part in the last photo, but the o-ring under it was hardened. The other o-ring was in better condition, but they both seemed quite thin to me. Anyway, I picked two similar from a local parts store. They said, they're not really meant to be in touch with diesel, so I'll have to replace those with something decent.

Made a really quick test run and at least it's not any worse. We'll see.

Solenoid has some weird marks on it, as seen in the second photo above the o-ring. What could that be? Corrosion?

That will be a return banjo pipe. The marks are probably just tar deposits left behind from the returning fuel.

Oh, and I somehow forgot to mention, that there's been occasionally a significant amount of white/blue smoke from the exhaust. It's not burning too much oil. I guess air in the fuel system and/or something electrical could cause that?

When you say occasionally...on starting from cold or when up to normal operating temp? If from a cold start it would point to bad glow plugs and if from warm engine it might be slightly advanced/over fuelling.

These don't typically burn oil but being a Renault unit they do tend to push out oil everywhere else